Spray foam insulation costs about $1.50 to $5.00 per square foot installed, on HomeGuide’s national figures (December 2025): $1.50 to $3.50 for open cell and $3.00 to $5.00 for closed cell. By the board foot, one square foot one inch thick, HomeAdvisor (June 2026) lists $0.60 to $1.60 installed for open cell and $1.30 to $3.10 for closed cell. Those are typical national ranges, not a quote. Most of our projects run between $3,500 and $12,500. The price of a job follows how much foam goes in, counted in board feet (the area sprayed times the inches), whether it is open or closed cell, how hard the space is to work in, and what comes before and after: old insulation out, air sealing, a fire barrier over the foam.
The national guides disagree with each other. Fixr’s guide, updated January 2025, puts spray foam at $2.75 to $6.50 per square foot in new construction and $3.15 to $7.50 in existing homes. All three are national averages that vary by region, none is our price, and a square-foot figure means little until you know how many inches it buys. Depth is the catch: Fixr’s own thickness table puts the material alone for 7 inches of closed cell, about R-49, at $7 to $10.50 per square foot, before labor. In New Jersey, New York and Connecticut the energy code’s ceiling table sets the target for those inches; the state-by-state section below has each state’s R-values.
Spray foam insulation cost per square foot and per board foot
A board foot is one square foot covered one inch deep, the unit Fixr’s guide says spray foam is sold and installed by. So 400 square feet of roof deck at 3 inches is 1,200 board feet, and at 7 inches it is 2,800.
The national figures, none of them a quote for your house or our price:
- Installed, per square foot: HomeGuide (December 2025) lists open cell at $1.50 to $3.50 and closed cell at $3.00 to $5.00, and counts the treated surface area, not the floor area of the house.
- Installed, per board foot: HomeAdvisor (updated June 2026) lists open cell at $0.60 to $1.60 and closed cell at $1.30 to $3.10.
- Material only, per board foot: Fixr (January 2025) lists open cell at $0.44 to $0.65 and closed cell at $1 to $1.50.
How to estimate what your project needs
A spray foam cost calculator multiplies area, inches and a price per board foot. You can pin down the first two:
- Measure the surface, not the floor. A sloped roof deck is bigger than the attic floor under it, and gable walls add more. Basement and crawl space walls are height times perimeter.
- Set the inches from the R-value. Divide the target by R-6.9 to R-7.1 per inch for closed cell, or R-3.9 to R-4.2 for open cell.
- Multiply for board feet. Area times inches. A 1,000-square-foot roof deck at R-49 takes about 7,000 board feet of closed cell, or about 11,700 to 12,600 of open cell; gable walls are figured separately, at the wall depth.
- List what isn’t foam: the fire barrier, vapor retarder paint where required, prep, and taking the old insulation out.
What does spray foam cost for a 1,500 or 2,000 square foot house?
Floor area doesn’t say how much foam a house takes. HomeAdvisor’s guide (June 2026) says a 1,500-square-foot home usually costs $1,500 to $7,500. Fixr’s guide (January 2025) puts fully insulating an existing home at $10,000 to $30,000 and a new one at $8,000 to $25,000, and says most homeowners spend around $20,000 on open and closed cell 6 inches thick in an existing 2,000-square-foot home. HomeGuide (December 2025) puts a whole house at $8,000 to $20,000. What gets sprayed, and how deep, is the difference.
Spray foam cost by project: attic, basement, crawl space, rim joists
HomeGuide and Fixr also price spray foam by the part of the house. Their figures are typical national totals, not quotes; Fixr says its figures assume typical sizes, and neither states the depth:
- Attic: $3,000 to $8,000 (HomeGuide, December 2025); $2,500 to $12,000 in an existing house and $2,500 to $8,000 in new construction (Fixr, January 2025); Fixr notes attic foam can go on the floor, the walls or the underside of the roof deck.
- Roof deck: $2,400 to $8,000 (Fixr, which prices it as closed cell), a separate line from its attic figure.
- Basement: $2,500 to $9,000 (HomeGuide); $2,400 to $8,400 (Fixr).
- Crawl space: $2,000 to $4,000 (HomeGuide); $1,000 to $5,900 (Fixr).
- Rim joists: $2,000 to $2,500 (HomeGuide).
- Garage: $2,000 to $7,500 (HomeGuide).
- All exterior walls: $4,000 to $10,000 (HomeGuide).
The spread inside each line is size, foam type, depth, access and the extras. Here is what moves each one.
Cost to spray foam an attic
When an attic is spray foamed, the foam usually goes on the underside of the roof deck rather than the attic floor, so the area is the roof deck plus the gable walls. The roof deck’s depth follows the ceiling requirement: R-49 under New Jersey’s 2024 energy code and New York’s 2025 code, which is about 7 inches of closed cell or 11 3/4 to 12 1/2 inches of open cell, and R-60 under Connecticut’s 2021 IECC, about 8 1/2 to 8 3/4 inches of closed cell. R-60 is 22% more than R-49, so the same roof takes about 22% more closed cell in Connecticut than in New Jersey or New York. Those are the code tables’ values. The code accepts one step less, R-38 for R-49 and R-49 for R-60, installed over the whole ceiling, where the full depth carries out over the wall plates at the eaves (Section R402.2.1), and work on an existing house follows each state’s rules for alterations, so the building official has the last word. Add the ignition barrier (a thermal barrier if the attic holds storage), vapor retarder paint on open cell in zone 5, old batts out of the rafters, and the vents sealed.
The Department of Energy’s guide says enough foam for the recommended R-value under a cold-climate roof may be expensive, and that adding inexpensive fiberglass or dense-pack cellulose under closed cell foam cuts the cost; the code sets the foam minimum for that hybrid at R-15 in zone 4A and R-20 in zone 5 (IRC Table R806.5). R-20 is just under 3 inches of closed cell: a third of the foam a full R-60 roofline takes in Connecticut, about two-fifths of an R-49 one. The same guide recommends more than the minimum: 4 inches of closed cell against the deck, with the fiber under it, in zone 5, and 3 inches in zone 4. Foam plus fiber to R-60 runs roughly 11 1/2 to 16 inches deep, more than a 2x12 holds, so the rafters often need furring. The guide also calls roofline foam much more expensive than batts or blown fiber, possibly cost-effective when reroofing or creating an attic room. With no ductwork up there, blown-in on an air-sealed attic floor usually costs far less; see attic insulation.
Rim joist spray foam cost
Priced on the foundation perimeter and joist bays, and slowed by pipes, wires, ducts and finished ceilings. Closed cell up to 3 1/4 inches, about R-22 to R-23, can stay exposed if it meets the code’s density (0.5 to 2 pounds per cubic foot), flame-spread and smoke limits (R316.5.11, R303.5.11), so there is usually no drywall. A small area, and worth doing while the rig is set up for basement or crawl space work.
Crawl space spray foam cost
Priced on wall height times perimeter, plus the rim. The Department of Energy’s guide lists 3 inches of closed cell for crawl space walls. A crawl space used for storage needs a thermal barrier, not just an ignition barrier. We install the ground liner and encapsulate the space, and can talk through a dehumidifier; drainage work is a waterproofing contractor’s. See crawl space insulation.
Cost to spray foam basement walls
Priced on wall area, and the cost people miss is the thermal barrier: a basement is inside the house, so foam on its walls gets covered, typically with 1/2-inch drywall. A leaking wall needs a waterproofing contractor first. Closed cell earns its price on rough stone and block; on flat poured walls, rigid foam board with taped seams is worth pricing too, and we install both. See basement insulation.
Spray foam cost in new construction and gut renovations
Open framing is the easiest spray foam there is: nothing to remove, nothing finished to protect, and the drywall that serves as the thermal barrier goes up anyway. The price moves with framing depth, the R-value the energy code requires, and trimming, since open cell can expand past the studs and gets cut back, as the EPA notes. HomeAdvisor (June 2026) puts new construction at about $1 to $4 per square foot nationally, against about $3 to $5 in existing homes.
Spray foam cost for existing walls, and injection foam
Standard spray foam needs open cavities, so drywall or siding comes off first, which is why HomeAdvisor (June 2026) puts existing homes at about $3 to $5 per square foot, against $1 to $4 in new construction, citing the labor of opening walls. HomeGuide notes siding matters: vinyl comes off and goes back easiest, brick and wood take the most labor. Fixr’s guide says the patching and finish work is why most people insulating existing wall cavities choose blow-in insulation. We dense-pack blown-in insulation through small holes, and we install injection foam, a different product made for closed cavities; either way the insulation is our line item, and the written scope says how the holes are closed and whether paint or siding finish is in our price. See wall insulation.
Open cell vs closed cell spray foam cost
Closed cell costs more per inch. The EPA describes professional open cell as low density, half-pound foam, and closed cell as medium density, 2-pound foam: roughly four times the material, by weight, in every board foot. The Department of Energy’s Building America insulation guide puts it simply: open-cell foam costs less than closed-cell foam, but has a lower R-value per inch.
What you are buying is R-value. Two inches of closed cell, about R-13.8 to R-14.2, matches a full 3 1/2-inch 2x4 bay of open cell, about R-13.7 to R-14.7. The sources split on what that does to the price: HomeGuide’s installed figures put open cell lower, while Fixr’s guide argues that because open cell needs more inches, there is little to no difference once installed. The space usually decides:
- Deep framing, such as 2x10 and 2x12 rafters, is where open cell’s lower price per inch can count, but even a full 2x12, 11 1/4 inches deep, holds only about R-44 to R-47 of open cell, short of the 11 3/4 to 12 1/2 inches R-49 takes, so open cell to code depth usually means furring the rafters deeper.
- Shallow framing, such as 2x6 and 2x8 rafters, needs closed cell, and even closed cell runs out of room: a 2x8, 7 1/4 inches deep, just holds R-49, a 2x6 holds about R-38 to R-39, and neither holds Connecticut’s R-60 without furring the rafters or adding rigid board. Where the code’s one-step eave allowance applies (see the attic section above), each of these targets drops a step.
- Water, vapor or below grade, meaning rim joists and crawl space and basement walls: usually closed cell, whatever the price. The Department of Energy’s guide calls closed cell the best moisture control of all interior foundation insulations, though it also lists about 10 inches of open cell for crawl space walls.
One code cost falls on open cell. In climate zone 5 and colder, foam under an unvented roof must be a Class II vapor retarder or carry a Class II coating (IRC Section R806.5, in the 2021 edition Connecticut uses, the 2024 edition New Jersey adopted, and New York’s 2025 code based on it). The Department of Energy notes closed cell is a vapor retarder and open cell is not, so open cell there gets a sprayed vapor retarding paint, one more line on the quote. See open cell vs closed cell spray foam.
What drives the price of a spray foam job
- Area and depth. Board feet set the material; the R-value the code or the assembly needs sets the depth.
- Access. HomeGuide notes installation costs less in open attics and unfinished basements than in tight crawl spaces or finished walls. Low eaves, knee walls and rim joists above a finished ceiling all add hours.
- Prep. Belongings moved, surfaces masked, and the heating and cooling shut down with vents sealed; the EPA lists skipping that among the practices that affect curing.
- Old insulation and wiring. Foam goes onto clean, dry framing, sheathing or masonry, so batts in rafter bays, rim joists and crawl space walls come out first. We do that removal ourselves, bagged out under containment with a HEPA insulation vacuum, and it is its own line on our quote. As a national benchmark, not our price, HomeGuide (December 2025) puts removing existing insulation at $1.00 to $2.50 per square foot. Wet or settled insulation comes out the same way, but mold itself is work for a remediation company; vermiculite, which the EPA says to assume contains asbestos and leave undisturbed, is work for a licensed asbestos professional; and active knob-and-tube wiring, which the Department of Energy says should be replaced before insulation work begins, is work for an electrician.
- The fire barrier. The International Residential Code requires foam to be separated from the inside of the house by a thermal barrier such as 1/2-inch gypsum wallboard (Section R316.4 of the 2021 IRC, which Connecticut uses; R303.4 of the 2024 IRC, adopted in New Jersey and New York). An attic or crawl space entered only for repairs or maintenance needs only an ignition barrier, or foam tested for that use (R316.5.3 and R316.5.4; R303.5.3 and R303.5.4); one used for storage doesn’t qualify.
- Setup, travel and small jobs. The EPA explains that professional foam is pumped from drums through heated hoses at high pressure, so the rig, heating and cleanup come with every job, one rim joist or a whole roof. Small jobs cost more per square foot: HomeGuide (December 2025) says most spray foam companies have minimum job fees of $1,000 to $2,000 or more, a national figure, and distance adds travel time.
Spray foam insulation cost in New Jersey, New York and Connecticut
None of the three national guides publishes a figure for New Jersey, New York or Connecticut. HomeGuide and HomeAdvisor say local labor rates move the price; Fixr and HomeAdvisor say the amount of foam depends on where you live, and HomeAdvisor says colder regions usually call for thicker layers. Here that shows up in three places: the depth the energy code asks for, the vapor retarder rule in the colder counties, and which incentive programs pay toward insulation. The fire barrier sections read the same in all three states’ codes: R316 in Connecticut’s 2021 IRC, R303 in New Jersey’s and New York’s 2024-based editions.
New Jersey
New Jersey’s 2024 energy code asks R-49 in a ceiling, about 7 inches of closed cell at the roofline. Bergen, Hunterdon, Morris, Passaic, Somerset, Sussex and Warren counties are climate zone 5, so open cell under a roof there gets the vapor retarder paint; the rest of the state is zone 4A, where the code doesn’t require it, though the Department of Energy’s guide recommends it on open cell under a roof in zones 4 and 5. The utilities run the incentive programs. New Jersey’s Clean Energy Program says Whole Home Energy Solutions, offered by PSE&G, JCP&L, Atlantic City Electric, Rockland Electric, New Jersey Natural Gas, South Jersey Gas and Elizabethtown Gas, involves insulation and air sealing performed only by BPI-certified contractors. The program’s New Jersey measures sheet says every project must include both, and sets its own minimums: at a roof deck with no insulation now, R-60, above the code’s R-49, or a cavity filled full. PSE&G offers rebates and interest-free on-bill repayment to customers who qualify. Income-qualified households may get the insulation and air sealing a program assessment recommends at no cost, through Comfort Partners or the utilities’ Home Weatherization programs, which assign the contractor. Detail: New York and New Jersey insulation rebates.
New York: Westchester, the Hudson Valley and Long Island
New York’s 2025 energy code asks R-49 in a ceiling in every climate zone in the state. Westchester, Nassau and Suffolk are zone 4A; every Hudson Valley county beyond Westchester is zone 5 or 6, which brings the vapor retarder rule for open cell under a roof. NYSERDA’s Comfort Home program offers incentives on “seal and insulate” packages for one- to four-family homes through its participating contractors. Its July 2026 program manual requires closed cell wherever two-part spray foam is used to seal and insulate the rim joists, and says homes served by PSEG Long Island are not eligible. On Long Island, PSEG Long Island pays its own insulation rebates through participating contractors, and only with blower-door assisted air sealing. In Westchester, Con Edison says its Weather Ready program is no longer accepting applications and points customers to Comfort Home. EmPower+, NYSERDA’s program for low- and moderate-income owners and renters of one- to four-family homes, funds air sealing and insulation. Detail: New York and New Jersey insulation rebates.
Connecticut
Connecticut builds to the 2021 IECC and IRC in its 2022 State Building Code, and the whole state is zone 5: R-60 in a ceiling, about 8 1/2 to 8 3/4 inches of closed cell at the roofline, and the vapor retarder rule for open cell under a roof everywhere. Energize CT’s 2026 insulation rebate names spray foam among its acceptable materials for the areas it lists: attic floors, floored-over attics, above- and below-grade walls, basement and garage ceilings, and rim joists. A roof deck is not on that list, so price a roofline foam job without the rebate. The insulation has to be recommended during a Home Energy Solutions visit and approved before installation, and a contractor must be in the Energize CT Insulation Installers Network for the professional-installation rebate. Households below 60% of the state median income can qualify for no-cost services that may cover up to 100% of approved insulation. Detail: Connecticut insulation rebates.
Spray foam tax credits and rebates in 2026
There is no federal homeowner tax credit for insulation installed in 2026. The IRS says the Energy Efficient Home Improvement Credit, Section 25C, can be claimed for improvements made through 31 December 2025. A quote or calculator that still subtracts it is out of date. What 2025 work can still claim, and the paperwork, is in our insulation tax credit guide.
The federal Home Energy Rebates are not a general substitute. In New York, NYSERDA offers the federal HEAR rebate through EmPower+, for income-eligible households; New Jersey’s state page says its programs are under development and not yet open for applications; Connecticut’s says the rebates are not currently available. The state and utility programs above pay, with few exceptions, through their own participating or assigned contractors, and most begin with an assessment or a program visit before any work. If you are counting on one, settle it before you sign.
How to compare spray foam quotes
- Foam type, inches and R-value for every area, in writing. “Spray foam the attic” is not a scope. HomeGuide advises getting the areas, estimated R-value, depth, and foam brand and type. With area and inches you can work out board feet and compare like with like.
- Air sealing. Foam seals what it covers; ask what else gets sealed. If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
- The fire barrier. Which one each area needs and whether it is in the price. Bare foam where the code requires a barrier is not a cheaper quote but an incomplete one.
- Exclusions. Mold remediation, drywall, electrical work. Removal and vapor retarder paint are in our scope; line the rest up before comparing totals.
- Who sprays it. HomeGuide’s questions for spray foam companies include whether the work will be subcontracted. Our crew is in-house and never subcontracts.
Price is a poor tiebreaker: HomeGuide lists spray foam as difficult and expensive to remove.
When spray foam is worth the cost
ENERGY STAR says sealing air leaks and adding insulation can provide up to a 10% savings on your annual energy bills. That covers sealing and insulating generally, not spray foam in particular.
The Department of Energy’s Building America guide sets the test. If your insulation is already adequate, adding more may not save enough to recoup the cost; if the house is poorly insulated or the bills are high, added insulation is likely to pay for itself over time. Its yardstick is simple payback: the cost of the work divided by the estimated annual savings, in years.
The same guide rates open and closed cell spray foam at four dollar signs for relative cost, against one for fiberglass batts and cellulose. So foam pays best where its air seal does what cheaper insulation can’t: rim joists, crawl space and basement walls, a roofline over attic ductwork, and the wall between garage and house, which the guide names as a place a perfect air barrier is needed.
Spray foam vs fiberglass, cellulose and rigid board cost
Installed per square foot, HomeGuide’s spray foam guide (December 2025) lists $1.50 to $5.00 for spray foam, $1.00 to $2.60 for fiberglass batts, $1.00 to $2.80 for blown-in and $1.20 to $3.70 for rigid foam board, thickness again unstated. The Department of Energy calls loose-fill fiber and fiberglass batts the least expensive types of insulation.
Those numbers leave out air sealing: fiberglass and cellulose slow heat but let air through, so sealing is a separate step, while foam seals where it goes. On an open attic floor, blown-in still wins. In Connecticut, where the code calls for R-60, open cell under the roof would need 14 1/4 to 15 1/2 inches; blown cellulose on a sealed attic floor gets there for far less. See types of insulation, and for what every other kind of insulation costs, room by room, insulation cost.
DIY spray foam kits
The EPA sorts spray foam three ways. Two-component high-pressure foam is a professional system that should only be used by a trained applicator. Two-component low-pressure kits and one-component cans are available to do-it-yourselfers, and professionals use them largely for air sealing and filling holes and gaps; the cans are for gaps of about half an inch to 3 inches.
The EPA says homeowners using them should learn the precautions professionals use, notes do-it-yourselfers are often unaware of the inhalation and skin hazards, lists asthma, sensitization and lung damage among the effects of exposure, and asks homeowners to consider having a trained professional install the product. A kit used as insulation still needs the code’s thermal or ignition barrier. A can around pipes and wires is a homeowner job; a kit on a roof deck or basement wall is not. More in is spray foam safe.
Common questions about spray foam insulation cost
How much does spray foam insulation cost?
HomeGuide (December 2025) puts it at $1.50 to $5.00 per square foot installed, a national average that varies by region and thickness. Most of our projects run between $3,500 and $12,500. The price follows the board feet of foam, open or closed cell, access, prep and the fire barrier.
How much does spray foam insulation cost per square foot?
It depends on the source and the thickness. HomeGuide (December 2025) lists $1.50 to $3.50 installed for open cell and $3.00 to $5.00 for closed cell; Fixr (January 2025) lists $2.75 to $6.50 in new construction and $3.15 to $7.50 in existing homes. Both are national averages, not our prices.
How much does closed cell spray foam cost per board foot?
HomeAdvisor (June 2026) lists $1.30 to $3.10 per board foot installed for closed cell and $0.60 to $1.60 for open cell. Fixr (January 2025) lists the material alone at $1 to $1.50 for closed cell and $0.44 to $0.65 for open cell. A board foot is one square foot, one inch thick.
Is open cell or closed cell spray foam cheaper?
Open cell; the Department of Energy’s guide says it costs less but has a lower R-value per inch. For equal R-value the gap narrows, since 2 inches of closed cell matches about 3 1/2 inches of open cell. Where depth is short or moisture is a risk, closed cell is the one that works.
How much does it cost to spray foam an attic?
National guides put it at $3,000 to $8,000 (HomeGuide, December 2025) or $2,500 to $12,000 in an existing house (Fixr, January 2025). Most of our projects run between $3,500 and $12,500, a range that covers every kind of job, not attics alone. A roofline is priced on the roof deck and gable area and the depth to code: for R-49, about 7 inches of closed cell or 11 3/4 to 12 1/2 inches of open cell. The ignition barrier, and taking the old batts out, add to the total.
Does spray foam cost more in Connecticut?
The national guides publish no state prices, but Connecticut’s code asks R-60 in a ceiling against R-49 in New Jersey and New York, so a roofline takes about 22% more closed cell: 8 1/2 to 8 3/4 inches instead of about 7. The whole state is zone 5, so open cell under a roof also needs vapor retarder paint. The rest follows the job: access, prep, the fire barrier and local labor rates.
Is there a tax credit for spray foam insulation in 2026?
No. The IRS says the federal 25C Energy Efficient Home Improvement Credit covers improvements made through 31 December 2025, so insulation installed in 2026 does not qualify. State and utility programs in New Jersey, New York and Connecticut still pay toward insulation, mostly through their own participating or assigned contractors and usually after an assessment.
Why does spray foam insulation cost so much?
It is made on site from two chemical components, pumped through heated hoses at high pressure by a trained applicator, and every job carries setup, prep, masking and cleanup. The Department of Energy rates it at the top of its relative cost scale; what the price buys is insulation and an air seal in one step.
Is spray foam insulation worth the cost?
Where its air seal matters: rim joists, crawl space and basement walls, a roofline over attic ductwork. ENERGY STAR says sealing and insulating can save up to 10% on annual energy bills; the Department of Energy notes more insulation in an adequately insulated house may not recoup its cost.
Can I save money with a DIY spray foam kit?
For small gaps, a can of one-component foam is a homeowner job. For insulating, the EPA says high-pressure two-component foam should only be used by a trained applicator, and kit users need the same precautions as professionals. A kit used as insulation still needs the code’s thermal or ignition barrier.
Spray foam quotes in New Jersey, Connecticut, the Hudson Valley and Long Island
We price spray foam after we have been in the space: the area and depth of each part, what is in the rafters or rim bays now, access, water, wiring, how the attic or crawl space is used, and whether foam is the right material at all. You get a written scope with the foam, the inches and the fire barrier for each area. Our estimate is free. It is our own, not a utility or state program’s assessment, so if you are counting on a rebate, book the program’s visit first.
Call 914-554-2289 or use the contact form, 8am–8pm, seven days. The Home Insulators is family-owned, based in New Rochelle, NY since 2015, with a 100-plus-person in-house crew that never subcontracts. We work across all of New Jersey, all of Connecticut, New York’s Hudson Valley and Long Island; see our service area.