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Air Sealing a Finished Basement – Vapor Membrane

rhl_ | Posted in General Questions on

I’ve been on a long basement renovation. drainage, new slab, insulation, floor heat, the works.

Now i’m onto the ceiling, I (painstakingly), installed staple up thermofin plates, pex-aluminum-pex 1/2″ pipe, soon will run new electrical, and some plumbing lines.

Next step, I will air seal the basement to first floor, and use closed cell HFO foam on the rim joists, then insulate each floor joist with something fluffy.

I was planning originally to use a solitex mento or intello product to provide an extra durable air seal. That stuff is expensive, and I may follow on with a layer of rigid foam.  If I do this, then the rigid is vapor closed, so I didn’t need the fancy membrane. Is there an inexpensive air barrier product I could use that would be similarly robust?

Would rigid + something inexpensive be a better build than intello (or mento) and drywall?

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Replies

  1. Expert Member
    Akos | | #1

    Basements should be conditioned, heated, cooled and overall connected to the rest of the house, there is no need to air seal between the two.

    Even when insulating the floor heat to keep heat gain the basement down, you still try to connect the spaces as much as possible. Regular drywall is perfect for this, no need for any special membrane products.

    I've never done anything more for finished basements.

  2. DCContrarian | | #2

    Agree with Akos. Even unfinished basements should be conditioned, unless you live in a climate where it never gets below freezing and you don't have to worry about pipes freezing.

    If the basement is insulated you don't gain anything by insulating between floors.

  3. rhl_ | | #3

    the basement is conditioned, but, it has a garage door, which despite our best efforts, isn't leak free. So I want to separate my garage from the rest of the house as best as possible.

    1. Expert Member
      Akos | | #4

      I doubt you'll ever seal a full ceiling with typical penetrations (wiring, pipes, ducts, stairs) as well as a garage door.

      Bit of weather stripping around the perimeter and install a threshold with a proper seal. You can also always replace your garage door with a proper exterior door.

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