Stringers below ceiling joists; also adding plywood plates on top of walls for air barrier attachment
I believe I’ve read in GBA the idea of putting 3/4″ plywood strips on top of both exterior and interior walls for attachment and sealing of interior air barriers. It is definitely discussed in FHB ( https://www.finehomebuilding.com/2014/03/05/a-practical-air-sealing-sequence )
My question is what is the nailing schedule for such a modification? The trusses or rafters are typically nailed to the top plate. However adding a piece of 3/4″ plywood and using the same nails as before assumes that (1) the plywood is fastened with enough appropriately sized nails that it is “one with the top plate,” and (2) the plywood grips the nails the same as the typical top plate. If these assumptions are false, then probably longer nails should be used. But none of this is spelled out in the code (for example, 2015 IRC Table 602.3(1) ). Is everybody just nailing down the plywood similar to a top plate and calling it good? Or has anyone actually engineered this connection?
A similar question — apparently in New England it is common to attach 1-by stringers to ceiling joists. How wide are these stringers and how are they fastened? Are they 1×3 or what? A couple nails at each joist intersection? Again I don’t see this as part of the prescriptive code, so are people just doing whatever and hoping the building inspector OKs it?
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