I have these solid insulation leftover panels and I am planning to reuse them to insulate the garage or a shed. It is going to happen in spring but till then they are in my way. As I am re-organizing the garage (for now it is literarily storage and small Woodworking area) I am looking for an area to store these and I just realized that for this winter I could just put them against the exterior walls of the garage, on the inside (this is an attached garage)

The space is not heated right now and I might install a vented/unvented heater very soon as I need to do some woodworking there The walls are cinder block with brick veneer on the outside and some very old plaster coating on the inside (no framing at all)

Is this a good or a bad idea?

The only downside I am seeing is that humidity might accumulate there ...condense maybe ? They will not be like very tight against the wall It is not a lot of insulation just what you see in the picture enter image description here

  • 2
    You might want to flame-test that stuff before deciding where to store it. Some of it resists ignition, other stuff is basically napalm and will incapacitate you with toxic fumes before you can make it to the exit door. Commented Nov 12, 2022 at 22:08
  • that is a good point. I guess the white stuff which is packing Styrofoam might not be very friendly in that respect and maybe I should trash it
    – MiniMe
    Commented Nov 12, 2022 at 22:40
  • The green and blue one is bought as proper insulation so that should be safe
    – MiniMe
    Commented Nov 12, 2022 at 22:42
  • 3
    EPS and XPS (what you have there) must be installed behind drywall. For more on fire safety have a look at my and Harper's answer here: diy.stackexchange.com/questions/256152/…
    – P2000
    Commented Nov 12, 2022 at 22:46
  • Yes so I guess I need to trash the white stuff anyway AND decide if I want to work with a heater there and the XPS exposed ... If I trash the white stuff I won't be left with a lot to store in the shed for the blue green stuff so that might be OK then to relocate from the garage because I already have enough wood in the garage to set Toronto on fire :-)) (plywood and 2 by Xes)
    – MiniMe
    Commented Nov 12, 2022 at 22:57

1 Answer 1


You can store these panels in your garage or elsewhere inside or outside. If store outside keep them in a dry place. Keeping wind and rain away will prevent them from getting grimy.

If you are concerned about moisture or mold, make sure they are set off from the wall so that the wall surface still has air flow. Leaning them under an angle should be fine. You can also put strips of the smaller pieces upright against the wall, and lean the larger panels against the strips. Do not expect an insulation benefit from them: leaning them against a wall will do nothing for insulation.

A further concern is fire hazard. These boards are highly flammable, and as a building material they are supposed to be covered by drywall. They will not ignite on their own from the warmth of the furnace, but once a fire gets to them they are an excellent source of fuel. Keeping them in the garage for a winter is not a serious concern, since many other flammable materials are kept there, including cars and everything that comes with them.

See Meeting the Fire Code with Continuous Foam Plastic Insulation, and also have a look at the earlier question Is there any reason *not* to add shipping styrofoam pieces to wall insulation?

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.