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Condensation at termite inspection strip

Samuel Hishmeh | Posted in General Questions on
I’m planning to have 2″ of closed cell spray foam installed on the walls and rim joist of my crawl space. I called two pest companies and one recommended to install a termite inspection strip at the bottom of the wall, and the other recommended the top of the wall. Both recommended a 6″ to 8″ strip, rather than the typical 3″ strip. My local building codes don’t seem to require an inspection strip. As a precaution I want to install one anyway. So I’m thinking the easiest place to install it will be near the top of the foundation wall, just below the existing vents.
 
I want to keep the inspection strip vapor and air tight. So I’m thinking I’ll put a clear polyethylene tape on the wall before the foam is installed, and to have the foam installed above and below the tape. The visibility through the tape will serve as the inspection strip. After the foam is installed, I want to install batt insulation in the strip, either fiberglass or mineral wool. My question is, do I need to worry about condensation accumulating on the strip during winter months? Seems like the answer is yes, if so how is this problem typically corrected?
 
I’m in Nashville, TN, climate zone 4A. My foundation wall consists of hollow concrete blocks. The top of the foundation wall varies from 1 to 2 feet above grade.

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Replies

  1. Expert Member
    Dana Dorsett | | #1

    >"My question is, do I need to worry about condensation accumulating on the strip during winter months?"

    The short answer is "not really".

    The foundation wall doesn't need to dry, is fairly vapor open, and will take on wintertime moisture as adsorb, not condensation, but would release moisture to the above-grade exterior to the drier winter air.

    In summer that strip theoretically represents an extremely modest latent cooling load, but nowhere NEAR the latent load of the "...existing vents...". If insulating the foundation wall with closed cell foam, close the vents too!

  2. Samuel Hishmeh | | #2

    >"The foundation wall doesn't need to dry, is fairly vapor open, and will take on wintertime moisture as adsorb, not condensation, but would release moisture to the above-grade exterior to the drier winter air."

    The winter condensation would be on the interior of the foundation wall I would think. If there's polyethylene over the strip the concrete block walls wouldn't be able to take on the the moisture from the condensation because of the poly. So I should leave out the poly/tape detail? What if I paint the strip with interior latex paint so that it's at least air sealed? That would probably stop adsorption too though.

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