How To Achieve 1 Hour Fire Rated Wood Roof Trusses

Trying to use section 721 6 1 of the ibc to acheive a 1 hour rating of existing floor assemblies in 20 buildings by using only 1 layer of 5 8 drywall.

How to achieve 1 hour fire rated wood roof trusses.

See full report for details. 1 hour rated wall bearing or non bearing with optional insulation with a finish rating of 20 minutes for 1 layer of gypsum each side for non bearing walls or 59 minutes with 2 layers of gypsum each side for bearing walls on a single gable truss with 2x3 o c. 12 x 24 2 x 4 8 w10 x 25 beam floor units and beam support 3 hr. Concrete with cellular steel 3 hr.

276 fire rated ceiling assemblies suspension ceiling designs floor ceiling designs a003 3 hr. Fire rated suspended ceiling wood truss council of america floor or roof fire notes 1. Wood joists wood i joists floor trusses and flat or pitched roof trusses spaced a maximum 24 o c. With 1 2 wood structural panels with exterior glue applied at right angles to top of joist or top chord of trusses.

Ibc section 722 6 could be used to calculate up to a 1 hour rating for a wood frame wall floor or roof assembly. Ibc table 721 3 item 21 1 1 describes a single prescriptive 1 hour rated floor or roof assembly that includes wood trusses. No minimum joist size is given except that it needs to be adequate for structural loads. For additional information on fire resistance rated assemblies see sbca research report 1509 01.

Floor joists vary in depth but maintain 16 o c or less. 3 4 fr 83 12 x 12 z runners fluorescent type none 2 1 2 concrete. Applied to bottom chord of each truss floor or roof 1 hour. Screw fastened perpendicular to lower chord of wood trusses of 2 x 4 38 mm x 89 mm.

According to the book commercial drafting and detailing a typical one hour fire rated wall consists of 2x4 studs spaced 16 inches from the center of one stud to the center of the next covered by 5 8 inch type x gypsum board. Gypsum wallboard roof ceilings wood framing pitched roof truss 11 1 hr. Ul p533 roof ceiling one layer 5 8 15 9 mm fire shield c ga rc 2603 wallboard attached to 1 2 12 7 mm resilient furring channel spaced 12 o c. Type x gypsum board is wallboard to which non combustible fibers have been added.

Ibc table 722 6 2 2 allows 10 minutes for wood floor or roof joists at 16 o c. Assemblies include ducts dampers lighting or other fixtures in the tested assembly. How do i get a 1 hour fire rating for the truss. The reluctance to rely on approved test results is unwarranted as explained in section 17a and section 17b of sbca s metal plate connected wood truss handbook.

I believe adding 5 8 drywall on both sides is the answer one hour fire rating for a truss drywall contractor talk. 2x4 studs spaced 24 o c.