Most garages aren’t designed to stay warm during cold weather nor are they designed to stay cool during hot weather either. Garages are generally designed to meet local building codes and no more, since adding insulation to them would unnecessarily increase the cost to the builder and thus the home buyer.
Garages are generally built without insulation on any walls or the ceiling. The thin metal garage door is usually also uninsulated and easily allows cold air in especially if there is a gap on the ground. The garage floor will remain cold during winter and drafts from a window or side door will also reduce the temperature inside the garage.
While insulating a garage door is a start, doing that on its own will hardly help to improve the temperature of a cold garage during winter’s coldest months.
What are the main reasons a garage gets cold?
- Lack of insulation in the garage itself including all walls and ceiling
- Uninsulated garage door
- Garage door that won’t close all the way to the floor and lets air in
- Cold concrete floor which has little insulation value on its own
- Gaps in a door or windows that cause drafts
While an enclosed garage may be expected to be several degrees higher than the outside temperature, it will still be cold in winter without proper insulation and an active heat source.
Let’s take a closer look at each reason for a cold garage and what you can do to address it.
Why is a garage typically cold especially in the winter?
There are a number of reasons a garage is cold in winter and while addressing one or more problem areas will help, addressing all sources of heat loss is your best bet to raise the temperature especially if you’re planning on adding a heater to make the space more comfortable.
Lack of insulation in the garage itself
Garages are generally built just to meet your local building standard and not more. If you have a finished wall(s) in your garage when you buy a new house, it’s likely because that was what the local building code requires.
If you have a room(s) directly above the garage it’s likely to be cooler in winter than other rooms in your house since it’s situated on top of the cold, uninsulated garage.
A standard unfinished garage with no insulation on the walls or ceiling with additional gaps and crevices drawing in air can get very cold in the winter as a result.
Uninsulated garage door
Most garage doors are made of metal or wood. Both on their own have a very low R-Value which is the rating used to determine how well a material resists heat transfer (loss). The higher the R-Value the better in terms of insulation.
An uninsulated metal garage door has an R-Value of 0 and an uninsulated wood garage door has an R-Value of 2. This indicates a very low insulation level in both cases. By comparison the R-Value in an average attic of a home should be from 30-60 with proper insulation depending on how cold your winters are.
Garage door that won’t close all the way to the floor
Garage doors often have a rubber seal (weather stripping) at the bottom which touches the ground when the door is fully shut. If this seal is damaged or if the door otherwise doesn’t close completely, it’s another way for your garage to have cold air introduced during periods of cold weather.
Same goes if the door is dented or closes on an angle: Gaps can allow cold air into the space that even the best insulated garage can’t prevent.
A rusted garage door with a gap or hole doesn’t help matters either.
And during a cold icy winter, it isn’t outside the realm of possibility that the weather stripping is partially or completely torn off the bottom of the garage door.
Cold concrete floor which has little insulation value on its own
Concrete has one of the lower R-Values of all building materials. Concrete slabs used for floors are said to have an R-Value of around 0.1 – 0.2 per inch of thickness. So a typical 6″ slab would have an R-Value of around 0.6 – 1.2 which is very low.
Concrete just feels cold to the touch particularly in winter, too. While not the biggest source of heat loss, a chilly concrete floor can add to the coldness in your garage.
If you were to finish your garage, you could for example increase the R-Value of the floor by finishing it with carpeting, cork or other material as part of a completely finished area.
Gaps in a door or windows that cause drafts
Does your garage have a separate side door and/or window? These can be notorious sources for air leaks. Windows can leak air around the seals more so if the windows don’t close properly.
And a cheap side garage door – usually made from the aforementioned low R-Value wood – can also contribute greatly to a cold garage.
Are Insulated Garage Doors Worth It?
Unless you’ve sorted out other issues discussed above that make your garage cold, insulating the garage door probably won’t help much on its own.
Because garage doors are sold new in both insulated and uninsulated versions, some homeowners think they are doing the right thing by simply switching to a more expensive insulated model.
Since garages are generally designed to be warm in the winter, simply adding an insulated door won’t help to change the temperature much since you still have a number of other problem areas that keep the entire area cold.
Insulating your garage door and the rest of your garage could be valuable if there is a room directly over top of your garage. This room will typically get colder than other rooms in the house due to the chilly garage directly below it.
If you do work in the garage in the winter, having an insulated garage can also be of value. Also if you plan on storing things in the garage that would be well-served by not freezing.
While some people feel that insulating the garage door can be a helpful selling feature if putting your house up for sale, the average person probably won’t even notice or place any sort of tangible value on it.
If you’re going to insulate a garage door, it’s best to also insulate and take care of the other reasons for the cold temperature and to do the necessary work for your specific needs and requirements.
Solving the problem of a cold garage
If you want to properly resolve all sources of cold in your garage you will need to address the following:
- Insulation of all walls including the ceiling.
- Insulating the border wall between the house and garage.
- Addressing the floor with some sort of higher R-Value flooring.
- Insulating the garage door itself.
- Resolving any other issues such as air leaks from malfunctioning doors or windows and from lack of weatherstripping.
At this point you might also choose to then provide some sort of heat source inside the garage to actually warm it up since simply insulating the garage won’t actually keep it comfortable enough to stay in for any amount of time.
Because a garage is enclosed and thus safe from wind, you will find that your garage will typically be at least a few degrees higher during the winter than the outside temperature but not much more than that without a heat source.
Summary
There are a number of reasons that a garage tends to get very cold during winter and other low temperature periods. It’s the general design of the garage that is the culprit: Garages aren’t normally designed with insulation and with concrete floors, they are going to get cold unless you do something to fix each source of heat loss.
While adding an insulated garage door is one step, it’s not enough on its own to raise the temperature inside the garage. Insulating all walls and the ceiling as well as the garage door itself is necessary.
And if you do have a cold garage in winter that you don’t plan on insulating? You might make use of it by storing items there that benefit from the cold weather such as food items or chilled drinks especially if you’re tight on fridge or freezer space.
Do take care though and ensure that the garage temperature isn’t too high or low for what you’re storing. One benefit of having an automatic garage door opener installed is that modern ones display the garage temperature on the control panel inside the garage itself.