We own a fourteen year old house outside of Nakusp. Our master bedroom is located above an unheated single car garage. I know the floor in our bedroom is insulated because the water pipes for our ensuite bathroom froze last year and we had to take part of the garage ceiling down to repair the leaks. Even though the bedroom floor is insulated and carpeted, it’s cold most of the year. I’ m wondering if it would help warm the floor if we replaced the overhead single wall metal garage door with an insulated overhead door?

Unfortunately, I don’t think you will achieve a warmer floor by installing an insulated garage door because there is a fundamental missing ingredient in this recipe: a lack of heat in the garage. In other words, the new insulated door will not retain heat that is not in the garage initially. A cold, unheated space is still a cold unheated space regardless of the amount of insulation we incorporate surrounding that space. For instance, your camping trailer is just as cold inside as the exterior air until a heat source is added to the interior.

 In your case the insulated door may help capture a very small amount of ambient heat that escapes through the insulated bedroom floor, but the ability for this heat to warm your bedroom floor will be negligible. One solution would be to install the insulated overhead door and add a heat source like an electric baseboard in the garage. However, before you do this, you should check the exterior walls of your garage to confirm whether or not they are insulated. If they are insulated, how much R value do these walls have? It is not uncommon to find that garage walls have less than the modern minimum R 20 ( 6 inches) of insulation because builders, insulation installers and a previous owner often agree to cut costs by deeming the garage “an unheated space” or a space  not meant for habitation. If you have to upgrade your wall insulation to the minimum R 20 standard, heating this space to achieve a warm floor may become costly.

You may also consider a retrofit in your bedroom. Electric radiant floor heating panels can be installed in your bedroom floor. The panels are controlled by a thermostat and programmable timer on the bedroom wall that can be set to begin and end warming cycles in the floor to suit your schedule. With this equipment you are targeting only the area you want heated, with focused energy at specific intervals. This would be a much more energy efficient alternative to heating the air space of the garage.