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RE: Screwed Gypboard Shearwalls

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Patricia,
I'm surprised at the lack of response you received regarding screws in
gypsum. I agree that Gypsum should not normally be used for shear, although,
even the IBC draft has a table of shear values for gypsum.
With that said, I have not designed a gypsum shearwall in more than 5 years
(before Northridge). I do, however, have every gypsum wall board in my home
screwed in place with drywall screws.
The screws don't back out with wood shrinkage, and you see very few "nail
pops". I have one location in my home where the wallboard mud popped out and
that was at a bull-nosed corner bead which was nailed in place.
I live in the desert and defects due to wood shrinkage from the nail shank
is very common - even with kiln dried wood. Therefore, most of the
contractors out here prefer screws over nails.
You also might try contacting APA since, I believe, they have done testing
with screwed, nailed and stapled connections. Screws are also very commonly
used to secure plywood or gypsum to cold-formed steel studs. Personally, I
believe their values for Gypsum would be, at worst, insignificant from nails
since the material will yield before the capacity of the material (gypsum).
That's my $0.02 worth.
-----Original Message-----
From: CTSTUC(--nospam--at)aol.com [mailto:CTSTUC(--nospam--at)aol.com]
Sent: Friday, June 19, 1998 10:40 AM
To: seaoc(--nospam--at)seaoc.org
Subject: Screwed Gypboard Shearwalls


Now I know that Gypboard shearwalls are not used in California, but I was
hoping that someone out in SEAOC Listserv world would have an answer for us.

The UBC has values for the nailing of gypboard shearwalls, but we have
contractors that want to screw the gypboard in lieu of nailing.  One of our
engineers was at a job site and the gypboard shearwalls were all beat up
from
the nailing while the screwed non shearwalls looked great.  Has anyone ever
seen or allowed screws to be used in lieu of the nails?

Patricia Small
Tucson, AZ