Nail direction for a wood panel shear wall

[dcarr82775]

I can't find the actual requirement (I imagine it is somewhere) but I believe the head of the nail has to be against the sheathing on a shear wall. In other words the nails must be driven from the sheathing side, not the opposite side.

I have a gable end type truss with 2x flat members. The contractor didn't nail the sheathing to the truss sufficiently and the sheathing side has been covered with insulation and other finish material. Before I have them rip it apart to add nails, I was looking at the possibility of using nails or approved screws from the accessible side of the assembly (the unsheathed side of the truss) but I don't think nails/screws from that side get me the same strengths.

Anyone know if I can nail/screw from the opposite side?

 

[jdgengineer]

You cannot install nails through the stud into the sheathing.

Per NDS SDPWS 4.3.6.3 "Fasteners: Sheathing shall be attached to framing members using nails or other approved fasteners. Nails shall be driven with the head of the nail flush with the surface of the sheathing"

Additionally, per NDS Table 4.3A you need to have a minimum of 1 1/4" - 1 1/2" penetration into your framing member. Your sheathing would not be thick enough to meet these penetration requirements.

 

[dcarr82775]

Thanks JDG. I figured it was written somewhere.

 

[boo1]

Might be able to use adheasive and blocking to obtain shear resistance..

 

[jdgengineer]

You can only use adhesives if you are in a very low seismic category. I'm in high seismic so I've never used them or would consider them.

Per NDS SDPWS 4.3.6.3.1 "Adhesives: Adhesive attachment of shear wall sheathing shall not be used alone, or in combination with mechanical fasteners" Exception: Approved adhesive attachment systems shall be permitted for wind and seismic design in SDC A, B, and C where R = 1.5 and omega = 2.5, unless other values are approved"

 

[msquared48]

The use of adhesives will not lower the capacity of the shear wall. You just cannot bank on additional capacity beyond the nails. If the client wants to use the adhesive, I would say OK - it's just an additional factor of safety as far as I am concerned.

Mike McCann
MMC Engineering

 

[JAE]

Wood screws?

 

[jayrod12]

Wood screws are great for pullout however they are generally not as good as nails in shear because the threads are (almost) always intercepted so you end up needing a larger screw for the same lateral capacity.

And trying to install wood screws from the inside would require them to either be screwed as toe screws (in which case how do you control and confirm the depth of penetration into the sheathing).

I guess you could theoretically use galvanized connectors but who's going to go and install them every 6" on-centre and then you still only are able to use screws that are smaller than 3/4"(or less depending on sheathing thickness). Seems sketchy.

Guess the contractor should've nailed it right in the first place. RTFD