If you’re looking to find the best insulation for your garage, you’ve come to the right place.

Insulating a garage is one of the best things you can do if you want to more easily control the temperature in your home and save on energy costs. The best overall type of garage insulation is spray foam, because it offers the best air sealing qualities, energy efficiency, durability, longevity, and R-value.

That being said, there are also numerous different options for insulation and not all of these options are created equally. To help you out we’re going to cover the top insulation methods, and then give you our idea on what we think is the best one.

Read on to find out more:

What Types of Garage Insulation Are There?

There’s many people who don’t even think of insulating their garage when they insulate their home. This is a mistake, because insulating your garage will help out significantly with saving on energy costs for the entire home (provided it’s attached).

It becomes especially important to insulate your garage if you have a room built over the garage. Since the garage is attached to your structure, it will allow outside air to get inside your house via the common wall. Plus, any rooms that you keep above the garage will no longer be able to maintain a constant temperature so long as the garage is not properly insulated.

Plain and simple, you should treat insulating your garage as an investment. It can help to lower your monthly energy bills, make it easier to regulate the temperature – not only of the garage but of the home as a whole – and just make home living more comfortable as a whole.There are also plenty of material options for insulating your garage, each with their own unique set of pros and cons:

Fiberglass Insulation

Fiberglass is arguably the most popular insulation material used in garages today. It consists of rolls that will be perfectly cut to fit into a ceiling or wall cavity and then stapled in.

It’s so popular because it’s inexpensive and can also be self-installed by most people. However, it can only be installed into open cavities, and you need to be careful that you don’t embed any fiberglass into your skin or inhale it while you’re installing it.Fiberglass can also only inhibit the flow of air movement: it cannot completely stop it. This is why it won’t be a good choice if you’re looking to completely stop the flow of air into your home.

Cellulose Insulation

Cellulose has been growing in popularity in recent years.

It’s made out of recycled newspaper material and then coated over with a fire retardant. When applied as insulation, cellulose is usually blown into a wall with a special blowing machine that will also aerate the cellulose (meaning the cellulose will fluff up to better insulate the garage). Most often, these blowing machines can be acquired at home centers where they can be rented.

Take note that you should only use cellulose for garage walls and ceilings that are already finished. Assuming that your garage is finished, but not yet insulated, you can install the cellulose by cutting holes into the wall and then spray the insulation into the cavities, before patching the holes.

Rigid Foam Insulation

Rigid foam insulation is usually available in 4 foot by 8 foot sheets, with a thickness up to 4 inches. It’s usually made out of a Styrofoam-type material such as expanded polystyrene or polyisocyanurate. Rigid foam is a good option because it offers a very high R-value, meaning that it can resist a significant amount of heat in order to keep the garage properly insulated.

When it comes to applications, rigid foam is best used for insulating garage door and thin walls. It’s not the best choice for insulating floors or thicker walls. You should also take note that most forms of rigid foam insulation are not very fire retardant either.

Spray Foam Insulation

Spray foam insulation offers excellent R-value properties much like rigid foam insulation does, but it also offers excellent air sealing qualities as well. Spray foam is a higher end insulation material that is more expensive but is also highly energy efficient. Honestly, it’s not truly needed for most suburban garages, although it may be a good choice if you’re going to be converting your garage into a living space.

Which Insulation is Best For a Garage Overall?

The best overall type of garage insulation is spray foam, because it offers the best air sealing qualities, energy efficiency, durability, longevity, and R-value. At the same time, it’s also the most expensive, and isn’t truly necessary for most garages in suburban homes either.

Fiberglass, as noted previously, is the most popular type of insulation method for a reason. It’s very affordable and will work for most applications. It will make it easier for you to control the temperature flow in your garage and it will severely inhibit the flow of air as well.

Regardless of what kind of insulation material you choose, you always need to quickly inspect the garage once it’s been insulated. It’s important that the garage be completely sealed off to get the most from your insulation.

Always ensure that there is caulk sealing up any cracks in the garage (check the floor and ceiling, where cracks are the most likely to develop). Have the door leading into your house weather stripped, and consider a metal door for extra safety. Also check for leaks around the windows, electrical outlets, and garage door for any air leaks that can lower energy efficiency.

Do I Need R13 or R15 for A Garage?

An R-Value is simply a measurement of how well a two dimensional barrier can resist heat. When you do insulate your garage, it’s critically important to ensure that you use insulation with the same R-value that was used for the rest of your house.

Both R-13 and R-15 are designed to fit a cavity that is three and a half inches deep. Since insulation will fit the depth and the width of the cavity, between studs, if you compress the insulation to fit the space you will also remove its insulating properties. Both R-13 and R-15 will work for the same wall cavity, and should enable a heat flow reduction in your garage of between 93% to 95%.

That being said, R-15 should be a little better than R-13, especially if you if you are using steel studs instead of wood (this is because R-15 has slightly greater conductivity).

Should You Insulate An Unheated Garage?

To put it simply, insulating is always the best value per dollar spent for warmth. It’s true that most garages are left uninsulated and unheated. This means that in the summer time they are incredibly hot and sweltering, while in the winter they are left very cold and freezing.

When you add insulation to a garage, it makes it easy to regulate temperature extremes, especially if the garage space is attached to the rest of your house (in which case adding insulation becomes extra important).

Also, when you add insulation to a garage it makes it easier for you to lower cooling and heating costs (and thus helping you to save money as well). This is because that an insulated attached garage acts as a buffer between a house and the rest of the outside world.


It’s key to understand the different insulation options available to you when looking to insulate your garage.

By reading this article, you should now know the primary different types of insulation options that are available to you and the pros and cons of each. Any one of the insulation materials that above will do a good job of enabling you to easily control the temperature of your garage and making your home more energy efficient.

Thank you for reading and have a great rest of your day!