Attached 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 properly insulated, temperatures can come very close to the extreme temperatures of the outdoor summer or winter air, and the whole thermal comfort of the house can be deeply affected by that.
Reduce energy costs
To overcome problems caused by the garage extreme temperatures into the house's living rooms, 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 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; an option that will help you to increase thermal comfort and reduce energy bills.
Insulating the wall edging the garage
Cold and heated air can be easily transferred between the garage and the home’s rooms via any shared wall. Insulating this or those walls is compulsory (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
Any door between the garage and the house is a potential 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 to 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 or substitute it, or at least to caulk and weather-strip any passageway associated to 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.