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Standard Test Methods for Determining Fire Resistance
of Roof Covering Materials |
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Test procedures to determine the fire
resistance of roof coverings were
originally developed by Underwriters
Laboratories prior to 1920. The test
standard (UL-790) has been amended
over the years to reflect changes in
roofing materials. The tests have also
been adopted by the National Fire
Protection Association (NFPA 256),
American Society for Testing and
Materials (ASTM-E108), and Uniform
Building Code (UBC 15-2).
The tests provide comparable fire resistance values among roofing materials.
The tests are considered to be representative of fire conditions that originate
outside of homes.
All roofing products are subjected to three tests:
- Intermitent Flame Test
- Spread-of-Flame Test
- Burning-Brand Test
With the introduction of fire retardant wood roofing materials, the tests were
amended to include additional tests for wood products. These are:
- Flying-Brand Test
- Rain Test
- Weathering Test
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Intermitent Flame Test
This test shows a roofing material's resistance to flames from adjacent burning
material. The roofing materials are exposed to intermittent gas flames of 1,300°
F to 1,400°F at 12 miles per hour wind is applied to the test deck until the test is
completed.
Spread-of-Flame Test
A spread-of-flame test is used to determine the fire resistance of most building
materials. For roofing materials, the roof deck is exposed to a gas flame of
1,300°F to 1,400°F for 4 to 10 minutes. A 12 miles per hour wind is applied to
the test deck until the test is completed.
Burning-Brand Test
This test exposes roofing materials to burning brands constructed of wood,
simulating an exposure to burning materials. A typical burning ember in a large
fire is approximately ¼" in size. The burning brands used in this test are 60 to
1,000 times that size. A 12 mile per hour wind is applied to the test deck until
the test is completed.
Flying-Brand Test
Treated wood roofing material is tested to determine if the product will create
flying embers in a fire situation. The treated wood is exposed to a gas flame of
1,300°F to 1,400°F for 4 to 10 minutes. The wind applied to the test deck is
increased to 18 miles per hour during this test.
Rain Test
This test is designed to try to flush fire retardants out of the treated wood. The
roofing material is exposed to twelve weekly cycles of 96-hours of water
exposure (67.2" of water) and 72 hours of drying at 140°F. The wood is
subjected to a total of 806.4" of rain, equivalent to 24 years of rain in the
Dallas/Ft. Worth area. The roofing material removed from the weather chamber
is again tested to the Intermittent Flame, Burning-Brand, and Flying-Brand tests.
Weathering Test
Treated wood roofing material is the only material exposed to actual outdoor
weather conditions when tested for fire retardancy. After one, two, three, five,
and ten years, the roofing material is subjected again to the Intermittent Flame,
Burning-Brand, and Flying-Brand tests. |
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At no time during or after these tests can--
Any portion of the roofing material create flying embers that will endanger other
structures. Nor can any portion of the roof deck fall to the ground in the form of
a glowing brand.
There be any burn-through of the roof deck. |
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CLASS A - PASSES ONE HOUR TEST (SUPERIOR)
CLASS B - PASSES 30 MINUTE TEST (GOOD)
CLASS C - PASSES 15 MINUTE TEST (SATISFACTORY)
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