# What is the correct plywood/OSB orientation for building a seismic shear wall?

We are building a shear wall by adding structural-1 plywood or OSB to the existing framing and nailing according to a nailing schedule. The wall is 13'x8'.

What is the best way to orient the plywood for the best shear strength and nail retention?

• Vertical?
• Horizontal?
• Horizontal in a brick-lay pattern?
• Other?

• A good shear wall starts with the studs, your wall studs need to be stuffed up a lot, including diagonals or brackets. See if you can get details from searching online, or consult with an engineer.
– r13
Commented Oct 10, 2021 at 0:54
• Horizontal. Brick pattern
– Kris
Commented Oct 10, 2021 at 0:59
• Strongest is the the sheets rotated 45 degrees and tiled squarely, because all the sloping blocking you'll need to add for that arrangement will also function as diagonal bracing. this is overdoing it. Commented Oct 10, 2021 at 10:28
• Back to your original concern, the board installed horizontally will be more stable than the other way around, because it has a lower geometric aspect ratio V/H (vertical length vs horizontal length) in direction of the shear force due to the seismic event. The brick pattern has the advantage over the butt-jointed boards, depending on the arrangement of the studs. woodworks.org/wp-content/uploads/…
– r13
Commented Oct 10, 2021 at 23:09
• @P2000 Yes, the vertical 2x4s were notched to allow the diagonal 2x4 to sit flush; this was in the 1960s. Our house built in 1965 still had the diagonal 2x4s there. (No drywall in the garage, so I could see them.) Commented Oct 11, 2021 at 13:56

Are you trying to solve a specific problem with the structure? If so, you might indeed want to engage an engineer.

If you are simply trying to add a little rigidity to your building, plywood is a good choice. It will work in either orientation, but horizontal brick pattern is most typical. Consider tying the ends (and sides) together with sheathing brackets, like this:

https://www.strongtie.com/clipsandties_miscellaneousconnectors/pscl-psca_productgroup_wcc/p/pscl.psca

They will add a great deal of shear resistance at a minimal cost.

• "It will work in either orientation" +1 for addressing the specifics of OP's question (and that peaked my interest too...) Commented Oct 10, 2021 at 15:46
• Thank you for pointing out the sheathing clips. Two questions: (1) How frequently should they be placed? (2) Do you have any documentation about the increase in sheer resistance? Commented Oct 11, 2021 at 2:10
• Every AHJ is different, but I can't imagine how H clips make better edge fasteners than solid blocking. To the OP: proceed carefully with information you get off the internetz for free. Commented Oct 11, 2021 at 2:40
• I'm adding the comment from @r13 here because it addresses the strength question of which pattern is strongest: "The board installed horizontally will be more stable than the other way around, because it has a lower geometric aspect ratio V/H (vertical length vs horizontal length) in direction of the shear force due to the seismic event. The brick pattern has the advantage over the butt-jointed boards, depending on the arrangement of the studs: woodworks.org/wp-content/uploads/… " Commented Oct 20, 2021 at 1:04

the wall is 13x8 and the boards are 4x8, the simplest way is to put the 8 dimesnion of the boards on the 8 dimension of the wall.

As the boards need to be nailed all round the perimeter, if you lay the boards horizontally you'll need to add blocking to catch the edges of the boards.

If you stand them vertically you'll need a stud where the edges of the boards meet. It looks like you have 16" spacing for your studs, so you'll only need to cut the end boards (and a hole for the electrical panel id that needs to be accessible from the side you are boarding)

When properly nailed both orientations are equal in strenngth

• Your answer addresses the puzzling part; could you also comment on the best orientation in terms of shear strength? Commented Oct 10, 2021 at 4:51
• See wiki entry on plywood This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent across all directions. Commented Oct 10, 2021 at 15:26
• @user2448131, yes that might be correct for shear strength (I don't know), which is what the OP asked about (but it is worth mentioning that in general, esp. for tensile strength in a floor assembly, the "strength axis of plywood" does matter). I think it would be helpful if you could qualify that, and perhaps even submit it all as an answer since it nails (!) the OP's question. Commented Oct 10, 2021 at 15:45
• Plywood is stronger than OSB. You could also go belt and suspenders; put steel strapping diagonals on the studs before plywood. Commented Oct 10, 2021 at 15:57
• @blacksmith37, according to this document on PDF page 48, OSB is stronger than plywood: woodworks.org/wp-content/uploads/… . OSB is known to be stronger for shear forces because the laminate layers are randomly oriented, not orthogonal. There is a bit of controversy on the subject, but I think the studies on the subject have worked that out. Commented Oct 11, 2021 at 2:01