Positive Roof Wind Load
Positive Roof Wind Load
(OP)
Is anyone designing roof structure specifically steel joists for the positive (non-uplift) wind? If so do you combine the positive wind with the roof live?
I have never heard of this and it seems like overkill. In high wind situations I'll check to make sure the positive roof wind is less than the roof live, which is virtually always the case. My logic is that the roof live will never occur at the same time as the worst case positive wind load.
Any thoughts are appreciated.
I have never heard of this and it seems like overkill. In high wind situations I'll check to make sure the positive roof wind is less than the roof live, which is virtually always the case. My logic is that the roof live will never occur at the same time as the worst case positive wind load.
Any thoughts are appreciated.






RE: Positive Roof Wind Load
See ASCE 7-05 (or ASCE 7-02). You must combine wind with live, but not both at a factor of 1.
Also, I am curious as to how you are getting a positive wind pressure for your roof. For a normal structure (enclosed), I don't think you get any positive pressure on the roof until the pitch of the roof reaches 45 degrees. I would guess that is not the case if you are using steel joists.
RE: Positive Roof Wind Load
RE: Positive Roof Wind Load
Thank you for the clarification. Can you point me in the right area of the code to find that?
RE: Positive Roof Wind Load
The 10 psf minimum is in Section 6.4.2.1 and 6.4.2.2.
RE: Positive Roof Wind Load
IBC 2000 1609.1.2
IBC 2003 by Ref to ASCE 7-02, 6.1.4.1 and 6.1.4.2
IBC 2006 by Ref to ASCE 7-05, 6.1.4.1 and 6.1.4.2