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Community and Q&A

Tyvek install/sealing this weekend

Jamie_K | Posted in GBA Pro Help on

We are currently building slab on grade shop to live in for 1-2 years while we  build our house and want to get the ventilation, moisture, air, etc. details as good as we can hopefully with your help. Already up:  slab, 4′ foundation walls, wood framing/trusses with 2-3′ eves, plywood sheathing for both exterior walls & roof (no OSB), roof getting dried in now.  Wall from outside in will be:  Hardie Board plank lap siding (possibly Hardie shingle siding at top of gable ends), Tyvek Housewrap, plywood sheathing, wood framing with paperless backed fiberglass insulation, drywall.    I’m thinking Hardie shingle still laps like the other, so there would be a little air space in between each lap layer.  We taped plywood sheathing seams with 3M Flashing Tape 8067 on walls only (for some air barrier) but did not extend sealing like that up into vented attic space’s plywood sheathing.  We are going to put up traditional Tyvek Housewrap this weekend (not DrainWrap) with Stinger cap staples but had questions on the sealing. 1) We will Tyvek tape vertical seams but should we tape horizontal seams also for some added air/water barrier protection horizontally? 2) At very top most last layers/perimeter, what should we seal that top edge with:  Tyvek tape or like OSI Quad Max?  (DuPont rep said their caulking didn’t perform great in Pacific NW.) ……Now bottom is the kicker. 3) We were thinking of applying 3 1/8″ Contego Solido Exo tape along seam where plywood sheathing interfaces with concrete foundation wall first to air seal and water protect that since it’s vapor open tape? 4) Then, would we apply Tyvek at/to bottom of plywood at sill plate or extend 1″ below plywood? 5) Then, if the Tyvek tape adheres [otherwise use maybe OSI Quad Max caulking] to skip seal with couple inches every 2 feet of the Tyvek to the Contego Solido Exo tape to allow not a full seal but some adherence while still allowing any water [that hopefully never will but if it does] to escape through bottom edge between plywood sheathing and Tyvek down over Contego Solido Exo tape and through skip sealed portions of Tyvek sealed to it? 6) Or completely disregard these last few steps (#3-5) at bottom and instead use Contego tape to cover/seal bottom seam of Tyvek interfacing concrete foundation wall; and installing first layer of Tyvek 2″ below sill plate so that if any water should collect and come down between plywood sheathing and Tyvek and puddle at Congego tape, it would at least be further below wood and form more at concrete level below?  We just aren’t sure which route makes most sense with the bottom. Thanks a bunch for any expert advice in our question(s) here.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    User-7152521,
    First of all, can you tell us your name? (I'm Martin.)

    You'll get more answers from the GBA community if you simplify your post -- make it shorter -- and stick to one question at a time.

    You have installed plywood sheathing with taped seams. If you did a diligent job, that's your exterior air barrier. Using the sheathing layer as the air barrier is common.

    Your water-resistive barrier -- in your case, Tyvek -- does not have to be airtight. It's not your air barrier. All you have to do is install the Tyvek in compliance with the manufacturer's installation instructions (these are available online) and stop worrying.

  2. Jamie_K | | #2

    Ope, I'm Jamie, Martin. I thought I added name correctly (I'm new) before I posted; hopefully, it comes through now as I updated screen name again. Thanks for your response and getting me familiar with posting.

    At that bottom edge thought, I would think we should hold Tyvek down 2" below sill plate and tape to concrete wall so that any rain/snow won't get up under Tyvek to our plywood sheathing? Holding down 2" below plywood, should any water accumulate between plywood/Tyvek it would puddle at concrete not plywood..

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