What is the best insulation for garage walls?

Posted on May 26, 2021 By Concord Garage Doors 
insulated garage walls

In this guide, we will look at insulation requirements for garage walls and examine a selection of different types.

Insulating your garage walls is an essential aspect of the remodeling process, whether you want to save on energy and control your home’s temperature. The best insulation for garage walls is spray foam, as it has excellent energy efficiency and insulates very well.

Therefore, knowing which type of insulation is better depends on your needs.

What types of insulation are available for garage walls?

When people insulate their homes, they usually only consider the main living areas. They don’t pay much attention to your garage, even though insulation in the garage can help lower energy costs for your entire property.

Insulating garage walls is critical if you live in a home with an upper level built over the garage. This will help maintain your house's temperature from fluctuating so wildly, and it will also stop any outside air from coming in through the shared wall. Not only does this increased insulation make the garage warmer in winter, but it also cools it off more quickly in summer.

To save on energy bills, maintain a regulated temperature, and make your living more comfortable, invest in insulation for your garage. There are various insulation materials for your garage wall, each with its own set of benefits and drawbacks.

Fiberglass Insulation

Fiberglass Insulation
Fiberglass Insulation (Shuterstock)

Insulating walls is a priority in many garages. The most popular type of insulation for garage walls is fiberglass which can be bought for a roll and then cut to fit any cavity.

One of the biggest reasons that it is popular among homeowners is because most homeowners can install it. Fiberglass can only be applied to open cavities and must not contact skin or clothing as it could cause respiratory damage. Fiberglass is generally not as effective at stopping air movement. If you’re looking for insulation to keep cold air from seeping through your walls, fiberglass won’t be the best option.

Cellulose Insulation

Cellulose Insulation
Cellulose Insulation (Shuterstock)

In recent years, cellulose insulation has grown in popularity.

The insulation is made of recycled newspaper and then coated in a fire retardant. When cellulose insulation is applied to the walls, it is usually blown using a particular blowing machine that also aerates the material. You can rent a blowing machine for your drywall needs at most home centers.

Cellulose should only be used on garage walls and ceilings that are finished. Suppose your garage is unfinished but not insulated yet. In that case, cutting holes in the wall can help prevent drafts by spraying insulation after installing it within those cavities before sealing them up again with a patching material like spackle or paintable caulk.

Rigid Foam Insulation

Rigid Foam Insulation
Rigid Foam Insulation (Shuterstock)

Rigid foam insulation is a cost-effective way to keep your garage well insulated. Pieces are available in 4'x8', with measurements of up to 4" thick. It's made from a type of Styrofoam material called expanded polyisocyanurate or polystyrene, and it offers very high R-values for maximum heating resistance.

Rigid foam insulation is best suited for garage walls and thin surfaces, but not on floors or thicker brick walls. It may also be less fire retardant than other types of insulation.

Spray Foam Insulation

Spray Foam Insulation
Spray Foam Insulation (Shuterstock)

Sprays foam insulation is a higher-end material than traditional insulations such as rigid foam, but it provides good air sealing properties. Spray foam offers excellent R-value levels, which means that the equipment required to heat or cool that space will be more energy efficient because less heat will escape and need to go in. But for most suburban garages, this is an unnecessary expense due to the cost-effectiveness of rigid foam, which has equally as good insulation properties.

So Which Insulation is the Best Types Of Insulation for a Garage Wall?

The best type of insulation to use in a garage is spray foam, as it has the most pros. However, unlike other types of indoor insulation that offer significant benefits over spray foam, such as if you live in the suburbs and don’t need energy efficiency or air sealing qualities, there are not many cons besides its high price.

Previously, we discussed fiberglass as the most popular insulation method. It’s inexpensive and can be applied to cover most applications. It will keep heat in better than other methods of insulation, which may make it a good option for your garage.

Regardless of the insulation material, an excellent way to make sure you’re getting your money's worth is by inspecting your property after the installation. Make sure everything is sealed off if doing so will maximize your insulation.

Ensure that any garage cracks are sealed up with caulking, and remove any electrical outlets nearby (situate them as close to your house as possible). Be sure that there is door-sealing weather stripping around the door leading into your house. This will keep cold air out of the home. Replace windows for double pane ones to lose energy efficiency when cold air enters through them.

I am thinking about adding insulation to my garage walls, but I'm not sure if the R-value should be 13 or 15.

To measure how well a barrier can resist heat, an R-Value is always used. If you are insulating your garage with insulation other than what is already in place, ensure that its R-value matches the house.

R-13 and R-15 insulation are both designed for use in a three-and-a-half-inch deep cavity. You should never press or pinch insulation when attaching it to the studs of a garage wall; this will reduce its effectiveness. Both R-13 and R-15 insulation work well together in the same wall cavity. Both are extreme insulators, reducing heat flow by 93%-95%

The R-value of 13 and 15 are virtually the same, but if you use a steel stud in place of wood studs, then an R-15 should be slightly better since it has more excellent conductivity.

If you have an unheated garage, should you insulate it?

Insulating your garage walls is the best value for your money. Most garages are uninsulated, which leaves you with air conditioning in the summer and cold weather during winter. This doesn't have to be!

Insulating your garage helps prevent temperature extremes, making it a wise decision for homes with a garage close to the living space.

By adding insulation to a garage, your cooling and heating costs are significantly reduced. One of the most significant benefits of garage wall insulation is that it buffers your house from the outside world.


Spray foam insulation has a lot of pros, but there are also some cons to consider. If you live in the suburbs and don’t need energy efficiency or air sealing qualities, then another type of indoor insulation would be better for your situation. However, if you're looking for an efficient way to insulate your garage walls that will keep them warm during winter months without breaking the bank on fuel costs, spray foam is worth considering!

Call Concord Garage Door today at 704-438-9600 with any questions about how to help make your home more comfortable this season.