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Tape OSB Seams?

3041 Views 6 Replies 5 Participants Last post by  Builder4070
Hi folks,

Our contractor asked if we want to tape the OSB seams.

He says that it isn't required but he does it because it helps to make the structure more air tight. He says he'll tape the seams if we buy the tape.

I did some research online and found that some high-end builders use Siga Wigluv or Zip System tape on OSB. But I didn't find anything really compelling that says this is a good practice or it makes a difference in addition to Tyvek.

To tape all the seams will cost about $600. Trying to understand if this is worth it or not. The house is in Northern California.

Any advice?

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If you are in an area that does not use a vapour barrier on the inside, I would think you want that. If you run AC for a good portion of the year, you want to keep warm air out and regulate incoming air if it is needed.
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I don't think there's a tape that will stick well and for long time to osb. OSB is too rough for one. Neither is there a long term study of these tapes. Warranty of them is only 10 years. This is recognized by some professionals so that they tape seal sheathing such as zip system, but also cover with house wrap.

If tyvek is conscienciously sealed, you don't need extra sheathing seals. I did, but I used tarpaper to wrap. As important is if foundation sill plates and the band joists are sealed (simple caulk where they join). It is also a good thing to seal the drywall to the studs and any gap around electric boxes, recess lights, plumbing chases.
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Why not use a liquid applied vapor barrier applied as per manufacture's instructions.
Thanks all. Appreciate the input.

Nealtw, yeah, we don't have a vapor barrier on the inside.
@carpdad, Interesting. I didn't know that builders are also wrapping the Zip System with house wrap. If you're going to wrap the house anyways, the Zip System feels like an overkill but I suppose it gives you a bit more protection.

The GC says the tape is cheap and adheres pretty well. It has the same adhesive as the Zip flashing tape, which adheres to OSB.

ClarenceBauer, he didn't mention liquid vapor barrier. I'll check with him.
Don’t know anything about long-term efficacy of taping osb seams.....but where I am inspectors say need to be taped they are.
@ront02769 - what tape do you typically use?
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