UFFI (Urea Formaldehyde Foam Insulation) is a type of spray-foam insulation used in the 1970s to make homes more energy efficient.
Concern over its safety arose when it was thought that unacceptable levels of formaldehyde were being steadily released into the atmosphere inside homes. As a result, the federal government banned its use in 1980. UFFI had been installed in approximately 100,000 Canadian homes.
Currently, the actual danger posed by UFFI is thought to be negligible, as released formaldehyde levels drop over time. Generally, new materials such as pressed wood, carpeting, and mattresses are thought to contain higher levels of formaldehyde than older homes with UFFI, although this can only be confirmed by lab testing. If you are selling your home and you know UFFI has been installed, it should be disclosed in agreements or contracts.