Expanding spray foam insulation is made of polyurethane or acrylic latex. The foam has been used in refrigerators and water heaters for many years.

Liquid polyurethane is pressurized and released through spray nozzles. When the spray lands on surfaces it expands and foams up, then hardens to a aerated material. Traditional insulation such as cellulose wool or spun fiberglass leave gaps and voids when applied as ceiling and wall insulation. Expanding spray foam insulation fills out to all cracks and into seams even if they are hidden from view. The sealing ability can practically eliminate air flow and energy transfer.

The resulting expanded polyurethane foam has a high R-value, which is the measure of resistance to energy flow relative to its thickness, when compared to other insulation materials. This high R-value feature can allow 4″ wall construction to achieve the same energy rating as a 6″ wall, providing improved performance at a substantial savings in construction materials and even increased floor area.

Because expanding spray foam insulation is dimensionally stable it does not settle or compress, and maintains its high performance characteristics. It does not absorb or transfer moisture, preventing humidity, condensation, and mold problems. It is also insect and flame resistant.

Although there are retail products for small crack filling tasks, expanding spray foam insulation for large areas is best left to professionally trained contractors who have the necessary equipment and expertise to apply this material effectively and economically.

There are hazardous materials handling issues when the polyurethane is in the liquid and aerosol state that require special precautions. Proper application and cavity filling requires experience and care to achieve the desired outcome and prevent damage or distortion of structural elements by over-expansion.

Coordination with plumbing and electrical installation is critical since the foam insulation encloses these utilities and makes it difficult to change or reinstall.

Expanding foam insulation costs about three times more than traditional materials to install initially. Some of this cost will be offset by savings in other areas and materials as mentioned above. However the longterm payback is increased energy savings year after year, with improved comfort and air quality, that justifies the investment in using expanding spray foam insulation.