Information Booklet No. 82, 1993

National Trust for Historic Preservation

TREATMENT OFFLOOD-DAMAGEDOLDER AND HISTORICBUILDINGS

Inside:

How to care for wet plaster

Problems with your foundation

Treatment for saturated wood-framed walls and floors

Exterior paint problems

Cleaning out the mud

How to treat historic wallpapers

Where to go for assistance

Checklist of practicalconsiderations

We encourage you to duplicate thismaterial for distribution to anyonewho might find it useful. It is our intentto get this information as quickly aspossible to those individualsresponsible for flood-damaged olderand historic buildings.

Photo: Bonaparte, Iowa, July 1993

Please note that to the best of our knowledge the information in "Treatment of Flood-Damaged Older and Historic Buildings" is valid for flooded structures in New Orleans and Louisiana towns. One difference, however, is that Louisiana experts tell us that, once the structure is opened up and ventilation is allowed, at some point, which could be a matter of several hours or a few days, the structure should be closed up and mechanical means such as dehumidifiers or air conditioners should be used. This is because of the extremely high humidity in New Orleans and lower Louisiana, and thus natural ventilation will only make so much progress. This is different than the advice contained in the booklet which was focused on more northern areas. For more specific Louisiana mold information, we suggest visiting: LSUAgCenter.com or LouisianaFloods.org.

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any older and historic build-ings have been affected by the

heavy rains and flooding thatoccurred during the spring and sum-mer of 1993. The purpose of thisbooklet is to help building ownersminimize structural and cosmeticflood damage. It contains generaladvice written to cover a wide varietyof buildings with varying degrees offlood damage. If you suspect thatyour building may have somestructural damage, contact a qualifiedstructural engineer or architect tothoroughly assess the situation andsuggest remedies. Your state historicpreservation office (SHPO) canprovide you with a list of architectswho are experienced in the treatmentof historic buildings.

A description of the tax credit pro-grams for rehabilitation of historicstructures, free technical publicationsavailable through your state historicpreservation office and the FederalEmergency Management Agency(FEMA), telephone numbers you cancall for more assistance, andadditional resources are provided atthe end of the booklet.

Once you are able to return to yourbuilding, the first tasks will likely beto remove mud and debris and toinspect the building for damage.Saving your building, no matter howhistoric, is not worth losing your lifeor risking permanent injury. Pleaseobserve these safety precautions:

• Do not walk through flowing water.• Do not drive through a flooded area.• Stay away from power lines and

electrical wires.• Make sure that all of your electricity

is turned off. If any electrical wiringwas submerged, have it inspectedbefore turning the power back on.

• Look before you step. Floods de-posit mud which makes mostwalking surfaces very slippery.

• Be alert for gas leaks.• Carbon monoxide exhaust kills. If

you use electrical generators or

charcoal grills, make sure that theyare properly vented.

• Clean everything that got wet.Floodwaters carry sewage andchemicals. Hose down concrete andmasonry walls. Scrub all surfaceswith disinfectant. Discard any foodand medicine that came in contactwith floodwater. Wear protectiveclothing and make sure the buildingis properly ventilated while workinginside.

Remember to follow local health guidelines concerning preventative shots or vaccinations.

After the Water Recedes

No other "element" is as destructiveto buildings as water. After yourbuilding has been saturated and oncethe floodwaters recede, it is importantthat the drying process beginimmediately. Most of the damagingeffects of water, such as rot, rust, andspalling, can be minimized byreducing both interior arid exteriormoisture levels.

The least damaging drying processappears to be one that begins by usingonly ventilation. To speedevaporation, interior air must bevented to the outside. The mosteffective way to do this is to openwindows and doors and allow themoisture to escape. Fans can be usedto speed evaporation by movinginterior air and exhausting humid airto the outdoors.

Using heat or dehumidification toosoon can damage your building. Asmaterials begin to dry, small amountsof heat or dehumidification can beintroduced. Use of mechanical meansrequires some caution:

• None of these devices should beused when water makes their op-eration dangerous.

• Ventilation remains the primary means of removing interior mois-

ture. All of these devices must beused in conjunction with a venti-

lation plan designed to exhaustmoisture-laden air.

• Beware of using industrial dryingequipment to remove moisture at avery fast rate. You are likely tocause permanent damage to woodand plaster.

• If heaters are used without venti-lation, the relative humidity in theinterior may actually increase andfurther spread moisture damage. Ifheaters are fuel powered, the lack ofventilation can be very dangerous topersons inside the building.

Enclosed portions of your building,such as wall cavities, may retainwater for long periods of time whichcan pose a danger particularly towooden elements such as wall studs,floor joists, and columns. It may benecessary to open walls and removeinsulation. Later sections of thisbooklet contain specificrecommendations.

Once the floodwaters recede, you willneed to rinse remaining mud, dirt andflood debris from all surfaces withfresh water as soon as possible. It issafer and easier to remove the mudwhile it is still wet. Do not wait untilthe material is dry. Make sure that allelectricity is turned off beforecleaning with water. Avoid usinghigh pressure water on historicmaterials and exercise extreme carewhen washing decorative features anddamaged or loosened elements.

Silt and mud will accumulate notonly on the floor and furnishings, butin interior wall cavities as well. Besure to open electrical outlets andmechanical chases and rinse theseareas thoroughly. Check wiring andconnections for damage and repair asrequired. Let areas dry before closingthem. Check heating and airconditioning ducts and clean out anymud or dirt before turning on theunits. Large systems may need to bedismantled or cleaned by aprofessional.

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To clean any remaining dirt andstains, use a standard non-sudsinghousehold cleaning product as di-rected by the manufacturer. Specialcare should be used when working onor around historic materials. Aftercleaning, use a disinfectant to kill thegerms, bacteria, and odor left byfloodwaters.

Keep in mind that floodwaters andthe remaining silt are contaminatedby sewage and chemicals. Protectyour eyes, mouth, and hands, andwear a mask and rubber gloves whencleaning out debris left byfloodwaters. Use disinfectants towash your hands before eating.

Before you begin to clean up yourhistoric property, it is important tocarefully document any damage to thestructure. This is essential not onlyfor insurance purposes, but also torecord important historic buildingfeatures. If building components areremoved for cleaning or repairpurposes, a photograph will help toensure that they are reinstalledcorrectly.

Take photographs and make writtennotes describing the damage. A videorecording is also a very effective wayto document flood damage. Takephotos or videos of any discardeditems. Because of the intensivecleanup that takes place following aflood, materials might be carted awaybefore an insurance adjuster is able toassess the loss.

Create an inventory of found items,dislodged architectural features,decorative fragments, and furnish-ings. Do not throw away materialsat will. Furnishings and architecturalelements can be carried a greatdistance by floodwaters, and itemsfound on your property may beextremely valuable to a nearbyrestoration project.

Hydrostatic Pressure

If your basement is flooded, it islikely that the level of water in yourbasement is the same as the ground-water level outside of your house.When this happens, pumping thewater from the basement will do nogood. New water will continue toseep in until the groundwater leveldrops.

Foundation Collapse

You should be aware that pumpingwater from your basement can bedangerous. This water may be pro-viding the necessary pressure to bal-ance the hydrostatic pressure of thegroundwater. If the groundwater levelis higher than your basement floorand you pump the water from yourbasement, the foundation walls couldbe pushed inward and collapse.

If your basement is flooded withseveral feet of water and you arereasonably certain that your floordrains are operational, you can as-sume that the groundwater table ishigh. It is advisable to leave the waterin place until the groundwater tablesinks and the water recedes by itself.If your basement contains only a fewinches of water, however, you may beable to pump it out safely. Keep inmind that if the groundwater level ishigher than the floor, the water willreturn.

Even if you cannot pump the waterout of the basement, you should stillbegin to ventilate the rest of thebuilding. The sooner these materialsdry, the less chance of water-relatedproblems. Consult with local healthofficials to determine if there is anysanitizing agent that can be used totreat standing water in the basement.

Water can exert tremendous pressureon foundation walls and floor slabs. Ifany portion of a building lies below

As the FloodwatersRecede-A Checklist ofThings To Do

The following checklist will help yourespond to flood damage in historicand older buildings. Read the stepsthrough carefully and take time toplan. While it is tempting to waderight in with a shovel and mop, it isvery important to develop a plan forcleanup and rehabilitation. Unfortu-nately, overly zealous cleanup effortscan result in historic materials beingcarted away, excessively roughcleaning methods, and the unneces-sary loss of historic fabric. The bestway to prevent additional damage tohistoric structures and materialsduring a time of duress is to usecaution and plan ahead.

Follow all emergency rules, laws,and regulations

Turn off all utilities

Document building damage

Wear protective clothing

Stabilize any unstable structureswith temporary bracing

Use caution when pumpingbasement water

Keep building properly ventilated

Clean everything that got wetwith a disinfectant

Allow saturated materials to dryusing natural ventilation

Check for foundation damage

Replace soil around foundation

Save historic materials if possible

Use caution when removinglead-based paint or any productscontaining asbestos

Clean and repair roof and roofdrainage systems to protect buildingfrom future damage

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he groundwater level, one of twohings will happen: basement slabeaving or loss of mortar.

asement Slab Heaving

f foundation walls are tight enougho hold back groundwater, it is likelyo seep through the floor slab, causingt to leak or heave. In some instances,ery high water pressure may benough to raise the floor slab.ortunately, this is not a commonccurrence in historic buildings.

If your basement slab heaves, youcannot correct the problem imme-diately. First wait until the soil be-neath the building dries thoroughly,as part of the problem may be thepresence of clay soils that expandwhen wet. Concrete slabs in newerbuildings are usually poured over asand bed, which helps them to resistsoil pressures, while older concretefloors were often poured right overthe existing dirt. If you pour a newslab or surface-coat the existing slab

before the clay dries, the new slab orsurface could crack when the clayshrinks to its normal dimensions.

If the slab is still heaved or cracksremain after the water recedes and thesoil has dried, there is little you cando except to repair the cracks or, inthe case of severe heaving, pour anew slab.

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Loss of Mortar

The basement may leak and fill withwater. This is usually the case witholder buildings and actually protectsthe foundation walls from collapse ifthe groundwater level is too high.Unfortunately, as water passesthrough stone and brick foundationwalls, it sometimes carries mortarwith it.

The foundations of most older andhistoric buildings are masonry. Stonefoundation walls with soft limemortar are very durable, although thelime mortar does not hold up well towater erosion. Inspect the mortar ofstone masonry foundation walls toensure that it has not leeched from thejoints and made the wall unstable. If asignificant amount of mortar has beenlost, it can usually be replaced with-out dismantling the wall. In manycases, a "loose" mortar can be pouredinto the joints to fill the voids.

Make sure that replacement mortar isnot too hard for the surroundingstone. If the wall is constructed of

sandstone, the new mortar shouldcontain at least two parts hydratedlime to each part of white Portlandcement and nine parts sand (known asASTM "Type 0" mortar). If thefoundation wall is constructed oflimestone or other relatively hardstone, a standard tuckpointing mortarmay be used (ASTM "Type N"containing one part hydrated lime toone part white Portland cement andsix parts sand).

If the foundation walls are con-structed of brick masonry or concreteblock, there will likely be lessleeching of mortar than if the wallswere constructed of stone. Never-theless, they should be inspected formissing mortar and repaired in thesame manner as aboveground walls,unless there is reason to suspect amore serious structural problem cre-ated by the flooding (see "FoundationErosion" below). Generallyfoundations constructed of concreteblock used a harder mortar containinggray Portland cement.

Erosion

Foundation Erosion

Water currents and water traveling inunderground "streams" can erode soilbeneath foundation walls andfootings. Although this situation isnot common, when it does occur thebuilding's foundation will bedestabilized and repairs will benecessary. The best evidence ofstructural destabilization is theappearance of cracks in the founda-tion walls and in plaster or drywallabove the foundations.

Keep in mind, however, that not allcracks that appear after a flood areindications of long-term instability.Some may result from temporaryexpansion of clay soil around thefoundation. When the soil returns toits natural water content, the cracksshould shrink or, at the very least, notexpand. Other cracks may result frommoisture-related expansion of woodbeams and joists tied to thefoundation walls. These cracksshould shrink as the wood dries.

Cracks from foundation erosion,however, can be expected to worsenover time as the building settlesslowly to its new soil support. Thebest indicator of this type of structuralproblem is cracks that move. Move-ment, particularly widening of cracks,is a sign of structural instabilitywarranting careful examination by aqualified structural engineer orarchitect.

The best way to determine whether acrack is moving is to purchase adevice called a "tell-tale." This smallgauge is glued to a wall on either sideof a crack. Its markings indicate thecrack's horizontal and verticalmovement over time. This device canbe obtained from engineering orscientific supply firms or by writingthe manufacturer directly. (AvongardCrack Monitor, 2836 Osage,Waukegan, IL 60087, 708/244-4179)

Another way to determine whethermovement exists is to glue a glassmicroscope slide across a crack. If theslide breaks, movement is occurring.

Soil Erosion

Water may erode the soil adjacent toyour building. This can lead to twoproblems:

The soil may be "dished" next tothe building which may result inadditional damage from future rain.The soil adjacent to the buildingshould slope away from it to ensurethat future rains do not drain intothe building. After the floodwaterssubside, check the soil drainagepattern and re-grade as necessary.

A less common soil problem is theloss of enough dirt to protect yourfoundation from frost-heavingduring cold weather. If the found-

ation is not sufficiently below thefrost line, it may heave upwardwhen the ground beneath it freezes.For this reason, it is best to replaceany lost dirt adjacent to thefoundation.

Heaving of Sidewalks and Slabs

Erosion can also affect paving. Froma building conservation perspective,the worst problem occurs wheneroded slabs of asphalt or concretechannel water into, rather than awayfrom, buildings. As with soil erosion,this can lead to water problems fromfuture rains.

If this condition exists, the slabshould either be raised (by mud-jacking, for example) or it should beremoved and replaced with one thatdrains properly.

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Saturation of Insulation

With few exceptions, any insulationthat has been immersed in watershould be removed for two reasons:

After being saturated, most insu-lation is rendered permanently in-effective, particularly loose-fillvarieties, such as cellulose, ver-miculite, rock wool, and blownfiberglass, which tend to collapseunder their own weight.

Saturated insulation holds waterwhich, if left in place, can perpetu-ate high moisture conditions de-structive to wood, masonry, andsteel.

Some types of insulation may be leftin place after water contact, such asclosed-cell styrene and urethaneboard insulations that do not absorbwater. These should be inspected todetermine whether they hold moistureagainst wood or masonry materials orsteel fasteners. if so, the insulationshould be removed until all materialsare dry. Any mud or silt that remainsin the cavity should be removedregardless of the insulation'scondition.

Other types of insulation, such asfiberglass battens, must be evaluatedon a case-by-case basis. Glass fibers,in themselves, are not waterabsorbent, but if they impede the flowof air in a wall cavity, and thus thedrying-out process, it may benecessary to remove them.

Wood Rot

Wood rot occurs when naturalfungi--present in virtually all con-struction lumber--grow in wood. Likeother living organisms, they needfood (wood), air, proper temperatures(between about 60-80 degrees F.),and water in order to grow. In mostwood construction, the missingelement is water which is whyordinary wood lasts for centurieswhen protected from moisture.

Fortunately for flooded buildings, thefungi must exist over a relatively longperiod of time in order for wood rotto be destructive. Damage from aone-time event, such as a flood, isusually negligible if the wood isallowed to air dry. Problems occurwhen saturated wood is encapsulatedso that the water cannot evaporate.

Two areas where wood is normallyencapsulated are wall cavities and sillplates, particularly when these areasare filled with insulation. Figure 3describes treatment of walls and sillplates. To properly ventilate walls, itwill probably be necessary to cut ordrill holes-taking care not to damagepipes and wires buried in thewalls-and remove the insulation.

Masonry and ConcreteDeterioration

Soluble Salt Damage

Masonry and concrete contain im-purities, including water-soluble salts.When these materials are saturated,the soluble salts dissolve and arecarried to the surface duringevaporation. The result is an un-sightly white residue called efflores-cence on the exterior or interior of thebuilding--wherever water evaporates.These deposits are not usuallyharmful and frequently they dissolveand disappear naturally when it rains.Stubborn efflorescence mayberemoved with water, detergent andbristle brushes, or with chemicals.

Soluble salts can cause significantdamage when the building's exteriorsurface has been treated with buildingsealer. If this is the case, the salts willtravel toward the outside surface, butbecome trapped behind the surface bythe sealer. The water vapor eventuallyevaporates, but the salts are leftbehind to crystallize and expand,pushing off the surface of the brick orstone in a process called spalling.

The presence of paint on masonry orconcrete walls may also retard thepassage of water. Because the paintdoes not penetrate the masonry orconcrete, it is usually removed by thewater passing through the wall or bythe salt crystallization that takes placejust under the paint layer. While thepaint may be removed, the surfaces ofthe brick, stone, or concrete remainintact.

The most obvious way to prevent saltdamage is to never apply sealer to abuilding. If your building has beensealed, there is little that can be doneto prevent spalling.

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Freezing and Thawing Damage

When water freezes, it expands. If thewater is encapsulated inside buildingmaterials, the expansion can tearthem apart. Thus, if significantamounts of water remain in masonryor concrete by early winter, when theweather goes through rapid periods offreezing and thawing, the result issimilar to the crystallization of salts:the faces of the masonry or concretemay spall.

Ordinarily, water will evaporate evenfrom saturated masonry and concreteat a rapid enough rate that freeze-thaw damage will not occur. Someconditions under which evaporationmay be impeded and spalling maytake place are described below.

Masonry or concrete has beentreated with a building sealer.Although newer building sealersallow the passage of water vapor,they inhibit the flow of liquid wa-ter and can slow the rate of evapo-ration. Unfortunately, little can bedone to mitigate the effects ofbuilding sealer. Some spalling mayoccur.

Masonry or concrete has beenpainted. The vapor pressure of thewater may cause some of the paintto fall off, helping to speed evap-oration. Otherwise, short of paintremoval, little can be done andsome spalling may occur.

Masonry or concrete has beencovered with another buildingmaterial, such as board insulation,wood siding or plasterboard. If thecovering was installed flushagainst the masonry or concrete, itshould be removed temporarily toallow the wall to dry out. If thematerial was installed over sleepersor spacers and an air space exists,it may not be necessary to comp-letely remove the covering mat-erial, but it would be helpful toprovide air holes to ventilate thewall.

Damage to Metals

Metal Fasteners

Most metal fasteners are made of ironor steel which rust and expand whenexposed to water. Fasteners, such asnails, should not be harmed byimmersion in floodwaters, as long asthey are allowed to dry soon after thewaters subside. Opening wall cavitiesand removing insulation may benecessary. If nails are subjected tolong-term moisture, rust may becomesevere and the nails may fail.

Rusted or weakened nails probablywill not cause significant structuralproblems in the lower portion of abuilding-the portion most likely to beimmersed by floodwaters. In mostcases, such as at the sill plate, thenails hold the wood in position butare not solely responsible for itssupport.

The exception to this is often porchfloor joists. Porches are frequentlyfastened to the house only with nailswhich, if they fail, may cause theporch to collapse. If your porch wassubmerged, make sure it is wellventilated by removing solid porchskirts and allowing the air to flowfreely.

Once the moisture is removed, ironnails pose cosmetic problems bycausing rust stains on finishedsurfaces. This problem can becorrected by driving the nails furtherinto the wood, caulking them, andapplying a primer paint with topcoat.

Damage to Exposed Metals

Most metals will not be permanentlydamaged by immersion in water.Durable metals such as aluminum,bronze, copper, and brass shouldsurvive the flooding completelyintact. Commercial storefronts withcast-iron columns and stoops mayexperience some rusting, but the

surfaces can be sanded clean andrepainted.

Stamped iron-based metal, mostcommonly found in "tin" ceilings andstamped metal cornices oncommercial storefronts, poses moreof a problem. Stamped metal consistsof rust-prone iron, coated with leadand tin (called "terne") or zinc (called"galvanized") to prevent rust. Thesecoatings are usually effective, unlesswater enters the insides of thestampings and is allowed to sit. Thestanding water penetrates theprotective coating and the iron rusts.Stamped metal cornices that havebeen immersed should be inspected tomake sure they haven't filled withwater. If so, find a way to drain thewater and ventilate the back side,either by carefully prying a portionaway from the building or by drillingsmall weep holes on the bottom. Theholes can later be filled with autobody filler and repainted.

There is no easy remedy for stampedceilings that have been immersedexcept to dry the building's interior

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and to monitor the ceilings for pos-sible rusting. Drilling holes to drainwater may be ineffective and remov-ing sections of the ceiling wouldlikely result in damage to the ceilingpanels.

When repairs are necessary, stampedmetal should be treated like auto bodywork. If surface rusting occurs onstamped metal, the rust should beremoved by carefully scraping onlythe rusted areas, priming with a rustinhibitive paint, and then painting. Donot sandblast or attempt to chemicallyclean stamped metal or the protectivecoating will be removed and the metalwill rust quickly.

Damage to Imbedded Metals

The problems of exposed andimbedded iron are fundamentallydifferent. When exposed iron cor-rodes, the problem is mostly cos-metic. When imbedded iron corrodes,it can damage surrounding materials.

When iron rusts, it expands and thisexpansion generates tremendousforce. Of particular concern inflooded buildings are metal lintels--the flat pieces of steel used to supportmasonry or concrete above

door and window openings. Metallintels are usually used on brickbuildings and, when they rust, theycan lift whole sections of a wall.

If your building has metal lintels andthey were immersed in water, somerusting is likely to occur, although therust expansion caused by the floodingalone will not cause a great deal ofimmediate damage. Of greaterconcern is damage to the surroundingmaterials that may allow water toenter on an ongoing basis and causemore severe rusting in the future.

After the water recedes and thebuilding materials dry, check themortar joints near the lintels to seethat the mortar has not cracked orfallen out. If it has, repoint the areaimmediately to make sure that watercannot enter to create further rusting.Before repointing, scrape the metal toremove any loose rust scale. It isuncertain whether rust inhibitiveprimers are effective in retarding rustin these situations.

If other iron-based metals are im-bedded in masonry or concrete, in-spect them periodically and repaircracks in the surrounding materials ifthey occur.

Damage to InteriorFinishes

Drywall

Drywall that was submerged willprobably have to be replaced. Drywallconsists of a relatively soft gypsummaterial held in place by a paper"sandwich." The paper does not holdup well to water saturation and, inmost cases, wet drywall will simplydissolve. If it was not wet severely,drywall may be salvageable after itdries. Even so, FEMA recommendsreplacement as contaminants maymake it a permanent health hazard.As with other aspects of floodcleanup, use your judgment aboutwhether to retain or discard affecteddrywall.

Plaster, on the other hand, is unpre-dictable when wet. Sometimes itsurvives with no damage, other timesit must be replaced. Its durabilitydepends on the plaster mix, the skillused in application, the degree ofsaturation, whether it is applied towalls or ceilings, and the type of lathused. Plaster over metal lath is morelikely to require replacement thanplaster over wood lath.

Check for obvious areas where plas-ter must be removed, such as ceilingswith large sags. If your ceiling sags inan area more than about three feet indiameter, it may be difficult to repairthe damage. That portion of theceiling may need to be removed--withcare. Falling plaster, especially wetfalling plaster, can be dangerous. Ifthe water level was above the ceilingand you suspect that it may containstanding water, you may want to pokedrain holes--with a nail attached to theend of a long stick--in the plasterbefore attempting to remove it. Donot stand directly under the areabeing prodded in case the plasterloosens and falls.

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Except for areas of obvious damage,the best way to determine whetherplaster must be replaced is to let it dryand then inspect it. Here are somesuggestions about how to determinewhether plaster should be replaced:

The surface condition of plastermay not tell you whether it issound. If the plaster keys (sectionsof plaster that serve to anchor theplaster to the lath) have fallen off orif the lath has come loose from thebuilding structure, the plaster mayneed to be replaced.

You can sometimes tell if plaster issound by tapping lightly on the wallwith a piece of wood. Unsoundplaster will sound hollow.

If you ventilate wall cavities byopening holes, look for brokenplaster keys. There will always be afew broken keys, but if the numberis excessive, the plaster is likely inpoor condition.

Plaster damage can be repaired byre-anchoring the plaster to the wallstuds and ceiling joists with screwsand plaster washers. Sound plaster,especially decorative plaster,should be retained in place if it issalvageable.

Damage to Wood Floors and Trim

It is difficult to determine whetherwood trim that has been submergedneeds to be replaced. Most wood willexpand and deform when wet andthen return more or less to its originalform as it dries. The behavior of anindividual piece of wood depends onits species, grain pattern, method ofanchoring, and whether its grainstructure was damaged when thewood expanded against othermaterials.

Tongue and groove hardwood floorsare unlikely to return to their originalcondition. When they expand, theirgrain structures are usually damaged.If you have a saturated hardwoodfloor, let it dry thoroughly. Then, if itremains cupped, you can decidewhether to sand the floor flat orreplace it. When possible, retainoriginal hardwood floors.

Non-interlocking board floors, suchas plain pine boards, stand a goodchance of returning to their originalshapes when dried. A light, surfacesanding and some re-nailing may benecessary.

Wood trim around baseboards, ceil-ings, doors, and windows is likely to

survive a flood because it can usuallyexpand without crushing its fibers.After drying, it should return to itsoriginal form and should be retained.

Wooden doors in older and historicbuildings are likely to be panel doorsthat add to the character of thebuilding. Replacement with standard,hollow-core, flush doors may not beappropriate and the original doorsshould be retained when possible.Fortunately, panel doors usuallysurvive flooding surprisingly well. Ifyou have panel doors, let them dry inplace. It may help to open them toallow better air circulation. As theydry, warping should disappear, andtheir fit and the condition of their gluejoints should be inspected before de-termining whether they need furtherrepair. Be sure that the doors arecompletely dry before attempting torepair or plane them. Also, if theoriginal glue was not waterproof, thejoints may have to be re-glued.

If you need to replace any doors,consider replicating original paneldoors. Hollow core doors will likelyneed to be replaced because their in-ternal spacers are usually made ofcardboard which dissolves in water.

Damage to Interior Paint

After the flood, most painted interiorsurfaces that were under water willhave to be repainted due to waterdamage or contamination. Do notpaint interior surfaces until they arecompletely dry and the interiorhumidity has returned to nearlynormal levels. The exception is thatwall surfaces can be painted with flatlatex paint even if some dampnessexists.

The paint on some surfaces, such aswindow trim, may have been dam-aged and soft enough to scrape off. Ifso, new paint will not adhere until theexisting paint is removed and thewood is dry. Because the wood trimmay contain lead-based paint, espec-

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ially in older buildings, observecaution when removing it and disposeof it properly.

Wallpaper

In many cases, older and historicwallpaper may be saved after a flood,but the decision to retain or remove itis a difficult one. On the one hand,FEMA cautions that wallpaper pastemay be a breeding ground for moldsand contamination and that wallpapersignificantly wet by floodwaters mayhave to be removed and replaced,even if it appears to be in goodcondition. On the other hand, if thewallpaper is of historical importanceor original to your house, you maydecide to retain it. The decision willbe based on the degree of water dam-age, the cost of replacement or re-production, and climate controls thatmay limit future growth of mold andbacteria.

If your house is historic and the ex-tent of damage determines that thewallpaper must be removed, carefullyremove several square feet, all theway down to the plaster. If possible,take samples from several differentlocations including the ceiling. Labelwhich room the paper came from andstore temporarily in a dry part of thehouse until the paper can bepermanently preserved.

Floor Coverings

Most older and historic homes retainfew of their original floor coveringsand most floor coverings can bediscarded with no effect on abuilding's historic character.

One exception to this rule is tilefloors which may be original. Eventhough tile is a durable material, thematerials beneath it, such as woodensub-floors and grout beds, may havebeen damaged. The only way todetermine whether a tile floor issound is to inspect it when

all of the building materials are dry.This might take a long time as the tileimpedes the evaporation process.

If a preliminary inspection shows thatthe underlying structure may bedamaged, the tile floor can be re-moved and re-laid when the materialshave dried. Or the decision whetherto remove or reinstall can bepostponed until the materials havethoroughly dried with the tile floor inplace. The latter method takes longer,but minimizes damage to the tiles.

The most common residential floorcovering is wall-to-wall carpeting.Because of the risk of contamination,carpeting touched by the flood watersshould be discarded, unless it is smallenough to be laundered, such as anarea rug, or valuable enough to beprofessionally cleaned, such as anOriental rug.

Floor tiles, such as vinyl flooring, andsheet flooring are probably nothistoric and should be removed to aidthe evaporation process if theunderlying wooden floor was sub-merged. On rare occasions, somesheet flooring, such as linoleum, maybe historically significant. If this isthe case and you wish to retain it, letthe floor dry as best it can. Once dry,if the floor is level and the flooringadheres, you may leave it in place. Ifthe bond between the floor and thecovering fails, you may be able toremove and relay the flooring. Thereis no guarantee that either of thesetechniques will succeed. If it isimpossible to relay the floor, makesure to save samples of the historicflooring.

Exterior Paint Problems

Paint failure is likely to occur on anypainted surface wet directly byfloodwater or on surfaces throughwhich excessive amounts of waterwill evaporate. Paint failure resultingfrom the passage of water or watervapor will show up as large sectionsof paint peeling all the way down tothe underlying building material. Ifthis happens, allow the underlyingmaterials to dry thoroughly beforeattempting to repaint. If you paintbefore all the building materials havedried thoroughly, the water vaporpressure will "bubble" the new paintand it too will peel.

If the building materials are very wet,it may be necessary to postponepainting for a long time. You maywish to use a water-repellent woodpreservative to help to protect thewood from water-related damage andthe effects of sunlight until you cansafely paint it.

Summary

Churches, schoolhouses, stores,banks, homes, courthouses, and barnsin river and coastal communitiesoften bear watermarks on the wallswhere owners pencil in the dates andlevels of significant floods-the 1937Flood, the 1973 Flood, the JohnstownFlood. Yet many of these buildingshave stood the test of time andsurvived devastating floods. Whilefloodwaters can cause significantdamage to historic buildings, they donot spell the end. With propercleaning and drying out procedures,the only reminder of floodwaters inhistoric structures should be awatermark and date on the wall.

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Acknowledgments

This Information booklet is adaptedfrom the State Historical Society ofWisconsin's Treatment ofFlood-Damaged and Older HistoricBuildings, prepared by Jim Sewell,senior preservation architect. RichardWagner of David H. GleasonAssociates drafted the illustrationsbased on Mr. Sewell's originaldrawings.

Resources

The National Trust for HistoricPreservation and the state historicpreservation offices are offeringemergency grants for flood-damagedhistoric properties through specialfunding from the National ParkService.

Grants from the National Trust areavailable to nonprofit incorporatedorganizations, educational institu-tions, governmental agencies andindividuals for a variety of preserva-tion activities. Assistance will not beprovided for construction projectsand, due to the federal nature of thesefunds, cannot be used for suchpurposes as lobbying, fund raising,aid to religious institutions,entertainment or to match any otherfederal grant.

Grant projects must specifically relateto damages incurred in connectionwith the flood, but may not be used toreimburse expenses prior to the datethe county in which the site is locatedwas declared a disaster area, unlessspecifically approved by the grantaward. No matching funds arerequired.

Contact the National Trust's MidwestRegional Office in Chicago or theMountains/Plains Regional Office inDenver for more information. Theaddresses for these offices are foundon the back cover along with a list ofthe states under the jurisdiction ofeach office.

The Preservation Briefs series, pub-lished by the National Park Service,provide useful technical informationin dealing with the effects offloodwater damage to your old orhistoric building. Contact your statehistoric preservation office or write:Superintendent of Documents,Government Printing Office,Washington, D.C. 20402-9325.Among the titles available are:

#1 The Cleaning and WaterproofCoating of Masonry Buildings

#2 Repointing Mortar Joints inHistoric Brick Buildings

#6 Dangers of Abrasive Cleaning toHistoric Buildings

#7 The Preservation of HistoricGlazed Architectural Terra-Cotta

#8 Aluminum and Vinyl Siding onHistoric Buildings

#9 The Repair of Historic WoodenWindows

#10 Exterior Paint Problems onHistoric Woodwork

#11 Rehabilitating Historic Storefronts#15 Preservation of Historic

Concrete: Problems and GeneralApproaches

#16 The Use of Substitute Materials onHistoric Building Exteriors

#18 Rehabilitating Interiors inHistoric Buildings

#20 The Preservation of HistoricBarns

#21 Repairing Historic Flat PlasterWalls and Ceilings

#22 The Preservation and Repair ofHistoric Stucco

#23 Preserving Historic OrnamentalPlaster

#27 The Maintenance and Repair ofArchitectural Cast Iron

#28 Painting Historic Interiors

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The Federal Emergency Manage-ment Agency (FEMA) also prod-uces several publications that may behelpful to you. These are: RepairingYour Flooded Home – FEMA 234,Flood Emergency and ResidentialRepair Handbook – FIA 13,Floodproofing Residential Struc–tures - FEMA 102, Design Manualfor Retrofitting Flood-Prone Resi–dential Structures – FEMA 114.

Copies of these publications may beavailable through your state or localoffice of emergency services. Other-wise, you may order them throughFEMA’s Chicago regional office bycalling (312) 408-5500, or by writingto: FEMA Publications Office, P.O.Box 70274, Washington, D.C. 20024.

The location of FEMA Regional Of-fices and the states served are listedbelow. If your state is not listed,contact: National Office, State andLocal Programs and Support Direc-torate, Office of Disaster AssistancePrograms, Washington, D.C. 20472or call (202) 646-3615.

If You Need Help

Assistance of various types is avail-able from your state historic preser-vation office. Assistance includessurvey and assessment of damage ofhistoric resources. In addition theSHPO administers the historic reha-bilitation tax credit program forowners of income producing prop-erties certified by the SHPO as his-toric rehabilitation projects. These taxcredits may help to offset the costs ofcarrying out flood damage repair.Other specific flood-related assistancemay be available in your states. Tofind the SHPO in your state, contact:National Conference of State HistoricPreservation Officers (NCSHPO),Suite 332, 444 North Capitol Street,Washington, D.C. 20001-1512, (202)624-5465, www.sso.org/ncshpo.

The National Endowment for theArts’ Museum Program is con-cerned primarily with works of artand with institutions that care for andexhibit works of art. Funds fromseveral categories within the MuseumProgram, as well as the Challengeand Advancement programs, can beapplied toward disaster planning. Formore information contact: NationalEndowment for the Arts, MuseumProgram, 1100 Pennsylvania Avenue,N.W., Washington, D.C. 20506 (202)682-5442.

The American Institute for theConservation of Historic and Artis-tic Works (AIC) and the NationalInstitute for Conservation of Cul-tural Property (NIC) have put to-gether a package of useful materialsrelating to the conservation of flood-damaged archival materials, textiles,art work, antiques, ceramics, etc. Toobtain a free package write: NationalInstitute for Conservation of CulturalProperty, 3299 K Street, N.W., Suite403. Washing-ton, D.C. 20007.

The Small Business Administration(SBA) can provide both direct andbank participation disaster loans toqualified homeowners and busi-nesses to repair or replace damagedor destroyed private property whenthe SBA administrator declares a“disaster loan area” under SBA’sstatutory authority. The disasterassistance numbers for SBA are:Iowa, Missouri, Kansas and Ne-braska (800) 473-0477; Illinois, Wis-consin, and Minnesota (800)359-2227; South Dakota and NorthDakota (800) 488-5323.

Regional and state museumassociations can help coordinateassistance by other museums andmuseum professionals.

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Copyright 1993, National Trust for Historic Preservation

The National Trust for Historic Preservation provides leadership, education, and advocacy to save America's diversehistoric places and revitalize our communities.

Support for the National Trust is provided by membership dues; endowment funds; individuals; corporate andfoundation contributions; and grants from state and federal agencies.

Preservation Books are published by the National Trust for Historic Preservation. For a complete list of titles call orwrite: Preservation Books, National Trust for Historic Preservation, 1785 Massachusetts Avenue, NW, Washington, DC,20036. Phone: (202) 588-6296, Fax: (202) 588-6223. Website address: www.preservationbooks.org.

Richard Moe, President, National Trust for Historic Preservation

Peter Brink, Senior Vice President, Program

Katherine Adams, Director, Preservation Services

Elizabeth Byrd Wood, Editor

Janie Blackman, Business Coordinator

National Trust forum is a membership program for preservationists—from board members to students, from architects toeducators, from preservation commissioners to planners, from volunteers to restoration contractors. Forum membershipprovides you with the knowledge, tools, and resources to protect your community. As a Forum member you receive asubscription to Preservation magazine, Forum Journal, and Forum News. Benefits also include discounts on conferences andall publications listed in the Preservation Books catalog as well as participation in financial/insurance assistanceprograms, technical advice, and access to forum Online, the online system designed for the preservation community.To join, send $115 to: National Trust Forum, National Trust for Historic Preservation, PO Box 96056, Washington, DC20077-7272.

Offices of the National Trust for Historic Preservation:

Headquarters1785 Massachusetts Avenue, NWWashington, D.C. 20036(202) 588-6000resource@nthp.orgpreservation_books@nthp.org

Southern OfficeWilliam Aiken House456 King StreetCharleston, S.C. 29403-6247(843) 722-8552soro@nthp.org(Alabama, Florida, Georgia, Kentucky,Louisiana, Mississippi, North Carolina,South Carolina, Tennessee, WestVirginia)

Southern Field Office1785 Massachusetts Avenue, NWWashington, D.C. 20036(202) 588-6107(District of Columbia, Puerto Rico,Maryland, Virginia, U.S. VirginIslands)

Northeast OfficeSeven Faneuil Hall Marketplace, 4th Fl.Boston, Mass. 02109-1649(617) 523-0885nero@nthp.org(Connecticut, Maine, Massachusetts,New Hampshire, New York, RhodeIsland, Vermont)

Northeast Field Office6401 Germantown AvenuePhiladelphia, Penn. 19144(215) 848-8033(Delaware, New Jersey, Pennsylvania)

Midwest Office53 West Jackson Boulevard, Ste. 350Chicago, Ill. 60604-2103(312) 939-5547mwro@nthp.org(Illinois, Indiana, Iowa, Michigan,Minnesota, Missouri, Ohio, Wisconsin)

Mountains/Plains Office910 16th Street, Suite 1100Denver, Colo. 80202-2910(303) 623-1504mpro@nthp.org(Colorado, Kansas, Montana, Nebraska,North Dakota, South Dakota, Utah,Wyoming)

Southwest Office500 Main Street, Suite 1030Fort Worth, Tex. 76102-3943(817) 332-4398swro@nthp.org(Arkansas, New Mexico, Texas,Oklahoma)

Western Office8 California Street, Suite 400San Francisco, Calif. 94111-4828(415) 956-0610wro@nthp.org(Alaska, Arizona, California, Hawaii,Idaho, Nevada, Oregon, Washington,Pacific island territories)