The following publication is posted at the request of the Preservation
Assistance Division, National Park Service. Please direct further inqueries
to the telephone number given at the end of this document.
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AFTER THE FLOOD:
Emergency Stabilization and Conservation Measures
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Preservation Assistance Division,
U.S. National Park Service
After the flood waters begin to recede, the focus of relief efforts becomes
returning things to normal. During this phase, many historic structures
and properties are needlessly lost and damaged through hasty clean-up
procedures. The best way to help a historic district, property, or
structure prevent additional damage and maintain its integrity and
character during these times of duress is with the use of proper caution
and concern.
While the water is receding, plan the future steps to rehabilitation and
restoration carefully. Each decision made today affects future decisions
which will need to be made tomorrow. The following areas of concern should
be addressed during planning.
PERSONAL SAFETY: The First Priority
1) Return to the area only after it has been declared safe by local
emergency management officials. Follow all emergency rules, laws and
regulations.
2) Identify potential hazards and solicit expert advice and assistance
to minimize the dangers. Report and stay clear from loose power
lines or damaged utilities.
3) Turn off all utilities associated with the historic property to
prevent further damage and minimize future hazards.
DOCUMENTATION: Developing a Condition Assessment Report
1) Prepare a visual record showing the scope of the disaster and the
damage to the historic fabric. This is best done through annotated
photographs, and narrated videotape taken before the cleanup actually
begins.
2) Create an inventory of found items, dislodged architectural
features, decorative fragments, furnishings, collections, etc. DO
NOT THROW AWAY MATERIALS AT WILL. Many items may prove their value
as the surrounding restoration or rehabilitation projects proceed.
3) Use the gathered information to have a team of preservation
professionals develop a prioritized plan of stabilization, repair,
and restoration.
STRUCTURAL STABILIZATION: Temporary Measures
1) Identify potential deficiencies and provide temporary shoring to
protect life, property, and belongings while the water levels are
receding. Successful shoring can be accomplished without increasing
the damage to the historic features or materials. All shoring
measures should be planned with the assistance of qualified
structural engineers or contractors.
* Support unstable or leaning structures or features with
temporary bracing and reinforcement.
* Strengthen exposed foundations or brace areas of undermining by
following engineers recommendations.
* Brace and strengthen decayed or damaged floor and ceiling
structure. Check bearing locations for movement or settlement.
2) Clean and repair the structure's roof and roof drainage system in
order to protect the building from future storm damage.
* Provide temporary protective roof coverings where the existing
roof has been damaged.
* Clean, repair and reconnect gutters and downspouts.
* Drain contained water slowly and carefully from the interior of
the structure to prevent undue stress which may cause
structural failure. Make sure the decreasing water level
remains equal to the exterior and adjacent conditions.
DRYING OUT: Natural Ventilation and Time
1) Carefully remove trapped mud and collected water/storm debris as
water recedes. Do not unnecessarily damage covered historic finishes
or materials.
2) Remove standing water and water-logged furnishings and debris that
maintain a source of moisture within the structure.
* Drain the water from the basements and crawl spaces. Standing
water will migrate and perpetuate the moisture problems on the
upper levels.
* Furnishing should be moved to allow air movement and
ventilation around them.
* Remove and dry water soaked rugs, boxes, and materials.
Paperwork and books may require special care and
considerations.
* Remove water soaked insulation from the attic and if easily
accessible without damaging historic fabric and materials,
remove insulation from cavity wall construction.
* Check and drain trapped water from mechanical chases,
equipment, and HVAC ductwork.
3) Remove residual moisture in a gradual and controlled process through
natural ventilation. Do not use mechanical dehumidification which may
cause additional damage.
* Open windows and doors. Provide protection and security
measures as required through the use of screens and vents.
* Provide moderate ventilation through the use of fans. Heating
may be provided when conditions warrant, but do not hurry the
process. Natural drying is preferred.
4) Allow plaster to dry gradually, avoiding cracking and separation of
layers.
Forced drying through the use of dehumidifiers and heaters may draw
excessive moisture through the plaster leading to excessive
expansion, cracking, and powdering of the finished surface.
Carefully remove all flood soaked Gypsum Wall Board. It is a porous
material which degrades under extreme moisture trapping fungus and
bacteria that pose health hazards.
* Remove trapped water from cavity wall construction and interior
partitions by carefully removing the baseboard and drilling a
drain hole through the plaster and lath near the bottom of each
wall cavity. Do not damage architecturally significant or
character defining features.
* Remove non-historic artificial wall covering and panelling
which may trap moisture within the wall. Consult a
preservation specialist on the treatment of historic wall
finishes.
5) Allow wood to air dry gradually. Promote even drying through proper
ventilation. In most cases, swelling and warping of the solid wood,
flooring and framing, will be minimal and decrease as the wood drys.
Laminate wood surfaces may experience separation and warping caused
by the uneven drying of the layers.
Forced drying through the use of dehumidifiers and heaters will cause
uneven drying, resulting in the cupping, warping, and checking of the
wood.
Monitor the wood. If wood elements remain damp after the other
moisture problems have subsided, fungus and/or rot and decay may
develop.
* Remove sheet vinyl, linoleum, or VCT tile to allow for maximum
evaporation. Protect and store historic floor finishes that
have been removed.
* Protect the wood floors from undue traffic and abuse, until
they are dry. Wood becomes soft and easily damaged when it is
wet.
HOUSEKEEPING MAINTENANCE: Initial Cleaning and Repair
1) Rinse remaining mud, dirt and flood debris from all surfaces with
freshwater. Do not use high pressure water on historic materials.
Use extreme care and caution around decorative features and damaged
elements.
* TURN OFF ALL ELECTRICITY BEFORE CLEANING WITH WATER.
* Open electrical outlets, mechanical chases, etc. and rinse
these areas thoroughly. Check wiring and connections for damage
and repair as required. Let areas dry before closing them.
2) Check for loose plaster; and either resecure it in place or carefully
record and remove it by hand. Decorative elements which are loose
may be carefully recorded, removed, labeled and saved for
reinstallation.
* Supporting loose plaster: Plaster may be temporarily supported
through the use of plywood and wooden T braces. Use padding
and care to protect all decorative elements from additional
damage when using this method.
* Securing loose plaster: Secure loose plaster and lath to the
original framing by using screws and plaster washers. Protect
decorative elements from damage by carefully selecting the
attachment locations.
3) Decorative wood elements may become loose or detached during
flooding. Check for loose, damaged or deteriorating wood. Either
resecure loose elements in place or carefully record and remove it by
hand, labeling and saving the element for reinstallation.
* Securing loose wood: secure loose wooden elements to the
orginal framing by using or reinstalling original fastenings.
Protect decorative elements from additional damage by carefully
reusing the attachment locations.
4) Use standard non-sudsing household cleaning products as directed by
manufacturers instructions to remove remaining dirt, and stains.
Special care and caution should be used when working on or around
historic materials. After cleaning, use a disinfectant to kill the
germs, bacteria and smell left by flood waters.
* Do not use cleaning solutions that will trap or impede moisture
movement within the historic materials.
Bibliography
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After the Flood; Water Damage and Your Historic Building (Video).
Historical Preservation Information Services, University of South Dakota,
1994. Produced by Video Reflections of Souix Falls, SD.
Bucher, Ward. "Drying-In and Drying-Out: Flood-damage lessons from
Hurricane Hugo," Old House Journal, March/April 1991, p. 40-43.
Federal Emergency Management Agency. Flood Emergency and Residential
Repair Handbook. Flood Insurance Administration 13, March 1986.
Federal Emergency Management and the American Red Cross. Repairing Your
Flooded Home. Washington, DC. 1992. FEMA document #234. This publication
is being distributed through FEMA and American Red Cross emergency efforts.
Single copies may be obtained by calling FEMA Publications Department,
Wash. DC. (202) 646-3484. FEMA Region 9 - CA region, phone: (415) 923-7100
or (415) 923-7120; FEMA Bldg. 105, Presidio of San Francisco, San
Francisco, CA 94129-1250
Flood Recovery Booklet. Iowa Cooperative Preservation Consortium. Iowa
City: State Historical Society of Iowa, 1993. This booklet reprints a
variety of preservation guidance fact sheets including excerpts from
Repairing Your Flooded Home by the American Red Cross and technical tips on
protecting paper documents and art work from the National Instititure for
the Conservation of Cultural Property (NIC) and the American Institute for
Conservation of Artistic Works (AIC). Tel. for Iowa Historical Society,
(319) 335-3916.
James, Sarah. Safeguarding Your Historic Site: Basic Preparedness and
Recovery Measures for Natural Disasters. Federal Emergency Management
Agency, Region 1. 1993. Developed with the assistance of the National
Trust, NPS North Atlantic Region, and SHPOs from Maine, Vermont, and New
Hampshire, this publication is currently being printed in a limited first
edition, due to a shortage of funds. Additional copies may be purchased,
printed and distributed. For further information contact Sarah James (617)
576-1745.
Treatment of Flood-Damaged Older and Historic Buildings. Information
Booklet No. 82, 1993. Washington, DC: National Trust for Historic
Preservation, 1993. Excellent 16 page bulletin discusses damage and
treatment with a practical checklist and lists of organizations that can
help.
Nelson, Carl L. Protecting the Past from Natural Disasters. Washington,
DC.: National Trust for Historic Preservation, 1991.
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This information was produced and compiled by the Preservation Assistance
Division, National Park Service, Washington, DC. (202) 343-9578
rev. January 17, 1995
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