COMBUSTIBILITY CLASSIFICATIONS Examples of types of construction assemblies containing noncombustible, limited-combustible, and combustible materials.

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CLASSIFICATIONS DETERMINING HOOD AND DUCT CLEARANCE
	NON-COMBUSTIBLE No Paneling or air space required	LIMITED COMBUSTIBLE 3" air space required; curb can be non-insulated	COMBUSTIBLE Requires insulated paneling and insulated curb
TYPE OF WALL ASSEMBLY	NON-COMBUSTIBLE	LIMITED-COMBUSTIBLE	COMBUSTIBLE
Brick, clay tile, or concrete masonry products
Plaster, ceramic or quarry tile on brick
Plaster on metal lath on metal studs
Gypsum board on metal studs
Solid gypsum board
Plaster on wood lath or metal lath, on wood studs
Gypsum board on wood studs
Plywood or other wood sheathing on wood or metal studs
FLOOR-CEILING OR ROOF-CEILING ASSEMBLY	NON-COMBUSTIBLE	LIMITED-COMBUSTIBLE	COMBUSTIBLE
Plaster applied directly to underside of concrete slab
Suspended membrane ceiling       (a) with noncombustible mineral wool acoustic material       (b) with combustible fibrous tile	(a)		(b)
Gypsum board on steel joists, concrete slab
Gypsum board on wood joists

   Note 1: Wall assembly descriptions assume same facing material on both sides of studs.
   Note 2: Categories are not changed by use of fire retardant-treated wood products
   Note 3: Categories are not changed by use of type X gypsum board

        
  ULTIMATE AIRE  HOODS A Pleeter Ventilation Product, Utica NY