Low-pressure spray polyurethane foam is typically applied around ductwork, electrical or piping penetrations, rim joists and roof repairs. This type of foam is used to insulate and seal small to mid-sized areas in homes and other buildings that are too large or extensive for smaller, insulating foam sealants. It is especially effective in weatherizing older homes that have many cracks, gaps and wall penetrations around doors, window frames, pipes and plumbing lines. The air- and heat-leakage improvements can be quite dramatic after a low-pressure SPF application, which can result in greater efficiencies.
R-value, the thermal resistance measure of insulation, varies between all insulation products whether they are fiberglass, cellulose, open-cell spray foam insulation or closed-cell sprayed-in foam insulation. Generally speaking the rule of thumb is the higher the R-value, the greater the insulating power. Focusing on spray foam insulation materials, there is a difference between the two main types. According to industry publication, Fine Home Building, the R-value for open-cell spray foam is between R-3.5 – R-3.6 per inch. However, there are open-cell spray foam insulation products actually offer R-3.7 per inch such as Icynene Classic and Icynene Classic Max. The open cell structure of low density foam insulation means the R-value is lower than its closed-cell counterpart. Nevertheless, open-cell spray foam does offer superior and consistent thermal insulation and air sealing properties.