After the Flood: Emergency Stabilization and Conservation Measures

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.
  2. Clean and repair the structure's roof and roof drainage system in order to protect the building from future storm damage.

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.
  3. Remove residual moisture in a gradual and controlled process through natural ventilation. Do not use mechanical dehumidification which may cause additional damage.
  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.

  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.

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.
  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.
  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.
  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.

Bibliography

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.

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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