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Thin thermal break?

user-7662801 | Posted in General Questions on


I’m looking for a bit of advice on how to tackle a small insulation issue.  I’m converting my garage to an adult and I’ll be installing 2″ rigid foam on the floor with OSB over that.  I have vapor barrier under the concrete slab as well.  

My question is what to do with what’s left with the stem wall.  It’s only about 6-7″ and only about 3″ or so will be exposed after the subfloor and flooring.  I really don’t want to lay foam on the stem wall as I’ll have a tiny little bump out all around the garage that isn’t behind kitchen counters or bathroom ‘stuff’. 

Is there any creative ways to create a very thin thermal break here behind the baseboards that will not create an unsightly tiny bump out?  Also, the weather isn’t too cold here and rarely gets below freezing (zone 5)


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  1. gusfhb | | #1

    Hide it behind fancy baseboard?
    It is amazing how you can hide offsets with trim, a 1x6 with scotia could hide a 1/2 or 3/4 inch of foam

  2. Expert Member
    Dana Dorsett | | #2

    >" Also, the weather isn’t too cold here and rarely gets below freezing (zone 5)"

    Every where in any IECC/DOE climate zone 5 freezing is extremely common. Are you referring to California Title 24 zone 5, or some other zone map?

    The answer matters, in terms of what might be the most appropriate approach.

  3. Reid Baldwin | | #3

    "converting my garage to an adult"

    Is it currently a child-garage?

    1. Expert Member
      Dana Dorsett | | #4

      >"Is it currently a child-garage?"

      They all grow up someday... (or so we hope.)

  4. gusfhb | | #5

    Get older, but do they grow up......

  5. user-7662801 | | #6

    It's a detached garage, yes. I'm zone 5 (climate zone 5 - but I see in the link you provided it would zone 4 there - just north of Seattle), on the west coast. We do get some freezing days, but there are not very many and when it does happen.

    The garage is 6 years old and the builder just put vapor barrier over the stem wall with drywall over that, which seems incorrect to me at first glance. But, it's going on 7 years now and there is absolutely no sign of mold or condensation damage, so it must have worked out ok ...?

    I was going to just do the same thing the builder did, but I also got advice from the city that I should be using at least 2" rigid foam on that stem wall, which seems to be a bit overkill as there is only going to be about 4" exposed above the subfloor after I install it (2" rigid foam with OSB over that). There is also vapor barrier under the concrete floor and the garage does sit on top of 4-5' of earth that was put over the original ground level of the forest there...

  6. gary__b | | #7

    It won't really answer your question, but I just finished something similar (here in Portland). I did 2" foam +OSB on the floor and carried it up the stem wall, which extended about 6" above the new subfloor. So as a result, yes, the stem wall bumps out a couple inches beyond the drywall. I ripped 6" tall MDF strips and joined those to a 2.5" MDF board, forming a baseboard stock material with a corner profile. Installed it over the foam.

    In the end, it looks quite good. I don't find the bump out unsightly at all, it seems like a design element. So perhaps instead of a weird tiny bump out, you just make it large enough to seem intentional?

  7. user-7662801 | | #8

    Sounds interesting Gary. Do you happen to have any pictures of that?

    That's my worry with adding the 2" foam (that it would look silly having 2" foam on only a 4" wall section). But I guess if I do bring it up a bit, it could look alright.

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