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Re: Can 2x6 T&G roof or floor consider to be a diaphragm?

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Are the 2x6's perpendicular to framing or diagonal ?
perpendicular   = 100plf
 diagonal        =  250plf
perpendicular     = 100plf
perpendicular     = 500plf
w/ wood flooring
 diagonal            =  250plf
w/ wood flooring  =  600plf
I believe it is 2-16d's @ each support min.
2007 CHBC Table 8-8A
Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA
In a message dated 11/18/2009 3:43:03 A.M. Pacific Standard Time, mStuart(--nospam--at) writes:

It is very likely that the existing deck was horizontally spiked together such that the spikes plus the T&G resistance will enable the deck to act as a diaphragm.


D. Matthew Stuart, P.E., S.E., F.ASCE, SECB

Senior Project Manager

Structural Department


Engineers and Consultants - CMX

200 Route 9

Manalapan, NJ 07726

732-577-9000 (Ext. 308)

908-309-8657 (Cell)

732-298-9441 (Fax)



From: ken ng [mailto:zy7up(--nospam--at)]
Sent: Wednesday, November 18, 2009 1:07 AM
To: seaint(--nospam--at)
Subject: Can 2x6 T&G roof or floor consider to be a diaphragm?


1. 1.  I have a 1945 building and it has 2x6 T&G (2" Vert. and 6" Horiz) roof and the floor is nailed directly to beams at 54"o.c.  Can I consider these are flexural diaphragms with 54” existing nail spacing?


2.  2.  What about additional floor or roof joists that were added @ 18” o.c. with new nails at 18” o.c.  Will this be considered to be a diaphragm?


3.   3.  Or ½” plywood shall be added on top of existing 2x6 T&G?


4. 4.   The drawing plan called out some live load for Storage in 1945.  However the hand created drawing was not so clear to read.  I could not read the numbers if it's 50#, 75#, 100#, or 125#.  Does anyone know what was the 1945 UBC required for this year?