WIJ-1.4 One-Hour Fire-Resistive Ceiling Assembly
Floora/Ceiling - 100% Design Load - 1 Hour Rating - ASTM E 119 / NFPA 251

1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping.
2. Floor Sheathing: Minimum 23/32 inch thick tongue-and-groove wood sheathing (Exposure 1). Installed per code requirements with minimum 8d common nails.
3. Insulation: Minimum 1 inch thick mineral wool insulation batts - 6 pcf (nominal) with width equal to the on-center spacing of the I-joists. Batts installed on top of furring channels and under bottom flange of I-joists with the sides butted against support clips. Abutted ends of batts centered over furring channels with batts tightly butted at all joints.
4. Structural Members: Wood I-joists spaced a maximum of 24 inches on center.
      Minimum I-joist flange depth: 1-1/2 inches Minimum I-joist flange area: 3.45 inches2
      Minimum I-joist web thickness: 3/8 inch Minimum I-joist depth: 9-1/4 inches
     
See ASTM D 5055-07 for qualification requirements.

5. Furring Channels: Minimum 0.019 inch thick galvanized steel hat-shaped furring channels, attached perpendicular to I-joists spaced 24 inches on center. At channel splices, adjacent pieces overlapped a minimum of 6 inches and tied with a double strand of No. 18 gage galvanized steel wire at each end of the overlap. Channels secured to I-joists with Simpson Type CSC support clips at each intersection with the I-joists. Clips nailed to the side of I-joist bottom flange with one 1-1/2 inch long No. 11 gage nail. A row of furring channel located on each side of wallboard end joints and spaced 2.25 inches from the end joint (4.5 inches on center).
6. Gypsum Wallboard: Minimum 1/2 inch thick Type C gypsum wallboard. Wallboard installed with long dimension perpendicular to furring channels and fastened to each channel with minimum 1 inch long Type S drywall screws. Fasteners shall be spaced 12 inches on center in the field of the wallboard, 6 inches on center at wallboard end joints, and 3/4 inches from panel edges and ends. End joints of wallboard continuous or staggered. For staggered wallboard end joints, furring channels extend a minimum of 6 inches beyond each end of the joint.
7. Finish System (not shown): Face layer joints covered with tape and coated with joint compound. Screw heads covered with joint compound.

      Fire Test conducted at Underwriter’s Laboratories, Inc May 11, 1983
      Third Party Witness: Underwriter’s Laboratories, Inc. Report No: UL R10371-1

STC and IIC Sound Ratings for Listed Assembly
Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad
STC IIC STC IIC STC IIC STC IIC
- - 46 68 51 47 50 73
a This assembly may also be used in a fire-rated roof/ceiling application, but only when constructed exactly as described.


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AMERICAN WOOD COUNCIL                       AMERICAN FOREST & PAPER ASSOCIATION, INC                                             January 2009