Ashburn, VA

How much does spray foam insulation cost?

$1.00 – $4.50 cost per square foot
$0.60 – $2.90 cost per board foot (1 SF 1" thick)
$1,300 – $4,000 average total cost installed

Get free estimates from insulation contractors near you, or view our cost guide below.

March 15, 2022

Reviewed by Tom Grupa and 3 expert insulation contractors on HomeGuide.

Spray foam insulation cost

Spray foam insulation costs $1.00 to $4.50 per square foot, depending on the type, R-value, and job size. The average cost of spray foam insulation is $1,300 to $4,000 installed. Closed-cell spray foam costs $1.30 to $2.90 per board foot and open-cell spray foam costs $0.60 to $1.30 per board foot.

Spray foam insulation cost
Location Average cost
Existing walls $3,200 – $8,800
Attic floor $1,100 – $6,800
Attic rafters / roof deck $1,500 – $9,000
Basement $1,500 – $5,600
Garage walls $2,600 – $8,900
Garage ceiling $1,500 – $3,000
Crawl space $1,200 – $6,700
Rim joists $1,200 – $2,000
Around HVAC $1,000 – $3,300
Whole house $4,000 – $26,000
Pole barn $3,500 – $16,500
Shipping container $800 – $3,200

Spray foam insulation cost calculator

The following table reflects the average cost to install spray foam insulation.

Spray foam insulation cost - chart
Spray foam insulation cost - chart

Spray foam insulation cost calculator
National average cost $2,600
Minimum cost $600
Maximum cost $8,000
Average cost range $1,300 to $4,000

Cost data is from research and project costs reported by HomeGuide members.

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Open-cell vs. closed-cell spray foam cost

Closed-cell spray foam costs $1.30 to $2.90 per board foot installed and open-cell spray foam insulation costs $0.60 to $1.30 per board foot. A board foot is one square foot with 1" thickness.

Open vs. closed-cell spray foam cost - chart
Open vs. closed-cell spray foam cost - chart

Open vs. closed-cell spray foam insulation cost
Factor Open-cell foam Closed-cell foam
Material cost (per board ft) $0.30 – $0.50 $0.90 – $1.00
Installed cost (per board ft) $0.60 – $1.30 $1.30 – $2.90
R-value per inch 3.5 – 3.7 5 – 7
Density (per cubic ft) 0.5 lbs. 2 lbs.
Expansion Expands to 3" Expands to 1"
Moisture barrier Semi-permeable Impermeable
Sound dampening Good Better
Vapor retardant Semi-permeable Impermeable
Roof sheathing application Not recommended Recommended
Best for Above-grade installations, like wall cavities and attic floors Below-grade applications, like basements and crawl spaces

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Spray foam insulation cost per square foot

Spray foam insulation costs $1.00 to $4.50 per square foot of surface area installed, depending on the project size, conditions, location, and whether it is open-cell or closed-cell foam.

Spray foam insulation cost per square foot
Square feet Average installed cost
100 $100 – $450
200 $200 – $900
300 $300 – $1,400
400 $400 – $1,800
500 $500 – $2,300
1,000 $1,000 – $4,500
1,500 $1,500 – $6,800
2,000 $2,000 – $9,000
2,500 $2,500 – $11,300
3,000 $3,000 – $13,500

Average cost to spray foam a house

The average cost to spray foam a whole house is $4,000 to $26,000, depending on home size, stories, areas insulated, foam type and thickness, and whether it's new or existing construction.

Spray foam insulation in existing walls cost

Installing spray foam insulation in existing walls costs $3,200 to $8,800 on average, depending on the project size. Installers spray slow-rising "injection foam" through holes drilled in the drywall or siding to fill the existing stud cavities.

  • Closed-cell injection foam adds strength to the walls.
  • Open-cell injection foam is better for sound dampening.

Open-cell spray foam insulation being applied in walls
Open-cell spray foam insulation being applied in walls

Attic spray foam insulation cost

Attic spray foam insulation costs $1,100 to $6,800+ on average for the floor, depending on the foam type and R-value. Attic insulation companies recommended open-cell foam in vented attics to fill floor nooks and crannies, but it may require a vapor barrier in cold climates.

Attic spray foam insulation cost
Location Average cost installed
Attic floor $1,100 – $6,800
Attic rafters / roof deck $1,500 – $9,000
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Contractor spraying closed-cell foam insulation in attic
Contractor spraying closed-cell foam insulation in attic

Roof foam insulation prices

Spray foam insulating a roof deck costs $1,500 to $9,000, depending on the foam type, roof size, and pitch. Roof insulation regulates attic temperature and improves air conditioning efficiency in attics with HVAC equipment and ductwork.

Closed-cell spray polyurethane foam (SPF) is best for roof deck applications in unvented attics.

Basement spray foam insulation cost

Spray foaming basement walls costs $1,500 to $5,600 on average, depending on the size and foam type. Open-cell and closed-cell foam provide an air seal, thermal resistance, mold resistance, and longevity.

  • Open-cell foam is best when finishing the basement walls with drywall.
  • Closed-cell foam blocks moisture, improves the walls' structural integrity, and is best when leaving the basement walls exposed.
  • Address any basement moisture problems before installing wall insulation.

Cost to spray foam insulate a garage

Insulating a garage door with spray foam costs $200 to $300, while insulating all the garage walls costs $2,600 to $8,900. Closed-cell spray foam is ideal for unfinished garage walls. Open-cell foam is better for a finished garage.

Cost to spray foam insulate a garage
Location Average cost installed
Garage door $200 – $300
Garage walls $2,600 – $8,900
Garage ceiling $1,500 – $3,000
Insulating the garage door with cellulose or rigid foam and air sealing with weatherstripping is typically more effective than spray foam.

Spray foam insulation for crawl space cost

Crawl space spray foam insulation costs $2 to $5 per square foot installed or $1,200 to $6,700 on average, depending on the area size and conditions. Combining closed-cell spray foam and rigid foam board is ideal for insulating a crawl space.

  • Closed-cell foam is recommended because it has air, moisture, and vapor barrier properties, adds strength to the walls, and provides a tight seal.
  • Open-cell spray foam is not recommended in below-grade crawl spaces because it allows moisture through.

Cost to spray foam rim joists

Spray foaming the rim joists costs $1,200 to $2,000 on average for labor and materials. Projects involving removing drywall to access the joists cost more. Insulating the rim joists with closed-cell foam reduces baseboard drafts and improves the home's structural integrity.

Consider insulating the joists with rigid foam board and using spray foam to seal the gaps and joints.

"Flash and batt" is a less expensive method that uses a thin closed-cell spray foam layer with a batt insulation layer to seal all joints and achieve the desired R-value.

Spray foam pole barn cost

Installing spray foam in a pole barn costs $3,500 to $16,500, depending on the project size, foam type, and climate zone. Closed-cell spray foam works best for pole barns because it adds structural strength and doubles as a vapor barrier.

  • Insulate the roof and walls when using the pole barn for storage or recreation.
  • Insulate only the roof if the pole barn houses livestock.

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Injection foam insulation cost

Injection foam insulation costs $2 to $10 per square foot installed. Injection foam is non-expanding, slow-rise foam used for enclosed wall cavities. Installers inject foam through holes cut in the interior drywall or exterior siding.

  • Available in closed-cell and open-cell varieties.
  • May require the wall cavity to be free of other insulation.
  • Drywall repair costs $200 to $750 and is typically included in the estimate.

Spray foam insulation price factors

The following factors can impact spray foam insulation price:

  • Insulation type – Open-cell foam is cheaper than closed-cell foam but provides less R-value per inch.
  • Project size impacts the labor and materials required.
  • New vs. existing home – Adding spray foam insulation is easiest during new construction. Existing homes require more labor to access areas and reseal the spaces created for foam injection.
  • Siding type – Contractors typically spray foam in existing exterior walls from the outside. Vinyl siding is the easiest to remove and reattach. Brick and wood siding require the most labor.
  • Labor – Contractors charge $50 to $100 per hour on average to install spray foam insulation. Labor prices are higher in major metropolitan areas with a higher cost of living.
  • Accessibility – A multi-story home requires more labor and equipment when insulating exterior walls. A tight crawl space or attic with hard-to-reach areas and a high-pitched roof may require more time to insulate.
  • Geographical location – Colder climates require thicker insulation than warm regions.
  • Vapor barrier – Open-cell foam installation may require a vapor barrier, depending on local building codes. Closed-cell spray foam doubles as a vapor barrier.
  • Removing old insulation costs $1 to $2 per square foot.
  • Minimums – Some insulation companies have a $1,200 to $2,000 or more minimum project charge.
  • Installing a roof vent costs $200 to $700 on average. Attic ventilation is necessary when spray foaming the attic floor. Installing spray foam at the roof deck does not require venting because the attic is sealed and becomes part of the conditioned home.
  • Attic cleaning costs $100 to $600 or more, depending on the condition.
  • Electricians charge $40 to $100 per hour to fix wiring damaged during the insulation process.
  • Professional mold removal costs $15 to $30 per square foot on average.
  • Asbestos removal costs $20 to $65 per square foot. Asbestos testing costs $250 to $750.
  • A pest inspection costs $40 to $150 and is recommended before adding insulation.
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Entire room at newly constructed home sprayed with foam insulation on walls and ceiling
Entire room at newly constructed home sprayed with foam insulation on walls and ceiling

Spray foam prices by thickness

Spray foam prices increase based on the foam thickness installed:

  • The recommended thickness for open-cell spray foam is 6" to 10" at the roof deck or ceiling and 3" in wall cavities.
  • Closed-cell spray foam requires 4" to 5" at the roof deck and 2" to 3" in the walls.
Spray foam prices by thickness
Foam Thickness (inches) Open-cell R-value Open-cell installed cost per SF Closed-cell R-value Closed-cell installed cost per SF
1” 3.5 – 3.7 5 – 7 $1.30 – $2.90
2” 7.0 – 7.4 10 – 14 $2.60 – $5.80
3” 10.5 – 11.1 $1.80 – $3.90 15 – 21 $3.90 – $8.70
4” 14.0 – 14.8 $2.40 – $5.20 20 – 28 $5.20 – $11.60
5” 17.5 – 18.5 $3.00 – $6.50 25 – 35 $6.50 – $14.50
6” 21.0 – 22.2 $3.60 – $7.80 30 – 42 $7.80 – $17.40
7” 24.5 – 25.9 $4.20 – $9.10 35 – 49 $9.10 – $20.30
8” 28.0 – 29.6 $4.80 – $10.40 40 – 56 $10.40 – $23.20
9” 31.5 – 33.3 $5.40 – $11.70 45 – 63 $11.70 – $26.10
10” 35.0 – 37.0 $6.00 – $13.00 50 – 70 $13.00 – $29.00

Spray foam brands

Most spray foam brands require a licensed contractor or certified technician to purchase the product. Popular spray foam brands include:

  • Demilec / Huntsman Building Solutions
  • Icynene
  • Johns Manville (JM)
  • Lapolla Industries
  • RetroFoam
  • Walltite / BASF

Spray foam cost vs. fiberglass, batt, and rockwool

Most spray foam insulation costs 2 to 3 times more per square foot than fiberglass batt insulation. Still, spray foam has a higher R-value per inch and lasts longer than other insulation types when properly installed.

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DIY spray foam insulation cost

Hiring a pro is best for large projects as spray foam involves mixing dangerous chemicals at specific ratios and temperatures. Safe, proper application requires training and skill. Many companies only sell or warranty spray foam to certified technicians.

Spray foam insulation kit prices

DIY spray foam insulation kits cost $300 to $500 to cover 200 square feet with 1" thickness. Spray foam kits work well for patching and insulating around doors and windows. Closed-cell foam kits cost more than open-cell kits.

DIY spray foam insulation kit brands include:

  • FOAM iT
  • Foam It Green
  • FomoFoam
  • Handi-Foam
  • Tiger Foam
  • Touch 'n Seal
  • Touch 'n Foam

Spray foam insulation FAQs

How long does polyurethane foam insulation last?

Most polyurethane foam insulation lasts 80 to 100 years when installed correctly. Spray foam insulation on the roof deck's underside lasts about 30 years.

Is spray foam insulation worth the cost?

Spray foam insulation is worth the cost and increases energy efficiency, adds structural integrity, air seals gaps, and may save 15% to 40% on utility and energy bills.

Spray foam insulation pros and cons
Pros Cons
  • Adds strength to walls (closed-cell)
  • Air seals gaps
  • Dampens sound
  • May increase resale value
  • Prevents pest and rodent intrusion
  • Provides a vapor and moisture barrier (closed-cell)
  • Reduces allergens in the home
  • Resists mold and mildew
  • Expensive initial cost
  • Hazardous if not applied correctly
  • Higher global warming potential (GWP) and environmental footprint
  • May contract and pull away from framing over time
  • May cause water damage if gaps are left uninsulated
  • Not DIY friendly
  • Requires temporarily vacating the space

What is the R-value of spray foam insulation?

The R-value of spray foam insulation is 3.5 to 7 per inch, depending on the type and manufacturer. R-value is the measure of a material's heat transfer resistance. Higher R-values indicate better insulation.

Spray foam insulation R-value
Type R-value per inch
Open-cell 3.5 – 3.7
Closed-cell 5 – 7

Insulation R-value recommendations
Insulation R-value recommendations

Is spray foam insulation safe?

Properly installed spray foam insulation is inert and generally safe after curing. Most spray foam is polyurethane, which contains chemicals dangerous to the skin and lungs. Installation requires protective gear. You must vacate the sprayed area for 24 hours or more until cured.

How much does spray foam expand?

Closed-cell spray foam expands to about 1" thick. Open-cell foam expands to 3" thick. Low-expansion spray foam expands 20 to 30 times its liquid size, while high-expansion foam expands 200 to 300 times its liquid size.

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Getting spray foam insulation estimates and quotes

Before hiring insulation contractors:

  • Get at least three quotes to compare.
  • Ask for a detailed quote including areas to be sprayed, estimated R-value, insulation depth or thickness, and spray foam brand and type.
  • Ask for a foam removal guarantee in the event of incorrect installation.
  • Look for certified spray foam insulation professionals.
  • Browse their reviews on HomeGuide and Google.
  • Select insured and bonded companies that have been in business for more than five years.
  • Ask for references.
  • Avoid selecting the lowest quote as quality may suffer.
  • Get a detailed estimate, contract, and warranty in writing before the work begins.
  • Never pay in full before the project starts. Use a payment plan instead for work completed.

Questions to ask spray foam installers

  • Are you licensed, bonded, and insured?
  • How long have you been in business?
  • What experience do you have with spray foam insulation?
  • Will the work be subcontracted?
  • Is spray foam the best insulation for my space?
  • Do you recommend open-cell or closed-cell insulation for my space, and why?
  • How long does it take to cure, and when can we safely re-enter the house?
  • Do you use a machine that automatically shuts off if the spray foam formula ratios are incorrect?
  • Is removing damaged or old insulation included in the quote?
  • Do you offer financing options?
  • Do you offer a whole-house discount?
  • Is there a warranty?
  • Can I be in the house during the insulation process?
  • How long will the project take?
  • How long should the insulation last?
  • Is there a warranty, and if so, what does it include?
  • What is and is not included in the price?
  • What additional costs should I expect?
  • Are there rebates available, and do you apply for them?

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