Chlorofluorocarbons (CFCs) have bee...

Chlorofluorocarbons (CFCs) have been used since the 1960 as blowing agents to effect insulation used for roofing, as well as for other applications.

However, the 1987 Montreal Protocol -- the international agreement that outlines the schedule for eliminating CFC -- focused attention upon the potentially harmful drifts of certain fully halogenated hydrocarbon gases. These include CFC-11 which has been commonly used as a blowing agent. In answer the roofing insulation industry has now substantially complet a conversion from CFC to hydrochlorofluorocarbons (HCFCs) which