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Community and Q&A

Economical, Long-Lasting, Flexible Sealant

user-4435615 | Posted in Green Building Techniques on

CZ-4. Net Zero Energy Home. New Construction Ranch . Concrete Slab-On-Grade. Planning for 0.1ACH50. Using Huber Zip-R panels with (1″PolyIso laminated to the OSB).
I want to use an economical flexible sealant between the Sill Plate and the Concrete Slab that will last as long as the house; and I want to use a sealant with similar characteristics between the foam of the Zip-R panels and the framing to ensure an air tight seal. I plan to use it liberally to help get to that 0.1ACH50 and it would be particularly nice if it were also economical. I’d appreciate advice on which sealants would meet these criteria.

I’ve read about the use of many sealants including acoustical sealants, Prosoco Joint and Seam Filler, etc. etc. and many others that I’m sure that are flexible and long lasting but I fear are not also economical. A product called Geocel has been locally recommended but I don’t know about it’s suitability.

Would folks with experience with sealants make some recommendations ?

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  1. GBA Editor
    Martin Holladay | | #1

    The best way to seal the edges of Zip-R panels is with Zip System tape, not sealant.

    If you want something better than sill seal for the crack between your concrete foundation and the sill plate, I would use an EPDM gasket (available from Conservation Technology).

  2. user-4435615 | | #2

    Of course the seams of the Zip-R panels will be taped with Zip tape. What I'm looking for is a sealant to apply to the framing, as the sheathing is being applied to it, to seal the areas around the windows and along the bottom and top plates where air could leak between the sheathing and the framing.

  3. GBA Editor
    Martin Holladay | | #3

    By the way, are you really aiming for 0.1 ach50? That is extremely ambitious. Are you sure that you aren't aiming for 1 ach50?

  4. user-4435615 | | #4

    Yes, I am shooting for 0.1ACH50. I've been reading GBA now for a couple years in preparation for building my own home and I'm inspired. My builder is on board; the contractors are aware of the goal; and I'll be serving as the Air Sealing Specialist (ASS).
    Which is the point of the question about the economical, flexible, long-lasting sealant as I intend to apply it liberally where needed. I am aware of the EPDM membrane from Conservation Technology for the sill plate and it's smaller half size that could be used on the framing before the ZiP R panels are put into place. However, I'm looking for something perhaps more economical, simpler and more familiar for the framers to use.

    The 2900sf. ranch style house has a reasonably simple footprint. The envelope will consist of a concrete slab; Zip-R sheathing on advanced framed walls; and a minimally penetrated (plumbing/radon stacks) OSB deck on top of ceiling trusses through which the HVAC and other utilities will run. The OSB deck will be taped and sealed one way or another to prevent air leakage through the OSB. { See Q&A "Paint as an Air Barrier".} The Rim Band will be sealed with 5 ½" of open cell SPF. A pressure/fog test will be used to ferret out air leaks after the envelope is completed and before insulation or cladding. Repeat pressure/fog tests will be conducted at intervals as work progresses.

    I hope to reach that 0.1ACH goal; if not, I should be able to come close by adhering to what I've learned here and at the BSI website.

  5. GBA Editor
    Martin Holladay | | #5

    Take photos. When you're all done, write a guest blog for GBA. As I said, that's an ambitious air-sealing goal. But you never know what's possible unless you aim for a difficult goal. Good luck.

  6. STEPHEN SHEEHY | | #6

    Ted: use the EPDM gssket. It is easy and quicker to install than any sealant. It just staples to the underside of the mudsill.

  7. Expert Member

    Ted, If you want a belt-and-suspenders approach to make sure there are no gaps, use a gasket as Stephen suggests, and then once the mud sill is installed run a bead of acoustical sealant on the inside between the sill and the concrete.

  8. gusfhb | | #8


    Haven't seen it fail yet, but only been using it 18 years, so YMMV

    I am also a fan of real Grace Ice and Water, just a step above other similar products

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