Document oene7x4YaBZknE5pkjYBYNNRR

GEORGIA-PACIFIC CORPORATION BESTWALL GYPSUM DIVISION September 29, 1966 Addendum to General Sales Bulletin #60-66 August 30, 1966 TO: ALL REGIONAL SALES MANAGERS SUBJECT: SUSPENDED CEILINGS WITH FIRESTOP ALL AREA SALES MANAGERS RE: Incombustible Assemblies ALL SALESMEN DISTRIBUTION DIVISION SALES PERSONNEL CC: R. I Fredericks, Paoli K. A. McCaski11, Paoli M. M. Powers, Paoli BY: G. C. Moore:jw It has been brought to our attention that additional information should be sub mitted to clarify the method in the construction of an incombustible suspended floor and ceiling assembly as described in General Sales Bulletin #60-66. Please delete the second and third paragraphs of the bulletin and substitute the following description. The floor and ceiling construction assembly originally fire tested and covered under UL Design No. 63, 2-hours consisted of a 2-1/2" concrete floor slab over metal lath supported by steel bar joists spaced 24" on center. 25 gauge furring channels were tied at right angles to the underside of the steel bar joists, spaced 12" on center, and they were tied at every other bar joist. One layer of 5/8" Type "X" gypsum wallboard applied at right angles to the furring channels and screw attached. In the duplicate fire test, 1-1/2" cold rolled channels (16 gauge) were suspended at right angles to the bar joists and spaced 48" on center and suspended from the bar joists with 8 gauge galvanized steel wire spaced 48" on center along cold rolled channels. 25 gauge furring channels were double wire tied with 18 gauge steel wire at right angles to the cold rolled channels and spaced 12" on center and tied at every intersection. One layer of 5/8" Type "X" gypsum wallboard, screw attached to the furring channels, with the wallboard applied perpendicular or at right angles to the furring channels In all of the floor and ceiling construction assemb1ies(incombustible) tested by the Bestwall Gypsum Division and other gypsum manufacturers in the Industry, 25 gauge furring channels were tied to the underside of the steel bar joists at every intersection or on 24" centers. Therefore, Underwriters' in their approval to the Bestwall Gypsum Division have stated that in incombustible suspended floor and ceiling assemblies the 1-1/2" cold rolled channels are spaced 24" o.c. and the 8 gauge hanger wires may be tied 48" o.c. along the cold rolled channels. The 25 gauge furring channels are spaced as tested in our various floor and ceiling construction assemblies, 24" o.c , except UL Design #2, spaced 16" o c. The list of assemblies covered under this duplicate test to substantiate direct attachment or suspended attachment of one layer of fire rated gypsum board in an incombustible suspended ceiling are: UL #2,l-hr; UL //1 9 1 - h r ; UL /.' 1 7 , 1-1/2 hr; UL //13,1-1/2 hr; UL //237,2-hr; UL #69,2-hr; and UL #259,2-hr. Attached is one copy of suspended ceiling construction details as constructed in the Gypsum Association duplicate fire test. Enel. SGP 0025652 IT /o ' \ SGP 0025653