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So today after a few weeks I went to go follow up on the progress of my tract home being built. Things are coming along well. One concern though I have that I found random was that there's about 60 or so feet of random non-OSB sheathed walls around the house. They just put some plastic coroplast feeling type of plastic against the framing and nailed Dupont Tyvek to it. I find this weird.

Wouldn't the whole house have the OSB? I have attached some pictures below. If this is a California code thing or something please let me now but its a little concerning. One of the areas they put the plastic was behind our heads in the master bedroom. Someone can just literally punch a hole through the house if they wanted to. I really hope they don't do this to save a couple hundred bucks on some wood. I would have paid the damn difference.

Any advice or if I should be concerned please let me know. I found this in four spots on the house listed below:

  • Master bedroom, directly behind my headrest of the bed 8 feet

  • Outside wall of entire garage - 20 or so feet

  • about 6 feet right behind the 3.0 ton AC connections near our rear sliding door.

  • about 8 feet in my spare bedroom external wall

The rest of the house seems sturdy with strong plywood or OSB on the 2x6 studs but this seems like a security issue as well as a strength issue.

Please check out the images:

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    This is not normal. What kind of siding are you using? Plywood siding could provide the shear resistance you need for the wind and seismic zone you live in. However, how are they going to handle the two layer system where the OSB board is installed and where it’s not installed? – Lee Sam Oct 16 at 6:25
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    They might have left it out n strategic places to bring the drywall in. They put up the tyvek to seal the building from the weather. Just a guess. – mikes Oct 16 at 10:42
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    I live in the Midwest and I have seen this as common practice over the last 20 years or so. A couple of sheets of plywood/OSB at each corner, then the rest of the walls sheathed with the same thickness of foam, then house wrap and vinyl siding. I could literally cut through the wall with a utility knife! We don't have the seismic activity that CA does, but we get some pretty good straight-line wind & plenty o' tornadoes. I guess it meets code because I've seen it 100s of times. I wouldn't want it, but that's what they throw up 'cause it's cheap. – FreeMan Oct 16 at 14:06
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    2x6 framing is adding a lot to the strength of the walls. Will this have brick or vinyl siding? – Kris Oct 16 at 14:33
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    @Tetsujin, Oriented Strand Board (OSB) is now used in many applications where plywood was formerly. – Jim Stewart Oct 16 at 18:49
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Why not ask the builder about the lack of OSB sheathing in those places?

We have lived for 42 years in Dallas, Texas in a 1970 build tract house which has no serious sheathing anywhere. The studs are sheathed in an insubstantial fiberboard (dark brown in color) with aluminum foil on the outside.

The corners are 45 deg angle braced with 1" x 4" boards let in to the studs. Yet the house seems structurally stable. A custom builder from California told me once that stud construction as practiced in the US is far above the minimum required for structural soundness.

EDIT

Impression from the pictures is absolutely 1st quality construction. Exterior studs 2x6 on 16" centers? Is there to be an exterior access tankless water heater in the metal box in the first picture or is that for the electric service panel?

I would bet the builder would have a good reason for leaving off the OSB in those selected locations. Ask them and tell us what they say.

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    Yes, fiberboard ("buffalo board") and gypsum (like water-resistant drywall) are common cost-saving sheathings used when lumber prices are high. They are now, thanks to COVID. – isherwood Oct 16 at 13:24
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The OSB is there to create a 'shear' wall. The OSB provides additional rigidity to walls that are expected to have to resist lateral forces due to wind, slope, etc. It's not needed on all walls and in tract homes it would be generally considered an unnecessary expense to place it on all walls.

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