Re: Non-combustible ceiling adjacent to exhaust hood
The ACT would have to meet the following in order to be within 18" of the hood. Remember the part of the hood above the ceiling has to meet 506.3.10
507.9 Clearances for Type I hood.
A Type I hood shall be installed with a clearance to combustibles of not less than 18 inches (457 mm).
Exception: Clearance shall not be required from gypsum wallboard attached to noncombustible structures provided that a smooth, cleanable, nonabsorbent and noncombustible material is installed between the hood and the gypsum wallboard over an area extending not less than 18 inches (457 mm) in all directions from the hood.
507.10 Hoods penetrating a ceiling.
Type I hoods or portions thereof penetrating a ceiling, wall or furred space shall comply with all the requirements of Section 506.3.10.
COMBUSTIBLE MATERIAL. Any material not defined as noncombustible.
NONCOMBUSTIBLE MATERIALS. Materials that, when tested in accordance with ASTM E 136, have at least three of four specimens tested meeting all of the following criteria:
1. The recorded temperature of the surface and interior thermocouples shall not at any time during the test rise more than 54ºF (30ºC) above the furnace temperature at the beginning of the test.
2. There shall not be flaming from the specimen after the first 30 seconds.
3. If the weight loss of the specimen during testing exceeds 50 percent, the recorded temperature of the surface and interior thermocouples shall not at any time during the test rise above the furnace air temperature at the beginning of the test, and there shall not be flaming of the specimen.
