Zip Sheathing Layout
Wunderbar
| Posted in Building Code Questions on
Im installing new zip 4×10′ sheathing on an old farmhouse in Oregon (zone 4) and was wondering the best practice for the sheathing layout.
The first story is 10′ ceilings and the second story is 8′ plus the rafter height (ill be notching and taping). Ive got 4×10 sheets and was going to install vertical but since the first story has 10′ ceilings, the panel doesn’t quite reach the second floor joists. So now i’m thinking it might be best to install 4×10 horizontal first and then 4×10 vertical that would tie the 2 floors together or would it be best to just install everything vertical?
Thanks
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Replies
Wunderbar,
Your main layout aim is to overlap the floor systems to provide structural continuity, and if your part of Oregon is in a high seismic zone, to make sure no panel edges are unsupported. How you run your sheets makes very little difference. On old houses the chances of the framing layout allowing vertical sheets to fall on studs is pretty low, but you may get lucky. For increased shear resistance in seismic zones, provide blocking in the stud bays to support the horizontal joints.
This seems to be mostly regional preference. Here in the northeast, we mostly install sheets horizontally, and in some situations the seams need to be blocked. Sheets are more resistant to deflection when installed horizontally, due to the "grain" of the panel, but in most cases that's probably not important. In other locations, running sheets vertically seems to be common, partly because it eliminates the need for blocking the seams. Are you in a high-wind or seismically active area?
Micheal,
Yes, im in a seismic area (Pacific NW) and im up on a hill that gets some fairly strong wind. The home does have large 3' overhangs and an open porch so was thinking there may be a layout that's best for uplift force but maybe it doesn't really matter?
Thanks!
The way that I would do it and have most commonly seen it done in the Bay area of California and now Washington state is to run the sheathing vertically, not staggered, and to have sheets end on rim joists whenever possible. It sounds like that won't be possible for you, so I'd run blocking (2x4 on the flat) centered at 10' up from bottom of mudsill and meet your sheets there.
You didn't say how tall your second story is, if you can cut the sheets to run from top of wall to rim joist on the upper story you might want to do that so you only have to install one course of blocking.
For uplift/seismic it's important to use the correct nails, you probably know this but I'll say it anyway, use 0.131" or 0.148" nails for sheathing. IRC has good info on this, my default is 2-1/2" x 0.131" nails at 6" edge spacing, 12" in the field.
Zak,
Great thanks, good tips!
This is a retrofit so i'm putting zip over the top of 1x12 boards that are run horizontal. I was thinking id up my nail size to 3" to insure good connection on studs as well. On the plus side, the 1920's 2x4" stud layout is 16" o/c so lucked out on that one.
Wunderbar-
This may be overkill for your project, but Huber puts out nailing schedules for their Zip-R to resist lateral forces, it's kind of analogous to your situation nailing through board sheathing. They specify 0.131 nails at 4/12 spacing, penetrating the framing a minimum of 1.5". It's in the Zip System R sheathing installation manual.
Like zak says, the IRC has guidance. It's not a simple answer. Here's the main section of the IRC that's relevant, assuming that's what you're required to follow; if you don't have to follow codes, the IRC provides a safe baseline. https://codes.iccsafe.org/content/IRC2018/chapter-6-wall-construction#IRC2018_Pt03_Ch06_SecR602.3
Thanks, ive got that bookmarked. Was mostly just wondering if the layout really mattered much as my structural engineer only specs no horizontal seams 12" from mudsill or top plate.
There is more resistance to uplift when the sheathing spans plates, but if your engineer isn't worried about it, I wouldn't be either.
Zip sheathing is a way to create a waterproof barrier. It goes on the roof decking before the roof membrane is installed. The sheathing is supposed to seal the VeePN roof decking against moisture, water, and termites.
SPAM
Can you cut the bottom piece to land on the rim joist and still fit the top piece? You'd have to cut both pieces, but you'd save on blocking.