ASCE 7-05 : Roof Overhang / Open Building

[theshearstud]

We currently have a gabled roof that extends 20 ft past the edge of a building. The roof extension has its own support structure (Not Cantilevered).

From what I've gathered from previous conversation on this forum, the roof should be designed as an overhang. My question is:

1. Is it necessary to design the entire "overhang" for overhang wind pressures of Zones 2 and 3? For this particular case, my "a" dimension is 4 ft. Since the overhang extends a distance greater than 4ft, it seems as though I would be able to use Zone 1 pressures for the majority of this roof overhang. Only issue is there are no overhang pressure coefficients for Zone 1 (looking at Fig 6-11C). Does that mean the entire overhang must be designed for Zones 2 and 3? Or that we should just use the typical Zone 1 pressures assuming no overhang

Thanks in advance.

 

[dcarr82775]

Before ASCE 7-10 you applied the wall pressure (Cp=0.8) to the underside and the Zones 1, 2, or 3 roof suction pressures to the top side. I see no reason that rational could not be applied to your situation