Wednesday, May 30, 2007

Re: Roof panel safety factors

Drew,

Not to be contentious, but I have to wonder about the Exposure D. Is this
an East Coast (i.e. hurricane zone) or West Coast island. If East Coast
(i.e. hurricane zone), then it would be Exposure C if you are in a
jurisdiction that makes use of ASCE 7. ASCE 7 specifically puts
"hurricane prone" regions into Exposure C. If it is a West Coast island,
then you can ignore my comments.

As to the SF, minimum typical SF for connectors from my experience is 3
but sometime greater than 3. I believe that the ICC-ES folks use 3 as a
minimum for connectors when they do their evaluation reports. You might
look in the NDS and/or NDS commentary to see if it offers any guidance (or
Buddy might chime in).

Regards,

Scott
Adrian, MI


On Wed, 30 May 2007, Drew Morris wrote:

> I am involved in a project where we are reviewing the attachment of
> light gage steel roof panels to 3/4" OSB. The project is on an island
> surrounded by the ocean in all directions (130 mph, Exposure D). The
> vendor has supplied the test data for the steel clip and we are
> discussing what sort of safety factor to use. At another firm we
> routinely used a safety factor of the 3, so the allowable loads where
> 1/3 the value of the tested ultimate value. The roofing vendor is
> choking at the SF = 3 since the wind pressures were grossly
> underestimated in the program he used. Does anyone know how the ICC
> applies a safety factor when evaluating roof panels and fasteners?
>
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