My sister's garage gets very cold and very hot as it is not currently insulated. She has the heating/ac unit in there as well as a deep freezer. The attic space directly above the garage has no insulation and the exterior wall is just cinderblock with plaster on the outside of house. All other walls are just cinderblock with a bedroom on the other side with regular drywall.

This racks up the electricity bill as both the ac/heater and freezer needs to compensate for the large temperature difference. Also the garage walls that are part of the interior of house are not insulated, so that breaks the buildings insulation envelope further.

We want to replace her current garage door with an insulated one. We also will be adding insulation to the attic space. So my questions are:

  • What types of insulated garage doors are available on the market, pros/cons?
  • How would we insulate the cinderblock exterior wall?
  • How would we insulate the cinderblock interior walls?

1 Answer 1


The easiest way to insulate concrete block is to glue foam insulation board directly to the block. These boards come in 4 ft X 8 ft sheets and different R values. The other method is to build a wood or steel stud wall along the block to hold blanket style insulation along with electrical wiring etc. This method is a lot more work, but gives you a base to install sheetrock later on.

Depending on whether or not you want the attic area insulated or not, blanket or blown in insulation can be installed into the ceiling. ( this assumes you have a sheathed ceiling). Otherwise, you can install blanket insulation between the rafters. Depending on budget, sprayed in foam insulation is fantastic. You may also want to look at some venting to help exhaust hot air during the summer months. I may add a few comments later, but here's a start.

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    If the garage will be conditioned to be the same as the house, there's few reasons to insulate the wall between. If it's not conditioned and you are just minimizing temperature swings, consider it an exterior wall. Garage doors available range from no insulation to nearly as much as a solid wall. If you were to list cost per R value provided for each, you would probably clearly see a point where more insulation is not cost effective. Also consider there is a fair amount of heat loss from perimeter infiltration, regardless of insulation.
    – bcworkz
    Dec 13, 2012 at 0:10

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