Garage insulation is probably not something you think about very often. Most homeowners keep their attics and walls well insulated because they know it saves on energy costs. But, since garages are unconditioned spaces, not heated or cooled, it does not makes sense to insulate them.
Or does it? An uninsulated garage can become as hot or cold as it is outside. This may not be a problem in the garage, but, with uninsulated walls and a ceiling shared between the garage and your home, it can become a costly source of energy loss. In addition, harmful fumes in your garage, from car exhaust, fertilizers, paints, etc., can easily enter your home.
The best way to keep the harmful elements in your garage from entering your home is to insulate the walls and ceiling that is shared between the garage and home. However, you have a number of options for insulating your garage walls and choosing the right one can make a big difference.
Batt insulation, long a popular choice for insulating attics and walls, is often the first type of insulation homeowners think of when insulating. While the R-values (the rating of insulation performance) for batt insulation may be similar to other insulating materials, it is not the best choice for garages.
Batt insulation is installed in rolls, or batts. The batts do not seal spaces between the wall and ceiling and gaps can form between insulation rolls. The gaps allow energy to escape from your home and fumes to enter. Batt insulation is also susceptible to damage from moisture, further reducing its insulating ability.
Foam-board insulation, solid sheets of molded polystyrene, offers similar R-values as batt insulation, but is less bulky. However, foam-board insulation also does not fill all the gaps in your wall and spaces can occur between the sheets of insulation.
To reduce energy loss and fume seepage from your garage as much as possible, you need insulation that fills every gap and covers your garage walls and ceiling with a tight seal. Spray foam garage insulation spreads on application and fills all the gaps. R-values are the same as similar thicknesses of foam-board insulation and spray foam insulation is resistant to moisture damage.