Roof Assembly Fire Class

The slope of the test specimen is preselected and since steeper slopes are more of a challenge due to melting material feeding the fire the rating applies to the maximum slope passed.

Roof assembly fire class. But by including a particular underlying material it can meet the requirements for a class a roof. The best rating achieved is class a which is described by ul as effective against severe fire exposure class 1 rating. For example shake roofing with a fire retardant treatment rates class b on its own but achieves a class a rating when combined with specified underlying materials such as type 72 roll roofing material. Assembly rated class a roof coverings are those that meet class a standards when combined with other elements.

Includes roof coverings which are effective against severe fire exposures class b. According to the scope of fm 4470. Class a roof assemblies and roof coverings shall be listed and identified as class a by an approved testing agency. The maximum flame spread is 6 feet for a class a rated roof 8 feet for class b and 13 feet for class c.

Class a roof assemblies are those that are effective against severe fire test exposure. Examples of a by assembly fire rating include fire retardant treated wooden shakes and aluminum roof coverings. Includes roof coverings which are effective against moderate fire exposures. The class 1 rating is an exclusive designation that can only be awarded by fm global which indicates the successful testing of the entire roof assembly using fm approval standard 4470.