Coldform / Gypsum Shear Wall

[cal91]

I've got a storage unit project using coldform framing. The exterior walls will be a typical coldform shearwall with gauge steel siding. However, the interior walls which I rely upon for shear, will only have 5/8" gyp board on both sides and no steel siding.

Do I need to use and R value of 2 instead of an R value of 6.5 ?! If so I'll need to put steel siding in all the interior walls. I'm hoping there's a way around this.

 

[XR250]

Make sure to verify you can use GYP for seismic resistance. IIRC, there may be a code issue with it.

 

[cal91]

ANSI 400 has provisions for it. But I can't make it work with a R value of 2 anyways... looks like i'll have to throw steel siding into the interior walls.

 

[mike20793]

I've had good success with the Sureboard product. It's steel lined gyp board. I have used it on several east coast seismic projects.

 

[Triangled]

ditto sure-board

 

[XR250]

You could also strap brace it. Might be cheaper overall than the other alternatives.

 

[cal91]

You could also strap brace it. Might be cheaper overall than the other alternatives.

What do you use for the flat straps? CS/CMST coiled straps? I'm wondering about holes in the straps because Fu*An must be greater than Fy*Ag

 

[XR250]

Have not done one in awhile but I never spec'd coiled strap as the loads were generally too high. I believe most of mine were 3 or 4" wide, 14ga strap that was made up by a sheet metal fabricator.
You would have to check the strap for reduced area from the holes, but in my experience, the ability to get enough fasteners in the strap was the limiting factor.

 

[Deker]

I second the use of flat strap bracing if you can make it work. Sureboard is great structurally but we get lots of complaints about it being costly and difficult to work with. This tech brief is a great introduction to cold-formed shearwalls and strap braced walls (Link).