ASCE 7 Wind Load & Overhangs

[spats]

It appears that ASCE 7 intends that edge zone width "a" be based on the footprint of the building, exclusive of overhangs. The implication also being that the edge zone starts at the building wall, and the overhang wind loads are just added beyond that. However, I don't find anywhere where it actually states this.

The problem comes in when you have a big overhang. In my case, there are some large covered second floor balconies, up to 10' wide. What's the proper way to treat such a condition?

 

[ajh1]

We've always taken the edge zones as measured from the edge of the overhang. In the old Guide to Wind Loads ASCE7-95 there is an example with a 7' overhang at the low eave and an effective "a" dimension of 4' due to the building size. The illustration clearly shows that the outer 4' of the overhang is Zone 2 and the inner 3' is part of the main Zone 1.

 

[spats]

Thanks ajh1. You reminded me that I have the same book, only for ASCE7-98. The 7' overhang example is still in there (Example 9). It also shows in the example that the least horizontal dimension used for calculating "a" does not include the overhang. That's intesting... almost a contradiction.