Spray polyurethane foam (SPF) is a commonly used air sealing and insulation material for weatherization work and this guide suggests its use in various applications. Exposure to isocyanates and other chemicals in the spray foam during the curing period or for some time after installation may cause health effects in some people. Care must be taken to control exposure of contractors and the occupants, including possibly vacating the home while spray foam is being applied and for up to 24 hours for large applications. In addition, some spray foam types (closed cell, medium density products) can only be applied in lifts of up to 2" at a time, should not be used to fill closed cavities, and require a cooling-off period between lifts for thicker applications.

Spray foam should always be installed by a trained contractor. This guide does not provide information or instruction on SPF installation and safety procedures. Refer to spray foam manufacturers for health and safety information. The US EPA has a website on the use of SPF in the home (www.epa.gov).