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Spray foam

Post in 'DIY and General non-hearth advice' started by Stegman, Sep 9, 2013.

  1. Stegman

    Stegman Feeling the Heat

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    I'm having spray foam installed in the basement in the next couple of weeks [around the rim joist and in between the floor joists] and I'm curious what to expect from folks who have used it. I've heard only great things about it.

    When we moved here three years ago there was pink insulation in the basement ceiling. Quickly discovered three problems:
    1. It wasn't particularly effective.
    2. We have an old house and mice found it to be a nice hiding/living spot
    3. The basement gets a bit humid in the summer, and we keep our cat litter down there. At times the cat pee smell tends to waft upstairs. [I'm convinced that the smell had actually gotten in to the insulation, much like your clothes pick up the smell of cigarette smoke when your in a bar].
    I'm led to believe that sealing the rim joist will be huge, especially for a house built in 1910. I'm hopeful the spray foam will also help with the other issues - as well as reduce the humidity since less outside air will be getting into the basement.

    Thoughts? Opinions?

    In case you're wondering, I'm paying $1,700 for two inches of closed cell foam for an 820 square foot area. I'll be getting a $300 rebate from my local utility, too.
    woodgeek likes this.

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  2. Retired Guy

    Retired Guy Feeling the Heat

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    After having owned two homes in this neighborhood that have had termite infestations, I have removed the insulation on the rim joist so that I can inspect it on a regular basis.If I lived in an area that didn't have termites, I'd foam the whole basement.
  3. peakbagger

    peakbagger Minister of Fire

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    Carpenter ants love to nest in it. Contrary to popular opinion it does not have to be damp from them to tunnel in it. I had foam sprayed on my sills and boxes, its did make a big difference in drafts. I have been resealing my sills from the exteriors and spraying borates to cut back on ants getting back in. They tried in one spot I didn't get to already in the year and a half since I sprayed it. I haven't found a firm that will guarantee against ant infestations. The can foamed folks offer one line that is supposed to prevent ants.
  4. begreen

    begreen Mooderator Staff Member

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    Let the cat live upstairs with the family.
  5. Stegman

    Stegman Feeling the Heat

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    Oh, the cats have the whole run of the house, believe me. But their "watercloset" is in the basement.
    Adios Pantalones likes this.
  6. Backwoods Savage

    Backwoods Savage Minister of Fire

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    We put in lots of spray foam a few years back and have been very happy with the results. Two others from this forum used the same company that we did and they too have been very pleased with the results.
  7. velvetfoot

    velvetfoot Minister of Fire

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    I think the smell might be mildew/mold or whatever rather than kitty pee.
    How about fireproofing?
  8. jharkin

    jharkin Minister of Fire

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    One suggestion is to think about whether you want to insulate the basement ceiling or the basement walls. If you do the ceiling you are cutting the basement off from the house turning it to unconditioned space. If you have heat and hot water equipment down there and/or like to use the basement for anything - even a workshop - where it would be nice to be a bit warmer you might get better overall results insulating the walls.

    The caveat being you want to be really sure you have no issues with moisture coming through the walls before you spray foam them. And if that 1910 house happens to have a mortared stone wall basement (unusual but not unheard of at that age) foaming walls would not be a good idea.

    There are lots of interesting articles on building science website related to this.
  9. woodgeek

    woodgeek Minister of Fire

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    I agree with Jeremy. Sprayfoam (properly applied) will be awesome for the rim/sill, and pay back. For the basement ceiling, except in special circumstances, it makes more sense to leave it uninsulated. And spray-foaming that big an area will be spendy. Poly-U foam can outgas some nasties, wouldn't personally worry about a sill job, the whole ceiling, however, might be a bigger concern. Higher fire risk that large of an area, etc.

    IOW, cut down the amount of foam 80-90%, and get the job done for <$500 (allowing for setup by the installer).

    And yes your humidity issue should be loads better.

    If you do want to do the basement walls, I would do rigid foam boards with wood furring strips tapconned to the foundation, then covered with drywall. Assuming there are no water issues and you want the conditioned space.
    Last edited: Sep 10, 2013
  10. firefighterjake

    firefighterjake Minister of Fire

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    Following this thread as I'm thinking of pulling out the fiberglass insulation I had wedged into the rim joist and using spray can foams in its place for a better seal.

    Eventually I'll probably insulate the walls.
  11. velvetfoot

    velvetfoot Minister of Fire

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    What kind of cans? Not the Great Stuff cans I hope.
  12. DaveGunter

    DaveGunter Member

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    That would get pricey, you might want to check into the 5G two part do it yourself kits of spray foam. I pieced in two inch foil faced poly iso foam board, and then spray foamed around the edges. Kind of a PIA job but worth it esp since my wood stove is in the basement.
  13. firefighterjake

    firefighterjake Minister of Fire

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    I was planning on doing so . . . any reason to not go with this foam?
  14. woodgeek

    woodgeek Minister of Fire

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    I think the issue is that it will be WAY too many cans, and v hard to dispense. DIY usually do as Dave said, cut boards inserted into place with can foam around the edges in a bead. Of you can have a company come in and spray foam the entire thing (with a much bigger/better dispenser). The company might be able to do it so fast and with so little material that their price is worth it compared to the DIY PITA. I love DIY sol'ns, but sometimes the tool makes the job.

    Edit: the rim joists need to be airsealed AND insulated to avoid condensation issues, so while you could airseal the rim/sill with cans, you can't build up a layer of foam with cans.
    Last edited: Sep 11, 2013
  15. semipro

    semipro Minister of Fire

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    I did some foam cost comparison calculations and found board foam to be much less expensive per unit volume than spray foam from either DIY cans or a pro's system.
    Sorry, don't have the numbers with me now.

    If someone decides to try the small cans of foam I'd strongly encourage you to check out my earlier post on use of the "pro" dispensers like the one below.
    http://www.hearth.com/talk/threads/spray-foam-gun-recommendation.73362/

    [​IMG]
  16. Stegman

    Stegman Feeling the Heat

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    We did this at a small cabin we have in Vermont and it's worked great.

    As far as my basement goes, it actually does have a mortared stone basement. But we have no intention of doing the walls or turning the basement into anything more than what it is, a basement. The goal is to simply tighten up the house, reduce mouse traffic/flow/habitat, and hopefully eliminate the occasional odor from the litterbox.
  17. woodgeek

    woodgeek Minister of Fire

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    Given that, then I suppose the foam under the floor is insulation AND airsealing, and it makes sense. Do you have a sheet-good subfloor that could be airsealed by other means? Or just old boards, where the foam is the best practice 'bandaid' for airsealing it?
  18. velvetfoot

    velvetfoot Minister of Fire

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    I tried to build up a spot with Great Stuff when I was doing the foam boards on the walls, and NO WAY. A big dripping, never-curing mess.
  19. Stegman

    Stegman Feeling the Heat

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    Don't know for sure, but from what I can tell from looking at areas where there are plumbing runs etc. it looks like it goes floor joists, ancient original subfloor planks, plywood over the planks, then the finish flooring.

    Thing is, I looked into a DIY approach with one of those kits they sell online, and the kits alone would have cost me something like $1,200. It's a no-brainer to bring in the pros for a couple of hundred dollars more.
    Huntindog1 and woodgeek like this.
  20. RustyShackleford

    RustyShackleford Minister of Fire

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    I had guys come in - about $4000 for 1700 sq-ft house - and do the plastic sealing of the floor and foam board on the walls. They pulled all the fiberglass batts in the crawlspace ceiling, but then went back and insulated around the rim joists with fiberglass. Reading this thread, I'm thinking they should have used spray foam, or boards cut and foamed into place.

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