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Crawl Space/ Basement finishing

cotto11 | Posted in General Questions on

Getting ready to tackle finishing my basement, I’m just trying to figure the best approach with my crawl space.

It’s about 2’6″ high and about 25′ x 12′ space.  The base is rough concrete and there are not any openings to the exterior.  Only access is from the basement which is currently drywalled off.

Just trying to decide the best way to handle that as well as framing/sealing  the half wall.  Rest of the basement is getting 2″ EPS to the walls were I can fit it.

Attached a couple photos to help.

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  1. Expert Member
    BILL WICHERS | | #1

    Insulate hose crawl space walls! You can use the EPS there too. It looks like that crawlspace is pretty dry, so you probably don’t need to worry about a liner.

    Note that code requires some air exchange in that space. You can’t just drywall over the hatch, sealing it off, and leave it walled off. You should also leave some kind of access hatch in case you ever need to get back in there for maintenance work.


  2. cotto11 | | #2

    Thanks for response. 2 ?’s

    Can you rigid foam the walls and not put anything else in front of it and not be against any codes? (Fire hazard)

    And what might be the best way to keep some venting to the crawl space without completely drywalling it off like it currently is. (Besides just a giant hole to the abyss)

    Def. planned on making a small hatch door to enter though.

  3. Expert Member
    BILL WICHERS | | #3

    You're not generally permitted to leave non-rated rigid foam exposed, but there are two exceptions: inaccessible attic areas (no access hatch), and certain crawl spaces. You’ll want to check with your local building department if they’re ok with EPS left exposed in your crawl space. If you’re not using the crawlspace for storage, they might be ok with it. Otherwise you need a thermal or ignition barrier, I’d probably use hardboard or sufficient thickness (I think 1/4” is code but I’d have to check), mainly because it’s a little easier to handle in a tight space than the much heavier 1/2” drywall.

    Vents in air ducts are one way to get some air exchange. It really depends on your space and what is easiest to implement. There are some articles on here with more specifies since there are some CFM requirements based on the size of the crawlspace.


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