Spray polyurethane foam (SPF) roof systems are unique and expose SPF applicators to a variety of dangers during the SPF application process, as well as some that are confronted by all roofing workers. If SPF applicators follow precautionary work practices, the hazards of SPF roof system applications can be reduced or eliminated.
A dual-component formulation is the basis for SPF roof systems. One part is an isocyanate, and the other part is a polyol resin. The components are transferred from their individual containers into a proportioning unit that pumps proper amounts of each through a hose to a spray gun where they are mixed and applied to a surface.
Components used in SPF roofing applications and certain top-coat products usually are characterized by the U.S. Department of Transportation as Class 3 hazardous materials because of their flammable and toxic natures. Breathing isocyanate vapors, especially when concentrations are increased during spray applications, can cause the following symptoms: