Should You Insulate Your Garage? (Door and Walls)


I’ve taken the time to frame, insulate and drywall my garage, so I often get asked, would I do it again? Is insulating your garage worth it? Do I recommend it to others?

Like most things, it depends.

Should you insulate your garage? If you have an attached, conditioned (actively heated or cooled) garage then definitely! Insulation is probably the single biggest factor in lowering your energy costs. If you have a detached garage, it’s probably not worth insulating it unless you’re spending a lot of time in there in extreme temperatures. For anything in between those two extremes, it really depends on your situation, where you live and how you use your garage.

First, let’s get some idea of the cost and then we’ll get into that in more detail and some recommendations below.

How much does it cost to insulate a garage?

It can cost as little as $100 to insulate your garage, depending on how in depth you want to go.

I installed the Matador garage door insulation kit for around $200 for my 2-car garage door and it’s had a big impact on the comfort level in my garage. Click on that link and you can see how easy the process was!

When I say that it had a big impact, I want to set the right expectations.

I’m talking about 10-15 degrees difference one way or the other. In my experience, I went from regularly having temperatures over 90 degrees in the summer to temperatures in the low-80’s.

In Florida, that’s the difference between oppressive heat and mildly warm.

Why should you insulate your garage?

If you’re like most people, there are two main reasons why people consider insulating their garage: Energy savings and regulating temperature.

The first thing you should do is ask yourself which camp you fall into.

For energy savings?

Anyone who is actively heating or cooling their garage will fall into this category.

Whether you have one of the best garage heaters in the freezing Minnesota winters or air conditioning in the hot Arizona summers, this would apply to you. If you have an attached garage with sleeping space above it, you’ll also want to pay close attention here.

Remember when your parents would yell at you for having the windows open when the air conditioned was on?

“I’m not paying to cool the outside!!”, my dad would yell.

It’s the same principal with your non-insulated garage.

The garage is usually the single biggest non-insulated space in your house and the biggest energy waster is your garage door. Simply insulating your garage, even just the garage door itself, can have a big impact on your electricity bill.

For temperature regulation?

Even if you don’t plan on adding heating or air conditioning to your garage, insulate can still help regulate the temperature and humidity.

You’ll see reports that insulation doesn’t have that big of an effect on the overall temperature, but I think that paints the wrong picture.

Studies have shown that just adding insulation can make the temperature 10-15 degrees (Fahrenheit) more comfortable (warmer or cooler) than the outside air.

10-15 degrees may not sound like that much, but when the outside temperature is below freezing, it may just be enough to keep your ice cold beer from actually turning into ice.  

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Recommendation: If you have an attached garage

If you have an attached garage with living space above insulating your garage should be a no-brainer.

AT THE VERY LEAST you should have an insulated garage door and insulation between your garage ceiling and the floor above it.

Attached garage with living space above it
Attached garage with living space above it

Most of the heat transfer (in or out of your garage) will take place through your garage door, especially if it’s a steel garage door. Steel )or any metal) is a great conductor of heat, so you’ll definitely want a high R-Value garage door here.

For more information on what R-Value a garage door should have, check out my recommendations here.

Similarly, if you have living space above your garage like I do (my master bedroom), you want the heat and air conditioning to stay where you want it and not spill over into your unconditioned garage space.

Think of it this way: Would you want all the heat from your garage to seep up into your bedroom in the summer? Of course not.

Finally, if you have taken the time (and money) to actively heat or cool your garage, you want that investment to pay off.

Seriously, why spend the money heating your garage if all that heat is going to go right through the garage door.

Recommendation: If you have a detatched garage (conditioned)

I’ve said it before: If you’re spending the money to actively heat or cool your garage, then some sort of insulation better be on your list.

Otherwise, you’re just throwing money out the window.

That said, I’d take a more measured approach to insulation if I had a detached garage than I would if my garage was attached to my home.

If you have a detached garage and are investing in heating or air conditioning, I recommend loading up on an insulated garage door. The same goes for windows if your garage has them. Finally, spring for the best door and window seals that you can find and then call it a day.

In my opinion, insulated walls would be overkill in this situation.

Detached garage
Detached garage

Recommendation: If you have a detached garage (non-conditioned)

This is the only case where it’s a bit iffy.

For the most part, insulating a detached garage that isn’t actively heated or cooled isn’t cost effective. As I’ve mentioned before, the temperature difference is only going to be about 10-15 degrees different from the outside air.

Because it’s a detached garage, you’re not going to be concerned about any heat transfer to the adjacent rooms because, well…there aren’t any adjacent rooms.

The only way I would consider insulating my detached garage is if I lived in an extremely cold climate and I needed to spend a lot of time working in the garage. Even then, I’d only insulate the garage door and windows. Think of it as a stop-gap measure before you get some active heating installed.

For most parts of the country, I would spend that money on other things.

One Big Caveat: Where you live matters

Depending on where you live, insulating your garage may not make sense for you.

If you live in the hot and humid south like I do, or up in the frozen north then insulating your garage is almost a necessity.

However, if you live somewhere the temperature is mild year-round with only small chunks of time that are extremely hot or cold, then don’t bother. Count yourself lucky and move on.

Or…if you live someplace milder and you REALLY want to get some sort of insulation, then look at insulating your garage door, but that would be as far as I go.

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