Flammability Of Attic Insulation

The dictionary defines flammable as capable of being easily ignited and burning quickly and cellulose insulation does not fit that definition.

Flammability of attic insulation. Fiberglass is an inorganic material and as such is a noncombustible insulation material that is not flammable. Insulation flammability isn t an issue with all recessed lighting fixtures though. Also referred to as loose fill cellulose insulation the small cellulose particles are flammable and can ignite if they re directly exposed to an overheated recessed can or electrical spark. As previously stated it takes 30 minutes for icynene spray foam to become flammable.

Cellulose smolders slowly when it starts to burn and if installed too close to an ignition source like a gas flue or recessed light fixture will eventually ignite and can spread to start a larger fire in nearby materials that are more flammable. The small insulation particles are predominantly made using recycled paper with a fire retardant. Many manufacturers make it clear that their radiant barrier material has a class a fire rating meaning that their radiant barrier insulation meets the fire and smoke safety requirements of building codes. But it is combusible which means capable of being ignited.

The main issue that arises is that many people will apply vapor retardant to the surface and the vapor retardants that are commonly used are flammable. If a fixture isn t rated for insulation contact no insulation should come within 3 inches of the fixture and. The flammability of radiant barrier insulation depends on the manufacturer. If a home has spray foam insulation in an attic or crawl space the building code requires using materials or assemblies that offer some fire resistance but not as much as is required for a thermal barrier.

While mineral based insulation materials are non combustible or low in combustibility the paper or foil backing surrounding the insulating material may be flammable. Insulation backing materials should be fire retardant and have a maximum flame spread rating of 25 when tested in accordance with astm e 84 standard test method for surface burning characteristics of building materials published by the american society for testing materials astm and as required by ul 723 standard for. Which is impressive in comparison to traditional insulation which are more prone to fires and contribute to the fire spread. The most flammable insulation materials is cellulose.