Spray polyurethane foam roofing systems consist of an application of specifically designed spray foam, covered with an elastomeric coating or aggregate covering to protect the foam from ultraviolet rays. Specialized equipment mixes two liquid components at the spray gun that applies foam to a prepared substrate. The mixed liquid expands to 30 times its original volume, forming a rigid foam plastic within 3 to 10 seconds, while chemically bonding to the surface on which it is sprayed. Spraying the foam in 1/2 to 1-1/2 inch lifts to a desired thickness (1" minimum) fills in low areas, builds in slope, and provides insulation.
Spray polyurethane foam has a closed cell structure and is water resistant. It must, however, be protected by elastomeric coatings or aggregate coverings to prevent UV-induced surface degradation. Such coverings can also be used for other purposes, including inhibiting moisture vapor transmission, enhancing the aesthetics of the system, increasing the impact and abrasion resistance of the system, achieving flammability, and code requirements.
Resources for more information:
A number of technical publications relating to sprayed polyurethane foam are available. The following guidelines and technical documents specifically relate to spray polyurethane foam roofing systems:
The following documents are also available from other organizations and include information furnished by SPFD and other sources.
From Martin Knowles. You can read the full article at:
For a video of spray foam roofing please click on the picture in the right hand panel.