1. Wall Assembly — The 1 or 2 hr fire-rated gypsum board/stud wall assembly shall be constructed of the materials and in the manner described in the individual U300, U400, V400 or W400 Series Wall or Partition Design in the UL Fire Resistance Directory and shall include the following construction features:

A. Studs — Wall framing may consist of either wood studs or steel channel studs. Wood studs to consist of nom 2 by 4 in. (51 by 102 mm) lumber spaced 16 in. (406 mm) OC. In 2 hr fire rated assemblies, steel studs to be min 2-1/2 in ( 64 mm) wide and spaced max 24 in. (610 mm) OC. In 1 hr fire-rated assemblies, steel studs to be min 3-5/8 in. (92 mm) wide and spaced max 24 in. (610 mm) OC. Max area of opening is 196 sq in. (1265 cm²) with max dimensions of 14 in. (356 mm).

B. Gypsum Board* — 5/8 in. (16 mm) thick, 4 ft (1.2 m) wide with square or tapered edges. The gypsum board type, thickness, number of layers, fastener type and sheet orientation shall be as specified in the individual Design in the UL Fire Resistance Directory.

The hourly F and FH ratings of the firestop system are equal to the hourly fire rating of the wall assembly in which it is installed.

2. Steel Duct — Nom 12 by 12 in. (305 by 305 mm) (or smaller) No. 24 gauge (or heavier) steel duct to be centered within the firestop system. A nom 1 in. (25 mm) annular space is required within the firestop system. Steel duct to be rigidly supported on both sides of wall assembly.

3. Firestop System — The firestop system shall consist of the following:

A. Packing Material — In 2 hr fire rated assemblies, min 3-1/2 in. (89 mm) thickness of min 4 pcf (64 kg/m³) mineral wool batt insulation firmly packed into opening as a permanent form. In 1 hr fire rated assemblies, 3-7/8 in. (98 mm) thickness of min 4 pcf (64 kg/m³) mineral wool batt insulation firmly packed into opening as a permanent form. Packing material to be recessed from both surfaces of wall to accommodate the required thickness of fill material.

B. Fill, Void or Cavity Material* — Sealant — In 2 hr fire rated assemblies, min 3/4 in. (19 mm) thickness of fill material applied within the annulus, on both surfaces of wall. Additional fill material to be installed such that a min 1/4 in. (6 mm) thick crown is formed around the penetrating item and lapping a min 1/4 in. (6 mm) beyond the periphery of the opening. In 1 hr fire rated assemblies, min 1/2 in. (13 mm) thickness of fill material applied within the annulus on both surfaces of wall. Additional fill material to be installed such that a min 1/2 in. (13 mm) thick crown is formed around the penetrating item and lapping a min 1/4 in. (6 mm) beyond the periphery of the opening.

RECTORSEAL — FlameSafe FS 1900, Metacaulk 1000, Metacaulk 350i, Biostop 350i or Biostop 500+