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Large Gap Between Wall Sheathing Panels OK?

Nat . | Posted in General Questions on

This is new construction, the wall is sheathed with zip-r. I noticed yesterday that at two areas the framer ended up with large gaps between adjacent zip-r panels. I found this by chance and I’m trying to figure out if it needs to be addressed.

One location is a horizontal joint, the upper panels along one wall sit about 3/4″ above the lower (this happened due to a weird sequencing where he had to leave those panels out and try to slip in after). It looks like he tried to cut thin strips of zip r and leave them in there before he taped the joint. That little strip, as you can imagine, is pretty unstable and wonky. I can see that in some areas it remained intact, in other areas the foam remained in place but the osb came off, and in some areas it looks like it’s gone missing and there’s a 3/4″ gap. So I’m left with zip tape bridging a good size gap. Feeling that tape floating over the gap worries me – it feels very not robust.

The other location of a large gap is at an interior corner where the gap at the butting panels varies from about 1/4″ to 3/4″. At this location the framer has sprayed that gap with low expansion window foam and has not taped it yet.

I’m trying to figure out if this is really an issue or just a crappy detail that I’ll have to live with. I am thinking the following:

Structure: Doesn’t seem to be an issue. The wall is blocked at these locations and the gap doesn’t reduce the wall shear capacity

Air sealing: Reliant on the tape whether it’s a 1/8 gap of 3/4 so I don’t know that it’s any worse off. If the tape ever fails then it’d be a lot worse to have a big gap. Since these are blocked I can’t get to the gap from the inside – but I could caulk all around the blocking although not sure it’s necessary.

Water: This one worries me. Again i’m reliant on the tape in general so if the tape fails anywhere it’s a problem. A 3/4 gap feels more worrisome than a 1/8 though. I also worry that the nature of hte 3/4 gap makes the tape more easily punctured or torn leading to a failure.

Solution: If I do need to address this what is the best option? I can’t very easily rip these panels out. 1) These wall segments are about 3ft long between windows and I have access from the side. I could get a long nozzle in there and spray low expansion foam. This would give the tape some backing/substrate, not much but better than air. 2) I could have him pull or cut the tape, rip 3/4″ x 2″ strips of wood, glob caulk/adhesive in the gap and insert the strips, re-tape. I’m not sure if zip can be pulled off without damaging the integrated wrb and according to huber taping over tape has limited adhesion (has a release agent on its back). 3) something else? 4) leave it alone and be annoyed but live with it

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Replies

  1. Steve Knapp CZ 3A Georgia | | #1

    Huber instruction guide calls for 1/8-inch gap between panels that don't have the built-in spacer.

    This is a premium product and the installation really should conform to the manufacturer's specification (for warranty if no other reason).

    I also would worry that someone might try to anchor to this undersized filler.

  2. Nat . | | #2

    Turns out that huber has a tech guide for this occurrence. For up to 1/2" they state to just bridge with zip tape (up to 1/4 is ok for liquid flash). Larger than 1/2 they recommend either cutting a small strip of zip-r or using low expansion foam. Since mine is already taped I'd have to pull the tape to do this. They told me that the tape can be pulled w/out damaging the wrb.

    I don't love either of those options. To me it seems better to rip solid wood to fill it, maybe glued/caulked into place. I'm not worried about tiny loss of insulation, so having a solid backing seems worth it. The low expansion foam is pretty squishy as a backing, it seems like it still leaves it vulnerable to puncture. Maybe it's ok though... Maybe I'll test an area.

    I also wondered about running a 4" and then a 6" piece of tape, i.e. 2x the tape to make it a bit tougher against puncture/tears.

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