Fire Rated Roof

External fire exposure class a b or c.

Fire rated roof.

One goal of this column will be to increase your understanding of each of these ratings and what the rating does and does not do for your peace of mind. A class a roof is ideal for fire protection and may be required by your building codes depending on your place of residence. Fire ratings for roofs are classified as either class a class b class c or are unrated if a roof covering cannot meet the requirements for any of these classifications. Fire ratings for roofs provide a measure of the amount of protection.

As applied to elements of buildings the fire resistance rating classifies the ability of an assembly to confine and isolate fire within a zone comprised of fire resistance rated walls ceiling and floor assemblies. The ul tests under ul 790 evaluate the behavior of a roof covering under three fire hazards exposure of the roof to intermittent flame. A variety of special sizes are also available to provide an accessible way to install or remove large pieces of equipment from a building. Roof hatches bilco roof hatches provide safe and convenient access to roof areas by means of an interior ladder ship stair or service stair.

The highest rating meaning the most fire resistant is classified as class a and is able to withstand severe fire exposure. Class a class b class c or unrated. Roof covering packaging that encloses shingles or other roofing that have a fire rating will display the level of fire or wind resistance rating of the materials. Your roof can have one of four fire ratings classifications.

Astm e108 defines fire test methods for roof coverings. Class a roofs are commonly available and can be very affordable so they can be well worth the cost. Class a provides the highest protection and class c the lowest. This is followed by class b which is moderate exposure and then class c which is the lowest rating.

Ul 790 is a quality assurance service listing. The different roofing materials that are available for installation on your home are all evaluated for their fire resistant capabilities. Roofing systems must meet or exceed building codes and insurance requirements. Refer to our roof ceiling assembly documents which includes ul fire rated roof assemblies for easy guidance through the assembly of a roof or ceiling on your next project.

Helpful documents and resources for usg s roof assemblies can be found on this page. These tests may be conducted at ul inc fm global or any other certified testing laboratory. How are roofs rated. The ratings relate to fire tests designed to determine how quickly fire can raise the temperature to unacceptable levels.

Fire ratings may pertain to resistance to fire from above the roof system the familiar class a b or c ratings or fire exposure from the building interior the underside of the roof deck. At a minimum unrated roofs such as an untreated wood shake roof should be replaced by a rated roof.