I live in Ohio and have created a golf stimulator in my attached garage. The garage typically stays around 10 degrees warmer than the outside without wall insulation except the interior wall.

I can raise the temperature with a 4000 watt electric heater another 20 degrees. The ceiling and walls are all finished with drywall.

What will provide better heat retention? Insulating the walls would be a big project; one that I want to avoid. I weather stripped the exterior garage door and that helped quite a bit. I suspect the priority should be the ceiling, then the door.

  • I use a torpedo heater in my minnesota garage without insultation and it works fine. Commented Feb 14, 2016 at 6:30
  • 2
    I have enough tools in the garage that I don't want to risk the moisture byproduct of the burning fuel rusting everything. Plus, dealing with the propane tanks is a pain. I also need to have a heater up on the ceiling, as I have two little ones.
    – Evil Elf
    Commented Feb 14, 2016 at 14:23

3 Answers 3


Stand in your garage with the lights off and the doors closed. Look for where light comes in (other than glazed windows) Those areas around the door are where there is open space that allows the door to open without rubbing.

Before you insulate anything, work on closing up or reducing those gaps. If you still want to open the garage door, remember that parts still have to move.

You can get various bristle brush products that will close off gaps while allowing things to move. Good for 10-25mm of gap.

If the gap is under 10mm you can use sticky-backed foam strips, often used for windows. These come in a range of thicknesses. Also window-worm can be handy to shove into holes.

Gaps of over an inch can probably be best reduced with permanent timber framing.

If your garage door already has rubber seals, that have hardened or squashed, then consider replacing them too. If the door has settled, then also look at what adjustments there are in the frame.

Second I'd insulate the inside of the door using closed cell foam board cut to fit. Polystychrene sheets are adequate and provide insulation too.

Remember you're adding weight to the door, so any opening/assist springs may need increasing to allow for lifting the additional weight.

The ceiling insulation would be my third choice - ceiling spaces are horrible to work in, but conversely are probably the most return.

Assuming you can get into the ceiling space over the garage, then at least check it out.

If you can measure the space between trusses, and get batts that are exactly the right width, then it saves a lot of effort. Wear a mask, and gloves and full length shirt and trousers. I even tape my trouser pants into my socks and shirt cuffs into my gloves to keep the fibres out.

Also work on a cold winter day, not a hot summer's day. I found a 4-5 foot (120-150cm) stick with a 4"/100mm nail poking sideways through the end to be a handy tool for shoving batts right out in the edges.

You should also cut one or two pieces of lumber to move around and stand/kneel/lie on while working. 6x2" or 8x1" is ideal, a 2x4" tends to be too narrow for knees. You can only stand on the trusses, not the battens/runners and absolutely never the cladding/lining.

Also set up several lights - perhaps one mains powered by the access point, one battery that you can clip to a rafter, and a forehead-lamp. Also carry a spare torch/flashlight in your pocket.

You can lay the batts over wiring, but not over through-ceiling light fittings. Leave breathing space for the fitting, or consider replacing them with lights that are below the ceiling, like LED or flourescent tubes.


Insulating a garage door is really quite easy. There are kits on the market here in the UK but I just used cellotex (foam sheet) because I had some lying around. A steel door has even less insulation value than a drywall-lined ceiling.

I'd do the door first as the least effort to get a noticable return.


Seeing as heat rises, and you don't want to get into the walls, I would recommend insulating your attic if you want maximum effect.

If the attic is not used for storage and is relatively easy to navigate, I would recommend:

  • cover any electrical boxes
  • install durovent panes if needed for existing soffit vents
  • stuff R30 at the base of the durovents to retain loose insulation
  • blow in insulation

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