We are designing a three-story timber frame building with shear walls. The architect has asked that we do not use plywood or osb sheathing for any of the walls for fire-rating reasons. It was proposed to use metal x-bracing straps secured to the studs and plates in lieu of sheathing.

Is this a common practice?

Can you direct me to any code, ICC, manufacturer, or other documents related to this?

Is this sheathing for the shearwalls you are talking about? are they using gypsum to finish the walls? OSB can get a similar fire rating to gypsum if thats the case.

Yes - but not so much anymore - Simpson at Strong-Tie.com sells it.
What is wrong with OSB??

Yes, it is sheathing for shear walls. They do not want to use OSB. They are specifying dens glass.

Mike, I can't find the product in the Simpson catalogues. Can you point me in the right direction?

The wall bracing by Simpson you are referring to is NOT designed to replace the shearwall gyp, ply or OSB elements - only serve as temporary bracing during construction. Look on p[age 193 of the 2011 - 2012 catalog - the first paragraph.

Better to use some CS/CMST coiled strap over the studs, connedcted to the timberframe posts. The problem will be to develop the force in the strap to the end posts. Nailing to the studs will have no value here. Holssowns may or may not have to be added at the timber frame column depending on the dead loaqd to resist the overturning and your details.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

THis type of bracing using metal strap cross bracing is very common in Australia. It has reasonable bracing capacities according to our timber framing code, however it is more flexible than sheet (ply) bracing, so we often try to not use it soley on lower floors as the structure can be wobbly.

I can send you the detail with capacities if you like..

I would like to see your detail, demayeng. I have heard of engineers in Canada using a similar system, but have never understood why it was preferred to OSB or plywood.

In either case, the fire rating is only as good as the drywall cover.

BA

You might be interested in www.sureboard.com

M^2 is more specifically correct. I just assumed you would read all the disclaimers...

Go to Strong-tie.com (sp??) and search on CS OR CSMT. It is there..

Look at page 10 of this document

http://www.pryda.com.au/media/fckuploads/files/Bra...