How Much Does Spray Foam Insulation Cost?
$0.25 – $1.50 Per Board Foot
Spray foam insulation costs between $0.25 and $1.50 per board foot or $1.36 to $2.63 per square foot depending on the type. Most homeowners spend $1,463 to $2,926 for professional spray foam installation with prices ranging from $627 to $8,000 depending on what needs insulating. Get free estimates from insulation contractors near you.
Spray Foam Insulation Cost
There are two types of spray foam insulation–open cell and closed cell. Open-cell spray foam costs $0.25 to $0.50 per board foot and closed-cell spray foam costs $0.90 to $1.50 per board foot. The average cost of spray foam insulation installation is $2,128 with most homeowners paying between $1,463 and $2,926. Pricing depends on how many parts of the home you wish to insulate and to what thickness.
|National Average Cost||$2,128|
|Average Range||$1,463 to $2,926|
Spray foam is used in new construction and can also be applied to existing structures. The savings in your energy bills will be noticeable, with most people seeing savings of up to 40%. One of the biggest reasons to use it is for its air-sealing and moisture barrier properties. It expands to 40–100 times its original size, sealing every crack and crevice.
Table of Contents
Types of Spray Foam Insulation
There are two types of spray foam insulation–open cell and closed cell. Open-cell spray foam costs between $0.25 to $0.50 per board foot and closed-cell spray foam ranges from $0.90 to $1.50 per board foot.
|Spray Foam Type||Cost Per Board Foot|
|Open-Cell Foam||$0.25 – $0.50|
|Closed-Cell Foam||$0.90 – $1.50|
Open-Cell Spray Foam Insulation Cost
Open-cell spray foam insulation costs $0.25 to $0.50 per board foot. Above-grade open-cell spray foam is used mostly in residential construction, mainly in attics, exterior walls, and rooflines; and it works well as a soundproofing agent. It is called open cell because the cells of the foam remain open, creating a soft, foamy looking texture when dry. These open cells mean there is a lot of air inside, so it doesn’t weigh very much. A cubic foot (12 x 12 x 12) weighs in at just half a pound.
Closed-Cell Spray Foam Cost
Closed-cell spray foam insulation costs $0.90 to $1.50 per board foot. Closed-cell spray foam is used in residential construction, but usually below grade—in crawl spaces and basements. It’s also used extensively in commercial development. Closed-cell spray foam contains cells that close when it’s sprayed into its final resting place which creates a denser, heavier product. A cubic foot of closed-cell spray foam weighs 2 lbs. The dry closed-cell spray foam turns into a hard plastic. It is an excellent moisture barrier, sealing out 100% of moisture.
Spray Foam Insulation Cost Per Square Foot
Spray foam insulation costs $1.36 to $2.63 per square foot depending on if it's open or closed-cell. For an average 2,200 square foot home, open-cell foam insulation costs $1,254 for the minimum 1.5” thickness and $2,926 to spray the maximum 3.5” thickness on average, while a closed-cell foam installation costs $6,776.
On the same 2,200 square foot home, closed cell foam insulation costs $6,776 for the minimum 3.5” thickness, and $10,648 to spray the maximum 5.5” thickness.
Foam Insulation Cost By Home Size
Prices below are for a 3.5” foam thickness which is the maximum for open-cell and the minimum for closed-cell.
|Square Feet||Cubic Feet||Board Feet||Open Cell||Closed Cell|
Calculating Spray Foam Insulation Costs
What Is A Board Foot For Spray Foam?
The cost of spray foam is calculated by board footage. A board foot is 12” wide and 12” long and 1” thick. To calculate the price, figure the square footage of the room and multiply it by the desired thickness.
For example, if you want to blow spray foam insulation into a wall of the home you’re building, figure the total square footage of the flat wall first. If your wall is 20’ long and 10’ tall, your square footage is 30 square feet. The spray foam goes into the 2 x 4 sections of the wall. Even though they are called 2 x 4s, they are actually 1 ½” x 3 ½”, so you’ll need 3 ½” of foam.
Calculating Board Feet For Spray Foam
Using the example of the wall size above, 30 sq. ft x 3.5” = 105 board feet x 0.50 = $52.50.
Since it’s an above-grade wall, you’ll use open-cell spray foam insulation. The desired thickness can be determined by the cavity you’re blowing into or the R-value you want to achieve. Generally, the R-value of open-cell spray foam insulation is 3.7 per inch. That wall, with a depth of 3 ½”, has an R-value of 13.
For the total square footage of wall space in a 1,600 square foot home, the following chart indicates the price for a range of house sizes for the different thickness of foam—2” and 3.5”—which will change based on the tested values for the brand of spray foam being used and the desired R-value for the geographic region. The prices below are given using the following costs:
- Closed cell - $0.88 – average cost per board foot
- Open cell - $0.38 – average cost per board foot
Spray Insulation Cost By Thickness
1.5” Minimum Thickness For Open-Cell
|Square Feet||Cubic Feet||Board Feet||Open Cell|
2” Average Thickness For Open-Cell
|Square Feet||Cubic Feet||Board Feet||Open Cell|
3.5” Maximum Thickness For Open-Cell And Minimum Thickness For Closed-Cell
|Square Feet||Cubic Feet||Board Feet||Open Cell||Closed Cell|
5.5” Maximum Thickness For Closed-Cell
|Square Feet||Cubic Feet||Board Feet||Closed Cell|
Spray Foam Insulation Vs. Fiberglass, Batt & Cellulose
Spray foam insulation costs $1.36 to $2.63 per square foot to install, and blown-in fiberglass insulation costs $0.40 per square foot to install. Spray foam insulation is substantially more energy efficient and does not lose R-value for its 80 years of life. Fiberglass will last 10 to 25 years if it stays dry and it's R-value decreases over time. While spray foam insulation costs more than standard fiberglass insulation, here's why it's worth the extra cost:
|Type||Cost||Efficiency||R-Value||Life Expectancy||Adds Structural Integrity|
|Fiberglass||$0.40 sq. ft||Less||Decreases over time||10–25 years if it stays dry||No|
|Cellulose||$0.32 sq. ft||More||Decreases with settling||20–30 years||No|
|Spray Foam Insulation||$0.90–$1.50 per board ft||Substantially More||Does not lose R-value||80 years||Yes for closed cell. Has been shown to add 250% racking strength to walls and roof.|
Fiberglass Insulation Cost
Blown-in fiberglass insulation costs $0.40 per square foot to install and is constructed of tiny strands of glass. If inhaled, the bits of glass can cause sickness, and if they land on your skin, itchiness and rashes are the results. It’s also a carcinogen. Be fully prepared to handle this insulation material with the safety equipment necessary to protect your eyes, lungs, and skin.
Fiberglass batt is the most common insulation. It comes in rolls that are cut to size and laid down like a blanket in the attic or hung in the walls. It comes in several levels of R-value; the higher R-values means a thicker batt. Comprised of glass fibers, it is an irritant to the lungs, skin, and eyes.
Cellulose Insulation Cost
Cellulose is mostly made up of recycled newspaper treated with borate to make it fire and insect resistant and costs $0.32 per square foot to install. It’s not fireproof, but it will give you and your family some extra escape time if the unthinkable happens. The borate also repels mice and other rodents. If cellulose becomes wet, perhaps due to burst pipes, it must be cleaned up. Cellulose insulation repair is a big job and preferably done by professionals from a water damage restoration company.
Where To Use Spray Foam Insulation
The two spray foam insulation types (open and closed cell) are intended for use throughout your home. Both types have specific applications, and you’ll reap the most benefits by using them where they are designed to be used.
- Open-cell spray foam insulation is used above the grade or above the ground. It is an air barrier when installed correctly. Use open cell in above ground walls and attics.
- Closed-cell is used below the grade (ground) in crawl spaces and basements. It is a very effective moisture barrier.
- Because spray foam insulation expands to such a significant degree, it’s excellent to use around your HVAC system to cut air loss and improve efficiency. It helps the HVAC not have to work so hard.
- Spray it around doors and windows to completely seal off any air leaks.
- Use on any part of the home’s exterior that needs to seal out drafts, moisture, or bugs. It can usually adhere to wood, metal, stone, brick, and PVC.
Spray Foam Insulation R-Value
R-Value is a critical part when comparing spray foam to other types of insulation. Open-cell has an R-value of 3.7 and closed-cell has an R-value of 6.5 based per inch of installed spray foam. The insulation is blown into the wall or attic one layer (1”) at a time. It’s expanding properties ensure that it covers every little crack and hole, but even with that ability, it still needs to be installed correctly. The foam can’t expand to fill all cracks and air holes if it never reaches a back corner or the farthest reaches of the attic. The R-value is not affected by moisture, as is the case with fiberglass insulation.
Spray Foam Insulation Thickness
The recommended maximum thickness varies depending on the manufacturer making the spray foam. Most spray foam is limited to a thickness of 5.5”, giving it an R-value of 20, but in the more northern areas of the country where the R-value is recommended to be at least 30, spray foam is not enough insulation.
Also, according to the ICC-ES (International Code Council Evaluation Service), if a particular spray foam has been tested and certified to give a certain R-value at a specific thickness, you cannot spray it any thicker than that. Some foams have a maximum thickness they can be installed to prevent the foam from degrading and reducing its effectiveness in the setting process, where it expands, or to prevent it from catching fire.
|Foam Type||Minimum Thickness||Maximum Thickness|
Spray Foam Insulation Pros and Cons
Spray foam insulation helps lower utility costs and protects against moisture, mold, and mildew. According to the U.S. Department of Energy, around 40 percent of all energy is lost in the home because of poor insulation. Also, spray polyurethane foam (SPF) insulates homes approximately 50 percent better than traditional insulation products.
Spray Foam Advantages
- Thermal Barrier – Open-cell spray foam in an excellent air barrier since a lot of heating/cooling gets lost due to tiny air holes and cracks. They may seem small, but add them up, and pretty soon you have the equivalent of a gaping hole in your attic. The beauty of open-cell spray foam is that it enters the space and then expands to fill it completely, blocking off all airflow for energy efficiency.
- Sound Barrier – You can also use spray foam as a sound barrier. If you live on a noisy street or you have a band practicing in your garage, some additional spray foam insulation in those walls can cut down on noise pollution.
- Protects against mold and mildew – The spray foam provides no food source for mold or mildew, making it an excellent barrier against its growth.
- Adds Structural Integrity – The closed-cell insulation attaches to the walls, helping to strengthen a structure during high winds.
- Moisture & Dust Barrier – It’s a moisture barrier, making it an excellent solution to wet basements. Closed-cell spray foam can keep your basement and crawl space dry. That same air/moisture barrier will also keep out dust and pollen.
Spray Foam Disadvantages
- Toxicity – A major disadvantage or spray foam insulation is the potential for toxic effects due to the chemicals used to create the spray foam. Toxicity is usually a problem with lower-quality brands of spray foam. The smell and fumes can cause respiratory distress in some people, as well as skin or eye irritation. Proper safety and protective clothing must be worn at all times during installation.
- Cost – Another disadvantage of spray foam insulation is the higher cost upfront. It cost 3–4 times more than fiberglass batt insulation. There will be payback with energy savings, but it can take 2–3 years before those are realized.
- Uneven application – If the foam is not sprayed evenly and into all corners of the area, the proper sealing will not happen. There will be spots with too much insulation and areas with too little. A complete air barrier will not be accomplished with an uneven application.
- Insufficient coverage – If you install an inadequate amount of foam, there will be bare spots which will allow air leaks to continue. The energy savings won’t be realized if the air barrier is incomplete.
- Failure to correctly identify the building envelope – Missing the building envelope leads to a condition called thermal bypass which will negatively affect energy efficiency. The building envelope is the barrier between the inside and the outside of a structure. For example, a wall is not just one layer of material between the inside and outside of your home. There is a total of seven layers that make up a wall—beginning with the outside and working your way inside—the exterior siding, exterior sheathing membrane, exterior sheathing, insulation, structural components, vapor barrier, and interior sheathing. So if someone applied insulation to the interior sheathing (drywall), they would have missed the building envelope.
- Improperly mixed chemicals or foam applied outside the recommended temperature range – If the foam isn't mixed correctly or at the correct temperature, not only will expansion not take place, but the opposite can happen—the foam will contract. Proper installation is just one reason why it’s important to hire a professional who is knowledgeable and experienced.
Foam Insulation Cost Difference for New or Existing Homes
New Home Construction
Depending on where you live, spray foam insulation in new construction for a 1,000-square foot home will cost an average of $5,000–$7,000.  That’s for top-to-bottom insulation from the basement to the attic, including all exterior walls. This cost is affected by the size of the home and the layout of the house. A simple, rectangular layout is less expensive to insulate than a home with a more complex design.
Insulating an existing home with spray foam is a more expensive proposition. In new construction, the insulation is applied before walls are closed up. When working with an existing home, you’ve got to find a way into those walls. The usual method is to pop off a piece of siding, drill a hole, and fill it with spray foam insulation. You must repeat this every 16” or so to fill every cavity in the wall. The cost for this varies but runs between $8,000–$20,000. That price is also affected by the size of your home, the ease or difficulty in accessing all parts of the outside walls, the opening in the attic, the pitch of the roof, and the crawl space to the basement.
DIY Spray Foam Insulation Cost
If you'd like to do it yourself, consider purchasing a spray foam installation kit if you're doing a small insulation project. Kits come in both open and closed-cell foam. Foam It Green open-cell will cover 602 sq. ft at a 2” depth, or 300 sq. ft at a 4” depth, and costs $885. Tiger Foam is a closed-cell spray foam and will cover 600 board feet for $585. 
DIY Spray Foam Insulation Kits
Foam insulation kits also come with different options such as fire retardant and anti-microbial properties. Spray foam kits contain everything you need to spray foam insulation such as hoses, guns, and nozzles; but it’s a good idea to purchase extra nozzles, as they do tend to clog up quickly. You’ll also need the proper safety equipment—protective clothing, safety goggles, gloves, and masks.
If you decide to install foam insulation yourself, here are popular brands to research:
- Tiger Foam
- Touch 'n Foam
- Dow FROTH-PAK
- Foam it Green
- GREAT STUFF
Kits are suitable for insulating small areas of your home, such as the attic, any open wall cavities, the crawl space, and rim joists. You can also make your home more airtight by applying it around windows and doors. It can also be used to patch any torn existing insulation.
Frequently Asked Questions
Is Spray Foam Insulation Worth It?
Spray foam is two to three times more expensive than cellulose or fiberglass insulation, but it lasts 2 or 3 times longer (up to 80 years). The savings in your energy bills will be noticeable, with most people seeing savings of up to 40%. Also, spray foam never loses any R-value while others decrease over time. Closed-cell spray foam has been shown to add 250% racking strength to walls and roof while the others add no structural integrity.
What is the R-value of 2 inches of spray foam?
The R-value of 2” open-cell spray foam is 7.4, and the R-value of 2” of closed-cell spray foam is 13.
How much does it cost to insulate a 1500 sq ft house?
The average cost to insulate a 1,500 square foot home with spray foam insulation is between $2,128 and $4,928 for professional installation.
Is Spray Foam Waterproof?
Yes, high-density closed-cell spray foam insulation is waterproof. However, open-cell or low-density spray foams are not waterproof or water-resistant.
How Long Does Spray Foam Insulation Last?
According to The International Association of Certified Home Inspectors, spray foam insulation can last for more than 80 years and is substantially more energy efficient than fiberglass or cellulose. Cellulose has a lifespan of 20 to 30 years, and fiberglass can last 10 to 25 years if it stays dry.
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