why not 5/8" struct 1 ply for shear wall sheathing??

[Engineerataltitude]

Anyone know why NDS does not allow (give specs for) shear walls sheathed with 5/8" Struct 1 ply? I've combed the commentary and can't find anything on the subject. I have a retrofit application where I'd love to sheath one side of an interior wall with 5/8" struct 1 ply to get the shear strength I need because single-sided 1/2" struct 1 ply isn't strong enough. It is prohibitively expensive to access the other side (built-in cabinets, etc.)

Clearly 5/8" struct 1 ply exists and is stronger than 1/2" struct 1 ply for sheathing. The NDS tables for horizontal diaphragms confirm this.

Why not for shear wall sheathing?

 

[msquared48]

Used to be in the UBC.

Mike McCann, PE, SE (WA)

 

[Engineerataltitude]

Hmmm...not the 97 UBC. At least not for Struct 1 ply. 19/32 is in both the old an new allowable shear tables but only for the lower grade. Max shear for single sided plywood sheathed wood framed shear walls for any panel grade is 870 lb/ft (ASD). I need something to get me 1050 lb/ft single sided. Was thinking 5/8" struct 1 ply might get me there if it was permitted.

I wonder if it has to do with nail sizes and embedment limitations into wood studs.

I may have to contact AWC technical support to answer this one.

 

[jayrod12]

I don't know about the IBC, but the CSA has it, however you need either double studs or 64mm wide studs at each panel edge to get that capacity.

 

[msquared48]

The 1997 UBC and 2012 NDS both give values for 15/32 Structural 1 plywood..
UBC Table 23-II-I-1 (ASD values)
NDS Table 4.3A (LRFD Values)

Agreed that 19/32 is not 5/8, but it's as close as you'll get.

Mike McCann, PE, SE (WA)