Attached Residential Garages


Homes with attached garages and above underground garages often have interface problems, with consequent heating and cooling losses. If the garage and its doors aren’t insulated, temperatures in it can become very close to the extreme temperatures of the outdoor air in the summer and winter, and the whole thermal comfort of the house can be deeply affected by that.

Reduce energy costs

To overcome problems caused by garage extreme temperatures in the house's living rooms, and to help you reduce energy costs, there are two alternative approaches:

- seal up all areas where air might be able to pass between the garage and the house living space.
- insulate the garage walls and its exterior door.


Sealing the areas where air might be able to pass

Sealing the areas where air might be able to pass, may include:

- insulating the floor of the room or rooms above the garage;
- insulating the shared wall (between the house and the garage);
- insulating and sealing eventual holes in the garage walls;
- replacing or improving the door between the garage and the home’s living space

Insulating and ceiling holes in garage walls

Look for anything as switches, light fixtures, plugs, etc. that may constitute holes in the walls, and seal them, carefully.

See: Caulking and Weatherstripping.

On the garage side of the wall you may use fire-rated caulk, or expanding foam to seal up penetrations. 

Insulating the floor of the room or rooms above the garage

When insulating floors over unconditioned garages, seal joints (between the header and the sub-floor, and the top plate and the header joist); seal also possible air leakage holes in the floor. Insulation should be applied carefully, without gaps.

In cold climates, vapor barriers may be advantageous: they will help stopping the transfer of cold air in the garage.

Replacing or improving the garage door r-value

A double steel garage door, with a proper layer of insulating material (polyurethane…) is a good and affordable option on garage doors: an option that will help you to increase thermal comfort and reduce energy bills. See:  Basics on Garage doors

Insulating the wall edging the garage

A lot of air – and cold and heat - can be transferred between the garage and the home’s rooms via their shared wall.

Insulating this wall is virtually mandatory (insulation should be fire-rated, by law), if the other walls of the garage and the exterior garage door aren’t properly insulated.

Door between the garage and the home’s rooms

The door into the house from the garage is often an air leak path. Pay attention to it.

If the garage is insulated (and the exterior garage door is a good insulated one), the garage-to-house door needn’t be insulated or of good quality. But if you are having thermal problems in your garage, and if you want them to be limited to it, then you need to insulate that door, or to repair and substitute it, or at least to caulk and weather-strip all the potential air passageways associated to it and around it.

Garage & Insulation materials

If your garage is an underground one, its insulation and its issues are very similar to those involving basements. See Basement insulation and basics.

For other attached garages, the insulation materials and techniques associated to insulation and sealing are the same used in other parts of the house. See, on these issues: Insulation basics.

 

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