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# ASCE 7-02 - Open Building - Load on Roof

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## ASCE 7-02 - Open Building - Load on Roof

(OP)
I have a simple 4 column "shed" with no walls, about 20ftx30ft with h=15ft.  I am trying to figure out the wind load to apply to the roof.  According to section 6.5.13, (Eq 6-25)F=qz G Cf Af.  Cf is taken from Figure 6-18, based on the B vs L of the roof as well as the angle.  I've got that.  My problem comes when determining F.  According to 6-25, Af is the projected area normal to the wind direction.  Does this projected area refer to a vertical projection of the roof (including the angle) or is the the plan area (BxL) of the roof. If it is indeed the projected vertical area, that is a very small number...roughly 1ft rise over 30ft so A=1x20ft=20sf.  But, if it is the roof plan area A=20x30=600sf.

Also, what about Comp&Cladding?  I was planning on using qh as the pressure because there does not seem to be anything specificaly designated as design of C&C for and Open bldg.

### RE: ASCE 7-02 - Open Building - Load on Roof

ASCE 7-05 has expanded it's evaluation of open roofs.  Check there.

I would use the projected area normal to the plane you're interested in, one area for the vertical component of the pressure, and another area for the horizontal component.

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