While you may not need (or even want) a garage to be as well insulated as the living spaces in a home, there are still several good reasons for insulating a garage.

Ultimately, the choice is up to each client whether or not they want you to insulate a garage. But, to make an informed decision, it’s important that they know what insulating a garage entails and why it is especially important for attached garages. So, before we dive into types of insulative material and how much insulating costs, let’s explore the pros and cons of added insulation for a garage.

Pros of Insulating a Garage

• Insulating a garage can make a home more energy efficient and reduce energy consumption.
• It can provide additional noise reduction from the garage to the home.
• Insulating the garage can increase overall home value.
• Insulation can extend the lifespan of the HVAC system and improve humidity control within the home.
• An insulated garage can be used year-round — even as an exercise space or workshop.

Cons of Insulating a Garage

• Insulating a garage can be expensive.
• Insulation can be messy and require additional work if the garage is already finished but not insulated.

The 4 Most Common Types of Garage Insulation

Just like with insulation for a home, there are a few options you can pick from when it comes to insulating a garage. Here, we will explore four of the most common options, which will be the easiest to find and work with.

To effectively compare the types of insulation listed below, we will use a standard measurement called an R-value. An R-value measures a given insulation material’s resistance to heat transfer. Each insulation material below has a range of R-values that you can typically find. Keep this value in mind when selecting the best insulation material for the garage you are working with.

Now, without further ado, let’s see what four types of insulation are commonly used for garages!

Fiberglass Insulation

Fiberglass is typically the most recognizable type of insulation. It is available in pre-cut rolls or wall-length batts to fit between joists and studs.

Simply cut the right size and then staple them into place to install them. This form of insulation is relatively easy to work with. However, it does require unfinished walls, so if there is already drywall in the garage, you’ll need to do some demolition before applying fiberglass insulation.

Average R-value for 1” installed: 2.2-4.5

Cellulose Insulation

Cellulose insulation is a great environmentally-friendly option for insulating a garage. It is made from recycled paper or denim and is coated with a fire retardant. This insulation is installed with a special blowing machine to insulate garage walls that are already finished.

One thing to note is that cellulose insulation is extremely absorbent and must be kept dry. If it gets wet, it will deteriorate, and the chemical fire treatment will be destroyed.

Average R-value for 1” installed: 2.5-4.3

Rigid Foam Insulation

Rigid foam insulation is made of a styrofoam-like material and is available in 0.5-4 inches thicknesses. It comes in 4x8 ft. sheets and can be cut to fit the garage walls. It is a great option for thin walls and the garage door itself, but it is not a good choice for thick walls.

It is affordable and easy to find, but it is not fire-retardant and is not a great deterrent to insects. However, it offers a greater average R-value than cellulose or fiberglass.

Average R-value for 1” installed: 3.6-4.2

Spray Foam Insulation

Spray foam insulation is a polyurethane foam made using two chemical products that react together. It has the highest R-value of the insulation types we’ve mentioned here and better air-sealing properties than rigid foam.

This insulation is also resistant to insects, mold, and moisture. However, with these properties comes a hefty price tag, and this type of insulation is the most expensive of the four.

Average R-value for 1” installed: 3.8-7

What Is the Best Insulation for a Garage?

Because people will have different needs for their garages, the type of insulation they choose will vary. Also, depending on the state of the garage, some types of insulation may be easier to apply than others.

Basically, if the garage you’re insulating doesn’t have finished walls yet and your client wants the highest level of insulation, then you will want to opt for spray foam insulation. Now, spray foam insulation is typically the most expensive, but for a good reason. It offers the best protection and thermal insulation — as detailed above.

If your client is not looking to achieve the highest R-value but still needs to insulate an unfinished garage, you can opt for fiberglass or rigid foam insulation. Both of these options can help save money on energy costs. Fiberglass is the most accessible and inexpensive option, and it is used in many homes and commercial buildings.

Alternatively, if the garage you are insulating already has finished walls, you will likely want to opt for cellulose insulation. With cellulose insulation, you won’t have to take down (and refinish) the walls in the garage and may be able to use it for the ceiling as well. While cellulose isn’t as moisture resistant — hence the need for finished walls and ceilings — it can still be an excellent choice for already finished garages.

How to Insulate an Attached Garage

When insulating a garage, it’s best to consider the project in two parts: the garage walls and ceiling and the potential leak points.

Let’s start with the largest area of insulation real estate — the walls and ceiling. As mentioned above, the type of insulation you use will depend on what level of insulation your client is aiming for and the state of the garage. For example, you may opt for cellulose insulation if there are already finished walls. Alternatively, you may opt for fiberglass or spray foam insulation if the walls are not finished yet.

Now, it’s time to assess those leak points, such as doorways and windows. For these areas, you will want to ensure an airtight seal with a good-quality silicone sealant and weather stripping. This will prevent hot or cool air from escaping from your garage when the weather is not cooperating. When these spaces are properly sealed, you dramatically reduce the risk of unnecessarily high heating or cooling bills for your clients because of air leaks.

How Much Does It Cost to Insulate Garages?

Cost can be a critical limiting factor for any project, and an attached garage is no exception. Whether you are working with a client or working on your own spaces, you will want to consider how much the overall insulation process will cost for a given garage.

The total cost of insulating a garage will depend on the size of the space and the type of insulation you opt for. Generally speaking, a one-car garage will be much less expensive than a two- or three-car garage — even if you use a more expensive type of insulation.

The average range for each type of insulation per square foot of coverage is as follows:

• Fiberglass: $0.30-$1.50
• Cellulose: $0.60-$2.30
• Rigid Foam: $1.20-$3.70
• Spray Foam: $2.75-$7.50

To get an accurate range estimate of how much insulating a garage will cost, you will want to know the exact square footage of the space since garages can differ dramatically.

Let Silicone Depot Help With Your Next Garage Insulation Project

Whether you need to insulate a new garage or refresh an existing one, using the right materials is the best way to ensure long-lasting, satisfactory results. This means picking the right insulation type for your needs and using high-quality silicone sealant for any thresholds or windows.

To find the perfect sealant for your next project, check out the many options available at Silicone Depot today!