What’s The Best Insulation For Garages? Top 6 Revealed

By Sarah Spoonhoward | Resources

Sep 17
Owens Corning 500824 - The-Best Insulation for Garages

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​Tired of freezing every time you go into your garage to work on a project or look for tools? While your garage may be attached to your home, it's likely that it doesn't have most of the same construction features. It's possible to turn your garage into a great, usable workspace, but if you plan to work in the depth of winter or during hot, midsummer days, you'll want the best insulation for garages. The right insulation will help keep your garage temperature more comfortable, which means you won't have to rush through your project list.

​Many people don't understand why they should prioritize their garages in home maintenance. After all, the environment in your garage doesn't matter that much, right? You only use it to park your car, and you don't spend much time in there. However, many people use it as their primary storage unit. Many also have garage doors that are attached to their homes, making it the main entryway. When you consider how much you use your garage, you may wonder why you neglect it. There are some exceptions, but a lot of the time, these spaces are not insulated, sealed, or hazard-proofed. There are many things you can do to improve the situation in your garage. However, a good start is learning more about insulating your garage. It can be very useful to know about the different types of material when it comes to the best insulation for garages.

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The Importance of Insulating Your Garage

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Many people spend a lot of time and money insulating their homes. It makes perfect sense that they would do this. After all, this is the best way to control the temperature in the building and to save money on heating and cooling costs. As we all know, the temperature is one of the main factors that affect the level of comfort in your home. Everything else can be just right, but if it is too hot or too cold, you almost can't think about anything else. Garages are infamous for their fluctuating temperatures. As such, it doesn't make much sense to put so much effort into insulating the rest of your home if you are going to neglect your garage.

Reasons to insulate your garage

Garage insulation is essential for many reasons. It helps to stop unwanted airflow from outdoors. This makes it easier to control the temperature, as well as air quality in your house; if you have a room above the garage, you can also control the temperature there. It can also help keep unwanted smells out of your garage and home. Additionally, it can prevent odors from entering your home from the garage. Insulation can also be a very effective sound barrier. If you spend a lot of time in your garage, insulation can absolve you of the worry that the neighbors are listening to everything you are doing. Conversely, you can have a more quiet and peaceful space in your own garage and not have to hear in detail what is going on outside.

Most notably, finding the best insulation for garages that you can find helps you save on energy costs. Not only will it make your home more energy efficient, but it should be easier to start your car in the winter as well. Once you put the effort into insulating your garage, you may even find it's a more pleasant environment to spend your time.

A Few Basic Things You Should Know About the Garage Insulation Process

People might not automatically think this, but you should make sure that you have some knowledge about the garage insulation process before choosing among the materials that form the best insulation for garages. You should make sure that you have your needs met for your particular garage, and that takes quite a bit of evaluation and physical measurement.

Preparatory work

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In order to prepare for the process of suiting up with the best insulation for garages, there are a few things you need to do. First of all, you need to figure out the area of the space that you want to insulate. Make sure that you count every bit of wall space, because insulation is most important at corners and edges. Do not forget the spaces above the windows and doors. Make sure that you measure the space between studs and joists, so you can determine the width of the material that you need. Many people use the basic rule of thumb that these should be spaced 16 inches on center, but this is not always the case.

Once you have figured out the area of the space that needs to be covered, add about 10 to 20 percent to that number. You will need some extra insulation in order to account for any mistakes that you might make, whether you make mistakes with the insulation material itself or in the measurement process where you end up forgetting about a few little spaces.

Where to put the insulation

Even if you don't have the time, energy, or resources to insulate your entire garage, you should at least protect the one wall that borders the interior of your home. Insulation of this one wall alone will save you a great deal on energy costs. There is a lot of air and heat that is transferred here.

Additionally, any material that you use to insulate this wall needs to be fire-rated. The reason for this is that you likely have many combustible liquids stored in the garage, coupled with the fact that you probably don't have a smoke detector in this room (you really should get one if you don't).

You should also make sure to insulate the ceiling of your garage, particularly if there is a bedroom or attic above it. The garage door is another important target, especially since this area has visible air gaps. If you are able to insulate the entire garage, you should do so. After all, any surface left unprotected is a surface through which air can flow freely. You would be surprised how effective the best insulation for garages can be at keeping the elements outside where they belong.

Keeping R-values in mind

If you are not a home repair buff, you may not know what an R-value is. Simply put, it is the capability of a material to resist heat flow. The higher the R-value, the more powerful of an insulator the material is. However, this is limited to the thickness of your walls. When you're insulating your garage, you should use a material that has the same R-value of the material that was used to insulate the ceiling and walls of your home. There are many choices when it comes to the best insulation for garages, but this is the first guideline that you should consider.


You should insulate both the walls and the ceiling of the garage using a material with the recommended R-value. If 2 by 4-inch studs make up your exterior walls, you should use insulation with a maximum of R-13 to R-15. Some people may think it a good idea to compress insulation in order to fit a small space, but this actually takes away the insulating properties of the material. The air trapped between the fibers of the material is what makes it a good choice for the best insulation for garages.


The R-value for the insulation in your ceiling depends on the construction of your home. If there is a room above your garage, the floor of the room will lie on boards that are supported by the joists. Given that the joists have a depth of 10 inches, you can use R-30 insulation. If the garage is open on top, you can use R-38 insulation between the rafters, given that they are 10 inches deep. There are many ceiling areas where you need to have an R-value of at least 38.

Garage door

Garage door insulation usually has a fairly low R-value, typically between 8 and 12. This is because the garage door itself is thin. People often used foil blanket insulation on the inside of their garage doors. You want to make sure that you are not interfering with the functionality of the door by insulating it. You can also opt to purchase a pre-insulated garage door that has a higher R-value. Many people may forget about the garage door when choosing the best insulation for garages. However, this would be a mistake. When it is cold, any heat in the garage can easily escape through an unprotected garage door.

What to do after the insulation

According to the experts at Home Advisor, you are not finished when you have added the best insulation for garages into your space. You will need to inspect the area. There are many dangerous chemicals involved in the insulation process, in addition to any hazardous chemicals that may be stored in your garage. You also need to remember that your car gives off exhaust, as well as carbon monoxide. As such, you want to seal everything off for your own safety after insulation. You should put caulk around the bottom of the drywall and seal this area to the ground. Make sure to weatherstrip the door that leads to your home. Seal around any electrical outlets, windows, and the garage door. If you can, purchase a metal door for additional fire safety.

How We Reviewed the Types of Insulation on the List

We took a look at several different types of garage insulation. These can all be considered the best insulation for garages, depending on the specific situation. The types of insulation on this list are the popular types of material that people tend to use for this purpose. Each one comes with its own set of strengths and weaknesses. It is up to you to decide which one would be best for your garage.

Range of Costs for Garage Insulation

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Depending on the type of material you use, garage insulation can vary in cost. When you consider the best insulation for garages, you are looking at a range of about $150 to $350 per 100 square feet. Fiberglass is generally the cheapest, while spray foam is the most expensive. The type of insulation that best fits your purposes (and thus how much you should spend) depends on a variety of factors.

Best Insulation for Garages: Different Types

When perusing information about the different choices of material that could be the best insulation for garages, you should consider all factors. Essentially, you should make sure that you're making a choice that is both effective and cost-effective for your own garage and home.



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Using cellulose as a loose-fill insulation has become an increasingly popular choice. This material consists mostly of recycled newspapers and is treated using a fire retardant. You use a special blowing machine to fill the ceiling and wall cavities with this material.

You can actually rent these blowing machines from home centers or tool rental stores. Because of the mechanism by which you install it, it is appropriate only for finished garage ceilings and walls. If you have a finished garage, you can cut holes in appropriate places within the wall material. Then, you can spray the cellulose into the cavities that lie between framing members. Finally, patch up the holes.



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Fiberglass may be the most popular type of insulation for both garages and homes. For this reason alone, many people would see this as the best insulation for garages. Retailers typically sell it in long blankets or pre-cut batts. The professionals who design the material do so in a way that it fits between ceiling joists and wall studs. Alternatively, you can purchase loose-fill fiberglass.

Using a machine, you can blow it into a garage attic space above a ceiling. If you have open walls and ceiling that do not have plywood or drywall covers, you can use encapsulated or paper faced fiberglass batts. These usually have plastic film wrappings and will give your walls a look that is somewhat more finished. Additionally, it will not involve exposed fiberglass that will easily attract dust to your wall.


Rigid foam

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If you are using this type of insulation, polystyrene is typically the main composing material. However, it can also consist primarily of extruded polystyrene or polyisocyanurate.

You can cut it to fit essentially any area. Also, it is a great choice for anyone who has thin walls or wants to insulate their garage doors. Typically, you don't need it to be very thick in order for it to give you a high insulating value. One inch of this material provides an R-value of about 6.5. This material very often has vinyl or aluminum on the surface.


Spray foam

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Spray foam is a great choice when looking at the best insulation for garages. It is great in terms of both air sealing and R-value. However, you should keep in mind that it is usually more than what you need. It is expensive and typically used for energy efficient construction. Although, it may be a good choice for you if you're planning to convert your garage into a living space.



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Batt insulation is known for its flexibility. Typically, people install it within exterior walls. Professionals know this material to primarily consist of fiberglass in most cases, though you will usually find it with a foil or paper backing. These act as barriers to air and vapor. For every inch of thickness, the R-value is 3 or 4.


Reflective material

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If you are using reflective insulation, it can have highly reflective aluminum foil on either one or both sides. This material can have different types of interiors, such as polyethylene bubbles or cardboard. Reflective insulation is a great choice when you are considering the best insulation for garages, particularly if you live in a place that gets very hot during the summer. This type of insulation reflects radiant heat. The R-value of this type of insulation can range between 3.5 and 6. The final rating depends on how you apply it in your garage.

What Type of Insulation is Best for My Garage?

If you have an interest in insulating your garage at this point, you are probably wondering which of the candidates for best insulation for garages you should choose. As you likely would guess, the choice depends on your situation. Different homes have different needs when it comes to garage insulation. If you live in a very hot climate, reflective insulation may be the most effective choice. If you live in an area that gets very cold during the winter, however, you may just want to find the insulating material with the highest R-value possible. A lot of the time, this will be a foam material. You can choose between rigid foam and spray foam, though spray foam may be excessive. You will also want to factor in whether or not there is a room above the garage and whether you want to insulate all or just part of the area.

Garage insulation can be a very useful do-it-yourself project, although some people may opt to hire a contractor in order to make sure there are no mistakes. You may want to seek a professional opinion when deciding on the type of insulation you use as well. However, no matter which route you choose to go with the insulation, you will likely see that this particular project ends up yielding great results. Taking advantage of the best insulation for garages that you can find can lead to not only a garage but an entire home that is happier, healthier, and much more comfortable at all times of the year.

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