Is gypsum board acceptable as diaphragm material?
Is gypsum board acceptable as diaphragm material?
(OP)
I am designing a new condo building and have minimal shear wall area on the exterior face of the building. The building has a center corridor which are shear walls and I want to transfer the roof forces back through the ceiling to the corridor walls. Is this acceptable? I am looking at the IBC code which gives design values for walls but I don't see anything about diaphragms.
Thanks.
Thanks.






RE: Is gypsum board acceptable as diaphragm material?
This is based on 1/2" thick material with 5d cooler nails or 1-1/4" drywall screws at 7"spacing at the edges and 10" spacing at intermediate supports.
RE: Is gypsum board acceptable as diaphragm material?
Call it over convservative but that is my two cents.
RE: Is gypsum board acceptable as diaphragm material?
How else does the connection between the top of an end wall and the gable end truss above it work? Unless you brace the end wall up to the roof diaphragm, using diagonal members, the GWB ceiling is what stabilizes this joint.
DaveAtkins
RE: Is gypsum board acceptable as diaphragm material?
If interior gyp is getting damp, consider getting a new roofer.
RE: Is gypsum board acceptable as diaphragm material?
Its always better to take the standard way out, especially in a litigious building group like condos.
RE: Is gypsum board acceptable as diaphragm material?
RE: Is gypsum board acceptable as diaphragm material?
IBc does publish allowables for gyp-clad shear walls (table 2211.1(2). However I think it would be a stretch to extrapolate these tables for use in designing a horizontal diaphragm. The shear wall allowables are probably based on actual tests, and it would be a gamble to try and forecast what changing the orientation of the gyp sheets might do to the allowable values.
Suggest you consider using a wood structural panel for your diaphragm or the bracing suggested by ArnieG. Regards
RE: Is gypsum board acceptable as diaphragm material?
The trusses are wooden. I have considered bracing from the ridge to the walls but the trusses have a truss at the ceiling level combined with the roof truss members. I am not sure about fitting braces through the members to attach at the wall plate. I have also thought about cable or strap "X" bracing in the ceiling plane but again I'm not sure about if this is installable.
Thanks - I appreciate all of your ideas.
mmintich
RE: Is gypsum board acceptable as diaphragm material?
This topic is addressed in the 2003 version of the IBC - Section 2508.5 There is an evaluation report by the Gypsum Association at
http:
mmintich
RE: Is gypsum board acceptable as diaphragm material?
Regards,
Lutfi
RE: Is gypsum board acceptable as diaphragm material?
"AF&PA's Wood Frame Construction Manual (WFCM) for One- and Two-Family Dwellings, 2001 Edition outlines a procedure for calculating diaphragm capacity to brace gable endwalls against wind loads. The tabulated gypsum diaphragm capacity is 70plf, with a note that it can be increased to 90 plf when ceiling framing members are spaced 16" o.c., per ICBO Report No. 1874-89.
Table 3.15 of the WFCM actually tabulates minimum attic floor/ceiling lengths for various wind loads and building geometries. WFCM Table 2.6 outlines lateral diaphragm loads that are used in Table 3.15. The WFCM Commentary provides background calculations for all these tabulated values."