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Has anyone used Knauf’s “ECOSEAL”?

Arapahoe | Posted in Energy Efficiency and Durability on

This is a water based elastomeric spray (fancy caulk) that seals off the stud bay where OSB meets 2X. Each bay is sealed, all double top plate connections etc are sealed with this caulk. Has anyone used or witnessed its effectiveness? The idea here would be to seal with this ECOSEAL, then use a blown in insulation after so as to avoid the high cost of closed cell spray foam for a good air seal.

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  1. jklingel | | #1

    Are you using a weather resistant barrier, like Tyvek/Typar? Why OSB instead of plywood? Are you air sealing on the inside as well, or will this be instead of?

  2. Arapahoe | | #2

    Hi John,
    I think we are going with DOW R5.5 Structural insulated sheathing....thus no Tyvek/Typar. Not sure what the interior of this is but it must be structural sheathing of sometype. This ecoseal would be to spray the corners where the SIS panel or OSB or plywood is nailed to the stud. Seal off all bay's and seams from the inside and you are hoping to get the air seal without the use of a closed cell spray foam. My thought is you would use the ECOSEAL then insulate with regular batts or BIB.

  3. jnarchitects | | #4

    I used it on my own house. It was installed back in October. The house is 2x6 @ 24" o.c. w/ zipwall sheathing taped and 15lb felt and cedar shingles. We did some additional sealing during framing (caulking sheathing at all rim joists, caulking bottom plates, etc.), but nothing exhaustive.

    We used ecoseal w/ damp spray dense packed cellulose in walls, closed cell foam at all rims joists and roof/ rafter connection. The roof is insulated w/ dense packed cellulose and 2" of rigid foam on the interior with taped seams.

    I will have to dig up the blower door results, but they were very good. The HERS score was 54. It seemed to be a very good system and one that I will specify in the future. Much cheaper than foaming the entire house and I think overall a better performing wall even if the r-values are less.

    As with all insulation systems it has to be done well, I could see situations where it would be a total waste if not done carefully. It goes on so thin that the installer really has to make sure that he is putting on just the right amount to fully seal without leaving gaps or building up too much (particularly a problem on the face of studs where it might affect how the sheetrock lays.)

  4. jnarchitects | | #5

    By the way, don't waste your money on batts. Take the small upcharge and go w/ cellulose.

  5. Foamer | | #6


    The SIS panel forms an exterior vapor barrier. I don't know where you live but if it's cold, you may have to add closed cell foam on the inside to avoid possible moisture issues. Check out "Moisture Control for New Residential Buildings", Building Science Digest # 012 (

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