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How to Repair a Foam Roof

Jane Humphries

Foam roofs are seamless roofing systems consisting of polyol and isocyanate in a mixture that sprays the polyurethane onto the roof. Often, damage to the foam occurs from wind-driven objects falling onto the surface and causing pits and cracks in the top layer. Repairing the sprayed polyurethane foam is essential to maintaining the integrity of the roof and preventing water penetration into the foam, which could exacerbate the problem further. Early identification of foam damage by periodic checking and regular maintenance saves time and money on more extensive repair work. Using polyurethane caulking sealant and disposable spray foam kits provide the means to repair the foam damage successfully.

Repairing a SPF foam roof correctly prevents the costs associated with internal water damage.
  1. Clear all debris off the roof using a push broom to prevent contamination of the repair or further damage to the roof. Minimize the amount of foot traffic on the roof and avoid dropping tools onto the surface.

  2. Count how many cracks or dents there are in a 100-square-foot area in the foam surface. Using a tape measure, measure the widest part of the cracks or dents and measure the depths of the damaged areas. According to the SPF Alliance, more than 20 cracks or dents in a 100-square-foot area that are over 3/4-inch wide and over 1/4-inch deep require at least half the roof surface scarified and re-sprayed with the manufacturer's foam.

  3. Check that there are less than 10 problem sites per 100 square-foot and that these will repair with caulk and disposal polyurethane spray foam. If there are between 10 and 20, contact the manufacturer to get the correct repair process for the foam product.

  4. Use a caulking gun to caulk the polyurethane sealant onto the exposed surface area of all cracks and dents that are under 3/4-inch wide and less than 1/4-inch deep. This procedure seals the foam. Spray a coating of disposal spray foam on top of the sealant to fill in the dent to the level of the foam roof surface.

  5. Remove damaged foam in dents and cracks that are over 3/4-inch wide and more than 1/4-inch deep with a roofing knife. Cut a 45-degree angled, tapered edge around the repair site. Caulk polyurethane sealant over the repair surface to seal the underlying foam.

  6. Spray the disposable polyurethane foam into the repair to fill to the level of the foam roof surface. Allow all repairs to cure for 15 minutes. Trim any overspill of foam with a roofing knife to the level of the main foam roof surface.