Miscellaneous
STATE OF FLORIDA
irpnrtmrht of ~tutr
THE CAPITOL
TALLAHASSEE 32304
Jesse
Jr.
L. ROSS MORRELL, ACTING DIRECTOR
DIVISION OF ARCHIVES, HISTORY, AND
RECORDS MANAGEMENT
(904) 488-1480
September 11, 1978
IN REPLY REFER TO:
Mr. William Roberts, Director
Monroe County Development Department
Post Office Box 1029
Key West, Florida 33040
Re: West Martello Tower Development, Phase I project,
#12-77-00172-00
Dear Mr. Roberts:
Enclosed are our comments on the preliminary report
prepared by Carr Smith and Associates, Inc. on the West
Martello Tower, and copies of several technical publications
dealing with the preservation of masonry structures.
As you will note in the commentary, we are somewh_at
concerned with the proposed waterproofing treatment. Al-
though ,a variety of masonry sealants have been widely used
in the past, it has become increasingly evident that this
can be counter productive. Once the roof or overhead leaks
are eliminated, the verticle surfaces may cease to be a
problem.
Sincerely,
.iJd~t~/?J; 1~Jv.~ >
William N. Thurston
Chief Preservation Planner
WNT: jb
Enclosu:res
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Comments on Carr Smi th_ and Associa tes Pre liminary Report,
West Martello Tower Develop~ent Project #12-77-00172-00
9 /1/78
The structural review of the facility pointed out the
major structural defects of tILe 'building. This s'ection of
the report was very informative and h,elpful in unders'tand-
ing the proposed restoration methods. Als'o included in the
report 'were the general cons'truction defects and. mechanical
and electrical deficiencies.
In regards to the proposed solutions for repairs, we
have the following cOJPJIlents:
1. The proposed repair of the 14" cavity brick wall on
the arcade and the rebuilding of the arches is an
appropriate and viable solution. An arched entry-
way would be preferable to a "window design. ft
Architectural drawings indicating precise dimensions
and design details should be provided, in addition
to written specifications, to assure that the recon-
struction is compatible with preservation objectives.
Technical drawings will also be necessary to assure
that the design of the buttressing of the broken
arch at the west end is appropriate and properly
carried out.
2. The proposed solution for the end vault repair
seems sound. Again, specifications and working
drawings must be carefully prepared.
3. as a general restoration note, it is of the utmost
importance that any new replacement bricks match the
existing ones and that any repainting be accomplished
with a mortar of similar strength, composition, color
and general characteristics as the original.
4. All proposed solutions to the architectural problems
listed are appropriate if the general restoration
note above is-followed. .
5. In regards to the proposed solutions to the water
infiltration problems, the procedure of removing
plant life, repainting, replacing the roof and in-
stalling cap flashing are all appropriate. We must
warn you, however, that the use of any form of
waterproofing wash, waterproofing and water repel-
lent coatings on vertical masonry surfaces is not
considered appropriate in a. restoration of historic
brick structures. It has been established that such
treatment can lead to the repid deterioration of the
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2
existing brick walls, by trapping moisture in the
bri ck its'elf. We have enclos'ed', for your revi,ew,
"Preservation Briefs' 1 and 2" and a copy' of part of
th,e text of technical manual TM 5-801-2 "Historic
Pres.ervation Maintenance Procedures" tnat deal
s'pecifically with. th.is' problem. We suggest that
Y'Oti weatherproof the s'tructureby completing the
oth~r proposed solutions and then observe ihe re-
s'ul ts for 6 to lZmonths' before attempting any
treatment to the s'urfaces. We have found that
repointing and correcting overhead leaks are, in
most cases, sufficient solutions to adequately
prevent water intrusion.
We have found no other major problems with the proposed
solutions. We suggest that you follow the master plan concept
as s'tated, but eliminate the waterproof "wash" during the
immediate phase. Waterproofing the brick work duririg future
project phases should be considered only if serious water
intrusion problems persist, and then only after additional
analysis and consideration of alternatives.
.
TM 5-801-2
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TECHNICAL MANUAL
.
HISTORIC
PRESERVATION
~
11
1
MAINTENANCE PROCEDURES
I
HEADQUARTERS, DEPARTMENT OF THE ARMY
. FEBRUARY 1977
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tion. Care rr'lust be tdken in rernoviny organic
growths from structures, and building restoration
should include sealing surfaces from root penetra-
tion. I t is not necessa ry to rer-nove a II root systems.
Low pressure steam cleaning and bristle brushin~l
the surface is very effective in the removal of vine
tendrils that remain on masonry surface following
clearing of vines from a building. (Figure 21).
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d,,\trlll}/,' 10 7TmOl',' thon. rlld l,rt'.\\lIfl .~tl'(H" (/nd II
hri~tlt> hrosh i, an ea.p,' wav (0 dran th,' U';J1l.
5-2.10. Relmoval of Graffiti. The inscription of
gra ff it ion thE~ wa lis of bu ildi ngs and publ ic places
is as old as history. In sorne cases t.he graffit i is an
important historic element of the building or site.
Care n'lust be taken to di f ferent iate between a
historic collection of names or unit designations
and modern graffiti that may be present on a
histor ic st ructu reo The pr act ice of rernov iny all
graffiti as it is applied t.o prevent its accumulation
is sound but the removal of modern graffiti and the
preservation of historic graffiti is difficult.
5-2.10.1. C:autions and Procedures. Most
modern graffiti are applied with paint, o1arking
pens or lipstick. These can be removed with sol-
vents but ex treme care is necessary. The marking
material must be analyzed or tested to determine
what its solvent may be. Solvents rTlust be selected
so that they do not carry the dissolved rnarking
material into the building rnaterial or spread it on
the surface as a stain. With a properly selected
solvent and working in a reasonably small area the
graffiti can be lifted from the surface. With particu-
larly stubborn mark ings or sta ins a solvent shou Id
be ~repared and applied and reapplied until the
stain is removed. Although these are slow pro-
cesses, they wi II leave the surface clean and
TM 5-801-2
uninlpai red. There is no "wipe on/wipe off"
remedy for graffiti markings. Under no circum-
stance should abrasive methods of grinding,
sanding or sand blasting be used to remove graffiti
from masonry. The application of coatings to wall
surfaces for protection or easy removal of graffiti is
aesthetically unacceptable for historic structures.
5-2.11. Removing Paint From Masonry.
5-2.11 .1. Introduction. Painting of masonry
surfdces was cornrnon in the nineteenth century.
This was especially true of brick. Brick masonry
was sometimes painted a dark red with a pattern of
brick joints penciled or striped in white. The paint
was generally applied to protect the masonry
against water penetration or in an effort to mask
later alterations.
5-2.1 , .2. Cautions and Procedures. Removal
of paint is difficult and in most cases undesirable,
since another waterproofing material may be
required. Many historic brick buildings were never
painted and care should be taken that the brick is
not painted unnecessarily. I n most cases it is logical
and less expensive to repair the existing paint after
rernoval of loose or blistering sections. If removal
of paint is necessary.care is required. Application
of specifically designed alkaline paint removers will
eventually strip off the paint coat but in some
instances the remover will cause efflorescence.
Thorough rinsing of the stripping agent is manda-
tory especially if a waterproofing agent is to be
applied. Sand blasting, grinders or sanding discs
must not be used to remove paint from brick or
soh stone. Even with extreme care the surface of
the nlasonry unit will be damaged allowing the
penetration of moisture and dirt.
5-3. WATERPROOFING AND DAMPPROOF~
ING MASONRY WALLS.
5-3.1. Introduction. Old masonry often con-
tains large amounts of moisture. I n such instances
it is important that the moisture should be able to
evaporate continuously. I f masonry of this nature
is treated with a water-repellent such as silicone, or
given a layer of imperv ious plaster, the means for
moisture to escape is obscured. Moisture will then
escape through cracks and minor faults or through
large cracks in the plaster. Waterproof ing of damp
masonry walls on their outer surface increases the
risk of damage due to moisture migrating to the
inside. The moisture fllust escape at some point
and generally it takes the easiest route. Treatment
with a water repellent also causes uneven soiling of
the facade because the areas exposed to rain are
usually washed clean while other areas may
beCOrllC heavi Iy soi led.
5-7
Ti\!1 5-80 '-2
5-3.2. Common Ty~~s of DClmage. Water
pnnetration to the interio~ of Illasonry walls usual.
Iy is not caused by .Jorou 5 masonry but by deteri-
orated gutters and de wnspouts, deteriorated
mortar, capillary ITlcisture from the ground (rising
dclmp) or condensation. In fact, moisture in
masonry is usually not caused bV rain on the wall
surface. Water in the masonry constantly evapo-
rates on the outer surfact~ of the walls, causing a
differential temperature (,n the wall surface and
constant mi!~ration of mDisture inside the wall.
This mi~Jrati()n within the Nail causes an accumula-
tion in the 'Nail of soluble salts fronl the soil or
from the masonry its(~rf. These salts re-crystallize as
efflorescence or crypto fluorescence CJnd in the
expansion of the crystals, particularly below the
surface, deteriorate the masonry. Coatings will not
cure problerns of moisture in the masonry. It is
cornman practice for architects to specify, and
contractors to encourage, the use of waterproofing
coatings following cleaninq projects, however, in
most cases this treatrnent is unecessary and
undesirable. Coatinga are easily penetrdted and
have a short life span. Before a coating is applied, a
thorough analysis of the proJ2lem to be solved and
the suitabilitv of the specit1f; coating rnateriaJ to
the building must be determined. I n many cases of
deteriorating rnasonry, coating materia Is are found
to be the vi lIa ins.
5-3.3. TYPt!s of Coatings.
5-3.3.1. WCllterproof COlltings. Coat ings that
seal the surface frorn water and water vapor are
referred to as waterproo'f coatings. They are
usually opaque such as bituminents and paint.
These coatings do not cause deterioration of the
masonry as long as they exclude all water from the
wall. If water does enter the wall, however,
through voids or ureaks in the coatings or uy
migration frorn other sources, the coating will
intensify the damage to the masonry. Peeling paint
is usuall y the first symptom of this problem which,
in the advanced stages, results in the spalling of the
surface and the deterioration of the masonry unit.
5-3.3.2. Water Repellent Coatings. Water repel-
lents keep water from penetrating the surface but
allow water vapor to leave through the "pores" of
the masonry. T'hey are usually transparent such as
silicone coatinqs but they often have reflective
properties that change the appearance of the
masonry. These coat ings can cause serious damaqe.
They are designed to "lJreathe" to allow moisture
nside the wall to be transpired; however, this
Jreathing allovvs water vapors outside to move
hrough the cOGiting and if the interior of the wall
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pr1tec'. i01, or ::~)rc :i1llr In C(::I~::; S folic I'." nq
~;alld blclStill~ Ci e)i, :;.\:l IV€~ lller/"'l!;;:i it n)a't IJe
de :med de: irab I~ tc :11 'e thl ::iurface ab~;()q'1 it)n
of noistun:. In 'I m e (DIn II:! bl?il'l I caused bV
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:) e I in 1 it t 'et '.0 thE p, (H. i i E !, I' d r 'e (Ii S. P r i 0 r to a p p i i c a-
tio'! of ,:1 tY :reat 11 en, t" d ! I)ti:~~r :,uun.:(~s ('If nloiSl,LJ re
t\iitllirl the 'vall shJ~Jld bE~ ellrninated, and the
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: onr'y, particlllalrl~ of ~it()ne, stE:~nlS frorn a lon~:4-
lterest by [urop'.!ar; rnus~:~urn conservators in the
( on::iolda:ion an<1 pn:.?serVc"t ion crf stone sClJlpture
(: nd arcr itec1:urc! n-10rlL rnents. .T echn iques 'for
(...Itt in~ nl.~w Ina1 eial Hllo old eJeteriorated work
(I"'ld thl~ n!palr of deteriorated or fllissing parts "nth
r astes rnade Lip I) ground stone with a chemical
binder have I::>een p ract ioed by sk i lied stone cutlers
ft >r centu r ies., 'iNi th the c1i sappf~ara nee of these sk i ills
(j H.j I h (~ d d f ; I::: lJ It,,:~ S 0 f a p pd \;1/ I n 9 the se t e c h n i q u es to
tIle overvvhelrninH rnagnitud'E' of ~;lone deterioratj1on
e\'ident in the world's rnonurnents, there has been
all ever. ~Jrowi nq ir terest by chern ists, geologi sts and
conservators to aJ:ply modern scientific methods to
Ii lding the mean:; of conso I idating and preserving
dl,ten,orati r")g tllaSon ry. Cu rrent. vvork is focused on
finding nevv vvays to repair rnasonry with stone or
b , i c k ITl ate ria I mat ch in 9 the 0 rig in a I , to deve lop
ccrnposli~ions that can he 'Norked as a pldstic nl,IX,
to repair or n~place missing I"nasonry surfaces, and
to find or9anic or inorganic chernicals that Cc.Hl be
inl,pregnated into the masonry to form a chemical
b()nd with the particles of the material and make it
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