Installation of flood damage-resistant materials

Building materials vary in their ability to resist flood damage. Flood-resistant material is defined by the National Flood Insurance Program (NFIP) as any building product capable of withstanding direct and prolonged contact (at least 72 hours) with floodwaters without sustaining significant damage. Any damage that requires more than cosmetic repairs is considered to be significant; cosmetic repairs refer to cleaning, sanitizing, and resurfacing (e.g., sanding and repainting).

Flood-resistant materials, such as flooring, wall, and ceiling materials and the adhesives used to install them, are classified according to their ability to resist damage. The NFIP provides five classes of materials – classes 1-3 are unacceptable for resisting flood damage, and classes 4 and 5 are acceptable for resisting flood damage. Clay tile, stone or brick with waterproof mortar; solid vinyl flooring with chemical-set adhesives; stained concrete; terrazzo; decay-resistant or pressure-treated woods; and rigid, and closed-cell foam insulation are examples of highly flood-resistant residential building materials.

Materials that are classified as resistant to flood damage can survive wetting and drying and may be successfully cleaned after a flood. The materials determined to be flood-resistant may be exposed to floodwater on the exterior or interior of buildings and do not require special water-proofing protection. For installation of flood-resistant materials, the manufacturers’ use and installation instructions must be followed to ensure maximum performance. Additionally, when installing flood-resistant materials, fasteners and connectors (nails, screws, bolts, and anchors) must also be flood damage-resistant and non-corrosive in order to extend the life of the project.

Replacing flood damage-prone materials situated below the Base Flood Elevation (BFE) with flood-resistant materials is a key part of the process of wet floodproofing. Wet floodproofing allows water into a structure while protecting its contents and building systems so that floodwaters won’t cause damage, reducing repair costs and speeding up the recovery process after a flood. Allowing water to enter a structure equalizes the pressure and reduces the potential for structural damage. However, a wet floodproofed structure still experiences the ordeal and expense of flooding. Before the flood, belongings that can be moved should be elevated to avoid damage. After the flood, cleanup, decontamination, and drying time are still necessary. The optimal time to install flood-resistant materials is while restoring a building following flood damage or during a remodeling project.

Next Steps: 

1. Consult your local floodplain administrator to find out what requirements or restrictions (if any) apply to your property, including the BFE and whether you will need a permit to incorporate wet floodproofing measures. Ask if they have a list of approved flood resistant materials.
2. Hire a registered design professional to – or, if you are knowledgeable enough, you can – identify which floors, walls, or ceilings are below the BFE and need retrofitting.
3. Choose flood-resistant materials (including any adhesives, finish materials, and substrate) based upon the Class Descriptions of Materials (Table 1) and Types, Uses, and Classifications of Materials (Table 2) in Flood Damage-Resistant Materials Requirements: Technical Bulletin 2.
4. Remove all damage-prone materials before installation since flood-resistant materials may be ineffective when installed over materials that are not flood-resistant.  (If any of the existing building materials contain hazardous substances such as asbestos, you will need a licensed professional to remove them.) 
5. When you have confirmed that the area is dry, install the new flood-resistant materials.

Special Considerations: 

• This mitigation option type is not recommended in areas with high velocity flooding, where water moves at more than 6 feet per second. If you do not know the projected flood velocity around your property, check with your local floodplain manager.
• If your structure is in less than fair condition, this mitigation option type is not recommended. The only mitigation option types recommended for structures in less than fair condition are acquisition, demolition, and the purchase of flood insurance or business interruption insurance.
• Ensure compliance with all applicable National Flood Insurance Program (NFIP) requirements and local building codes.  The NFIP sets minimum standards and allows individual communities to adopt their own additional or more stringent requirements via local floodplain management ordinances, regulations, and laws. Under the NFIP, wet floodproofing for homes located in the Special Flood Hazard Area (SFHA) is allowed only in limited situations.  
• If your building sustained substantial damage during a recent flood event, you may be required to bring it into compliance with NFIP and local floodplain management regulations.
• Contact a local flood insurance representative to learn more and get a quote, if you do not already have flood insurance. (Most homeowner’s insurance policies do not cover flood damage.)
• Renters and those who own specific types of property may be limited in which mitigation options they can undertake or have different requirements to which they must adhere. If you are a renter or own any of the following listed property types, click through to learn more: Renter; Unit in a multifamily residence; Manufactured home; Farm/ranch; Historic property; New construction.