For air sealing, the two-component urethane foams are usually used in kit form with densities ranging from 1.0 to 1.75 lb per ft 3 . There are different sizes for a wide variety of applications. Large refillable cylinders are also available. Portable kits are generally packaged with their own gun and hose assemblies. And because nozzles tend to plug with reacted foam if not used continuously, kits usually come with a supply of spares.
Various nozzles are available for spray, pour, and caulking applications.
In new construction, bulk sprayed foam is increasingly being used as an insulating air barrier system in cavity wall designs. The U.S. Society of Plastics Industry and Canada's Urethane Foam Contractors Association have both developed training and quality control programs to improve skills and ensure uniform quality of installed product. The window industry is particularly sensitive to the quality of foam application, because of concerns about size distortion of the window opening. In Canada, foam is applied to most windows when they are installed, while in the United States acceptance has been slower because of the distortion problems. Installation of too much foam in large gaps by inexperienced applicators can warp vinyl or insubstantial metal frames.