What Is the Best Insulation for a Garage

What Is the Best Insulation for a Garage?

What Is the Best Insulation for a Garage?

If you are looking to build or make updates to your garage, you will want to choose your materials wisely, with an eye for both cost efficiency and quality. One such material is insulation. You may not realize this, but insulation actually comes in several different kinds. Some are better for different applications, and some are certainly more cost-effective for your project than other options. What is best for your garage is going to largely depend on the space itself and the scope of your project– for instance, are you insulating from scratch, or are you replacing existing insulation?

Below, we go over some of the best insulation options for your garage, as well as some of their pros and cons. Read on to learn more!

Why Should I Insulate My Garage?

First of all, is it even worth it to spend the time and money to insulate your garage? The answer is a resounding yes. Not only will this increase the value of your space and be a draw to homebuyers on their tours, but it can be beneficial to you in your day-to-day while using the garage. Some of these benefits are explored in more detail below. 


Most of us do realize that insulation helps us to warm a space, but this is only one of the many reasons that you should insulate your garage. Insulation also helps to regulate the temperature of the space, so that it is not too hot in the summer months or too cold in the winter. Without insulation in your attached garage, you may end up letting some of this colder air into your house, which could then affect your heating bill.


Insulation can be a benefit for both the garage and the house itself. It is like padding for the walls of your space and can reduce the amount of noise that is coming into the garage from outside or through the house. It can also decrease the amount of noise that is coming into the house through the garage, which can be especially helpful if you are using your garage as a workspace or have a particularly loud car, for instance!

Living Space or Workspace

If you are using your garage for either a living space or a workspace– not simply for storage of your vehicle or other items– insulation can be very important. When you plan to be spending time in this space, you also need to ensure that the garage is comfortable. Without insulation, it is very likely that the space will not be comfortable, and therefore will not be suited for the additional purposes you hope to use it for. Insulation will keep the room warm and soundproofed, as we mentioned above, which can be helpful for whatever you plan to use it for. The insulation also helps you to better regulate the temperature of the garage. 

Basics of Garage Insulation

It is important to note that, when you add insulation, you do not actually add heat to the garage space. This is a popular misconception. Instead, you are slowing the transfer of heat– or cold!– through the insulated barrier, which helps you to better regulate the temperature in that space. This is good for both hot and cold climates. 

If you are adding heat, such as a garage heater or space heater, it can be even more important to install insulation in order to keep this heat in the garage space. Additionally, if your garage is attached garage to the rest of the house, insulation can help to offer a thermal buffer between the outdoors and the home itself. That being said, there are no regulations in most areas that make this a requirement, so you could choose to forgo the project if you so choose. The walls that are shared within the house, though, should be insulated to their maximum value. 

Air Sealing

Ensuring that your garage is airtight should also be one of your primary concerns when you are considering insulation. Typically, garages are not built to be airtight, so they have lots of air gaps that connect to the outside. This is where cold air can get in to make your garage drafty and uncomfortable. If you insulate your space but do not deal with the air gaps in the garage, you largely render your insulation efforts moot. After all, it is difficult to regulate the temperature of the garage if cold– or hot– air is still getting in!

Due to this, air sealing is extremely important in conjunction with insulation. Before insulating the garage, you should work to make sure that your garage is airtight and properly sealed. Luckily, this is easily something that you can do yourself! You can purchase a can of low-expanding spray foam at most home improvement stores. Then, take a lap around your garage and spray it into any cracks, holes, or other gaps in the space. This should be done prior to insulating, as it is messy and more difficult if you wait to do it until after the insulation is installed. 

In addition, you should check to be sure that the weatherstripping around your windows, door frames, and along the bottom of the garage door is intact and therefore able to seal off any drafts.

Types of Garage Insulation

There are five main types of insulation that can be used in your garage– certain types are better than others, depending on the details of the project. You will need to educate yourself on each of these and be sure to choose one that is going to best fit your individual needs. 

Fiberglass Insulation

First up is fiberglass insulation, which is the most popular insulation material for garage projects. It’s also the most commonly used in homes! You can find it sold in either long blankets, which fit between wall studs and ceiling joists and precut batts. Loose-fill fiberglass is another available option and is typically used for blowing into spaces such as garage attic spaces above finished ceilings. Fiberglass insulation is best for framing.

If you do not plan to cover the walls in your basement with drywall or plywood, you should use paper-faced or encapsulated fiberglass bats which are wrapped in a plastic film. Not only do these give the walls a more finished look, but they protect you from the itchy fiberglass fibers. They also ensure that these fibers are not exposed and catch dust. 

Some of its key features are below:

  • Best for framing
  • Inexpensive
  • Easy to handle
  • Easy to place in framing
  • Vulnerable to moisture
  • Fire hazard if incorrectly installed
  • Can irritate skin, eyes, and lungs 

Cellulose Insulation

Cellulose insulation is a loose-fill option that is rising in popularity lately. It’s made from recycled newspapers and treated with a fire retardant. When it is installed, it is usually blown into the wall or ceiling cavities with a blowing machine that aerates and fluffs up the cellulose, too. It is best suited for finished garage walls and ceilings. 

Loose-fill options can only be used for finished walls or ceilings, in fact. If your garage is finished and walls are up, you can cut strategic holes in the wall material to spray the cellulose inside, and then can patch the holes. You can also rent the blower that is needed for cellulose insulation, rather than purchasing one to complete your project. 

Some of its key features are below:

  • Fire resistant
  • Environmentally friendly
  • Insect-resistant
  • Costly
  • Inflexible
  • Also requires drywall 
  • May settle over time

Rigid Foam Insulation

Rigid foam insulation comes in sheets, and these sheets can vary in thickness from ½ inch to 4 inches thick. They are usually made of expanded polystyrene– which is comparable to styrofoam–, extruded polystyrene, and polyisocyanurate. This insulation option offers a high R-value per inch of thickness and is best used for thin walls or for insulating doors. It can also be cut to fit almost any space. 

Some of its key features are below:

  • Affordable
  • High R-value
  • Good noise reduction
  • Insects or pests can tunnel through
  • Installation can be difficult around pipes or wiring
  • Can be too airtight and therefor not meet venting codes

Spray Foam Insulation

Spray foam insulation is a great option with consideration to R-value and air sealing. It is one of the more high-end options and can often be found in environmentally conscious construction. That being said, it may not be the best fit for a home garage project because it may be more than is necessary, and you may be able to save money by going with one of the other insulation options. However, if you are converting your garage to a living space, spray foam insulation can be a great choice. 

Some of its key features are below:

  • High R-value
  • Mold and insect repellant
  • Airtight seal
  • Best for tight spaces
  • Costly 
  • Can shrink as it ages
  • Can expand too much or too little
  • Should be installed by professionals

Garage Door Insulation

You may not have thought about insulating your garage door, but this is an important step that should not be overlooked! There are kits out there for garage door insulation, which you can easily find and purchase. Alternatively, you can cut pieces of rigid foam insulation or Reflectrix sheets to fit each panel or section of your garage door. The structural metal ribbing of garage doors is a conductor of heat and does not get insulated, which means that the thermal performance of your door will still be lower than the insulation option that you decide on. 

Some of its key features are as follows: 

  • Reduces noise
  • Can add durability and stability to your door
  • Can affect inside temperature by between 12-20 degrees
  • Added weight can wear out older springs
  • Panels can become misaligned if not properly installed
  • Not always necessary

Frequently Asked Questions

What insulation should I use in my garage?

There are several different kinds of insulation that you can use in your garage. One of the most popular is fiberglass, which is also often used in the walls of your home itself. You can find it sold in both long blankets and precut bats, which can fit between ceiling joists and wall studs.

What is the best R-value for a garage?

When it comes to garage insulation, most of the options have an R-value between R-8 and R-12, because it is thin enough that it can fit the space. What is best for the space does partially depend on the garage itself– for instance, if this is a detached garage, you will need insulation with a lower overall R-value, between 0 and 6. 

What is the most cost-effective way to insulate a garage?

If your walls have not yet been constructed, the cheapest insulation option is fiberglass insulation, which can come on a roll. The kind that comes on a roll is cheaper than other kinds of fiberglass insulation. It is also easy to install, which can cut down on potential labor costs. 

Will insulating my garage make a difference?

Insulating your garage can have a few different perks. The first is that, of course, it helps to keep your garage warm and traps heat, so that the space is not cold or drafty. Another benefit that you may have not considered is that insulating your garage also helps to soundproof it and keep it quieter from any noises coming through from the house or outside. 

What is the proper way to insulate a garage?

When you are insulating a garage, it is important that you choose the correct type of insulation for the project– pay attention to where the insulation will be going in order to choose the right option. You should then air seal the entire space with a can of spray foam in order to avoid any drafts. Then, you can go ahead and install whatever insulation you have chosen.