My detached, unfinished garage is pretty sucky because the walls are only 6' high. Based on quick and dirty math, it'd make more sense to tear it down and start over than to try and finish it, but I don't have that much $$. I can't install a ceiling due to the garage doors passing through what would be the ceiling, and now I'm just trying to make the space usable without spending money since it's mostly a lost cause until I can save enough to just demo it and rebuild from scratch. I live in a cold/hot area (Indiana) and would like to insulate it so I can work in it and let the dogs stay in it when we're in those more extreme temperature swings, but I just don't know if it's worth bothering.

If I just insulated the roof would that be worth anything, or would the fact that the walls and doors aren't insulated make it pointless?

  • That sounds like a tool shed I had in Dayton and I think it would help to insulate the roof (if it’s big enough I might suggest lifting the roof like we did) we added 2’3” to the walls the roof was really nice had just been redone, jacked it up and made it useable. Just make sure no bad weather is forecast you don’t want it coming down if the winds kick up.
    – Ed Beal
    May 18, 2021 at 21:13
  • What color is the roof? May 18, 2021 at 21:20
  • Without doing the walls the benefit will be minimal. Whether it's "worth it" is a matter of opinion. Plus, you haven't said anything about whether or how you'll try to heat it. Without a heat source you may end up colder than before due to the loss of solar gain.
    – isherwood
    May 18, 2021 at 21:21
  • The solar gain is decided by the color of the roof. May 18, 2021 at 21:43
  • you can make no-cost insulation. Not as good as commercial, but a better value. My treehouse had packing foam, old towels, and carpet padding stapled to the wall. Even wadded up grocery bags behind cardboard stapled to the wall will greatly multiply the R-value. (you're tearing it down anyway, right?). Keeping it warm in winter is easier, use a black roof as mentioned. A tent inside the garage would protect dogs in all but blizzards.
    – dandavis
    May 18, 2021 at 21:58

1 Answer 1


It would be a huge waste of time and money to insulate only the roof area. Insulating overhead would only make any (small) sort of noticeable difference if the roof were black and you had a yard configuration where the garage roof was fully exposed but the surrounding area was shaded.

If this thing is sitting out by itself in the open then there is no gain for sure.

Now I see two options:

  1. Raise that garage up - this may not be as hard as you think. I just did this for a 10x16' barn.

  2. Insulate from the outside. You can attach rigid insulation + covering on the outside that could dramatically help. This is what we are doing with a lot of older HOMES in my area that did not get properly insulated. On some of them we are adding a good 3-4" to each side. If you can do this than doing the roof/ceiling is appropriate.

  • "in the open then there is no gain" What about solar gain in the summer? Wouldn't it be cooler if insulated? For instance, it can get very hot under a coloured outdoor party tent, sometimes hotter than in the direct sun.
    – P2000
    May 18, 2021 at 22:41

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