We have a project that is using TJI wood joist (composite wood Joists), they are 16 deep spaces 18 on center and are 20 long. There is gypsum board attached directly to the bottom of the joists along with 3 of insulation at the bottom to reduce sound transmission. The area is about 1400 sq.ft.
Reference is NFPA #13 2013 edition section 11.2.3.1.4(4)(j) Light or ordinary hazard occupancies where noncombustible or limited combustible ceilings are attached to the bottom of composite wood joists either directly or on to metal channels not exceeding 1 in depth, provided the adjacent joist space channels are firestopped into volumes not exceeding 160 cubic feet using materials equivalent to ½ gypsum board and at least 3 ½ of batt insulation is installed at the bottom of the joist channels when the ceiling is attached utilizing metal channels. If each channel space formed by two joist is 40 cubic feet, so the adjacent space is 40 cubic feet, I see no need to fire stop them into volumes less than 160 cubic feet as they are already less than 160. The AHJ is saying that we must firestop every 4th joist space with gypsum to create spaces of 160 cubic feet, so we would need to break the space into 12 spaces of 160 cubic feet for the 1400 sq ft area. Am I reading this correctly or do we need to break the space into sections of 160 cubic feet? Thank you James Crawford Phaser Fire Protection Ltd. Phone 604-888-0318 Fax 604-888-4732 Cel 604-790-0938 Email jcrawf...@phaserfire.ca _______________________________________________ Sprinklerforum mailing list Sprinklerforum@lists.firesprinkler.org http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
