ASCE 7-10 Wind load on external stair

[designforce]

Hi all,
I have an external stair, wood framed, going up the side of a single family house from 1st to 2nd floor. Just wood stringers and tread/risers. Risers are closed. I can't figure out which section of ASCE applies. None of the classifications in the component and cladding section really applies, I think. Roof overhang is way conservative for something like this, plus, the roof is 2 floors up. Non-building/appurtenance doesn't give me uplift, which I think is absolutely needed.
I can take CC and go, to be conservative, but the thing will look ridiculous! What would you recommend?
Thanks

 

[26sig]

You are correct, your roof would seem to be too high to have any effect on the wind pressure for the external stair.

I believe Component and Cladding is the way to go here, and I would use the same pressure as the surrounding walls, but applied normal
to the underside of the stair. The idea being if the wind is acting like a fluid, you'd have the same fluid pressure as the walls.

If you look at Figure 30.7-2 in ASCE 7-10 this idea is supported. The figure shows how the roof overhang C&C loads are determined, but
in your case you wouldn't have the p(ovh) load, only the p(s) which is equal to the p(w), the C&C load on adjacent walls.



CF