Multi-Story Wood Exterior Shear Wall - Horizontal Joint Location/Panel Layout

[abusementpark]

For an exterior multi-story wood shear wall, is there any issue with the horizontal joint of the sheathing occurring at the floor truss space, as long as blocking is provided between the trusses at the joint? This would be for 4'x8' sheets oriented horizontally. I have seen where some engineers do not allow the joint to occur at the floor. They want the sheathing to be continuous from the top plates of the lower floor to the bottom plate of the upper floor. Is there any reason for this?

Also, is there any reason to require the layout of the sheathing panels to have staggered end joints? I have seen in SDPWS where this is requirement for gypsum wallboard, but don't see anything requiring that for wood sheathing.

 

[phamENG]

As long as you're designing it as two shear walls stacked on top of each other with cumulative tension loads and not one giant one, the break in the middle is ok (just pay attention to your load path). One of the primary reasons for "lapping the floor band" with the sheathing is to eliminate the need for additional metal connectors to establish a positive load path for uplift in the wall (separate load case from the laterally loaded shear wall). This doesn't always work - where I am it does work for most homes, but if it's in Exposure D I've often had to bump it up and use straps regardless.

 

[abusementpark]

phamENG - I am not sure I follow what the difference in the two approaches you mentioned would be. Seems like either way you have the same tension.

I could see the uplift consideration in high wind regions.

 

[phamENG]

The tension load at the foundation will be the same, but you can step it down and optimize framing at the upper levels (lower tension/compression at upper floors means smaller end chords, etc.). Reading through these again I probably just confused the issue by saying that - sorry.

Generally, though, no - it's not a problem to have a joint in the sheathing at the floor band/floor truss space. As long as you provide a path for all of the loads, which it seems like you are (blocking, strapping, etc.), then you should be ok.

As for the end joints - yes, they should be staggered. I don't have my NDS or SPDWS with me at the moment so I can't verify, but I think there is a penalty in design capacities if all of your joints align in both directions. It's either a reduction factor to be applied or values in a totally different table. Standard practice for me has always been to require staggering, so I don't recall specifically where to find it.

 

[abusementpark]

phamENG - I don't see that requirement for woos shear wall in SDPWS. I know it matters for wood diaphragms and gypsum shear walls, but don't see that requirement for wood shear walls.

 

[msquared48]

PhamEMG:

For wood diaphragms, yes on the staggering.

For shear walls, though, never heard of the staggering.

Mike McCann, PE, SE (WA, HI)