How much does it cost to install spray foam insulation?

Reviewed by Tom Decker remodeling expert. Written by Fixr.com.

With the rising energy costs, many homeowners are turning to insulation to cut energy usage. Many insulation types are on the market, and spray foam is one of the most effective at insulating and creating an air and vapor barrier. It can be used in areas where other forms of insulation cannot go, and it can last up to 80 years without degrading.

Many factors determine spray foam insulation costs, including the amount, depth, and insulation type. The national average cost to fully insulate a home with spray foam is $10,000 to $30,000. Most homeowners spend around $20,000 on a mixture of open and closed cell insulation 6 inches thick in an existing 2,000 sq.ft. home. This project’s low cost is around $7,000 for 7 inches of open cell foam covering the attic floor. The high cost is $40,000 for 10 inches of closed cell foam insulation to create a net zero 3,000 sq.ft. home.

Cost to Install Spray Foam Insulation

What Is Spray Foam Insulation?

Spray foam insulation is polyurethane mixed with water or another fluid before being sprayed into the walls. The foam expands quickly upon installation before hardening. Because it sprays in a liquid form, it can be applied to wall cavities and other hard-to-reach areas in new and existing homes. Applying the correct depth - a minimum of 6 inches for closed cell and 7 inches for open cell insulation, with depths of up to 12 inches being common - can dramatically reduce thermal transfer. This makes your home more comfortable and energy-efficient.

Spray Foam Insulation Cost by Type of Installation

Spray foam insulation is more common in new home construction than in existing homes. It is easier to add foam to wall cavities, basements, and other areas before they are finished in new home construction. It takes more work and effort to get it into wall cavities in finished walls in an existing home. While material costs do not change, the cost of installing in an existing home can be much higher than in a new home. You may have further costs in patching walls and other finish work once the insulation is in. That is why most people who want to add insulation to an existing wall cavity choose blow-in insulation rather than spray.

For areas like attics and other open spaces, this type of insulation is applied similarly to a new home. If you insulate your entire existing home with spray foam insulation, you do not pay more for the insulation. But you have additional finishing costs associated with the project. The below costs are for adding insulation to different construction types. Costs vary depending on the thickness of the insulation added. More insulation or thicker applications will have higher costs.

Spray Foam Insulation in New Home Construction

Adding spray foam insulation to new home construction costs between $2.75 and $6.50 a square foot installed. Costs vary due to several factors. The foam depth is the biggest contributing factor. Most need to be installed between 6 to 12-inches thick to have a significant impact on your comfort and energy bills. However, not every area needs the same thickness of insulation. In addition, there are two types of insulation - open and closed cell. While closed is technically more expensive, you can often get away with less of it. Depending on where it is installed, this can impact your final costs.

Spray Foam Insulation in Existing Walls

The cost to install spray foam insulation in existing homes is $3.15 to $7.50 a square foot. Adding insulation to an existing home has the same cost factors and variables as a new home installation. Thickness and location change the cost of the project dramatically. In addition to these factors, you also have accessibility to contend with. While some areas in an existing home are identical in accessibility to a new home, other areas are hard to reach. Existing finished walls require the installer to open the walls in certain areas. This can add to the insulation cost and finishing costs.

Spray Foam Insulation Cost per Square Foot

Spray foam insulation has a wide range of costs per square foot. This is because it is actually sold and installed by the board foot. A board foot of spray home insulation is defined as 1 square foot of space covered in 1 inch of insulation. You will never purchase a board foot because the insulation you need ranges from 6 to 12 inches, and the amount varies based on the location and insulation type. This means square footage costs vary widely. You rarely use the same amount and insulation type in your entire home. It is much more likely to switch types and thicknesses throughout the project. The costs below are for a broad range of what you could pay based on the number of square feet you cover. Keep in mind your costs could fall anywhere within the range based on your needs. Costs vary for each area covered by the insulation depth and the space type and size. The table below shows the insulation square footage, not the square footage of the house.

Spray Insulation Cost by Category

Spray foam insulation has two categories - open and closed cells. This describes the way the foam looks. Of the two, closed cell is better at insulating. It is also stronger, harder, and more difficult to place in tight areas like around pipes. Closed cell is also water-resistant, meaning it works on exterior walls.

Open cell typically must be thicker to achieve the same insulating power as closed cell. For example, 8 inches of open cell insulation or 6 inches of closed cell reach the same R-factor. For this reason, while open cell is less expensive, you use more overall. This means that functionally, there is little-to-no difference in costs between the two materials once they are installed.

Open Cell Spray Foam

Open cell spray foam costs between $0.44 and $0.65 a board foot for the material. Open cell is created through lower pressure and has a more open structure. That means air and moisture can pass through the foam. It does not provide as high an R-value as closed cell and is not waterproof or water-resistant. You need more material to cover the same-size space, so while it costs less, you use more of it. This results in nearly identical costs. It is used solely for interior purposes. It gets into tight spaces better than closed cell so that it can fit in tight corners and around pipes in existing home installations better than closed cell.

Closed Cell Spray Foam

Closed cell insulation costs $1 to $1.50 a board foot for the material. Closed cell is produced under high pressure, which closes the openings in the foam. It costs more than open cell, but you use less for the same R-value. It is also incredibly strong. It can add strength and structural integrity to your home, and a smaller amount does a better job at insulating. It keeps water and moisture out but does not allow for permeability, which is a problem that can lead to mold. You can use this material on exterior applications and basements, and it can adhere to materials like PVC, brick, mortar, and wood.

Closed cell foam at 2” deep or more is used in masonry applications, in crawl spaces under your home and in high moisture areas like indoor swimming pools. Open cell foam is a soft product and when applied to a minimum of 3” up to 14” deep is a fantastic air seal / insulation that will produce energy efficient, quiet homes that use a minimum of heating and cooling year round.

Tom Decker, insulation expert

What Is the R-Value of Spray Foam Insulation?

All insulations are ranked on how well they resist thermal transfer. This is known as the R-value, and a higher R-value means it resists more thermal transfer.

In general, closed cell has a higher R-value per inch than open cell. The R-value of each increases with the thickness. For example, a 2-inch open cell application may have an R-value of 7.6, while a 3-inch application might have an R-value of 11.4. The same thicknesses of closed cell have R-values of 14 and 21, respectively.

The amount of spray foam you need to achieve the recommended R-value for your home varies by the location you install it in and where you live. Check this guide by Energy Star to find the recommended R-value for the various areas of your home, based on the climate you live in.

Your climate plays a role in what the best R-factors are for the different areas. Homes in very hot and very cold climates need more insulation than homes in moderate climates. If this is an existing home, you likely already have some insulation in place. This also needs to be taken into consideration when determining the correct amount of spray foam to add.

Spray Foam Cost by Thickness

Spray foam can be applied in many thicknesses. You likely do not need more than 6 to 7 inches of closed cell, even in extremely hot or cold climates. However, you may need much more open cell to achieve the same level of insulation. On average, an inch of closed cell foam has an R-value of 7, while an inch of open cell has an R-value of 3.8. Your exact numbers vary depending on what you apply and the foam your installer uses. Below is an average range of R-values and square foot costs for applying the foam by inch.

Closed Cell Insulation Cost by Thickness

Open Cell Insulation Cost by Thickness

Labor Cost to Install Spray Foam Insulation

Labor costs to install spray foam insulation vary depending on the insulation’s new location, installation type, accessibility, and how much you apply. Costs for labor are typically between $50 and $100 per hour. The amount of time needed depends on the job size. For example, spraying a small basement takes 2 to 3 hours, whereas a large attic could take 6 to 8 hours, and an entire house may take 3 to 4 days. The more accessible the area, the faster the installation and the lower the costs.

The labor for spraying a 2,000 sq.ft. home costs between $1,200 and $4,800 out of the $20,000 total. Some installers may also include additional costs for equipment, and you may also have setup costs.

Costs for labor do not vary tremendously based on open cell or closed cell because the process is the same. The amount of insulation, location, and accessibility dictates your labor, while the material cost drives the remainder.

This type of insulation looks deceptively easy to install. It consists of two large drums, each holding a separate chemical mixture. The first contains the insulation. The other has a catalyst that turns it into foam, along with a combination of control agents that specify how big it gets, how far it spreads, and other factors. These two chemicals are heated and mixed under pressure while being sprayed directly at the surface they cover. The foam begins to expand up to 150 times its original size within seconds. Therefore, the installer must calculate where and how much to spray to fill the area.

Cost to Install Spray Foam by Location

While some people may choose to spray foam their entire home, others only want to insulate specific areas such as their attic or basement. Costs are typically higher for existing structures than for new construction, and final costs are based on factors like thickness and foam type.

Below are the average costs based on typical sizes, assuming all relevant areas have been insulated. In some areas, such as attic floors, basements, and crawl spaces, costs are identical for existing and new construction because access remains the same.

Crawl Space Spray Foam Insulation

The cost to spray foam a crawl space is between $1,000 and $5,900. Crawl spaces are rarely finished or insulated in new homes. This is because of how they are created and how they may be used in the future. However, insulating them can make a big difference in your energy bills and comfort. The floor above your crawl space is often more comfortable after insulating rather than taking on the outdoor temperature. Due to how they are constructed, insulating in new construction or an existing space has similar cost ranges.

Spray Foam a Shipping Container

The cost to spray foam a shipping container ranges from $1,800 to $2,500. Shipping containers have become popular for use in various ways. This includes creating homes and workspaces from them. It does not have new build costs because you are repurposing the space. Spray foam is the ideal insulation for a shipping container. It sticks to the metal and goes on quickly and easily without needing cavities.

Roof Foam Insulation

The cost to spray foam your roof deck averages $2,400 to $8,000. However, it is not always recommended for this space. If you choose to apply spray foam to your roof deck, you must use closed cell foam. This is because moisture can infiltrate this area. This can mean that roof leaks and other problems go undetected for longer, leading to bigger repairs down the road. Because the roof deck is fully accessible in existing homes and new builds, there is no cost difference.

Spray Foam a Basement

The average cost to spray foam a basement is $2,400 to $8,400. Due to how basements are created, the cost is the same in an existing home as in a new build. Spray foam is a great way to insulate all areas of the basement. It does well on concrete, around pipes, and HVAC equipment. Only closed cell foam can be used here because of the high moisture levels in basements. Spray foam can be added at any time to a basement but is most often done before finishing.

HVAC Spray Foam Insulation

The cost to spray foam your HVAC system averages $2,500 to $3,000. Spray foam insulation is an excellent choice for sealing the area around an HVAC system to prevent air loss and improve efficiency by having the unit not work as hard. It does this by expanding to fill all air gaps in the system. You use spray foam on ducts, connections, exhaust, and other areas where air leaks or air gaps may be discovered. The best way to find out where to insulate is to have your system inspected and tested for air leaks and then insulate. This can be done after the system is installed.

Spray Foam an Attic

The cost to spray foam an attic ranges from $2,500 to $12,000. There are many areas in an attic you can spray. Costs may fluctuate between new construction and an existing home, but may not, depending on what you have in the attic. Spray foam can be applied to the attic floor, walls, ceiling, and roof deck underside. This is best used in unfinished attics because it is quick and easy to apply. However, it can be added to finished spaces, adding to the cost of an unfinished attic installation.

Spray Foam Insulation in a Garage

The cost to spray foam a garage is $3,600 to $7,800 for a new or unfinished garage. Costs for an existing finished garage average $4,000 to $8,600. Unfinished garages and new garages have similar costs for installation. It is only after the garage is finished that the cost rises. Spray foam is an excellent material for garages. It can be applied to all areas, including the back of the garage door and the ceiling. If your garage is attached to your home, this can make it more comfortable and help prevent it from becoming a source of energy leaks.

Spray Foam a Pole Barn

The cost to spray foam a pole barn ranges from $6,000 to $18,000 for a new build. The cost to insulate an existing pole barn is $8,000 to $20,000. Many people choose pole barns to build as a home, barn, or other outbuilding structure. They are fast and easy to put up, which generally makes them inexpensive. However, they can be harder to insulate using other methods. Spray foam can cover all areas and air leaks in the structure. This means a much more comfortable and energy-efficient structure once complete.

Spray Foam a House

The cost to spray foam a new home averages $8,000 to $25,000. The cost to spray foam an existing home is $10,000 to $30,000. Spray foam makes a great choice for all home types. It expands to fill areas of many sizes, including some that may be hard to fit with fiberglass batts and other traditional insulation types. It is also fast and easy to apply, so it can often be done in less time than other insulation types. The insulation amount and type used in the space vary throughout the house. You will likely need a combination of thicknesses and open and closed cell insulation.

Spray Foam Insulation Removal Cost

Spray foam insulation is very durable and long lasting. In most cases, you do not need to remove it once it is in place. However, it can be damaged due to pests or construction, meaning you need to remove what remains and replace it. The cost of removal varies depending on the type, depth, and its condition. Most spray foam can be removed by a machine, but some areas like walls may have insulation that needs to be chipped free by hand, which can increase costs. For most jobs, expect costs of between $1.50 and $3 a square foot to remove the insulation. However, if a lot of chipping needs to be done by hand or there is other manual labor that must be done to remove the insulation, you will pay closer to $5 a square foot for total removal costs.

Spray Foam Bases

Most spray foam insulation contains polyurethane as a base. Not all are created equally, however. Some are made of greener materials than chemicals typically used in polyurethane production. Choosing a different spray foam can create a healthier home while avoiding some of the off-gassing polyurethane is known for. While traditional polyurethane is the most common type, you may also find soy-based, water-based, and vegetable-oil-based options. Your project’s cost ranges from $2.75 to $7.50 a square foot, regardless of which type you use because of other factors like location, installation type, and foam thickness.

Traditional polyurethane is the most common type and what your installer will likely use unless they say differently. It contains high levels of VOCs and has a strong odor. Soybean-based, also known as vegetable oil-based, insulation is more sustainable with no VOCs or strong odor. This type also contributes to LEED credits. Water-based foam is a good choice for zero VOC, although it is only available in open cell insulation. Because traditional is more common, you may need to ask for these alternatives or seek out a contractor who specializes in them.

Pros and Cons

Like any material, spray foam insulation has advantages and disadvantages. The material is made up of two liquids heated and sprayed together. On contact, they expand to fill the cavity. The material is quick and relatively easy to apply. It also fills gaps, no matter how small, and can be used around things like pipes and ducts where fiberglass batts may not be able to go.

Spray foam offers superior insulation in many instances to other forms. You can get very high R-values with this type of insulation, often with less insulation needed than other types. Spray foam also acts as a sound barrier, so your home can be quieter.

Unfortunately, it has several drawbacks. Some types give off high levels of VOCs, which may be irritating. Because there are two types, you must apply it professionally to ensure it is done correctly and the correct product is used in the right area. Trying to save on a DIY insulation job is not possible with spray foam. Finally, it is not always the right insulation for the job. For example, using it on a roof deck may obscure water leaks until too much damage has been done.

How Long Does Spray Foam Insulation Last?

It is estimated that spray foam insulation can last for up to 80 years. While this seems like a long time, other insulation types like fiberglass and cellulose last for more than 100 years. For many homeowners, however, 80 years is much longer than they own the property, making it a good investment from a resale and energy cost savings standpoint.

Spray Foam vs Fiberglass Insulation

Spray foam is one type of insulation. Another more readily recognizable form is fiberglass. Fiberglass insulation comes in batts and loose-fill. It is much healthier than spray foam because it does not emit VOCs. It also does not degrade when wet, but it should not be used on exterior walls. So, it can be more limited in placement than spray foam. Fiberglass is also the least expensive insulation on the market.

Rockwool vs Spray Foam

Rockwool or mineral wool is another insulation used in homes. It is not used nearly as frequently as fiberglass or spray foam. It does not emit as many VOCs, but it can contain formaldehyde. Rockwool is made in stiff lightweight batts. It cannot be used in all areas that spray foam can and is limited to stud interior walls. It does a good job of thermal insulating and soundproofing, but it is not as versatile as spray foam because it cannot be used in as many places.

Blown-In Insulation vs Spray Foam

When insulating an existing home, consider blown-in insulation in addition to spray foam. Blown-in insulation can be fiberglass or cellulose. It is made up of loose material that can be blown into a cavity, propelled by air. It is less expensive than spray foam and healthier with no VOCs. However, it often does not insulate as well and cannot be used in open spaces like how spray foam insulation can.

Cellulose Insulation vs Spray Foam

Cellulose insulation is a type of blown-in insulation made of cellulose from paper. It is treated to be flame-retardant before being used in the cavities. It is eco-friendly, does not emit VOCs, and is best inside cavity walls in existing homes. Unlike spray foam, it cannot be used in open areas or on exterior walls. This makes spray foam the more versatile of the two.

Enhancement and Improvement Costs

Soundproofing

Spray foam insulation acts as an acoustic absorber, helping stop some sounds from entering. While you can use it as a sound barrier, you may want to take this a step further. Soundproofing a room to truly improve the acoustics costs around $1,000 to $2,500.

Mold Remediation

One reason to install new insulation is to remove old insulation affected by mold from moisture infiltration. If this is the case, you need mold remediation before installing the new material to ensure the area is clean and ready for new insulation. The cost for mold remediation is between $1,500 and $3,500.

Humidity Repairs

Closed cell insulation acts as an air barrier, meaning water vapor cannot escape. In some instances, you may need to have a vapor barrier installed to prevent issues from occurring. This is not always the case, but it costs between $0.65 and $1 a square foot if needed.

Additional Considerations and Costs

• Moisture. Closed cell insulation is water-resistant and not affected by water. Open cell insulation does not keep water out, so moisture passes through it, meaning it cannot be used on exterior walls or in areas of high moisture.
• Strength. Spray foam insulation does not rot or degrade, even when wet. It can add considerable strength and structural integrity to many areas.
• Energy audit. Having an energy audit conducted before installing insulation can help find the best areas to insulate.
• Professional installation. Spray foam insulation must be installed by a professional. In addition to requiring specialized knowledge, it may be hazardous to the health of the installer if handled incorrectly.
• Air barrier. Closed cell insulation creates a very tight air barrier. Used on the building envelope, it may lead to a buildup of interior condensation. Use a vapor barrier to prevent this.