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RE: Snow Loads

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Martin,

 

I presume you’re talking about the typical valleys in a gable/dormer roof system? (As opposed to industrial sawtooth roofs, folded-plate roofs, etc.)

 

There is not, to my recollection, a specific provision for typical valleys in ASCE 7-05. The question has come up a couple of times in the Snow Loads subcommittee as we work on the ASCE 7-10 updates. The general feeling seems to be that there is not an issue as long as the valley is unobstructed by a parapet or other feature; the assumption is the snow will still slide off. If you feel the snow won’t slide, you could take Cs = 1.0 and also Ce = 1.2 for a “sheltered roof” (per footnote ‘a’ of Table 7-2). Or you could use the sawtooth roof provisions, which I have done in the past, and you’ll be conservative. (At least according to the committee…)

 

Regards,

Gary

Gary J. Ehrlich, PE
Program Manager, Structural Codes & Standards
National Association of Home Builders (NAHB)
1201 15th Street, NW, Washington, DC 20005
ph: 202-266-8545  or 800-368-5242 x8545
fax: 202-266-8369
gehrlich(--nospam--at)nahb.com


From: Martin N. Pohll [mailto:mpohll(--nospam--at)ranchomurieta.org]
Sent: Friday, May 02, 2008 4:03 PM
To: seaint(--nospam--at)seaint.org
Subject: Snow Loads

 

1997 UBC Appendix Section 1641.3.2 had provisions for snow loads at valleys.

 

Is there a similar provision in ASCE 7-05

 

Martin N. Pohll

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