Home renovations continue to be a priority in flood-damaged areas like New Orleans and New York City, which have been hit by recent hurricanes and tropical storms. But it’s not just hurricanes that cause water damage; flood-prone areas are all over the country. In fact, according to Claims Journal, more than $9.1 billion in claims from homeowners in 2011 were attributed to water damage.

When it comes to preventing moisture damage, mold and other hazards caused by excess water, using water-resistant insulation in floors, walls and ceilings is crucial. Any area that is at or below ground level needs to be prepped for potential water infiltration, even if the area has never flooded before. As the water table rises in flood-prone areas, hydrostatic pressure is exerted underneath basement floors and against basement walls. The force of the hydrostatic pressure forces water in through cracks in foundation walls, through openings caused by expansion and contraction of the foundation wall joint and up through floor cracks. These areas may never have flooded before but are still at risk for extensive water damage.

When specifying products in home renovations where there has been previous water damage, it’s important as professional contractors to know what products are accepted as flood-resistant materials. Many materials such as open cell plastic foam, fiberglass, mineral wool, batts, blankets, cellulose and cotton (Class 1-3), which are commonly used as insulation, are not acceptable products for use in flood-prone areas, according to the U.S. Army Corps of Engineers’ Flood Proofing Regulations.


The National Flood Insurance Program regulations require the use of construction materials that are resistant to flood damage. Flood damage-resistant material is defined as “any building product [material, component or system] capable of withstanding direct and prolonged contact with floodwaters without sustaining significant damage.”

The Federal Emergency Maintenance Agency has specified closed cell spray polyurethane foam as a flood-resistant material with a Class 5 rating, meaning:

It is highly resistant to floodwater damage, including damage caused by moving water.

It can survive wetting and drying and may be successfully cleaned after a flood to render it free of most harmful pollutants.

It is permitted for partially enclosed or outside uses with essentially unmitigated flood exposure.

In addition, closed cell SPF can be used in wet flood proofing, which is a method to reduce damage that typically involves three elements: allowing floodwaters to enter and exit to minimize structural damage; using flood damage-resistant materials; and elevating utility service and equipment. 


Because of the chemical composition of closed cell spray polyurethane foam, it’s able to resist moisture—preventing water infiltration, mold growth and future expansion and contraction problems in the structure.

Characterized by rigidity and strength, closed cell SPF incorporates an insulating gas that is retained within the cells. Closed cell SPF is among the most efficient insulating material commercially available. It provides a highly effective air barrier, low moisture vapor permeability and excellent resistance to water. The most common foam density for closed cell polyurethane foam is 2.0 pounds per cubic feet, providing the optimum insulating and strength characteristics for building applications.

Areas where you’ll want to insulate with a closed cell product include walls, floor to wall joints and, if possible, the flooring. You’ll also want to perform a complete air seal, filling in all cracks and crevices to prevent further water damage and mold problems.


As professional contractors, it is more important than ever to specify flood damage-resistant products that are environmentally friendly in your rebuilding projects. Because these flooded areas are in homes, you want to make sure the product you’re specifying is not causing more harm to the inhabitants. There are several certifications for environmentally friendly products, but one of the most commonly known is GreenGuard Certification. Products that are GreenGuard certified meet some of the world’s most comprehensive standards for low emissions of VOCs, helping to identify products that contribute to the creation of healthier indoor environments.


As always, proper personal protective equipment should be used when handling any spray polyurethane products, and Handi-Foam E84 should be used by professionals only. The product is cuttable in two to five minutes and is completely cured within an hour. 

(Source: “Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood Hazard Areas,” in accordance with the National Flood Insurance Program Technical Bulletin 2 / August 2008)
This information is provided as a service, and is not necessarily meant to reflect any recommendation, guideline or position of Fomo Products. Each individual user must determine product suitability for any particular purpose.