Resolution 069-2021 1
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9 MONROE COUNTY,FLORIDA
10 MONROE COUNTY BOARD OF COUNTY COMMISSIONERS
11 RESOLUTION NO. 069 -2021
12
13 A RESOLUTION OF THE MONROE COUNTY BOARD OF
14 COUNTY COMMISSIONERS ADOPTING FEMA TECHNICAL
15 BULLETIN 3 "REQUIREMENTS FOR THE DESIGN AND
16 CERTIFICATION OF DRY FLOODPROOFED NON-
17 RESIDENTIAL AND MIXED-USE BUILDINGS" DATED
18 JANUARY 2021 AS REQUIRED PURSUANT TO MONROE
19 COUNTY CODE SECTION 122-2(C)
20
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22 WHEREAS, Monroe County is currently a participating community in the National
23 Flood Insurance Program (NFIP) and is working on internal County policies to improve upon its
24 interpretation of NFIP regulations;and
25
26 WHEREAS, Monroe County desires to maintain eligibility and improve its standing in
27 FEMA's Community Rating System(CRS);and
28
29 WHEREAS, Monroe County Code Section 122-2(c), in part, requires that in interpreting
30 other provisions of this chapter, the Building Official shall be guided by the current edition of
31 FEMA's 44 CFR, and FEMA's interpretive letters, policy statements and technical bulletins as
32 adopted by resolution from time to time by the Board of County Commissioners;
33
34 NOW, THEREFORE, BE IT RESOLVED BY THE BOARD OF COUNTY
35 COMMISSIONERS OF MONROE COUNTY, FLORIDA:
36
37 Section I. Pursuant to Monroe County Code Section 122-2(c), the Board hereby adopts
38 _ FEMA Technical Bulletin 3 `Requirements For the Design and Certification of Dry
39 Floodproofed Non-Residential and Mixed-Use Buildings" dated January 2021, a copy of which
40 is attached hereto.
41
42 Section 2. The Clerk of the Board is hereby directed to forward one (1) certified copy of
43 this Resolution to the Building Department.
44
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1
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3 PASSED AND ADOPTED by the Board of County Commissioners of Monroe County,
4 Florida, at a regular meeting held on the I Ph of March,2021.
5
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8 Mayor Michelle Coldiron Yes
9 Mayor pro tem David Rice Yes _.,
I0 Commissioner Craig Cates Yes
II Commissioner Eddie Martinez Yes
12 Commissioner Mike Forster Yes
13
14
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16 a BOARD OF COUNTY I to a ISSIONERS
17 * � :- OF MOIyR, yt•��OS FLar
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Mayor Michelle Coldiron
23 . VIN MADOK, CLERK
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26 As Deputy Jerk - _-- - - -- ---
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Requirements for the Design
and Certification of Dry
FloodproofedN n-R id nil
o es e t a
and Mixed-Use Buildings
Located in Special Flood Hazard Areas
in Accordance with the National Flood Insurance Program
NFIP Technical Bulletin 3 / January 2021
�ynxrM
�� FEMA
LAND SECJ,
Comments on the Technical Bulletins should be directed to:
Department of Homeland Security/Federal Emergency Management Agency
Federal Insurance and Mitigation Administration (FIMA) Risk Management Directorate
Building Science Branch
400 C Street, S.W., Sixth Floor
Washington, DC 20472-3020
All images in this report were taken or created by FEMA.
NFIP Technical Bulletin 3 (2021) replaces NFIP Technical Bulletin 3 (1993), Non-Residential Floodproofing
—Requirements and Certification for Buildings Located in Special Flood Hazard Areas in Accordance with
the National Flood Insurance Program.
NFIP Technical Bulletin 3 contains information that is proprietary to and copyrighted by the American
Society of Civil Engineers and information that is proprietary to and copyrighted by the International Code
Council, Inc. All information is used with permission.
For more information, see the FEMA Building Science
Frequently Asked Questions website at https://www.fema.gov/ To order publications, contact the FEMA
emergency-managers/risk-management/building-science/fag. Distribution Center:
If you have any additional questions on FEMA Building Call: 1-800-480-2520
Science Publications, contact the helpline at FEMA- (Monday—Friday, 8 a.m.-5 p.m., EST)
Buildingsciencehelp@fema.dhs.gov or 866-927-2104. Fax: 719-948-9724
Email: FEMApubs@gpo.gov
You may also sign up for the FEMA Building Science email
subscription, which is updated with publication releases Additional FEMA documents can be
and FEMA Building Science activities. Subscribe at.https:// found in the FEMA Media Library at
service.govdelivery.com/accounts/USDHSFEMA/subscriber/ https://www.fema.gov/media-librar
new?topic id=USDHSFEMA 193 resources.
Visit the Building Science Branch of the Risk Please scan this QR code '❑ '❑'
Management Directorate at FEMA's Federal Insurance to visit the FEMA Building
and Mitigation Administration at https://www.fema.gov/ Science web page. �.
emergency-managers/risk-management/building-science.
Table of Contents
Acronyms..............................................................................................................................................................ii
1 Introduction......................................................................................................................................................I
1.1 Definition of Floodproofing..................................................................................................................1
1.2 Floodproofing Certification..................................................................................................................3
1.3 Limitations on the Use of Dry Floodproofing.....................................................................................4
1.4 Dry Floodproofing Measures.................................................................................................................5
2 National Flood Insurance Program Regulations...............................................................................................6
3 Building Codes and Standards.........................................................................................................................7
3.1 International Residential Code.............................................................................................................8
3.2 International Building Code and ASCE 24..........................................................................................8
3.3 ANSI/FM 2510, American National Standard for Flood Mitigation Equipment.......................................11
4 NFIP Flood Insurance Implications.................................................................................................................II
5 Planning Considerations.................................................................................................................................12
5.1 Flood Hazards and Site Conditions....................................................................................................13
5.2 Flood Warning Time............................................................................................................................14
5.3 Functional Use Requirements.............................................................................................................15
5.4 Safety and Access..................................................................................................................................15
5.5 Required Plans.....................................................................................................................................16
6 Dry Floodproofing Design Process.................................................................................................................19
6.1 Step 1: Determine Flood Design Class ...............................................................................................21
6.2 Step 2: Determine the Flood Protection Level ..................................................................................21
6.3 Step 3: Determine Flood Loads..........................................................................................................22
6.4 Step 4: Perform a Condition Assessment (Existing Structures) .......................................................26
6.5 Step 5: Design or Check Structural Components for Resistance to Flood Loads...........................27
6.6 Step 6: Evaluate Building Utility Systems and Equipment ...............................................................27
6.7 Step 7: Design and Specify Flood Shields...........................................................................................28
6.8 Step 8: Design Waterproofing System.................................................................................................30
6.9 Step 9: Design Interior Drainage........................................................................................................32
6.10 Step 10: Certify the Design and Satisfy Requirements for Plans......................................................33
7 References.....................................................................................................................................................34
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 i
Appendix A: FEMA Form 086-0-34, National Flood Insurance Program Floodproofing Certificate
for Non-Residential Structures ................................................................................................36
Appendix B: Example Calculation for EstimatingTotal Seepage................................................................42
List of Figures
Figure 1: Steps in designing a dry floodproofing system..........................................................................20
Figure 2: Example FIRM showing building location and BFE.................................................................22
Figure3: Hydrostatic loads.........................................................................................................................23
Figure 4: Hydrodynamic forces on a building...........................................................................................25
Figure 5: Mixed-use building with non-residential building utility systems and equipment in a
dry floodproofed below-grade equipment room and elevated systems that serve the
residentialuses.............................................................................................................................28
Figure 6: Common types of flood shields..................................................................................................29
Figure 7: Typical seepage paths for water entering through joints between wall,footer, and slab.......31
Figure8: Typical sump pump detail ..........................................................................................................33
Figure A-1: Typical FIRM title block..............................................................................................................37
Figure A-2: Typical FIRM map index.............................................................................................................37
Figure B-1: Example building plan view.......................................................................................................43
List of Tables
Table 1: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements....8
Table B-1: Example Building Information .................................................................................................43
Acronyms
ACI American Concrete Institute ICC® International Code Council®
ANSI American National Standards Institute I-Codes® International Codes®
ASCE American Society of Civil Engineers IRC® International Residential Code®
BFE base flood elevation LiMWA Limit of Moderate Wave Action
CFR Code of Federal Regulations NFIP National Flood Insurance Program
CMU concrete masonry unit ORNL Oak Ridge National Laboratory
DFE design flood elevation SEI Structural Engineers Institute
FEMA Federal Emergency Management Agency SERRI Southeast Region Research Initiative
FIRM Flood Insurance Rate Map SFHA Special Flood Hazard Area
FIS Flood Insurance Study USACE U.S.Army Corps of Engineers
IBC® International Building Code®
ii NFIP TECHNICAL BULLETIN 3 JANUARY 2021
1 Introduction
This Technical Bulletin explains and provides guidance NFIP TECHNICAL BULLETIN 0
on the National Flood Insurance Program (NFIP)
floodplain management requirements for the design and NFIP Technical Bulletin 0, User's Guide
certification of dry floodproofing. This guidance applies to to Technical Bulletins, should be used as
new and substantially improved non-residential buildings a reference with this Technical Bulletin.
and mixed-use buildings in Special Flood Hazard Areas Technical Bulletin 0 describes the purpose
(SFHAs) identified as Zone A(A,AE,Al-30,AH, and AO) and use of the Technical Bulletins. It includes
on Flood Insurance Rate Maps (FIRMS). This Technical common concepts and terms, lists useful
Bulletin includes guidance for certification of dry resources, and includes a crosswalk of the
floodproofed buildings for the purpose of obtaining NFIP sections of the NFIP regulations identifying
the Technical Bulletin that addresses each
flood insurance coverage with floodproofing credit. section of the regulations and a subject index.
The NFIP regulations do not permit the use of dry Readers are cautioned that the definitions
floodproofing for residential buildings in Zone A, and dry of some of the terms that are used in the
floodproofing is not permitted for any buildings in SFHAs Technical Bulletins are not the same when
that are subject to high velocity wave action, called coastal used by the NFIP for the purpose of rating
high hazard areas and identified on FIRMs as Zone V(V, flood insurance policies.
VE,V1-30, and VO).
The design and certification of dry floodproofing measures
involve engineering evaluations and calculations. FEMA FEMA P-936, FLOODPROOFING
P-936, Floodproofing Non-Residential Buildings (2013), NON-RESIDENTIAL BUILDINGS
contains detailed guidance that supplements this Technical FEMA P-936 provides guidance on
Bulletin.ASCE 24, Flood Resistant Design and Construction, regulatory requirements, design
is referenced throughout this Technical Bulletin because considerations, design loads, site
it is the standard of practice for the design of dry characteristics, and descriptions of dry
floodproofed buildings. ASCE 24 is a referenced standard floodproofing methods and equipment. Key
in the International Codes° (I-Codes°). information includes:
• Functional, operational, and economic
1.1 Definition of Floodproofing factors to consider
The NFIP regulations define floodproofing as "any • Tools such as a vulnerability checklist
combination of structural and non-structural additions, to help the designer or building owner
changes, or adjustments to structures which reduce or determine the best dry floodproofing
eliminate flood damage to real estate or improved real option for a particular building
property, water and sanitary facilities, structures and • Case studies of applied dry floodproofing
their contents" (Title 44 Code of Federal Regulations techniques
[CFR] § 59.1). In the NFIP regulations "floodproofing"
is understood to refer to dry floodproofing. For the Equations for determining flood forces
purposes of this Technical Bulletin, "dry floodproofing" and loads
means a combination of measures that make a building • Summary of results from dry
and attendant utilities and equipment watertight and floodproofing research and testing for
substantially impermeable to floodwater, with structural new construction
components having the capacity to resist flood loads.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 1
"Wet floodproofing"is not defined in the NFIP regulations.The term is used in FEMA guidance publications and
by floodplain management professionals to mean the use of flood damage-resistant materials and construction
techniques that intentionally allow floodwater to enter and flow through a structure without causing damage
that requires more than cosmetic repairs. "Wet floodproofing" is sometimes used to refer to the requirements for
enclosures below elevated building in Zone A when the enclosures are used only for parking of vehicles, storage,
and building access.
Wet floodproofing measures are not covered in this Technical Bulletin.For more information on wet floodproofing,
see FEMA P-936; NFIP Technical Bulletin 1, Requirements for Flood Openings in Foundation Walls and Walls of
Enclosures; NFIP Technical Bulletin 2, Flood Damage-Resistant Materials Requirements; NFIP Technical Bulletin 7,
Wet Floodproofing Requirements; and FEMA P-2140, Floodplain Management Requirements for Agricultural Structures
and Accessory Structures (2020a). FEMA P-2140 describes wet floodproofing measures as they apply to specifically
defined agricultural structures and small accessory structures.
TERMS USED IN THIS TECHNICAL BULLETIN
• Active: Dry floodproofing measures or system components that require human intervention or action
before the onset of flooding to be effective(e.g., flood shields that must be installed, valves that must
be closed).
• Ancillary area: Common area such as a lobby, foyer, office used by building management, exercise
space, meeting room, and mail room (FEMA P-2037, Flood Mitigation Measures for Multi-Family
Buildings [2019a]).
• Basement: "Any area of the building having its floor subgrade(below ground level)on all sides"
(44 CFR§59.1). The NFIP regulations do not allow basements to extend below the base flood elevation
(BFE) except in dry floodproofed non-residential buildings.
• Flood protection level: Elevation to which flood protection measures are designed. The flood
protection level is the most restrictive of(1)the BFE plus the prescribed amount of freeboard specified
in ASCE 24, (2)the design flood elevation (DFE) if a different flood is used for regulatory purposes, and
(3)the elevation relative to the BFE specified in local floodplain management regulations.
• Flood shield: Removable or permanent, substantially impermeable protective cover or panel for
openings in the portions of a dry floodproofed building that are below the flood protection level
(e.g., door, window, louver).
• Floodproofing: "Any combination of structural and non-structural additions, changes, or adjustments
to structures which reduce or eliminate flood damage to real estate or improved real property, water
and sanitary facilities, structures and their contents" (44 CFR § 59.1).
• Mixed-use building: Building that has both residential and commercial or other non-residential
uses. The term does not include multi family residential buildings that have ancillary areas but no
non-residential uses.
• Non-residential building: Building that has a commercial or other non-residential use.
• Passive: Dry floodproofing measures or system components that do not require human intervention
or action before the onset of flooding to be effective(e.g., specially designed doors that are sealed
when closed, designed window systems, flood shields that are designed to close automatically when
triggered by rising floodwater).
(continued on page 3)
2 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
TERMS USED IN THIS TECHNICAL BULLETIN (continued)
• Residential building: Building designated for habitation. Ancillary areas of residential buildings that
serve only residents are residential ancillary areas and include laundry facilities, storage rooms, mail
rooms, recreational rooms, parking garages, and exercise facilities.
• Substantially impermeable: The use of materials and techniques that restrict the passage of water
and seepage through pathways(joints, cracks, openings, channels) and points of entry and that limit
the accumulation of water during flooding. According to ASCE 24 and the U.S. Army Corps of Engineers
(USACE), a structure is considered substantially impermeable if the maximum accumulation of water
is not more than 4 inches in a 24-hour period without relying on devices for the removal of the water
(USACE, 1995).
• Zone A: Flood zones shown on FIRMs as Zone A, AE, Al-30, AH, AO, A99, and AR.
• Zone V: Flood zones shown on FIRMs as Zone V, VE, V1-30, and VO.
Other terms used in this Technical Bulletin are defined in the glossary in Technical Bulletin 0.
1.2 Floodproofing Certification
When a building owner proposes dry floodproofing measures for a non-residential building that is in an NFIP-
participating community,the owner must provide certification that the structural designs,specifications, and plans
for the construction of the dry floodproofing measures were developed and/or reviewed by registered professional
engineers or architects (design professionals). The certification must state that the proposed dry floodproofing
design and proposed methods of construction are in accordance with accepted standards of practice for achieving
the required performance. Design professionals who sign and seal certifications must be licensed to practice in the
state where projects are located.
FEMA Form 086-0-34, NFIP Floodproofing Certificate for Non-Residential Structures (FEMA, 2019b),provides
information necessary for insurance underwriters to rate dry floodproofed buildings. The same form should be
used to satisfy the requirement for design professionals to certify designs and as-built drawings and inspection.
The certificate identifies ASCE 24-14 and ASCE 24-05
(or equivalent) as the accepted standard of practice.
The certificate requires the building owner's name ASCE 24 IS THE STANDARD OF PRACTICE
and the address or other description of the building FOR DRY FLOODPROOFING DESIGN
location. It has three sections: ASCE 24, Flood Resistant Design and
• Section I: Site information from the FIRM. Construction, is a consensus standard that
was developed and is maintained by the
• Section IL• Certification of the elevation to which American Society of Civil Engineers (ASCE).
the building is floodproofed. The elevation (where ASCE 24 is a referenced standard in the
BFEs are provided on FIRMs) or the height above I-Codes, which means it is considered part of
the lowest adjacent grade (where BFEs are not the requirements in these codes.
provided) to which the building is floodproofed. ASCE 24 represents the standard of practice
Section II must be signed and sealed by a land for the design of buildings and structures in
surveyor, engineer, or architect authorized by law to flood hazard areas, including the design of dry
certify elevation information. floodproofed buildings.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 3
• Section III: Certification by a registered professional engineer or architect that"the structure,based upon
development and/or review of the design, specifications, as-built drawings for construction and physical
inspection"has been designed and constructed in accordance with "the accepted standards of practice
(ASCE 24-05,ASCE 24-14, or their equivalent) and any alterations [of the structure]" meet these standards
and specific listed provisions (i.e., are watertight and substantially impermeable and have structural
components that are capable of resisting flood forces).
See Appendix A for further instructions on completing the certificate.
1.3 Limitations on the Use of Dry Floodproofing
Dry floodproofing is permitted for new and substantially improved non-residential and non-residential portions
of mixed-use buildings in Zone A, but not for residential buildings in Zone A or any building in Zone V. The
NFIP regulations and published FEMA guidance use "residential" and "non-residential" but do not define these
terms. However, "residential" in general refers to dwelling units and the building systems and ancillary areas
that support the units. Building systems include electrical, heating, ventilation, plumbing, and air conditioning
equipment and other service equipment.Ancillary areas include areas that are designated or used by on premises
guests. "Non-residential" refers to buildings with commercial or other non-residential uses. ASCE 24 has a more
extensive definition of"residential" and defines "non-residential" as buildings that are not classified as residential.
ASCE 24 commentary defines "mixed-use" and "residential portions of mixed-use buildings."
FEMA considers buildings with both non-residential
and residential uses to be mixed-use buildings. The non- HOTELS AND MOTELS
residential portions of mixed-use buildings are allowed Hotels and motels are commercial buildings.
to be dry floodproofed provided that all residential For floodplain management purposes, guest
units, building systems and service equipment that rooms and the building systems and service
serve residential units, and ancillary areas used by equipment that serve guest rooms are
residents are elevated above the required elevation. See considered residential and are not permitted
FEMA P-2037,Flood Mitigation Measures forMulti-Family to be located in areas of the building that
Buildings, for more information. are dry floodproofed. The requirements for
In keeping with the requirements for enclosures below building systems and service equipment that
serve guest rooms and access to guest rooms
elevated residential buildings, lobbies that provide are the same as the requirements for the
access to both residential and non-residential portions of residential portions of mixed-use buildings.
mixed-use buildings are allowed to be dry floodproofed
provided there are separate accesses to the residential ----
portions. When an access to the residential portion of
a mixed-use building is below the flood protection elevation and the access is enclosed by walls, the walls must
comply with the requirements for enclosures below elevated buildings (sometimes called wet floodproofing).
The NFIP regulations for dry floodproofing apply only in SFHAs identified on FIRMS as Zone A(A,AE,Al-30,
AH, and AO). Dry floodproofing is not permitted in SFHAs identified as Zone V (V, VE, V1-30, and VO). For
Zone A, the regulations do not specify limits on the use of dry floodproofing based on flood depth,flood velocity,
or the presence of waves. However, FEMA does not recommend use of dry floodproofing systems in areas where:
• The depth of water under base flood conditions is greater than 3 feet.
• Base flood velocities exceed 5 feet per second.
• Moderate wave heights (1.5 to 3 feet) are present during base flood conditions.
4 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
1.4 Dry Floodproofing Measures
Dry floodproofing measures include but are not limited to the following:
• Portions of a building,including walls and slabs, reinforced to resist water pressure and floating debris impacts
• Doors and windows that are specially designed to be watertight when closed without flood shields
• Removable or permanently installed, substantially impermeable panels to cover doors,windows, and other
openings
• Paints, membranes, gaskets, and other sealants that reduce water seepage
• Sump pumps or self-priming pumps that control the level of seepage water
• Backflow(non-return)valves or shutoffvalves that prevent floodwater from entering through sewer and
drainage pipes and/or sewage ejectors that pump sewage to above the flood protection level before the pipes
connect to a vertical sewer line
• Seals that prevent the entrance of floodwater through joints and utility penetrations
• Electrical equipment and circuits that are protected to the flood protection level
• Backup or emergency power for sump pumps and other seepage control measures that is protected to the flood
protection level
The planning considerations in Section 5 should be
reviewed before determining which dry floodproofing LEVEES AND FLOODWALLS
measures or combination of measures are feasible for Levees and floodwalls are not considered
specific locations and before undertaking structural designs dry floodproofing measures for buildings
to ensure that the measures will provide the appropriate because they are separate structures
level of flood protection. Planning considerations include and not part of the buildings. Levees
building location, flood characteristics (flood velocities, and floodwalls that are designed and
depths, duration of flooding, how quickly floodwater constructed to provide flood protection to
rises, and debris impacts), level of protection required, a single building or a group of buildings
flood warning time, safety and access, flood emergency are not addressed in this Technical
operations plan, and inspection and maintenance plans. Bulletin. Although levees and floodwalls
Questions about dry floodproofing requirements should be can be used to mitigate flood damage,
they may not be used to bring a building
directed to the appropriate local official, National Flood into compliance with NFIP requirements.
Insurance Program State Coordinating Office, or FEMA
Regional Office.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 5
2 National Flood Insurance
Program Regulations
An important NFIP objective is protecting buildings constructed in SFHAs from damage caused by flooding.The
SFHA is the land area subject to flooding by the base flood. SFHAs are shown on FIRMS prepared by FEMA as
Zones A and V. The base flood is the flood that has a 1 percent chance of being equaled or exceeded in any given
year (commonly called the "100-year" flood). The NFIP floodplain management regulations include minimum
building design criteria that apply to:
• New construction
• Work determined to be Substantial Improvements, including improvements, alterations, and additions
• Repair of buildings determined to have incurred Substantial Damage
A defining characteristic of the NFIP regulations applicable in any Zone A is the requirement for the lowest floor
(including basement) of residential buildings to be elevated to or above the BFE. Non-residential buildings in
Zone A must be elevated or dry floodproofed to or above the BFE. Dry floodproofing is not permitted in Zone V.
The NFIP regulations for dry floodproofing of non-residential buildings are codified in 44 CFR Part 60, Criteria
for Land Management and Use. Specific to this Technical Bulletin, 44 CFR§ 60.3(c)(3) states that a community
shall:
Require that all new construction and substantial improvements of non-residential structures within
Zones Al 30, AE and AH zones on the community's firm [sic] (1) have the lowest floor (including
basement) elevated to or above the base flood level, or (ii) together with attendant utility and
sanitary facilities, be designed so that below the base flood level the structure is watertight with
walls substantially impermeable to the passage of water and with structural components having the
capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
Section 60.3(c)(8) states that in Zone AO (areas of sheet flow with depths of 1 to 3 feet), a community shall:
Require within any AO zone on the community's FIRM that all new construction and substantial
improvements of nonresidential structures(i)have the lowest floor(including basement)elevated above
the highest adjacent grade at least as high as the depth number specified in feet on the community's
FIRM (at least two feet if no depth number is specified), or (ii) together with attendant utility and
sanitary facilities be completely floodproofed to that [base flood] level to meet the floodproofing
standard specified in [44 CFR}§ 60.3(c)(3)(ii).
Section 60.3(c)(4) requires that floodproofing designs be certified in the following manner:
Provide that where a non-residential structure is intended to be made watertight below the base
flood level, (1) a registered professional engineer or architect shall develop and/or review structural
design, specifications, and plans for the construction, and shall certify that the design and methods
of construction are in accordance with the accepted standards of practice for meeting the applicable
provisions of paragraphs (c)(3)(11) or (c)(8)(11) of this section, and (ii) a record of such certificates which
includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed
shall be maintained with the official designated by the community under [44 CFR] § 59.22(a)(9)(iii).
6 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
NFIP REQUIREMENTS AND HIGHER REGULATORY STANDARDS
State or Local Requirements. State or local floodplain management requirements that are more
restrictive or stringent than the minimum requirements of the NFIP take precedence. The Technical
Bulletins and other FEMA publications provide guidance on the minimum requirements of the NFIP
and describe best practices. Design professionals, builders, and property owners should contact local
officials to determine whether more restrictive provisions apply to buildings or sites in question. All other
applicable requirements of the state or local building codes must also be met.
Substantial Improvement and Substantial Damage.As part of issuing permits, local officials must
review not only proposals for new construction but also for work on existing buildings to determine
whether the work constitutes Substantial Improvement or repair of Substantial Damage. If the work is
determined to constitute Substantial Improvement or repair of Substantial Damage, the buildings must
be brought into compliance with the NFIP requirements for new construction. Some communities modify
the definitions of Substantial Improvement and/or Substantial Damage to be more restrictive than the
NFIP minimum requirements. For more information on Substantial Improvement and Substantial Damage,
see FEMA P-758, Substantial Improvement/Substantial Damage Desk Reference (2010a), and FEMA 213,
Answers to Questions About Substantially Improved/Substantially Damaged Buildings (2018a).
Higher Building Elevation Requirements. Some states and communities require that non-residential
buildings be elevated or dry floodproofed (allowed only in Zone A) above the NFIP minimum requirement.
The additional elevation is called freeboard. Design professionals, builders, and property owners should
check with local officials to determine whether a state or community has freeboard requirements.
References to building elevations in the Technical Bulletin, including the required flood protection level,
should be construed as references to the community's elevation requirement where freeboard is required.
3 Building Codes and Standards
In addition to complying with NFIP requirements, all new construction, Substantial Improvements, and repair
of Substantial Damage must comply with the applicable building codes and standards adopted by states and
communities.
The I-Codes, published by the International Code Council®
(ICC®), are a family of codes that includes the International INTERNATIONAL BUILDING CODE
Residential Code® (IRC®), International Building Code® AND ASCE 24 COMMENTARIES
(IBC®), International Existing Building Code® (IEBC®), and The ICC publishes companion
codes that govern the installation of mechanical, plumbing, fuel commentary for the IBC, and ASCE
gas service, and other aspects of building construction. FEMA publishes a companion commentary
has deemed that the latest published editions of the I-Codes for ASCE 24. Although not regulatory,
generally meet or exceed NFIP requirements for buildings the commentaries provide information
and structures in flood hazard areas. Excerpts of' the flood and guidance that is useful for
provisions of the I-Codes are available on FEMNs Building complying with, interpreting, and
Science Flood Publications webpage (https://www.fema.gov/ enforcing requirements.
emergency-managers/risk-management/building-science/flood).
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 7
3.1 International Residential Code
The International Residential Code (IRC) applies to one- and two-family dwellings and townhomes not more
than three stories above grade plane. The IRC does not allow dry floodproofing of buildings within its scope.
3.2 International Building Code and ASCE 24
The International Building Code (IBC) applies to
all applicable buildings and structures. While used ASCE 24 AND NFIP DRY
primarily for buildings and structures other than FLOODPROOFING REQUIREMENTS
dwellings within the scope of the IRC, the IBC may also FEMA interprets the NFIP regulations to
be used to design dwellings. be more restrictive than ASCE 24 in two
respects:
The flood provisions of the latest published editions of Temporary flood protection systems that
the IBC generally meet or exceed NFIP requirements for cover exterior walls cannot be used in lieu
buildings through reference to the standard ASCE 24, of a substantially impermeable wall (see
Flood Resistant Design and Construction. "ASCE Interpretation of ASCE 24-14 Flood
ASCE 24 applies to structures that are subject to Shield Requirements and FEMA Position
on Whether a Flood Shield Configuration
building code requirements. ASCE 24 requirements for Meets NFIP Dry Floodproofing
dry floodproofing, summarized in Table 1, are similar Requirements" at the end of Section 3.2 of
to the NFIP requirements. Table 1 refers to selected dry this Technical Bulletin).
floodproofing requirements of the 2018 IBC and ASCE
• Flood damage-resistant materials are
24-14 and notes changes from 2015 and 2012 IBC and required where seepage would collect
ASCE 24-05 along with a comparison to the NFIP inside dry floodproofed areas up to at least
requirements. Subsequent editions of the IBC and ASCE 4 inches above the floor.
24 should include comparable requirements. _
Table 1: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements
Summary of Selected 2018 IBC/ASCE 24-14 Requirements 4W W=
r J1 and Changes from 2015i12 IBC/ASCE 24-05 Comparison
Definition 2018 IBC Section 202 Definitions. The definition of"dry
of dry Defines dry floodproofing as a combination of design floodproofing" (IBC and
floodproofing modifications resulting in a building, including the attendant ASCE 24) is equivalent to the
utilities and equipment and sanitary facilities, being watertight NFIP definition of"floodproofing"
with walls that are substantially impermeable and able to resist in NFIP 44 CFR§59.1.
the loads required by ASCE 7,Minimum Design Loads and
Associated Criteria for Buildings and Other Structures.
Change from 2015 to 2018 IBC: No change.
Change from 2012 to 2015 IBC:Added "and equipment."
ASCE 24-14 Section 1.2 Definitions.
Defines dry floodproofing as a combination of measures that
results in making a structure and its utilities and equipment
watertight with all elements substantially impermeable and with
structural components having the capacity to resist flood loads.
Change from ASCE 24-05: Expands the definition to require
building and utilities and equipment serving the building to
be watertight with walls substantially impermeable and able
to resist flood loads rather than only requiring the building
envelope to be substantially impermeable.
8 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Table 1: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements(cont.)
Summary of Selected 2018 IBC/ASCE 24-14 Requirements
and Changes from 2015112 IBC/ASCE 24-05 Comparison
General flood 2018 IBC Section 1612.2 Design and construction. Exceeds NFIP 44 CFR
hazard area Requires buildings and structures located in flood hazard areas § 60.3(a)(3)with more specificity.
requirements to be designed and constructed in accordance with Chapter 5
of ASCE 7 and ASCE 24.
Change from 2015 to 2018 IBC: Section renumbered from
1612.4 to 1612.2.
Change from 2012 to 2015 IBC: Applies coastal high hazard
area requirements in Coastal A Zones, if delineated.
Flood hazard 2018 IBC Section 1612.4(1.3) Flood hazard documentation. Equivalent to NFIP 44 CFR
documentation Requires submission of a certification statement prepared §60.3(c)(4).
and sealed by a registered design professional that dry
floodproofing is designed in accordance with ASCE 24.
Change from 2015 to 2018 IBC: Section renumbered from
1612.5 to 1612.4.
Change from 2012 to 2015 IBC: Applies coastal high hazard
area requirements in Coastal A Zones, if delineated.
Elevation ASCE 24-14 Section 1.5.2 Elevation Requirements. Exceeds NFIP 44 CFR
Allows for dry floodproofing of non-residential and the non- §60.3(c)(3)and (8) by requiring
residential portions of mixed-use buildings below the BFE plus freeboard
specified freeboard or the DFE, whichever is higher, provided
the dry floodproofing measures meet the requirements in
Chapter 6.
ASCE 24-14,Section 2.3, Elevation Requirements.
Allows for dry floodproofing of non-residential and the non-
residential portions of mixed-use buildings below the BFE plus
specified freeboard or DFE, whichever is higher, provided the
dry floodproofing measures meet the requirements in Chapter 6.
Change from ASCE 24-05: Requires Flood Design Class 4
buildings to be elevated or to be protected to BFE plus 2 feet, or
DFE, or 500-year flood elevation, whichever is highest.
Dry ASCE 24-14 Section 6.2 Dry Floodproofing. Exceeds NFIP 44 CFR
floodproofing . Permits dry floodproofing of non-residential buildings and §60.3(c)(3)with more specificity,
non-residential portions of mixed-use buildings when the except(1)the NFIP requires the
buildings are located outside High Risk Flood Hazard Areas, use of flood damage-resistant
Coastal High Hazard Areas, and Coastal A Zones materials in areas where seepage
• Requires techniques that make structures substantially can accumulate and (2) FEMA
impermeable and requires the use of flood damage-resistant deems that temporarily installed
materials, except on the interior of structures means of flood protection that
cover walls are inconsistent with
• Requires sump pumps to remove water that accumulates from the requirement that walls be
the passage of vapor and seepage during flooding substantially impermeable(see
• Limits dry floodproofing to flood hazard areas with flood text box"ASCE Interpretation
velocities that are less than or equal to 5 feet per second of ASCE 24-14 Flood Shield
during the design flood Requirements and FEMA Position
• Requires walls below the minimum elevations of dry on Whether a Flood Shield
floodproofing specified in Table 6-1 to be substantially Configuration Meets NFIP Dry
impermeable to passage of water Floodproofing Requirements" on
page 10).
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 9
Table 1: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements(cont.)
Summary of Selected 1
and Changes from 2015112 IBC/ASCE 24-05 Comparison
Dry • Requires walls, floors, and flood shields to resist hydrostatic,
floodproofing hydrodynamic, and other flood loads, including the effects of
(cont.) buoyancy
• Specifies that soil or fill adjacent to a structure must be
compacted and protected from erosion and scour
• Requires that at least one door, window, or other opening
for emergency escape and rescue be above the elevation
specified in Table 6-1
• Specifies several limitations when human intervention
is necessary to activate or implement dry floodproofing
measures
Change from ASCE 24-05: Does not require flood damage-
resistant materials on the interior of dry floodproofed portions of
buildings.
ASCE INTERPRETATION OF ASCE 24-14 FLOOD SHIELD REQUIREMENTS
AND FEMA POSITION ON WHETHER A FLOOD SHIELD CONFIGURATION
MEETS NFIP DRY FLOODPROOFING REQUIREMENTS
In November 2016, ASCE issued a formal interpretation of whether a specific configuration of flood
shields meets the dry floodproofing requirements of ASCE 24-14.1 The configuration is described as a
building that is supported by an impermeable reinforced concrete stem wall (foundation) with permeable
exterior walls such as glass curtain walls. The question was whether the use of removable flood shields as
a component of the exterior building facade would render the exterior walls impermeable along the entire
length of the facade. Diagrams included in the request for the interpretation show flood shields attached
at the base to the impermeable foundation stem wall and attached to vertical, structural columns between
spans of the glass curtain wall system.
The ASCE interpretation determined that the flood shield configuration described and shown in the
request meets the dry floodproofing requirements of ASCE 24-14 provided the building and shields
meet all other dry floodproofing requirements, provided the flood shields are "close to and attached to
the building facade," and provided the shield attachment is "via guides, fasteners or supports that are
permanent parts of the building facade."2
The FEMA position is that the ASCE interpretation is contrary to the NFIP requirements because exterior
wall sections that are neither substantially impermeable nor able to resist flood loads will not meet the
intent of 44 CFR § 60.3(c)(3)that walls must be"substantially impermeable to the passage of water and
with structural components having the capability of resisting hydrostatic and hydrodynamic loads and
effects of buoyancy." Therefore, any temporarily installed means of flood protection that cover such walls
would not be considered compliant.
1 Jonathan C.Esslinger,Director,Technical Advancement and Codes&Standards,ASCE,written communication,November 29,2016.
2 Ibid,Page 5.
10 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
3.3 ANSI/FM 2510, American National Standard
for Flood Mitigation Equipment
ANSI/FM 2510,American National Standard for Flood Mitigation
Equipment (ANSI/FM, 2020), describes performance and ANSI/FM 2510, AMERICAN NATIONAL
testing requirements that must be met for flood mitigation STANDARD AND APPROVED
equipment and products, as defined in the standard, to be EQUIPMENT AND PRODUCTS
approved. Performance testing criteria are established for ANSI/FM 2510: www.fmapprovals.com
each type of equipment and products. The following types of FM Approved equipment and products:
equipment and products are addressed in the standard: https://nationalfloodbarrier.org
• Opening barriers (called flood shields in this Technical
Bulletin)
• Flood glazing(permanent,passive barrier of reinforced glass material that is set and sealed within a
structural frame)
• Flood mitigation valves (called backflow, non-return, or shutoffvalves in this Technical Bulletin)
• Flood mitigation pumps (sump pumps, self-priming pumps, and other types of pumps used for
seepage control)
• Penetration sealing devices
• Perimeter barriers (not applicable to this Technical Bulletin)
4 NFIP Flood Insurance Implications
Careful attention to compliance with the NFIP requirements,
local building codes and standards, and floodplain management NFIP FLOOD INSURANCE FOR
regulations is important during design,plan review,construction, DRY FLOODPROOFED BUILDINGS
and inspection. Compliance influences both vulnerability to While current owners and developers
flood damage and the cost of NFIP flood insurance. who are considering constructing
An insurance agent with NFIP experience should be consulted dry floodproofed non-residential
during the design phase of buildings with dry floodproofing to buildings may not intend to purchase
NFIP flood insurance coverage, the
estimate the cost of NFIP flood insurance. The consultation is cost of the coverage may be a factor
particularly important when considering whether to include for future owners.
dry floodproofing of non-residential portions of mixed-use
buildings or dry floodproofing of' below-grade parking areas
under non-residential and mixed-use buildings (see NFIP
Technical Bulletin 6, Requirements for Dry Floodproofed Below-Grade Parking Areas Under Non-Residential and
Mixed Use Buildings).
Designers should pay particular attention to the flood protection level (level to which buildings will be dry
floodproofed). The NFIP regulations applicable to non-residential structures in Zone A require the lowest floor
(including basement) to be elevated to or above the BFE or the structures may be dry floodproofed below the
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 11
BEE. However, the NEIP flood insurance rating procedures provide credit for dry floodproofing only if the dry
floodproofing measures are certified to be at least 1 foot above the BEE, even if that level of protection is not
required by local floodplain management regulations.The NEIP also requires applications for insurance coverage
for dry floodproofed buildings to include the NEIP Eloodproofing Certificate (see Section 1.2 and Appendix A of
this Technical Bulletin).
The methodology used by the NEIP to determine the NEIP flood insurance rate for dry floodproofed
non-residential buildings and non-residential portions of mixed-use buildings is based on the "non-subsidized"
rate with a credit (percentage discount) applied to that rate. The amount of credit is based on the information
about the dry floodproofing components that must be included with NEIP flood insurance applications. Building
owners and designers should consult with flood insurance providers before starting design work to understand
how design decisions can impact NEIP flood insurance premiums.
5 Planning Considerations
Many factors and planning considerations influence the decision-making process when determining the feasibility
of dry floodproofing options for specific buildings. Whether buildings are new construction designed to be dry
floodproofed or existing buildings being considered for retrofitting with dry floodproofing measures, the dry
floodproofing options that are examined and selected should:
• Comply with the applicable floodplain management and design requirements
• Reduce flood damage below the flood protection level
• Provide for the safety of personnel responsible for the deployment of components that require human
intervention
• Be feasible to implement, maintain, and operate
• Be usable following recommended cleaning after flood events
• Result in a level of residual risk that is acceptable to the owner
Design professionals should assess the site during the planning phase to determine site-specific flood hazards that
will influence the design of dry floodproofing measures, building vulnerability, and how well the building may
perform during flood events (see Section 5.1). The assessment should include a flood vulnerability assessment
to examine site conditions and, for existing buildings, the vulnerability of architectural and structural systems,
building envelope, and utility systems (mechanical,plumbing, gas, electrical).
Other important planning considerations include determining the available warning time prior to the onset
of flooding (see Section 5.2), functional use requirements (see Section 5.3), safety and access before and during
flooding (see Section 5.4), and early consideration of required plans (Section 5.5), including flood emergency
operations plans and maintenance and inspection plans.
The design professional should review the assessment findings with the building owner to determine whether dry
floodproofing is appropriate and whether the results indicate any constraints on the design. Determining the flood
warning time, described in Section 5.2 of this Technical Bulletin, is critical before deciding whether active dry
floodproofing measures are feasible or appropriate,or whether passive measures or elevation should be considered.
12 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Active dry floodproofing measures require human
intervention or action before the onset of flooding PLANNING, DESIGN,AND OPERATIONAL
and passive dry floodproofing measures do not CONSIDERATIONS
require human intervention. For guidance on conducting a flood vulnerability
Building owners should also consider residual risk assessment and designing dry floodproofing
as part of determining whether dry floodproofing measures to reduce flood damage and interruption
is an appropriate solution. Residual risk is the of building operations, see:
remaining exposure to loss after the designed • FEMA P-936, Appendix C, "Checklist for
floodproofing measures have been implemented. Vulnerability of Flood-Prone Sites and Buildings"
For example, losses could be higher than expected. . FEMA P-2022, Mitigation Assessment
Dry floodproofing systems are designed for a Team Report.Hurricane Harvey in Texas,
selected flood protection level, but during extreme Appendix C, "Dry Floodproofing: Planning and
events,floodwater may rise higher than the selected Design Considerations(Recovery Advisory 1)"
flood protection level and high water may affect (FEMA, 2018c)
some sites for longer than the anticipated periods
of inundation. In addition, dry floodproofing For guidance on how to effectively implement dry
floodproofing measures, see:
systems can fail. Common causes of failure are
unidentified points of entry for floodwater, poorly FEMA P-2023, Mitigation Assessment Team
maintained components of a system, components Report. Hurricane Irma in Florida, Appendix C,
with insufficient resistance to flood loads, and "Dry Floodproofing: Operational Considerations
failure to implement active measures that require (Recovery Advisory 1)" (FEMA, 2018b)
human intervention (especially for complex
systems).
Designers and owners should evaluate the residual risks associated with dry floodproofing measures, and owners
should consider the financial impacts if the dry floodproofing system fails. Added costs include down time, clean
up, and repairs. Some financial risk can be offset by purchasing flood insurance.
5.1 Flood Hazards and Site Conditions
Selecting eflective dry floodproofing measures requires
evaluating the flood hazard conditions at the site for the RESTRICTIONS BASED ON FLOOD
flood used for design purposes, typically at least the base ZONE AND CONDITIONS
flood J-percent-annual-chance flood). The assessment should The NFIP regulations do not allow
determine flood velocity, depth of flooding, rate of floodwater dry floodproofing in Zone V. ASCE 24
rise and fall, frequency of flooding, duration of flooding, and restricts the use of dry floodproofing in
possible debris impacts. Zone V and in Coastal A Zones if a Limit
of Moderate Wave Action (LiMWA) is
Design professionals and building owners should review delineated on flood maps. Communities
Chapter 2 in FEMA P-936 for guidance on determining may have additional requirements, such
design loads and the site characteristics that need to be as not allowing dry floodproofing to be
identified in order to determine whether dry floodproofing used in floodways.
is feasible and to successfully design and construct a dry
floodproofed building.
A factor that may influence the decision to use dry floodproofing is flood velocity. The USAGE recommends in its
Flood Proofing Regulations (1999) that dry floodproofing not be used where expected flood velocities exceed 5 feet
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 13
per second.ASCE 24 limits the use of dry floodproofing to where expected flood velocities adjacent to a structure
are less than or equal to 5 feet per second, although ASCE 24 commentary suggests that local officials may accept
certified designs that demonstrate resistance to higher velocities. In this Technical Bulletin, see Section 6, Step 3B,
for possible sources of data for determining expected flood velocities.
5.2 Flood Warning Time
Flood warning time is an important factor when considering active dry floodproofing measures. Flood warning
time is the length of time between the recognition that flooding may occur and when floodwater begins to affect
a site. Designers should determine whether warnings issued by credible sources would provide enough time to
implement any active dry floodproofing measures.
The first step is to determine the flood warning time, which is
site specific. The next step is to determine whether the flood SOURCES FOR ESTIMATES
warning time would be sufficient to implement the measures OF FLOOD WARNING TIME
the designer is considering (see Section 5.5.1 of this Technical Possible sources of information about
Bulletin) and to provide time to safely evacuate the site. flood warning time are state or local
Flood warning time varies depending on the source of flooding emergency management agencies,
and the capabilities of the entities that are responsible for local floodplain managers, river basin
monitoring flood conditions or issuing flood warnings. Flood authorities and drainage districts, state
warning times can vary widely: water resources agencies, National
Weather Service, U.S. Geological
• Small watersheds, especially those in mountain and hilly Survey, and USACE District Offices.
regions, may be subject to flash flooding with very little or
no warning before the onset of flooding.
• Larger rivers and waterways may take hours, days, or weeks for floodwater to crest.
• Flooding in coastal areas usually has several days of warning, although storm paths can change abruptly,
which can shorten or lengthen warning times.
Dry floodproofing measures are active or passive. Active
measures require human intervention to install, deploy,
or otherwise activate. When feasible, building owners and DESIGN LIMIT
designers should consider passive measures because effectiveness ON HUMAN INTERVENTION
does not depend on human intervention. Examples of passive Active dry floodproofing measures
measures are specially designed doors that are always sealed should be designed to meet the limit
when closed, designed window systems, and flood shields that for human intervention specified in
are designed to automatically close when triggered by rising ASCE 24—a minimum of 12 hours
floodwater on the site. of flood warning time unless the
community operates a flood warning
A key consideration f community
determining flood warning time is not system, which case the designer
the time it takes for floodwater to reach the flood protection should determine how much time may
level but the time it takes for flooding to begin to affect the be available.
site and reach the point where water enters the building
if dry floodproofing measures have not been deployed.
For example, if floodwater reaches the lowest point of entry
14 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
during a 10-p ercent-annual-chance event, the flood warning time must be sufficient to allow the implementation
of active measures prior to floodwater reaching the 10-percent-annual-chance elevation.
The amount of time needed to implement active dry floodproofing measures varies depending on factors such
as the number and complexity of the measures that require timely action to function as designed. Determining
whether the flood warning time would be adequate requires estimating the total time needed to:
• Recognize the threat, including whether anticipated storm conditions will have high winds that could hamper
installation
• Notify persons or contractors responsible for installation or deployment
• Travel to building locations
• Locate, activate, deploy, and install the measures,which may require heavy equipment not typically on site,
such as forklifts
• Evacuate people implementing the measures using predetermined evacuation routes, taking into account
whether roads or bridges may be closed by state or local officials(e.g.,when high winds or overtopping by
floodwater are anticipated)
For more information on flood warning time, see FEMA P-936, Chapter 2.
5.3 Functional Use Requirements
The functional use of buildings and the spaces within them must be evaluated when considering dry floodproofing
measures. If extended interruption of function would be detrimental, building owners should consider whether
dry floodproofing is a viable option compared to elevating buildings. The location,purpose, and frequency of use
of entrances may dictate the type of dry floodproofing measure that is selected. For example, doorways that are
used often may not be suitable for special doors that are designed to seal when closed because the gaskets may
wear more quickly. Another example is vehicle openings and delivery doors where accidental vehicle impact may
damage permanently mounted brackets for flood shields.
Mixed-use buildings have additional functional use considerations because separate access must be provided to
the elevated residential portions of these buildings when shared accesses(lobbies to residential and non-residential
portions) are dry floodproofed. When the separate access to the residential portions of a mixed-use building is
enclosed by walls,the walls must comply with the requirements for enclosures below elevated buildings(sometimes
called wet floodproofing).
5.4 Safety and Access
For safety, dry floodproofed buildings should not be occupied during flood conditions. Safety and access
considerations are especially important when evaluating mixed-use buildings and whether it is appropriate to
design dry floodproofing measures for the non-residential portions of these buildings. Flooding may rise higher
than the flood protection level or dry floodproofing system components may fail, endangering the occupants.
Flooding may limit access and timely response by emergency personnel. ASCE 24 requires an exit door, exterior
door, or window at or above the flood protection level that can be used as an emergency escape and rescue
opening. The opening must be capable of providing human ingress and egress during flooding.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 15
5.5 Required Plans
FACTORS THAT CONTRIBUTE TO THE
Buildings that will be dry floodproofed should FAILURE OF DRY FLOODPROOFING SYSTEMS
have both flood emergency operations plans and The Mitigation Assessment Teams that FEMA
inspection and maintenance plans. When active deploys after some major disasters issue
dry floodproofing measures are specified (human reports that include observations of damage and
intervention is required to implement), ASCE 24, factors that contributed to flood damage. The
Chapter 6, requires flood emergency plans that are reports issued after Hurricane Harvey in Texas
approved by local officials. See Section 5.5.1 of this (FEMA, 2018c) and Hurricane Irma in Florida
Technical Bulletin. (FEMA, 2018b) identify the following factors
Communities are encouraged to require submission that may have contributed to the failure of dry
of these plans along with the construction documents floodproofing systems:
and design certifications required as part of an • Lack of plans that detail installation
application for a building permit. The required requirements for active dry floodproofing
submission of a flood emergency operations plan and measures or operations and inspection and
inspection and maintenance plan may be specified in maintenance plans with insufficient detail
local floodplain management regulations or building • Occupants and building managers who were
codes. not aware of the dry floodproofing systems
Emergency operations plans and inspection and • Missing, damaged, degraded, and leaking
maintenance plans are required to be submitted gaskets around flood shields
with applications for NFIP flood insurance coverage . Modification of dry floodproofing components
to receive credit for dry floodproofing measures (see by uninformed maintenance contractors
Section 4 of this Technical Bulletin).
L
5.5.1 Flood Emergency Operations Plans
Flood emergency operations plans address the
implementation of active dry floodproofing PERIODIC PLAN REVIEWS,
measures when flood events are anticipated. Design DRILLS,AND INSPECTIONS
professionals engaged in designing dry floodproofed An annual review of flood emergency operations
buildings should evaluate flood warning time and plans, with exercises for personnel to practice
the estimated time and level of effort necessary to installing and deploying measures that require
install and deploy various measures that require human intervention, is critical for success when
human intervention well in advance of the onset flooding occurs.
of flooding or high winds (see Section 5.2 of this Some communities conduct periodic inspections
Technical Bulletin). When there may be insufficient of dry floodproofed buildings, and some require
time to implement specific measures and evacuate, the submission of reports documenting third-
designers should re-examine the measures and party inspections.
specify those that can be installed safely within the
available warning and evacuation time. If the entire
dry floodproofing system cannot be implemented
and personnel safely evacuated in the available time, designers should specify alternative dry floodproofing system
components or advise owners to consider elevation when compliance is required.
16 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Building owners, operators, and responsible personnel must
be able to implement the plan and make sure that occupants REQUIRED POSTING OF FLOOD
are aware of what is required when plans are activated. Flood EMERGENCY OPERATIONS PLANS
emergency operations plans must be tailored for each dry IN VISIBLE LOCATIONS
floodproofed building. At a minimum, plans should specify the ASCE 24, Chapter 6, requires
following: flood emergency operations plans
• The personnel, equipment, tools, and supplies needed to be permanently posted in dry
to deploy all dry floodproofing system components with floodproofed buildings in at least two
sufficient time prior to the onset of flooding or conditions clearly visible locations.
such as high winds that could interfere with efficient
deployment of measures
• Clearly defined chain of command and assigned responsibilities for personnel involved in the installation of
dry floodproofing measures
• Procedure for notifying personnel responsible for installing dry floodproofing measures, along with a list of
duty requirements
• Decision tree that identifies the sequence, timeline, and responsible parties for installing the dry floodproofing
components, including the triggers or benchmarks that will initiate procedures
• Written description and map of the storage locations and types of dry floodproofing measures to be installed
or deployed, along with any equipment, tools, and materials required for installation
• Conditions that require the deployment of active dry floodproofing measures (e.g.,installation of flood shields,
closing of flood doors, closing of manual valves, staging of pumps)
• Instructions for installing or deploying each dry floodproofing measure and the order of installation if
important for effectiveness
• Repair procedures and component maintenance procedures that may be necessary during a flooding event
• Instructions for connecting standby(emergency)power source (e.g., generator)for critical equipment such as
sump pumps and egress lighting
• Contact information for the manufacturer and designer to expedite obtaining replacement parts and support
as needed
• Evacuation plans for all personnel(see Section 5.2)
• Requirements for installation and deployment drills and training program(at least once a year)
• Requirement for regular review and update of the plan procedures
5.5.2 Inspection and Maintenance Plans
A comprehensive inspection and maintenance plan for the entire dry floodproofing system is needed to ensure
that the system components, measures, materials, and equipment required for the system to function as intended
are inspected and maintained periodically. The design professionals who design and certify dry floodproofing
systems should prepare the inspection and maintenance plans. It is good practice for building owners or operators
to engage design professionals to coordinate regular inspections and address significant deficiencies identified
during inspections.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 17
Observations by FEMA Mitigation Assessment Teams after significant flood events indicate that some dry
floodproofing systems did not provide the intended level of protection in part because components of the systems
were not regularly tested or properly maintained. For additional information, see Appendix C in FEMA P-2022
and Appendix C in FEMA P-2023.
Inspection and maintenance plans should include a schedule for regular inspection and maintenance of the
components, materials, and equipment that are needed to activate dry floodproofing measures. Manufacturer
manuals typically provide recommendations for the aspects that need to be checked during inspections and
maintenance, the frequency of inspections, and ordering information for replacement parts.
FEMA Form 086-0-34, NFIP Floodproofing Certificate for Non-Residential Structures, lists the minimum
information that maintenance plans must have in order to obtain NFIP flood insurance coverage (see Section 4
and Appendix A of this Technical Bulletin). The content of a comprehensive inspection and maintenance plan
depends on the elements of the specific dry floodproofing system. At a minimum, the following should be
addressed:
• Exterior envelope of the structure, such as wall and foundation systems, to identify possible structural and
waterproofing deficiencies such as cracks,water staining, and penetrations
• Slabs and wall/slab joints,including structural and drainage deficiencies
• Flood shields, gates,panels, doors, glazing, and other components designed to provide dry floodproofing
protection, including seals, gaskets, fasteners, and mounting hardware and tools
• Sump pumps(or self-priming pumps) and interior drain system
• Testing of emergency generators, sump pumps, and other drainage measures
• Backflow(non-return)valves or shutoffvalves
• Location of all flood shields, gates,panels, and other components including all hardware along with any
materials or tools needed to seal the dry floodproofed area
• Contact information for the manufacturer of the shields and other components to determine the availability of
replacement gaskets, seals, and other parts and to ask questions
• Cadence of inspection and maintenance plan
Inspections should be performed regularly, usually once a year.
Inspections can be coordinated with regular drills during which ANNUAL INSPECTION
responsible personnel practice deploying measures that require AND MAINTENANCE
human intervention and other actions specified in flood emergency Performing annual inspections
operations plans. The inspection should identify items that are also helps increase personnel
deficient, items in need of repair or replacement, and the materials and occupant awareness of the
and equipment needed to implement repairs. Building owners and presence and importance of the
operators should examine the inspection reports and promptly make dry floodproofing systems.
repairs and address deficiencies.
18 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
6 Dry Floodproofing Design Process
Section 1.2 of this Technical Bulletin explains that
communities must require dry floodproofing designs USE OF ANSI/FM 2510 APPROVED
to be certified and that the NFIP Floodproofing EQUIPMENT AND PRODUCTS
Certificate for Non-Residential Structures (FEMA The use of equipment and products that are
Form 086-0-34) should be used for this purpose tested and approved in accordance with
(see Appendix A of this Technical Bulletin). The ANSI/FM 2510,American National Standard for
certificate requires registered design professionals Flood Mitigation Equipment, is not required for
to certify that dry floodproofing measures have compliance with the NFIP or ASCE 24. However,
been designed and constructed in accordance specifying approved equipment and products
with ASCE 24 or its equivalent. The certificate may provide designers with more assurance
requires certification of designs and "as-built when developing designs for dry floodproofing
drawings for construction and physical inspection." systems.
Certification of as-built dry floodproofed systems ANSI/FM 2510, described in Section 3.3 of this
provides increased assurance to building owners and Technical Bulletin, specifies the flood conditions
operators. for the testing of each type of equipment and
The accepted standard of practice for the design product. Designers should verify applicability
of' dry floodproofing measures is ASCE 24. of approved equipment and products for
This section provides a step-by-step guide for site-specific flood conditions.
developing dry floodproofing designs that comply
with ASCE 24. Designers should first evaluate the
planning considerations described in Section 5 of this Technical Bulletin and review additional guidance in
FEMA P-936. The process is applicable to the design of new construction with dry floodproofing systems and
retrofitting of existing buildings with dry floodproofing measures.
An overview of the design steps is shown in Figure 1.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 19
Step 1
Determine Flood
.Design Class (ASCE 24, Table 11).
.,..,..,..,..I
Step 2
Determine flood protection level based on most restrictive of BFE, ASCE 24, and local regulations.
Step 3
Determine flood loads (ASCE 7).
Existing Is the structure New
existing or new?
Step 4(Existing Structures)
Perform condition assessment of portions
of structure that will be relied on to resist
flood loads.
Step 5(Existing Structures) Step 5
Check whether existing structural elements Design structural elements
have adequate strength and stiffness to to have adequate strength
resist flood loads. Check that the structure and stiffness to resist flood
has adequate resistance to buoyancy. loads. Design foundation to
have adequate resistance
Is structural to buoyancy.
strengthening or modification Yes
needed?
No
Step 6 —199
Evaluate building utility systems and equipment.
Step 7
Design/specify flood shields at openings
(e.g., doors, windows) below the flood protection
level to resist flood loads.
Step 8 Step 9
Design waterproofing system. Address Design interior drainage
penetrations and joints in walls and slabs. system for amount of
Perform seepage calculations to demonstrate expected seepage calculated
Select fewer/alternate that expected amount of seepage through wall in Step 8. Locate and sizesump pumps to expel the
flood shields and/or systems,joints, and around flood shields is less expected seepage volume.
waterproofing than 4 inches of water depth during a 24-hour
membrane to reduce period if no devices are provided for removal.
seepage.
Step
Certify the design.
Satisfy
No Is expected Yes requirements for flood
seepage less than 4 inches emergency operations plans
in 24 hours? and inspection and
Figure 1: Steps in designing a dry maintenance plans.
floodproofing system
20 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
6.1 Step 1: Determine Flood Design Class
When designing in accordance with ASCE 24, the design professional begins the design process by determining
the Flood Design Class (called "classification" in the 2005 edition). Flood Design Class is based on the use or
occupancy of a building or structure, and the risk to the public should the building be damaged or the occupancy
function be impaired by flooding.ASCE 24,Table 1-1, defines four Flood Design Classes.
6.2 Step 2: Determine the Flood Protection Level
The flood protection level is the elevation to which flood protection measures will be designed. The NFIP
regulations specify that when non-residential buildings are dry floodproofed, the structures must be watertight
and substantially impermeable below the base flood level or BFE.
ASCE 24 requires the minimum flood protection level to be the elevations listed in ASCE 24,Table 6-1,but state
or local floodplain management regulations may require higher levels. ASCE 24 specifies flood protection levels
based on the assignment of one of four Flood Design Classes (similar to risk categories).
The minimum flood protection level for Flood Design
Class 2 and Class 3 buildings is the BFE plus 1 foot or "DESIGN FLOOD ELEVATION" IN ASCE 24
the design flood elevation (DFE), whichever is higher. ASCE 24 defines and uses the terms "design
The minimum flood protection level for Flood Design flood" and "design flood elevation" (DFE)
Class 4, considered critical and essential facilities, is to account for communities that elect to
the highest of the BFE plus 2 feet, the DFE, or the 500 adopt flood hazard maps based on floods
year flood elevation. Flood Design Class 1 includes that are higher than the base flood (the
temporary structures, accessory storage structures, small 1-percent-annual-chance flood) or to include
parking structures, and certain agricultural structures additional areas not shown on FIRMS.
and also requires protection to BFE plus 1 foot or the Adding freeboard above the BFE as an
DFE,whichever is higher. Local floodplain management additional factor of safety is also a common
officials should be consulted to determine whether local practice for establishing a minimum elevation
regulations require the flood protection level to be higher requirement.
than the minimum elevations in ASCE 24. When communities simply adopt FEMA FISs
The BFE is the computed water surface elevation for and FIRMs and use the base flood and BFE
the 1-percent-annual-chance flood. When shown on for regulatory purposes, the DFE is the same
FIRMS, the BFE is often rounded to the nearest whole as the BFE.
number. Designers should also check elevations shown --------
in Floodway Data Tables and Flood Profiles included in
Flood Insurance Studies (FISs)when FEMA has developed engineering analyses. Figure 2 shows a sample FIRM
marked to show a building location and applicable BFE.
Some FISs and FIRMS do not provide detailed information and/or BFEs for all sources of flooding, particularly
smaller streams and tributaries. When a FIRM panel does not show a BFE or when detailed flood elevation
information is not available, designers will need to take additional steps to determine the BFE. Local officials may
have information from other sources or may direct designers to other sources, including USAGE District Offices
and FEMA Regional Offices. Additional steps may be necessary when 500-year flood elevations are not included
in the FIS but are needed for the design of critical facilities. Statistical methods or engineering analyses may be
required to identify critical flood characteristics.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 21
,0�$
40
fi 023 �
ZE X
Bi 'rr nch ' /ZO N E AE
�: 1 SMe�xrr��I
(Basar� � , .
• ZO N E X �
479
Figure 2: Example FIRM showing building location and BFE
An important consideration is that the flood protection level specified in ASCE 24 or local regulations is the
minimum level to which buildings must be dry floodproofed.There is no restriction on designing dry floodproofing
to provide protection for a higher flood elevation than what is required. Incorporating additional freeboard could
help accommodate increases in future flood elevations, which may be caused by changes in storm intensity,
increased development of surrounding areas, or ground subsidence. Owners and designers should discuss the
acceptable level of protection given the value of the buildings, contents, occupancies, availability of replacement
equipment, costs associated with business interruption and function, and cost-effectiveness of dry floodproofing.
Owners may decide that a higher level of protection is appropriate.
6.3 Step 3: Determine Flood Loads
After the flood protection level has been determined, the next step is to determine the flood loads that would act
on a building at the selected location. For design purposes, flood loads are the result of floodwater rising to the
flood protection level and moving past an object such as a building or component of a building foundation. Flood
loads are discussed in ASCE 7, which should be the primary source for calculating flood loads. Resources such as
FEMA P-936 and FEMA P-55, Coastal Construction Manual(2010b), provide helpful information on determining
site-specific loads. The four types of flood loads are:
22 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
• Hydrostatic loads, including buoyancy,which is the vertical hydrostatic force resulting from the displacement
of a given volume of floodwater(Step 3A)
• Hydrodynamic loads (Step 313)
• Wave loads (Step 3C)
• Impact loads (Step 31))
Step 3E is load combinations,which are combinations of
all types of loads, including flood loads. DETERMINING DEPTH OF FLOODING
All applicable flood loads must be considered over The depth of flooding is critical in calculating
the entire dry floodproofing system below the flood flood loads. Designers of dry floodproofing
protection level, including the portion above the BFE. systems should use the flood protection level
Flood loads act on above-grade portions of buildings elevation rather than the BFE or DFE when
when floodwater is present and on below-grade determining the depth of flooding for the
foundation walls and slabs when saturated soil conditions calculation of flood loads.
may be present or may occur during flooding.
An overview of the types of flood loads is provided in
Step 3A through Step 3E.
6.3.1 Step 3A: Hydrostatic Loads
Hydrostatic loads are imposed by standing water on an object or building. Hydrostatic loads on specific buildings
are determined using the flood protection level and must be applied to all building surfaces, both above and
below the ground surface. Hydrostatic loads, also called pressures, are oriented horizontally on wall elements and
increase linearly with depth of water(see Figure 3). For buildings with below-grade areas (basements), hydrostatic
loads extend to the bottom of below-grade walls and are calculated using a saturated soil condition (see ASCE 7,
Chapters 3 and 5).
Flood protection
level Water surface level
Hydrostatic load
_y Ground
Buoyancy force -� F
Additional pressure
from saturated soil
Buoyancy force
Figure 3: Hydrostatic loads
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 23
Vertical hydrostatic force (buoyancy) can be determined by multiplying the specific weight of water and the
volume of floodwater displaced by a submerged object. Buoyant forces act upward on the bottom of foundation
walls and base slabs and are resisted by the weight of the building and the structural capacity of the slab to resist
uplift loads.
See FEMA P-936, Chapter 2, for information on determining hydrostatic loads and analyzing buoyancy forces.
When flood shields are included in dry floodproofing systems to prevent floodwater from entering openings in the
building envelope (such as windows and doors), the shields must extend up to at least the flood protection level.
A common practice is to extend flood shields an additional foot or more since even small amounts of splash or
overtopping of a shield could result in a significant volume of floodwater entering the building. Flood shields must
be designed to resist the hydrostatic load applied over the entire shield, and there must be a continuous load path
through mounting systems to the walls and ultimately to foundations. See Step 7 for additional information on
designing flood shields.
6.3.2 Step 3B: Hydrodynamic Loads
Hydrodynamic loads are imposed by water flowing around fixed objects such as buildings. These loads are a
function of flow velocity and the geometry of the object or building. Upstream surfaces receive positive (frontal)
pressures, side surfaces experience the effects of drag, and downstream surfaces have negative (suction) pressures
(see Figure 4).
Hydrodynamic loads are determined by basic fluid mechanics. They increase as the size of the object around
which the flow passes increases and with the square root of the flow velocity. Hydrodynamic loads vary with the
shape of the object and associated drag coefficients.
ASCE 24, Chapter 6, limits the use of' dry floodproofing
to areas where flood velocities are less than or equal to 5 DETERMINING FLOOD VELOCITY
feet per second. ASCE 24 commentary acknowledges that Possible sources of data for determining
eflective designs may account for higher velocities and notes expected flood velocity include studies
that it is the community's decision as to whether to accept by government agencies, hydraulic
dry floodproofing proposals in areas with velocities higher calculations, historical measurements,
than 5 feet per second. and Floodway Data Tables in FEMA FISs,
Determining the flood velocity can be a challenging part among others. The Floodway Data Tables
of estimating hydrodynamic loads on structures. Local, represent conditions during a 1-percent-
state, and federal government agencies and the Floodway annual-chance event. Where the flood
Data Tables in FEMA FISs developed for waterways where protection level is higher, designers should
consider that flood velocities for an event
FEMA performed detailed analyses are potential resources equaling the flood protection level may
of velocity information. be higher. When data are not available for
ASCE 7 provides guidance on how to determine estimating flow velocities for a specific
hydrodynamic loads and makes allowances for conditions site, designers should contact experienced
when it is possible to calculate hydrodynamic loads as an hydrologists or hydraulic or civil engineers
equivalent hydrostatic load. FEMA P-936, Chapter 2, to develop estimates.
also describes hydrodynamic forces and how to determine
a drag coefficient based on the shape of buildings and
produce the total hydrodynamic force against a building or
a given surface area.
24 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Negative pressure/suction
on downstream side
0
0
Flood protection level
Frontal impact on
Drag effect on sides upstream side
Figure 4: Hydrodynamic forces on a building
6.3.3 Step X Wave Loads
The NFIP regulations do not permit the use of dry floodproofing in SFHAs that are subject to high velocity wave
action, called coastal high hazard areas and identified on FIRMS as Zone V(V,VE,V1-30, and VO). FEMA does
not identify other areas that may experience waves,including expansive riverine floodplains.
ASCE 24 does not permit dry floodproofing in Zone V or in Coastal A Zones when a Limit of Moderate Wave
Action(LiMWA) is delineated on a FIRM. In addition,ASCE 24, Section 3.7.2, requires structures in noncoastal
flood hazard areas subject to wind-driven waves that are equal to or greater than 3 feet high to be designed in
accordance with the requirements for coastal high hazard areas. While wave loads are typically not considered in
dry floodproofing designs,ASCE 24 commentary cautions that waves less than 3 feet in height can cause damage
and should be considered in calculating flood loads. These waves may occur inland of the Zone V boundary
where a LiMWA has not been delineated and in other floodplains where wind-driven waves may develop. Critical
facilities could be located landward of Zone V and Coastal A Zones but under a design condition where the flood
depth could support higher wave heights,which should be addressed in the design.
Design professionals should investigate historical flood damage near the site to determine whether wave forces
could be present and could be significant enough to address in determining flood loads. Investigating historical
flood damage is also appropriate for sites that are landward of Zone V boundaries if a LiMWA has not been
delineated. Guidance on evaluating and determining appropriate wave loads and how to calculate the forces on
various structural elements is included in ASCE 7, and additional information is provided in FEMA P-55.
6.3.4 Step 3D: Impact Loads
Impact loads result from debris that is transported by floodwater and strikes buildings. Such debris includes
trees, boulders, ice floes, unsecured tanks and containers, vehicles, and material from damaged buildings. The
magnitude of impact loads is difficult to predict due to the uncertainty of the size and weight of the objects.
Determining the magnitude of debris impact loads should be based on a rational approach. The loads should be
applied as a horizontal, concentrated load acting at the most critical location at or below the flood protection level.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 25
ASCE 7 should be used as the source of how to calculate debris impact loads with FEMA P-936 as the source of
helpful information and guidance on evaluating debris impact loads.
6.3.5 Step 3E. Load Combinations
Buildings need to be designed to resist all loads and load combinations. The applicable flood loads that are
described above must be combined with other loads in accordance with ASCE 7. The design professional is
permitted to combine loads by using Allowable Stress Design (ASD) or Strength Design (also known as Load
Resistance Factor Design [LRFD]).
6.4 Step 4: Perform a Condition Assessment (Existing Structures)
When considering retrofitting an existing structure for dry
floodproofing measures, design professionals must perform a CONDITION ASSESSMENTS
condition assessment of the portions of the structures that will OF EXISTING STRUCTURES
be relied on to resist the flood loads determined in Step 3. The See ASCE 11-99, Guide for Structural
assessment should be performed in two steps. The first step is a Condition Assessment of Existing
preliminary assessment consisting of a visual examination of the Buildings, and Appendix C of FEMA
building and a review of available structural and architectural P-936 for useful information on
drawings. performing condition assessments of
If' the preliminary assessment suggests that dry floodproofing existing structures.
may be possible, the second step is a more thorough assessment
involving a review of as-built drawings (if available) and any
plans or other documents related to any modifications of the structural elements after initial construction. Where
adequate plans are not available,invasive testing to determine the structural aspects and condition of the building
may be necessary. Cracks and penetrations through walls and slabs must be identified and examined to determine
whether they would become pathways for seepage. The assessment results should be documented in written
reports.
Design professionals use condition assessments to design modifications to existing structures that will satisfy dry
floodproofing performance requirements. Modifications and key areas to identify include:
• Strengthening structural walls or floor systems
• Sealing wall penetrations
• Installing waterproofing membranes
• Locating where flood shields are needed
• Locating where seepage will accumulate and sump pumps are needed
If soil boring information for the site is not available, a geotechnical investigation may be necessary to determine
lateral earth pressures and allowable soil-bearing capacities. Other geotechnical issues that may need to be
considered include the presence of expansive or collapsible soils, potential for scour, permeability of soils, and
compaction behavior of soils. See the discussion of site factors in FEMA P-936, Section 2.4, for additional
information.
26 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
6.5 Step 5: Design or Check Structural Components
for Resistance to Flood Loads
After flood loads have been determined in Step 3 and for existing buildings, the condition has assessed in Step 4,
design professionals should next demonstrate that the structural elements (walls, foundations, and slabs) within
areas to be dry floodproofed will have adequate strength to resist flood loads. To comply with ASCE 24, the
structural components of new construction must be designed in accordance ASCE 7 to resist combined flood and
other loads(e.g., dead load, live load,wind loads, seismic loads).
For existing buildings, the structural components that will resist flood loads need to be checked to determine
whether they have adequate strength and stiffness. Structural components such as exterior walls, foundation
elements, and diaphragms will likely experience substantial increases in loads after dry floodproofing measures
are applied. Exterior walls commonly require strengthening with supplemental vertical or horizontal structural
members to resist flood loads. Existing cracks and penetrations below the flood protection level must be sealed to
limit seepage during flooding.
Another aspect of resistance to flood loads is whether building elements, such as slabs, have adequate resistance
to uplift caused by buoyancy.ACI 350.4R 04, Design Considerations for Environmental Engineering Concrete Structures
(ACI, 2004), is a helpful resource in determining the appropriate factor of safety to use to check uplift due to
buoyancy. Some building elements may require strengthening or other modification to accommodate uplift
pressures caused by buoyancy.
6.6 Step 6: Evaluate Building Utility Systems and Equipment
Designers must determine the needs of building utility systems and equipment in dry floodproofed buildings and
identify the appropriate ways to satisfy floodplain management and building code requirements.The requirements
apply to building utility systems(mechanical, electrical, and plumbing) and equipment(including fire controls and
emergency power or generators).
The preferred solution is to locate building utility systems and equipment above the flood protection level.
Building utility systems and equipment that serve non-residential buildings and non-residential portions of
mixed-use buildings are allowed in dry floodproofed areas. If dry floodproofing systems fail or are overtopped by
floodwater rising above the flood protection level, building utility systems and equipment may be damaged and
not repairable, which could contribute to loss of building functionality. Backflow (non-return) valves or shutoff
valves should be installed to prevent floodwater from entering through sewer and drainage pipes, and sewage
ejectors should be installed to pump sewage to above the flood protection level before connecting to a vertical
sewer line.
The NFIP regulations and ASCE 24 permit equipment and service facilities to be below the flood protection level
when "designed ... to prevent water from entering or accumulating within the components during conditions of
flooding" (44 CFR§ 60.3(a)(3)(iv)). The expectation is that after being submerged, equipment and facilities below
the flood protection level will be able to be restored to functioning with minimal cleaning and repair. Unless
equipment and service facilities are specifically designed to be submerged,they should be elevated on platforms or
located on the roof,inside a freestanding engineered dry floodproofed walled area, or inside the dry floodproofed
building. A good practice is to install connections for temporary equipment above the flood protection level or
design interior core areas, as discussed in Section 3.3 of FEMA P-936.Additional guidance is available in FEMA
P-348,Protecting Building Utility Systems from Flood Damage(2017).
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 27
When non-residential portions of mixed-use buildings are designed with dry floodproofing systems, the building
utility systems and equipment that serve the residential uses are required to be elevated above the flood protection
level and not located in areas that are protected with dry floodproofing(see Figure 5).
Residential building utility
Rooftop HVAC unit system in penthouse
Wet
EM floodproofed
residential
access
Flood
r protection
level
i - Flood shield
i
i
i
i
Below-grade FIRST FLOOR: Non-residential
non-residential
building utility system SECOND FLOOR: Residential
and equipment room
Figure 5: Mixed-use building with non-residential building utility systems and equipment in a dry floodproofed below-grade
equipment room and elevated systems that serve the residential uses
6.7 Step 7: Design and Specify Flood Shields
When dry floodproofing systems are designed with doors,windows, or other openings below the flood protection
level, design professionals must design or specify flood shields so the entire system performs as intended. Before
finalizing designs, designers must determine the available warning time and the likely ability of personnel who
would be responsible for deploying active dry floodproofing measures. Designers must also understand the
requirements for installing different types of shields (see Section 5.2 of this Technical Bulletin).
Flood shields must be strong enough to resist all
imposed flood loads. It is also critical to determine SPECIAL GLAZING SYSTEMS
whether the shields will be mounted on structural
elements of buildings or on door and window Some manufacturers produce glazing (window)
frames. When mounted on door and window systems with laminated glass, seals, and frames
frames, the frames must be capable of carrying designed to resist flood loads while meeting
the loads exerted on the shields. Designers should occupant needs for natural light. These window
consider specifying flood shields that are tested systems (sometimes called submarine or aquarium
and certified to the requirements of ANSI/FM glass)are passive dry floodproofing measures
2510 (see Section 3.3 of this Technical Bulletin). because installing flood shields is not requiredwhen flooding is anticipated.
28 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
To limit seepage, flood shields typically have flexible gaskets around their perimeter. Various manufactured
products are available. Figure 6 illustrates common types of shields, although other types may be available. Some
permanent doors can be designed to function as flood shields when closed, although this may not be a viable
option when doors are used frequently because of wear on gaskets and seals. Some flood shields are mounted next
to openings to facilitate rapid deployment. Many flood shields are modular, can be stored nearby, and installed
when needed.
FAII!
Drop In Drop In
' IIIIIi 111111-
Bolt On Sliding
Hinged Automatic/ Passive
Figure 6:Common types of flood shields
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 29
Building owners and designers are cautioned that FEMA does not consider temporarily installed flood protection
that covers walls, including glass curtain walls, to meet the NFIP minimum requirement that walls must be
"substantially impermeable to the passage of water and with structural components having the capability of
resisting hydrostatic and hydrodynamic loads and eflects of buoyancy" (44 CFR§ 60.3(c)(3)).
6.8 Step 8: Design Waterproofing System
In addition to ensuring that structures are capable of withstanding flood loads, design professionals need to
ensure that areas below the flood protection level are watertight and substantially impermeable. To be considered
substantially impermeable, the waterproofing system below the flood protection level must limit seepage through
walls, floors, utility penetrations,joints, cracks, and around flood shields. The system must not allow more than
4 inches of water depth from seepage to accumulate during a 24-hour period without relying on devices to
remove the water(e.g., sump pumps). Estimating seepage from each component of the waterproofing system is an
important step because designers may need to alter designs to be able to certify that the designs stay within the
accumulation limit.
6.8.1 Step 8A: Estimate Seepage through Wall Systems
Estimating the total seepage accumulation through a given wall system is challenging due to the many types
of systems and the lack of available testing information for each type. However, in 2011, Oak Ridge National
Laboratory (ORNL) tested 11 common wall assemblies under a simulated hydrostatic load for a 3-foot water
depth to measure seepage when exposed to flooding over a 24-hour period. SERRI [Southeast Region Research
Initiative] Report 80024-01,Floodproof Construction: Working for Coastal Communities,describes the test methodology
and measured seepage accumulation for the 11 wall assemblies (ORNL, 2011).
The wall systems considered in the SERRI study included concrete masonry unit blocks with sprayed- and sheet-
applied water-resistive membranes,insulated concrete formwork, and metal structural insulated panels. Designers
should review the SERRI report to determine whether one of the tested wall systems could be considered similar
enough to the wall system under consideration. If the wall systems are similar enough, the measured seepage
accumulation results documented in the SERRI report could be used to derive approximate seepage values over a
24 hour period. Appendix B of this Technical Bulletin provides an example that illustrates the use of the SERRI
results to estimate the seepage rate through a wall system to determine whether the dry floodproofed space is
substantially impermeable.
The total seepage through a given wall system can be estimated by applying seepage rates to the area of wall
exposed to floodwater. When using the SERRI report, the designer should recognize that the amount of seepage
accumulation recorded in the study may not be fully representative of actual seepage volumes when there are
differences in construction materials and methods from those described in the study and when flood conditions
differ, such as flood depths other than 3 feet. When greater precision of wall seepage rates is desired, it may be
necessary to construct a mockup for a particular wall assembly to test under hydrostatic load to measure seepage
rates.
For an example calculation of seepage through walls, see Steps la and lb in Appendix B.
30 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
6.8.2 Step 8B: Estimate Seepage through Joints and Penetrations
Various joints and gaps around utility penetrations are typically present in below-grade foundation systems
and, in particular, the joints between foundations and lowest slabs. Because of the difficulty of sealing the joint
between the exterior wall and slab, this joint is the most prone to allowing seepage into dry floodproofed areas
(see Figure 7). In new construction, designers should specify and detail waterstops or joint seals that can resist the
anticipated hydrostatic pressures.
Flood protection level
Utility penetration
Wall Seepage
Saturated soil
Sla
LFooter
Figure 7:Typical seepage paths for water entering through
joints between wall,footer,and slab
A common approach for existing buildings is to inject chemical grout into joints, wall penetrations, and cracks.
The grout reacts with water and expands to form watertight, flexible seals. When determining whether this
method is appropriate for expansion joints, the designer should evaluate whether the chemical grout would allow
the joints to perform as intended. Alternative sealing products use a flexible material that fills the space between
the utility penetration and the wall when fasteners are tightened. If known cracks or joints are not sealed, the
designer will need to take these seepage sources into account when determining total seepage in a 24-hour period.
During the design of floodproofing systems for new buildings and when assessing the condition of existing
buildings, designers should identify all joints and penetrations in the walls and slabs. Seepage through joints and
penetrations must be estimated. An example of the calculation of seepage through expansion joints is shown in
Appendix B. Manufacturers of some of the materials that are used to seal expansion joints and other penetrations
may provide information that can be used to estimate seepage rates.When seepage rates under flood conditions are
not provided or deemed inadequate for the purpose of dry floodproofing, designers may decide that it is necessary
to perform mock-up testing of joints or penetration assemblies using the anticipated hydrostatic pressures.
For an example calculation of seepage through expansion joints, see Step 2 in Appendix B.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 31
6.8.3 Step 8C: Estimate Seepage around Flood Shields
When flood shields are included in dry floodproofing systems,
designers need to estimate the expected seepage around the GASKET AND SEAL MAINTENANCE:
wetted perimeter of each shield, which typically has a gasket CRITICAL FOR PERFORMANCE
that seals the shield to the building walls, frames around post-disaster assessments have
openings, or foundations. The amount of seepage depends on indicated that poorly maintained shield
several factors,including the duration of flooding and integrity gaskets and seals are a common
of the seal which, in turn, depends on maintenance and source of excessive water leakage.
installation. Designers may need to adjust the initial designs, This situation can occur when gaskets
reduce the number of flood shields, or specify a different types and seals deteriorate due to weather
of flood shield if the calculations indicate that the seepage will or dry rot or are torn during handling or
exceed the total allowed accumulation of seepage (4 inches storage and are not replaced.
over a 24-hour period).
Manufacturers of various types of flood shields with gaskets and seals have tested some products under hydrostatic
load to measure seepage rates (see Section 3.3 of this Technical Bulletin). Testing information should be obtained
from manufacturers to estimate the volume of seepage,which may be provided as gallons per hour per linear foot
of wetted perimeter.
For an example calculation of seepage around flood shields, see Step 3 in Appendix B.
6.8.4 Step 8D: Estimate Total Seepage through Waterproofing System
After estimates of seepage through wall systems, through joints and penetrations, and around flood shields
are calculated, the total seepage can be estimated. For buildings to be certified as meeting the substantially
impermeable requirement, the maximum accumulation in the dry floodproofed portion of the buildings must
not exceed 4 inches of water depth over a 24-hour period without relying on devices for removal of water. If the
total seepage estimate exceeds the 24-hour limit, the designer must adjust the design and selected components as
necessary to satisfy the accumulation limit. Although sump pumps are required to handle seepage (see Step 9),
sump pumps cannot be relied on to meet the maximum accumulation limit of 4 inches over a 24-hour period.
For an example calculation estimating total seepage, see Step 4 in Appendix B.
6.9 Step 9: Design Interior Drainage
Most spaces below the flood protection level of dry floodproofed buildings will not stay completely dry during
flood events. Therefore, interior drainage systems should be designed to limit the accumulation of seepage.
Designs must specify the paths along which seepage will flow and collect and where drains and sumps will be
installed. ASCE 24 requires the use of sump pumps to remove water accumulation due to any passage of vapor
and seepage of water during flooding events, described in Step 8.
If a building loses power,backup power fails to work properly, or sump pumps fail to operate, significant amounts
of seepage could accumulate. For this reason, sump pumps cannot be relied on as the sole or primary means of
meeting the dry floodproofing requirements. Sump pumps should only be relied on to address minor seepage and
leaks that were not properly identified during condition assessments of existing buildings.
Sump pumps should be located at the point of lowest slab elevation, with the bottom of sump pits positioned well
below the bottom of base slabs.A typical sump pump detail is shown in Figure 8. In large below-grade areas, it is
common practice to install piping in gravel-filled trenches below the base slab at the perimeter of the foundation
32 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Check Discharge
valve pipe Cord and
To battery or
plug backup power unit
Sump Sump cover Drain line
77
-.77777
oa o�Lo LU (D.....
�Lo v d�Lo v o
Drain line Varies(typically18 to
Submersible 24 inches)
sump pit
Varies
(typically 18 to 36 inches)
Figure 8: Typical sump pump detail
walls to provide a path for groundwater to access one or more sump pumps. A quickly rising water table or
saturation from surface water,which occurs in many flood conditions, can produce enough seepage to overwhelm
sump pumps if seepage rates into dry floodproofed spaces are high. Backup or emergency power for sump pumps
is necessary due to the potential for power outages during flood events.
To select a sump pump as part of a dry floodproofing system, the designer should consider the advantages of each
pump type and make the selection based on the estimate of total seepage rate(Step 8),pump capacity(gallons per
minute),pump head, and electrical power required to operate the pump.
6.10 Step 10: Certify the Design and Satisfy Requirements for Plans
The final step in the dry floodproofing design process is
for registered professional engineers or architects to certify REQUIRED DOCUMENTS FOR NFIP
designs. FEMA Form 086-0-34, NFIP Floodproofing FLOOD INSURANCE POLICIES FOR
Certificate for Non-Residential Structures, is used by DRY FLOODPROOFED BUILDINGS
most communities to meet the NFIP requirement that When building owners apply for NFIP flood
communities obtain certifications for dry floodproofing insurance policies for a dry floodproofed
designs. See Section 1.2 of this Technical Bulletin for building, the NFIP requires a signed and
additional information on the certificate and Appendix A sealed NFIP Floodproofing Certificate,
for instructions on completing the certificate. flood emergency operations plan, and
When human intervention is required to implement any inspection and maintenance plan.
component of dry floodproofing systems,ASCE 24 requires
designers to meet specific requirements related to flood warning time (see Section 5.2 of this Technical Bulletin),
flood shield design (Step 7, above), and flood emergency operations plans (see Section 5.5 of this Technical
Bulletin). These requirements are also discussed in FEMA P-936. When dry floodproofing system designs are
complete, designers should verify that flood emergency operations plans address all required elements and should
review the plans with building owners.
Inspection and maintenance plans, described in Section 5.5 of this Technical Bulletin, are necessary for the long-
term functioning of dry floodproofing systems. When dry floodproofing system designs are complete, designers
should verify that inspection and maintenance plans address all required elements and should review the plans
with building owners.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 33
7 References
This section lists references cited in the Technical Bulletin.Additional resources related to NFIP requirements are
provided in Technical Bulletin 0.
ACI(American Concrete Association). 2004.ACI 350AR 04,Design Considerations for Environmental Engineering
Concrete Structures.Available at https://www.concrete.org/store/productdetail.aspx?ItemID=350404&Format=
DOWNLOAD&Language=English&Units=US_AND_METRIC.
ANSI/FM (American National Standards Institute/FM Approvals). 2020.ANSI/FM 2510,American National
Standard for Flood Mitigation Equipment.Available at https://www.fmapprovals.com/approval-standards.
ASCE/SEI(American Society of Civil Engineers/Structural Engineers Institute). 1999.ASCE 11-99, Guide for
Structural Condition Assessment of Existing Buildings.Available at https://www.asce.org/.
ASCE/SEI. 2005.ASCE 24-05, Flood Resistant Design and Construction.Available at https://www.asce.org/.
ASCE/SEI. 2014.ASCE 24-14, Flood Resistant Design and Construction.Available at https://www.asce.org/.
ASCE/SEI. 2016.ASCE 7-16,Minimum Design Loads and Associated Criteria for Buildings and Other Structures.
Available at https://www.asce.org/.
FEMA(Federal Emergency Management Agency).Various. NFIP Technical Bulletins. Current
editions available at https://www.fema.gov/emergency-managers/risk-management/building-science/
national-flood-insurance-technical-bulletins:
• Technical Bulletin 0, User's Guide to Technical Bulletins
• Technical Bulletin 1,Requirements for Flood Openings in Foundation Walls and Walls of Enclosures
• Technical Bulletin 2,Flood Damage-Resistant Materials Requirements
• Technical Bulletin 6,Requirements for Dry Floodproofed Below-Grade Parking Areas Under Non-Residential and
Mixed Use Buildings
• Technical Bulletin 7, Wet Floodproofing Requirements
FEMA. 2010a. FEMA P-758,Substantial Improvement/Substantial Damage Desk Reference.
Available at https://www.fema.gov/emergency-managers/risk-management/building-science/
multi-hazard#:—:text=Document-,FEMA%20P-758.
FEMA. 2010b. FEMA P-55, Coastal Construction Manual.Available at https://www.fema.gov/media-library-
data/20130726-1510-20490-2899/fema55 voli_combined.pd£
FEMA. 2013. FEMA P-936,Floodproofing Non-Residential Buildings.Available at https://www.fema.gov/
emergency-managers/risk-management/building-science/flood#:—:text=FEMA P-936.
FEMA. 2017. FEMA P-348,Protecting Building Utility Systems From Flood Damage.Available at https://www.fema.
gov/emergency-managers/risk-management/building-science/flood#:—:text=FEMA P-348.
34 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
FEMA. 2018a. FEMA 213,Answers to Questions About Substantially Improved/Substantially Damaged Buildings.
Available at https://www.fema.gov/emergency-managers/risk-management/building-science/multi-
hazard4:—:text=FEMA 213.
FEMA. 2018b. FEMA P-2023,Mitigation Assessment Team Report.Hurricane Irma in Florida.Available at
https://www.fema.gov/emergency-managers/ri sk-management/building-science/mitigation-asse ssment-
team#::text=FEMA P-2023.
FEMA. 2018c. FEMA P-2022,Mitigation Assessment Team Report.Hurricane Harvey in Texas.Available at
https://www.fema.gov/emergency-managers/risk-management/building-science/mitigation-assessment-
team#::text=FEMA P-2022.
FEMA. 2019a. FEMA P-2037, Flood Mitigation Measures for Multi-Family Buildings.Available at https://content.
govdelivery.com/attachments/USDHSFEMA/2020/06/24/file_attachments/1481529/16-J-0218_Multi-
FamilyGuidance_06222020.pdf
FEMA. 2019b. FEMA Form 086-0-34, NFIP Floodproofing Certificate for Non-Residential Structures.
Available at https://www.fema.gov/flood-insurance/find-form/underwriting#::text=floodproofing.
FEMA. 2020a. FEMA P-2140,Floodplain Management Requirements for Agricultural Structures and Accessory
Structures.Available at https://www.fema.gov/media-collection/floodplain-management-requirements-
agricultural-and-accessory-structures#::text=FEMA P-2140.
FEMA. 2020b. National Flood Insurance Program Flood Insurance Manual.Available at https://www.fema.gov/
flood-insurance/work-with-nfip/manuals.
ICC (International Code Council). International Codes.Available at https://codes.iccsafe.org/category/I-Codes.
• 2012 International Building Code
• 2015 International Building Code
• 2018 International Building Code
ORNL(Oak Ridge National Laboratory). 2011. SERRI Report 80024-01,Floodproof Construction: Working for
Coastal Communities.Available at https:#staticl.squarespace.com/static/5450Od67e4bOfe2b86e37264/t/54
9343ale4bOd5186e34f6 e 6/1418937249160/SERRI+Report+80024-01_Floodproof+Construction+%28 Se
pt+2011%29.pdf
USAGE. 1995.Flood Proofing Regulations.Available at https://www.publications.usace.army.mil/Portals/76/
Publication s/Eng ine erPamphlets/EP 1165-2-314.pdf
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 35
Appendix A: FEMA Form 086-0-34, National Flood
Insurance Program Floodproofing
Certificate for Non-Residential Structures
Appendix A of the National Flood Insurance Program's Technical Bulletin 3, Requirements for the Design
and Certification of Dry Floodproofed Non-Residential and Mixed-Use Buildings, includes guidance on completing
FEMA Form 086-0-34, National Flood Insurance Program Floodproofing Certificate for Non Residential
Structures. Communities that participate in the National Flood Insurance Program (NFIP) must require that
designs for dry floodproofing be certified by a registered professional engineer or architect. The registered
design professional must develop or review the structural designs, specifications, and plans for the construction
of dry floodproofed buildings and must certify that the designs and methods of construction are in accordance
with accepted standards of practice for achieving the required performance. Communities must maintain the
certifications in their permanent records. These requirements are established in the Floodplain Management
Criteria section of Title 44 Code of Federal Regulations (CFR)§§ 60.3(c)(3) and(4).
The following instructions are based on the NFIP Floodproofing Certificate that was issued in Dec. 2019, and
that is scheduled to expire on Nov. 30, 2022. Design professionals must use the current NFIP Floodproofing
Certificate or an equivalent statement to comply with the requirement.
TOP OF THE FORM
FLOODPROOFING CERTIFICATE FOR NON-RESIDENTIAL STRUCTURES
The floodproofing of non-residential buildings may be permitted as an alternative to elevating to or above the Base Flood Elevation,-
however,a floodproofing design certification is required.This form is to be used for that certification.Floodproofing of a residential building
does not alter a community's floodplain management elevation requirements or affect the insurance rating unless the community has been
issued an exception by FEMA to allow foodproofed residential basemerrts.The permitting of a foodproofed residential basement requires a
separate certification specifying that the design complies with the local floodplain management ordinance.
BUILDING OWNER'S NAME
FOR INSURANCE COMPANY USE
- , POLICY NUMBER
STREET ADDRESS(Including Apt.,Unit,Suite,and/or Bldg_Number)OR P.O.ROUTE AND BOX
NUMBER
COMPANY NAIC NUMBER
OTHER DESCRIPTION(Lot and Block Numbers,etc.)
CITY STATE Zip Code
Instructions:
FAJ Enter the building owner's name and the address of the building.
36 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
SECTION I
SECTION I—FLOOD INSURANCE RATE MAP(FIRM)INFORMATION
Provide the following from the proper FIRM:
COMMUNITY NUMBER PANEL NUMBER SUFFIX DATE OF FIRM INDEX FIRM ZONE BASE FLOOD ELEVATION
❑ (in❑0 Zones,Use Depth)
FRIIndicate elevation datum used for Base Flood Elevation shown above: E NGVD 1929 0 NAVD 1988 ❑OtherlSouroe:
Instructions:
REnter the following information from the Flood Insurance Rate Map(FIRM)and Map Index:
• Community Number—Six-digit identification number assigned to the community(also referred to as the
community identification number or C;ID). Shown in the title block of the FIRM(see Figure A-1).
• Panel Number and Suffix—Identification of the FIRM panel that includes the subject property, shown in the title
block of the FIRM(see Figure A-1).
• Date of FIRM Index—Most recent revision date for the community's FIRMS is the date on the FIRM Map Index,
which may or may not be the date on the FIRM panel for the property(see Figure A-2).
• FIRM zone—The flood zone in which the building is located, obtained from the FIRM.
MEnter the base flood elevation(BFE) at the location of the building. Special Flood Hazard Areas(SFHAs)identified as
Zone AO do not have BFEs;instead,a depth number may be shown(use depth of 2 feet if no depth number is shown).
❑D Select the elevation datum used for the BFE. The vertical datum is shown on the FIRM map legend or in "Notes to
Users"on the FIRM.
NATIONAL FLOOD INSURANCE PROGMM-1 NATIONAL FLOOD INSURANCE PROGRAM
i.
FIRM FIRM
FLOOD INSURANCE RATE MAP FLOOD INSURANCE RATE MAP
1'LO0D COUNTY, FLOOD COUNTY,
I
USA USA �
AND INCORPORATED AREAS AM) 1N")RP',RA1E.0 AREAS
,agLE)
PANEL 25 OF 40
MAP INDEX
� SEE wMv iHo Foci N.w[E5 III eq,.iEo',
I ca ra s PANELS PRINM; 25,38,60
�M�am ruuazn vum_ stirs.,
ra000 c«.r. , awree oeu
If�
NUMBER PANEL SUFFIX
990099 0025 D
MAP NUMBER MAP NUMBER
996U9COU25 U 996G9C000U
EFFECTIVE DATE EFFECTIVE UAT
AUGUST 19,1998 _ AUGUST 19,1998
".I Emcrgcncy Managc—t Agency I rdrral Emergency Manage m Agency)
Figure A-1:Typical FIRM title block Figure A-2:Typical FIRM map index
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 3%
SECTION II
Section II is used to certify the elevation (where BFEs are provided on FIRMS) or the height above the lowest
adjacent grade (where BFEs are not provided) to which the building is floodproofed. Section II is to be signed
and sealed by a land surveyor, engineer, or architect authorized by law to certify elevation information. Persons
who sign and seal elevation information must be licensed or authorized to practice surveying in the state where
projects are located.
SECTION II—FLOODPROOFED ELEVATION CERTIFICATION(By a Registered Professional Land Surveyor,Engineer,or Architect)
All elevations must be based on finished construction.
Floodprooftng Elevation Information:
Building is floodproofed to an elevation of M feet(In Puerto Rico only: meters).
M❑NGVD 1929 ❑NAVD 1988 ❑Other/source:
(Elevation datum used must be the same as that used for the Base Flood Elevation.)
Height of floodproofing on the building above the lowest adjacent grade is El feet(In Puerto Rico only: meters).
For Unnumbered A Zones Only:
Highest adjacent(finished)grade next to the building(HAG) ❑H feet(In Puerto Rico only: meters).
M❑NGVD 1929 ❑NAVD 1988 ❑Other/Source:
(NOTE:For insurance rating purposes,the building's floodproofed design elevation must be at least 1 foot above the Base Flood Elevation to
receive rating credit.If the building is floodproofed only to the Base Flood Elevation,then the building's insurance rating will result in a higher
premium.See the Instructions section for information on documentation that must accompany this certificate if being submitted for flood
insurance rating purposes.)
Instructions:
MEnter the floodproofing elevation in whole and decimal units.The floodproofing elevation is the top of the floodproofing
measures("height of floodproofing").
The floodproofing elevation must be referenced to the same vertical datum as the BFE identified in Section I.
❑F Enter the vertical datum the floodproofing elevation is referenced to (NGVD 1929, NAVD 1988, or a locally adopted
vertical datum). For a locally used vertical datum, check "Other/Source" and describe the datum and provide the
source.
MEnter the height of the floodproofing measures above the lowest adjacent grade.The lowest adjacent grade is the lowest
ground next to the building.
❑H For unnumbered A Zones,enter the elevation of the highest finished grade adjacent(HAG)next to the building.
❑j Enter the vertical datum the HAG is referenced to (NGVD 1929, NAVD 1988, or a locally adopted vertical datum).
For a local vertical datum,check"Other/Source"and describe the datum and provide the source.
38 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
SECTION II (cont.)
FLOODPROOFING CERTIFICATE FOR NON-RESIDENTIAL STRUCTURES
Non-Residential Floodproofed Elevation Information Certification:
Section II certification is to be signed and sealed by a land surveyor,engineer,or architect authorized by law to certify elevation information
i certify that the information in Section 11 on this Certificate represents a true and accurate interpretation and determination by
the undersigned using the available information and data. I understand that any false statement may be punishable by fare or
imprisonment under'18U.S. Code, Section 1001.
CERTIFIER'S NAME LICENSE NUMBER(or Affix Seal)
TITLE COMPANY NAME
ADDRESS CITY STATE ZIP CODE
0
SIGNATURE DATE PHONE
Instructions:
Enter the name, license number, title, company name, and address and phone number of the individual completing
I� Section IL Section II is to be completed(signed,dated,and sealed)by a land surveyor,engineer,or architect authorized
by law to certify floodproofed elevation information.
SECTION III
Section III is used by a registered professional engineer or architect to certify that "the structure, based upon
development and/or review of the design, specifications, as-build drawings for construction and physical
inspection" has been designed and constructed in accordance with "the accepted standards of practice
(ASCE 24-05, ASCE 24-14, or their equivalent) and any alterations [of the structure]" meet those standards, are
watertight and substantially impermeable and will perform in accordance with 44 CFR§ 60.3(c)(3). The designer
also certifies the structure has structural components that are "capable of resisting hydrostatic and hydrodynamic
flood forces,including the effects of buoyancy, and anticipated debris impact forces."
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 39
SECTION III—FLOODPROOFED CERTIFICATION(By a Registered Professional Engineer or Architect)
Non-Residential Flood roofed Construction Certification:
1 certify the structure,based upon development andlor review of the design,specifications, as-built drawings for construction and physical
inspection, has been designed and constructed in accordance with the accepted standards of practice(ASCE 24-05.ASCE 24-14 or their
equivalent)and any alterations also meet those standards and the following provisions.
The structure,together with attendant utilities and sanitary facilities is watertight to the flood proofed design elevation indicated above.
is substantially impermeable to the passage of water,and shall perform in accordance with the 44 Code of Federal Regulations
K (44 CFR 60.3(c)(3).
All structural components are capable of resisting hydrostatic and hydrodynamic flood forces,including the effects of buoyancy,and
anticipated debris impact forces.
1 certify that the information in Section 11l on this certificate represents a true and accurate determination by the undersigned using the
available information and data. I understand that any false statement may be punishable by fine or imprisonment under 18 U_S. Code,
Section 1001.
CER❑TIFIER'S NAME LICENSE NUMBER(or Affix Seal)
TITLE COMPANY NAME
ADDRESS CITY STATE ZIP CODE
SIGNATURE (DATE PHONE
Instructions:
n K The signer of Section III certifies that floodproofing has been designed and constructed to meet accepted standards of
practice.Accepted standards of practice must ensure that the criteria of the 2005 or 2014 editions of ASCE 24, Flood
Resistant Design and Construction(or the equivalent), are met and that the two specific design statements are valid.
ASCE 24 contains several criteria for dry floodproofing.Design professionals who prepare designs for dry floodproofed
buildings and certify NFIP Floodproofing Certificates should review all ASCE 24 criteria before completing and
signing the certificate.Also see Technical Bulletin 3 and FEMA P-936,Floodproofing Non-Residential Buildings.
FL 1 Enter the name, license number, title, company name, and address and phone number of the individual completing
Section 111. Section III is to be completed(signed,dated,and sealed)by a registered professional engineer or architect
authorized by law to certify structural designs.
40 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
END OF THE FORM
The end of the NFIP Floodproofing Certificate lists information that must be attached. The information is
needed by the program's underwriters to provide credit for floodproofing. The information also helps to ensure
compliance and provide reasonable assurance that due diligence has been applied in designing and constructing
floodproofing measures. When the Floodproofing Certificate is used to obtain flood insurance coverage from
the NFIP, building owners should consult with flood insurance providers to determine additional required
documentation described in the National Flood Insurance Program Flood Insurance Manual(FEMA, 2020b).
FLOODPROOFING CERTIFICATE FOR NON-RESIDENTIAL STRUCTURES
Instructions for Completing the Floodproofing Certificate
for Non-Residential Structures
To receive credit for floodproofing,a completed Floodproof ng Certificate for Non-Residential Structures is required for non-residential
and business buildings In the Regular Program communities,located in zones Al—A30,AE,AR,AR Dual,AD,AH,and A with BFE.
M In order to ensure compliance and provide reasonable assurance that due diligence had been applied in designing and constructing
floodproofing measures,the following information must be provided with the completed Floodproofing Certificate:
•Photographs of shields,gates,barriers,or components designed to provide floodproofing protection to the structure.
•Written certification that all portions of the structure below the 6FE that will render it watertight or substantially impermeable to the
passage of water and must perform in accordance with Title 44 Cade of Federal Regulations(44 CFR 60.3(c)(3)j.
•A comprehensive Maintenance Plan for the entire structure to include but not limited to:
• Exterior envelope of the structure
• All penetrations to the exterior of the structure
• All shields,gates,barriers,or components designed to provide floodproofing protection to the structure
• All seals or gaskets for shields,gates,barriers,or components
• Location of all shields,gates,.barriers,and components as well as all associated hardware,and any materials or
specialized tools necessary to seal the structure.
Instructions:
RThe additional information listed in the"Instructions for Completing the Floodproofing Certificate for Non-Residential
Structures"at the end of the Floodproofing Certificate must be included.
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 41
Appendix B: Example Calculation for Estimating
Total Seepage
Appendix B of the National Flood Insurance Program's Technical Bulletin 3, Requirements for the Design and
Certification of Dry Floodproofed Non-Residential and Mixed-Use Buildings, contains an example calculation for
estimating the total expected seepage into a dry floodproofed area. Total seepage is the combination of seepage
through the wall system, seepage around flood shields (barriers), and seepage through joints and penetrations.
A description of the calculation of seepage that is illustrated in this appendix is provided in the Technical Bulletin,
Section 6.8, Step 8: Design Waterproofing System.
To be able to design and certify that a building is substantially impermeable, the design professional needs
to estimate the total expected seepage into dry floodproofed areas. A dry floodproofed building that is made
substantially impermeable through the use of materials and techniques allows limited accumulation of water to
pass or seep through pathways (e.g., cracks, openings, channels) and points of entry during flooding. Water is
allowed to accumulate to a depth of not more than 4 inches in a 24-hour period without relying on devices for
removal of water.
The estimate of expected total seepage is used to determine whether the proposed dry floodproofing measures
will meet the requirement (expected depth of accumulated water is not more than 4 inches). If the expected total
seepage accumulation exceeds the maximum allowance, the designer must select one or more alternatives to meet
the requirements, such as a different wall system, fewer openings that require flood shields, different types of
shields, or relocating utility penetrations.
The example calculation in this appendix illustrates how
to calculate seepage for an example building. To estimate SERRI REPORT
the seepage through the wall system, the example applies BASED ON 3-FOOT FLOOD DEPTH
the results of a seepage study by Oak Ridge National It is important to note that the seepage
Laboratory, which were published in SERRI Report accumulation in the SERRI report is based
80024-01, Floodproof Construction: Working for Coastal on a 3-foot flood depth (ORNL, 2011).
Communities (ORNL, 2011). The study tested a series of Designers should use caution when
"pods" constructed of different materials using different estimating total seepage rates for greater
methods by exposing them to 3 feet of water over more flood depths because the seepage rate
than 24 hours. may be higher because hydrostatic loads
The wall system selected for the example calculation is would be greater.
identified in the SERRI report as "Test Pod H." Test Pod
H was constructed of 8-inch concrete masonry unit(CMU)
blocks with elastomeric weatherproofing membrane sprayed onto the exterior of the CMU block face. Excerpts
from the SERRI report are included in this appendix, including a diagram of Test Pod H and observations from
the flood simulation tests.
42 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Calculation of Expected Seepage in an Example Building
Table B-1 and Calculation Steps I through 4 illustrate the calculation of the expected seepage for an example
building with a wall system that is similar to the one used for Test Pod H in the SERRI report(CMU block with
liquid membrane sprayed onto the exterior of the CMU face). Figure B-1 is the plan view of the example building.
Table B-1: Example Building Information
Flood depth h=3 feet
Building length L=30 feet
Building width W=40 feet
Exterior doors
Number ndaa,.=3
Width Wdoo,.= 6 feet Each door is 6 feet wide.
Length of joints in exterior LEj=48 feet The assumption of 48 feet for the example building is
wall through which seepage is based on the likely placement of expansion joints.
expected
Door
1�
6 feet
a�
a?
0
m
6 feet Door
6 feetfeet>�
I I
Jv
Door
40 feet
Figure B-1: Example building plan view
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 43
Calculation Step 1a. Estimate the seepage rate through the wall system.
This example uses the seepage rate through the wall system of Test Pod H from SERRI Report 80024-01. The
seepage rate through the walls of Test Pod H is calculated using the volume of seepage that accumulated during a
24-hour period, divided by the area of the pod.
Area of test pod Apod = 6 ft x 6 ft= 36 ft2
Test pod wetted perimeter ppod_, = 6 ft+ 6 ft+ 6 ft+ 6 ft= 24 ft
Test pod wetted area(flood depth is 3 feet) Apod_,,, = 3 ft x ppod, = 72 ft2
Depth of water(inches)in test pod in d,, = 15.5 in = 1.3 ft
24 hours Note:Depth of water selected from the SERRI report,
page A-5,Table A.2 (shown below)
Volume of seepage in test pod in 24 hours Vpod_s = d, x Apod = 46.8 ft'
Seepage rate through walls of test pod Rwa11 = Vpod_s -Apod_w = 0.65 ft3/ft2 per 24 hours
Calculation Step 1b. Apply the estimated seepage rate to the example building to determine
the volume of seepage through the walls of the example building in
24 hours
This example uses the seepage rate determined in Calculation Step 1 for the wall system of Test Pod H from the
SERRI Report 80024-01.
Example building area Ab1dg = L x W = 1,200 ft2
Total width of doors L'door = ndoor X Wdoor = 18 ft
Building wall wetted perimeter pw = (2 x L) + (2 X W) — Ldoor = 122 ft
Building wall wetted area Awa11 = pw x h = 366 ft2
Seepage through wall system Swall = Awall x Rwall = 238 ft3 per 24 hours
44 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Calculation Step 2. Determine the volume of seepage around flood barriers (shields)
installed over doors of the example building in 24 hours
Some manufacturers test flood shields and gaskets under varying conditions to determine seepage rates (see
Section 3.3 in the Technical Bulletin). Seepage rates are often reported in the volume of seepage per length of
gasket in a given period of time(ft3/ft-hr or gal/ft-hr).
Door wetted length Ldoor-w = ndoor X (h +h +wdoor) = 36 ft
Flood barrier(shield) seepage rate RFB = 0.08 gal/ft-hr = 0.011 ft3/ft-hr
Note: 0.08 gal/ft-hr is based on a manufacturer's technical
specification. Designers must determine the actual rate based
on specified flood shield(s).
Seepage through flood barriers (shields) SFB = Ldoor_w x RFB X 24 hr = 10 ft3 per 24 hours
Calculation Step 3. Determine the seepage volume through expansion joints in the example
building over 24 hours
Determination of the seepage rate through expansion joints may be difficult and may require more research than
wall seepage estimates or flood shield gasket seepage rates. Some manufacturers may provide sufficient product
information to allow the designer to estimate the amount of seepage through joint sealants under flood conditions.
When seepage rates under flood conditions are not provided or are deemed inadequate for this purpose, designers
may decide that it is necessary to perform mock-up testing of joints or penetration assemblies using the anticipated
hydrostatic pressures (see Section 6, Step 8B, in the Technical Bulletin).
This example considers only seepage through expansion joints. Additional estimates must be made if there are
penetrations and cracks below the flood protection level.
Seepage rate at expansion joints REJ = 0.80 gal/ft-hr = 0.107 ft3/ft-hr
Note: 0.80 gal/ft-hr is based on testing of similar joint sealants.
Designers must determine an appropriate seepage rate based
on specified sealants.
Seepage through all expansion joints SEJ = LEJ x REJ x 24 hr = 123 ft3 per 24 hours
Calculation Step 4. Calculate the total estimated seepage for the example building
Seepage through walls, plus flood barriers STota1 = Swa11 X SFB + SEJ = 371 ft3 per 24 hours
(shields),plus expansion joints
Depth of seepage per 24 hours dseep = STota1 -Abldg = 0.31 feet or 3.72 inches per 24 hours
Conclusion
For the example building, the total estimated seepage is less than 4 inches in 24 hours, which means the example
building meets the requirement to be considered substantially impermeable. The designer must also satisfy other
requirements including determining where the seepage will accumulate and the paths along which seepage water
will flow to get to the accumulation area. The interior drainage collection system must be designed to limit the
accumulation of seepage (see Section 6, Step 9, of the Technical Bulletin).
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 45
SERRI Report Excerpts
Southeast Region Research Initiative
4.2.8 Test Pod H:Weatherproofed Block
Test pod H:weatherproofed block(Fig.4.15)was a CMU block structure with a
liquid membrane sprayed onto the exterior of the CMU face.
• First course(8"in height)of CMU cells filled with mortar.
• Fully grouted CMU cells located at corners and at the middle of each wall.
• The flood resistive layer was an elastomeric waterproofing coating for
masonry and concrete,applied in four thick coats.
• Design was developed as an inexpensive alternative to test pod A:sealed
block which performed well with a high-end spray-applied water resistive
layer.
• Elastomeric coating was applied with a residential sprayer.
1
GROUT FILL WITH WATER
RESISTANTADOFNE
8XRX18CMl1
VERTICAL REINFORCING BARS(EVERY 30"}
MORTAR CEMENT WITH
WATER RESISTANT ADDITIVE
r
TRUSS MESH REINFORCEMENT Iv
STAINLESS STEEL TRUSS MESH
ELASTOMERIC WEATHERPROOFING
SLAB
Fig.4.15.DIAGRAM:test pod H:weatherproofed block.
56 SERRI Report 80024-01
46 NFIP TECHNICAL BULLETIN 3 JANUARY 2021
Southeast Region Research Initiative
A.2 Observations From Flood Simulation 2
Table A.2 is a log of the visual observations taken during flood simulation 1,which took
place between June 281h,2011 and June 29th,2011.At specific time intervals,which are noted
in the second column of this table,interior water depths were recorded for each test pod.
Also,key observations regarding assembly changes are noted where applicable.
Table A.2.Observations from flood simulation 2.
Test Pod G Test Pod H Test Pod A Test Pod 32 Test Pod D2 Test Pod F2
Flooding Interior Interior Interior Interior Interior Interior
Simulated Water Depth Water Depth Water Depth Water Depth Water Depth Water Depth
Date Time Depth(in) (in) (in) (in) (in) (in) (in)
28-Jun 7:45 AM 0 0 0 0 0 0 0
8:36AM 10
seepage 0 0 0 seepage two seepage two
south wall corners corners
more
8:SOAM 14
seepage, seepage 0 0 more more
capillary started seepeage seepage
action
seepage,
9:45 AM 24 0 seepage 0 early cells areseepage 0.13
seepaging
more
10:45AM 36 0.25 1.5 0 0.5 0.5 0.25
corner
11:45 AM 36 0.5 3.75 1.5 0.5 0.25
seepage
12:45 PM 36 0.75 6 0 2.25 0.5 0.25
1:45 PM 36 1 6.5 0 3 1 0.25
2:45 PM 36 1 8 0 4 1.25 0.25
3:45 PM 36 1.25 9 0 5 1.25 0.25
5:45 PM 36 1.5 10 0 7 3 0.5
7:45 PM 36 1.5 12 0.25 8 3 0.5
9:45 PM 36 2.5 12.5 0.25 9 2.5 0.5
11:45 PM 36 2.5 14 0.25 10 2.5 0.5
29-Jun 1:45AM 36 3 13.5 0.25 10 3 0.5
3:45 AM 36 3 15 0.25 13.5 3 0.5
5:45 AM 36 3 15.5 0.25 13.5 3 0.5
7:45 AM 36 3.5 15.5 0.25 13.5 3 0.5
9:45 AM 36 3.5 16 0.25 14 3.5 0.5
10:45 AM 36 3.75 16.5 0.25 14.5 3.75 0.5
11:45AM 31 3.75 16.75 0.25 14.5 3.75 0.5
1:45 PM 12 3.75 17 0.25 15.5 3.75 0.5
5:00 PM 0 3.75 17 0.25 15.5 1 3.75 0.5
SERRI Report 80024-01 A-S
NFIP TECHNICAL BULLETIN 3 JANUARY 2021 l%