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RE: UBC/IBC: Question re CFS with Gypsum Board Sheathing (Shearwall)

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It sounds like it wouldn't matter to you; but as a warning to others 
considering gyp board shearwalls - the vast majority of fire-rated gypsum 
board wall assemblies only satisfy the rating requirements with the long 
dimension of the sheets parallel with the studs.

Roger C. Davis
Architect
SDS Architects, Inc.

-----Original Message-----
From:	Bill Polhemus [SMTP:bill(--nospam--at)polhemus.cc]
Sent:	Thursday, July 25, 2002 3:24 PM
To:	seaint(--nospam--at)seaint.org
Subject:	RE: UBC/IBC: Question re CFS with Gypsum Board Sheathing 
(Shearwall)

Nah, you're making it too complex.

In the first place, this is just a one-story building. It's a metal 
building
frame and roof, and has brick cladding.

The shearwall will be enclosed by the brick so no problem with asking the
gyp board to take wind; the wind will be taken by the brick and go into the
studs. The studs however WILL be sheathed with the gyp board.

Oh, and the straps are BLOCKING. They are "prescriptive" to the code.

This is all being done based on "who's cheap and available." The guy 
running
the show is a construction manager. He's rounding up all the various 
trades,
etc.

BTW, I do find it interesting that IBC won't allow "flammable materials" 
for
interior partitions any longer.

Still looking for answers to my original questions. Regards.

William L. Polhemus, Jr. P.E.
Polhemus Engineering Company
Katy, TX, USA
Phone (281) 492-2251
FAX (281) 492-8203
email bill(--nospam--at)polhemus.cc

-----Original Message-----
From: James Lane, P.E. [mailto:jamesalane(--nospam--at)hotmail.com]
Sent: Thursday, July 25, 2002 1:15 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: UBC/IBC: Question re CFS with Gypsum Board Sheathing
(Shearwall)

Bill,
If the gyp board is on the outside face of the wall and taking wind out of
plane you will have a hard time finding a gyp board that is rated for
pressures. I would recommend talking the client into dense glass, it has
around a 75psf out of plane pressure rating and also has good shear
capacity. Also has class A fire rating and termites do not like it.
Flat straps in CFS are never taught and are never properely terminated to a
diaphragm so in my opion they are worthless. I do not recommend using them
as a tension brace for stud out of plane bending at midpoint or whatever
point. Design for full height unbraced struds based on construction loads
then get the sheathing on for continuous braced in weak direction for total
load.
James
fellow Houstonian



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