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Thread: Insulating a Basement?

  1. #1

    Insulating a Basement?

    Good afternoon! I hope some of y'all know more about insulation than I do.

    I have a raised ranch (split level) style home, with a partially finished basement. On the front of the house, a part of the foundation is fully exposed. Inside this corner of the foundation is an unfinished store room. This room faces west, is closed off with a door, has no AC or return vent, and is easily 20* hotter than the rest of the basement, or the whole house even. I believe heat is leeching from this room into the rest of the home.

    I'd like to use construction adhesive and glue some foil face rigid insulation directly to the foundation walls, but I'm reading all sorts of stuff about EPS, XPS, faced, unfaced, concrete breathing, moisture levels, vapor barriers, etc. My plan does not involve studding it out or drywall or anything... it's just a small-ish junk room. Do I have to worry about moisture or breathability considering that both sides of the concrete are fully exposed? Foil facing the room or the concrete?

    The foundation is sound everywhere with no cracks or water issues. The basement was finished around 15 years ago and there's no evidence of damage OR repairs.

    Pics attached. The yellow area is the fully exposed area I'm talking about. House is located in the Heartland; 100+ degree summers, 10 degree winters.

    Sorry for the shotgun approach; there's a lot of conflicting info out there... Thanks.
    Attached Thumbnails Attached Thumbnails topElevation.jpg   frontElevation.jpg  

  2. #2
    Join Date
    May 2007
    Location
    Kansas City, Missouri
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    13,451
    Solid concrete has very little R value (1 - 1.5). Gluing up the 2" pick rigid insulation should help and give you about an R-10 value (11 - 11.5 total). You mostly don't want any paper that moisture/mold can feed on. I'd probably insulate the ceiling joists around the header plate too with batt insulation. I assume the wall against the garage side is insulated correct?
    Last edited by Darren Wright; 07-23-2012 at 07:25 PM.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  3. #3
    I just looked at it... between the joists is already stuffed with pink fluffy fiberglass insulation. Yes, there's a regular framed wall to the garage, and it's insulated. But looking at this... there's the un-insulated foundation wall, the ceiling of the room is un-insulated floor in my house, then the opposite wall (opposite of the foundation) is an un-insulated wall dividing the basement stairs.

    So it looks like there's a sheet of drywall, 6 feet of air, and four (6?) inches of concrete between my basement and the great outdoors. This is bad.

    Should I glue the foil side to the concrete or the non-foil side? Or should I get that pink-board unfaced stuff? Did "pick" = "pink" in your second sentence? Should I do anything special at the base of the wall (leave air space, rest on PT board, etc) or just run it to the floor?

    Thanks.

  4. #4
    Join Date
    May 2007
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    Kansas City, Missouri
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    I guess I'd check the board you're thinking about using to make sure it's fire resistant, I think the pink board is. I took a bunch of that foil type out of my shop as it was highly flammable. Not sure that the direction will make a lot of difference, but I'd probably face the foil into the room. I'd suspect you have an 8" thick wall unless you have a brick facade, then it' would be even thicker.

    Does the sun shine on that concrete wall for a good part of the day? If so, adding R-value will help more than anything, which is why I suggested the 2" foam, can do more if you think it will help, but start with one layer.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  5. #5
    Thanks for all the help, Darren. Checking on the board's details means my plans need to be modified. Owens Corning pink board's FAQ says:


    Q: Can FOAMULAR® be left exposed in a basement wall application?

    A: No. To comply with building codes, all foam plastics must be covered with a 15 minute thermal barrier. Gypsum board, ˝” thick is a common covering.

    Q: Can FOAMULAR® be used as interior basement wall insulation?

    A: Yes, but to comply with building codes, all foam plastics must be covered with a 15 minute thermal barrier. Gypsum board, ˝” thick is a common covering.



    So if I want to be up to code, I've got to cover it... I was not planning on that. It does have a "Class A" fire rating, whatever that means.



    Oh yes, it's shined on. The front facing wall is a few degrees south of due West; ergo, the wall facing the driveway is a few degrees West of due North. No tree shade. Plus the wife convinced me the house should be painted "Federal Blue" so it's sucking up the BTUs. It's 77* on the main floor, 75* in the basement, but 82* in that storeroom. It'll be 90* or 100* in a few hours after the heat soaks through the wall. Heck, the garage is only 80*, but the AC ducting runs through it and we have some VERY nice insulated garage doors.

    Thanks again for the tips. Time to grab some 2" foam, some twoBys and some drywall.

  6. #6
    Join Date
    May 2007
    Location
    Kansas City, Missouri
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    Well, if you're going that far...I'd probably put the pink board up, stud a wall out in front of it, stuff the studded wall with fiber insulation, put up a vapor barrier, and then drywall. Should be equal to what they did for the rest of your basement that way.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

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