Nail plywood sheathing from backside?

[StructuralEd]

Would nails have any shear value if installed through framing outward into the plywood sheathing with the head on the framing side, not the plywood side, and the nails not protruding from the sheathing so they can't be cinched over?

 

[dhengr]

NO

 

[jdgengineer]

What is the application?
My only guess would be that you are trying to install a new collector to an existing floor/roof without removing the finish.
If this is the case, Simpson Strong-Tie has done testing with their A35 clips using very short screws.

See link below.

http://www.strongtie.com/ftp/letters/generic/L-A35SHTG.pdf

 

[StructuralEd]

Application is increasing sheathing attachment for shear loads by nailing through interior blocking avoiding removal of exterior finish.
My thought is that lack of restriction from nail heads or chinching on the plywood face could allow movement and preclude shear value.

 

[dhengr]

StructuralEd:
You’ve got the right idea. It’s the holding power (pull through at the plywd.) of the nail head or a clinched nail, plus some min. amount of nail penetration into the structural member which counts, for the shear cap’y. And, you don’t have the first item. Nor do you have sufficient penetration into a thin piece of plywd. Take a look at the nail failure mechanisms in the NDS manuals, the nail will just bend over and pull out of the plywd.

 

[jdgengineer]

I agree with the others I wouldn't count on shearvalues for that installation. All the shear wall values are based on testing with very specific installation requirements. I'd be hesistant to modify them much.

How about sheathing the interior face?

 

[woodman88]

Maybe, it depends on how the completed system will work. I have mainly used this when I can calculate the normal nailing to work, per the code, but feel more is needed.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[mbullism]

We had a job several years ago with blocked seam plywood shearwalls... the GC was reminded of the blocking requirement, but omitted the blocking and installed the exterior brick veneer. The sheathing was only 1/2"... We ended up x-bracing the interior face of stud with heavy gage metal and plate prior to the gwb going up, basically abandoning the shearwall and x-bracing to the same corner anchors. The number and size of screws was cumbersome at best and it was tough to install finishes over.

I wouldn't trust nails from the interior side into the sheathing .02

 

[StructuralEd]

Thanks all.