How much does it cost to insulate a garage?

Reviewed by Adam Graham remodeling expert. Written by Fixr.com.

If you plan to use your garage for more than storing your car or it is a source of air leaks for your home’s heat, insulating it may be a good idea. Most garages are not insulated when built, but they are generally fairly easy to insulate because most do not have finished walls until a garage conversion takes place. You can use all the same insulating materials as the rest of your home, such as batts or spray foam insulation, although the type you use may be dictated by whether your walls are drywalled.

The national cost range to insulate a garage is $2,000 to $6,000, with most people paying around $4,500 to fully insulate the walls and ceiling of a 2-car garage with a mixture of batts and blown-in insulation. This project’s low cost is $600 to insulate a 1-car garage with batt insulation. The high cost is $8,000 for a full spray foam insulation in a 2-car garage.

Garage Insulation Cost

Garage Insulation Cost by Size

Most garages fall into a set of sizes based on how many cars they hold and what you plan to do with the space. This means that most garages tend to fall between 240 and 600 sq.ft. in size.

Like homes, insulating costs vary, depending on the insulation type and where and how much you use. Insulation costs range from $0.65 to $7.50, but it is possible to insulate the entire structure or just the walls, ceiling, door, or wall adjacent to your home. While a 1-car garage is 240 sq.ft., you will not pay between $156 and $1,800 because insulating the walls and ceiling will result in a much higher square footage. It is more likely that your costs will fall between $572 and $6,600, depending on the materials used. Below are the average costs to insulate a garage based on the most common garage sizes.

Garage Insulation Cost by Number of Cars

Most people think of their garages in terms of how many cars they can hold rather than in total square feet. Garages tend to be fairly standard in size, based on how comfortably they can hold a certain number of cars. The calculation for the cost of insulating the garage is the same as when you know the square footage. Take into account all the spaces being insulated and not just the overall size. Below are the average costs to insulate a garage based on how many cars it holds.

Insulate a 1-Car Garage

The cost to insulate a single-car garage is $572 to $6,600. This assumes that the garage is the standard size of 12’x20’. If your garage is a single with different dimensions, your costs could differ. The wide range of costs for insulating this garage is due to the many different insulation types that can be used. Garages are most commonly insulated with batts, loose fill, and spray foam insulation, with each having differing costs to consider.

Insulate a 2-Car Garage

The cost to insulate a 2-car garage averages $780 to $9,000. This assumes an average garage size of 20’x20’. If your 2-car garage has different dimensions, your costs could vary. 2-car garages are among the most common sizes. Like other structures, they can be insulated with a variety of materials and in many areas. This can lead to a wide range of project costs.

Insulate a 3-Car Garage

The cost to insulate a 3-car garage ranges from $1,040 to $12,000. This assumes an average garage size of 20’x30’. If your 3-car garage has different dimensions, your costs could be different. 3-car garages are often used as car storage and work areas at the same time. Therefore, this is a common garage size to finish and insulate. Your costs to insulate the garage depend on the material and where it is applied.

Price to Insulate a Garage by Type

Many insulation types can be used in a garage, and it is very common to mix and match them, depending on where in the garage they are used. For example, you may choose batts for the ceiling and blown-in insulation on the walls. It is also common to change the insulation type based on things like whether the walls are open or have drywall installed or how the space will be used.

Below are the average costs per square foot for the different insulation types commonly used to insulate garages.

Batt Insulation

The cost of batt insulation is $0.65 to $2 a sq.ft. installed. Batt insulation is a good choice for wall cavities and ceilings. It can be made of many different materials, with fiberglass being the most common. Batt insulation is best installed in walls that are still open where the area can be easily accessed. This is a good, economical choice for garages that are not yet finished and without drywall. The walls can be drywalled once the batts are in place.

Blown-In Insulation

The cost of blown-in insulation averages $1.65 to $3.80 a sq.ft. installed. Blown-in insulation is a good choice for attic spaces above the garage and drywalled walls. The insulation can be blown into empty cavities, including behind existing drywall. The two most common materials for blown-in insulation are fiberglass and cellulose. Both do a good job of filling cavities and insulating walls and ceilings. If your garage walls are not currently finished, they should be drywalled before using this insulation.

Foam Board

The cost of foam board insulation ranges from $2.40 to $3.75. Foam board insulation is used on the exterior of your garage. It is installed beneath your siding to create a tight building envelope. This makes it a good choice when doing exterior renovations to the garage. The foam board helps prevent thermal transfer at the source and helps stop air leaks. If your garage interior is fully finished and you want to add additional insulation, this is a good choice.

Spray Foam a Garage

The cost of spray foam for your garage is $3.15 to $7.50 a sq.ft. Spray foam insulation is a good choice for nearly all garage areas. It works best in open cavities, such as walls, but can be used in finished spaces as well. The cost of insulating an open wall with spray foam is considerably less than insulating a finished wall. To reach the interior of the finished walls, small holes are usually drilled in the siding outside. This does not impact the appearance of the garage, but it raises costs.

Rigid Board

Rigid board insulation costs $5.75 to $15 a sq.ft. installed. This is one of the least common materials for use in garages. It may be used to insulate sheathing, the back of a garage door, and add additional insulation to attic spaces. This material is usually made of cork or wood. It is not water-resistant and must be used in a completely finished garage. This is a good soundproofing material and may make a good choice for insulating the wall between the garage and house if the garage will be used for loud activities.

Cost to Insulate a Garage by Material

In addition to the insulation type, you also have a range of materials. When comparing the different materials, first consider how each is used, its R-factor, how sustainable it is, and how healthy it is to use. Not every material is interchangeable. Some can only be used in specific ways.

For example, fiberglass can be used as both batts and blown-in insulation, while cellulose is only blown-in. Things like blue jeans and sheep wool are used primarily as batts. Polystyrene can be found as both spray foam and foam boards, but polyisocyanurate is only found in foam board form. Determining the type of insulation you plan on using helps you narrow down the material type.

What Does R-Value Mean in Insulation?

When you insulate a space, one of the factors to consider is the R-value - both of the material and what you hope to achieve with the space. As defined by Energy.gov, the R-value is a measure of a material’s resistance to conductive heat flow. This essentially means that the higher a material’s R-value is, the more it will resist thermal transfer, helping a space stay warmer and hold its heat better.

All materials have an R-value, which is the measure of resistance per inch of material. Therefore, the thicker the material, the higher its R-value and the greater insulating properties it has. Homeowners living in very cold or very hot climates may find that they need higher R-values to help their homes become and stay more energy-efficient than homeowners who live in more moderate climates.

Below are the average R-values of the different insulation types based on 1” of material installed.

Average Cost to Insulate a Garage by Location

Like any structure, it is possible to insulate many areas. In a garage, you can choose to insulate the door, walls, ceiling, floor, or the underside of the roof deck. Each of these areas has a range of costs, depending on the material and space size. Below are the average costs to insulate each of the various areas in an average 2-car garage.

Insulate a Garage Ceiling

The cost to insulate a garage ceiling averages $260 to $3,000. This assumes an average size of around 400 sq.ft. If your garage is larger or smaller, your costs could be different. Garage ceilings can be insulated using a wide range of materials, from fiberglass batts to spray foam. This results in a wide range of costs. The cost is based on factors like the ceiling parts, whether the ceiling is finished, and whether you are insulating the roof deck.

Garage Door Insulation

The cost to insulate a garage door ranges from $500 to $700. This assumes that you are insulating an existing door that is already installed. Garage doors can be insulated using various types of foam insulation. This can include limited amounts of spray foam but more commonly uses a type of foam board. The boards can be cut to fit and installed on the backside of the door in a way that still allows for full door movement. This helps seal any air gaps, which can lead to thermal transfer.

Garage Floor Insulation

The cost to insulate a garage floor is $600 to $900, assuming your garage floor is roughly 400 sq.ft. If your garage is larger or smaller, your costs could be different. To insulate the garage floor, it must be done before the concrete is poured. Therefore, this is a project best done during concrete replacement or when the garage is built. Special foam insulation types can be used along with plywood sheeting to insulate the floor. The concrete is then poured over them to finish the floor.

Garage Wall Insulation

The cost to insulate garage walls averages $780 to $9,000. This assumes that the garage is 20’x20’ in dimensions. If your garage is larger or smaller, your costs could differ. Garage walls have many choices for insulation and material. You can use batts, blown-in insulation, or spray foam on the interiors and foam boards on the exterior. You can also insulate at any time - when the walls are open or drywalled. This provides the greatest flexibility in how you insulate and what level of insulation you add.

Garage Roof Insulation

The cost to insulate your garage roof is $1,600 to $3,000. This assumes an average 2-car garage with a gable roof. Your costs could be different if you have a larger or smaller garage or a more intricate roof type. To insulate the roof, you need to insulate the underside of the roof deck. This is the underside of the roof visible from within the attic. The most common material used for insulating this is foam. Depending on your preference, you can use both foam boards and spray foam insulation to cover this area.

Labor Cost to Insulate a Garage

The average labor costs to insulate a garage vary based on the materials you choose. Each insulation type is installed differently, meaning each one can have a different cost per square foot. Labor can range from $0.25 to $2.50 a sq.ft. In the case of spray foam, which is priced by the hour, you could have costs of between $50 and $100 an hour. Depending on the material you choose, the labor costs for installing insulation in a 2-car garage may range from $300 to $4,000. Below are the average costs to install different insulation types in your garage.

Cost to Insulate and Drywall a Garage

It is common to insulate a garage before finishing it. This often occurs when the walls are open so that you can install the insulation and then finish the walls with drywall. Based on the material and insulation type, there can still be a wide range of costs for insulating a garage. The average costs to drywall a 2-car garage range from $900 to $1,200. To fully insulate the space, your total costs are $1,680 to $10,200.

Enhancement and Improvement Costs

Energy Audit

Before you install insulation, it is always good to have an energy audit. Energy audits help you pinpoint where your home or garage is losing the most energy so that you can take the appropriate steps to correct it. The cost of an energy audit ranges from $145 to $420.

Soundproofing

In many cases, insulating your garage will also help soundproof it at the same time. Insulating has many sound-absorbing qualities. However, if you want to specifically soundproof the space, costs average $230 to $450.

Mold Remediation

If your garage has moisture problems, you may have mold growth in the areas to be insulated. In this case, you need to deal with this before you can add insulation. The cost of mold remediation is $1,500 to $3,500 on average.

Weatherstripping

Weatherstripping your garage also helps make it more comfortable and energy-efficient. Weatherstripping goes around your garage door, windows, and other openings to help seal them. The average cost to weatherstrip a garage is $130 to $400.

Additional Considerations and Costs

• Climate. It is important to consider your climate when insulating your garage or home. If you live in a very cold climate, you need more insulation in this area than if you live in a moderate climate.
• Permits. In most areas, you do not need permits to insulate your garage. However, this varies by area, so check with your municipality before proceeding.
• Vapor barrier. You may need to install a vapor barrier over the studs after insulating. This helps prevent moisture from building up on the insides of the walls.
• Estimates. Always get at least 3 estimates when hiring someone to insulate your garage. This allows you to compare and find the right person for the job.