Consider an open structure (picnic shelter)
Should the roof be considered as an overhang for calculating the wind load pressure by the ASCE7-98 procedure?
or what is the true definition of an "overhang" in ASCE7-98?
We just faced that decision on a swimming pool bathhouse where a portion of the bathhouse had a large roof overhang - we opted to go with the overhang uplift pressure - We just felt that we could visualize a high wind sending the 15 feet of roof sky high.
v2...I look at those in two different ways. In one, I use the approach JAE mentioned. Another, if the roof is flat, I use the "open structure, monoslope roof" approach. The second approach does not consider overhang. It's a judgment call, and it doesn't hurt to be conservative! If the shelter is contiguous with another structure, use the overhang approach whether flat or not.
Yes, I'd agree with Ron - our project was a complete building with a portion (about 15' x 70') that was really an overhang even though it was a simple extension of the roof.
For a completely open building - some kind of monoslope system would be appropriate - the primary failure is really a straight-upward suction.