Wednesday, December 12, 2007

Re: Uplift on Roof Sheathing - "Pull Through" Resistance

Jerold,
 
        I think washers would be very labor intensive.  My preference would be to use more nails.
 
Regards,
 
H. Daryl Richardson
----- Original Message -----
Sent: Wednesday, December 12, 2007 9:45 AM
Subject: Uplift on Roof Sheathing - "Pull Through" Resistance

I would like to ask for feedback on the design / specifying of sheathing for uplift.
 
For uplift on roof sheathing in HIGH WIND areas, is "Pull-through" a concern for the Plywood or OSB?  For Component and Cladding loading at some of the end zones, net uplifts can exceed 100 psf (for example, ASCE 7-02, V=130 mph, Exp. C, Bldg Class. III and Zone 3). 
 
APA provides design data for allowable stresses for spans and thicknesses of material, but for a situation where loading can be concentrated at the nail head "bearing" (kind of a reverse punching shear), are there special precautions I should warrant against?  Are there some type of washer that is sometimes typically used at these locations to help "spread out" the load?   
 
I have tried to find specific info on the Internet, without success, so I was hoping for some assistance from those who work with such high uplift pressures more frequently than I.
 
Thanks
 
Jerold Taylor PE

Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now.
at