Spray Foam Insulation Cost: $1,400 to $4,300 (2026 Average: $2,800)
Author: CostGuideHQ Editorial·✓ Fact-checked·Updated July 2026·5 min read·4 sources Quick answerQuick answer: Spray foam insulation costs $1,400 to $4,300 for most home projects, averaging about $2,800 nationally. Per square foot, expect roughly $1-$4 installed for open-cell foam and $1-$5 for closed-cell, with foam type, thickness, and job location driving the biggest swings.
- ✓The national average for a spray foam insulation project is about $2,800, with typical jobs ranging $1,400-$4,300 (HomeAdvisor, Bob Vila).
- ✓Open-cell foam installs for roughly $1-$4 per square foot, while denser closed-cell foam runs about $1-$5 per square foot (HomeAdvisor).
- ✓Retrofitting an existing home costs more than new construction - $3.15-$7.50 per sq ft versus $2.75-$6.50 per sq ft - due to extra access and prep labor (Fixr).
- ✓A typical attic job runs roughly $1,500-$9,000 while a crawl space runs $1,000-$6,900, depending on size and foam type (Bob Vila, HomeAdvisor).
How much does spray foam insulation cost?
National average
$2,800
total project
Typical range
$1,400–$4,300
Most projects
Whole project
$1,400–$4,300
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Cost by material / type
| Type | Low | High |
|---|
| open-cell spray foam (per sq ft installed) | $1 | $4 |
| closed-cell spray foam (per sq ft installed) | $1 | $5 |
What affects the cost?
- Foam type: open-cell installs for about $1-$4 per sq ft, closed-cell (denser, higher R-value per inch) runs about $1-$5 per sq ft (HomeAdvisor)
- Thickness/R-value target: per-sq-ft pricing roughly doubles going from 1 inch to 3 inches of coverage (This Old House, HomeAdvisor)
- Project location: attic, crawl space, basement, and garage jobs each carry different typical price bands (Fixr, HomeAdvisor, Bob Vila)
- New construction vs. existing-home retrofit: existing walls cost more due to extra access and prep labor - $2.75-$6.50/sq ft new vs. $3.15-$7.50/sq ft existing (Fixr)
- Labor rate: professional installation runs about $0.44-$4.90 per sq ft, or $50-$100 per hour in some markets (Fixr, Bob Vila, HomeAdvisor)
- Add-on work: old insulation removal, mold remediation ($1,125-$3,345), and drywall repair ($300-$920) can add to the total (Bob Vila, HomeAdvisor)
- Total job size: whole-house or large roof-deck projects scale well past a typical single-area job (Fixr)
Why does spray foam insulation cost more than other insulation types?
Spray foam costs more than fiberglass or blown-in insulation because it’s applied wet, expands on contact, and cures into an air-sealing layer in a single step - material, equipment, and skilled labor are all priced into the job. Nationally, a typical project runs $1,400 to $4,300, averaging around $2,800 (HomeAdvisor, Bob Vila). Per square foot, installed pricing generally lands between $1 and $5 depending on foam type, with material-only costs (measured per board foot, a unit equal to one square foot at one inch thick) running $0.44-$0.65 for open-cell and $1.00-$1.50 for closed-cell foam (Fixr, Bob Vila).
The premium comes largely from labor: professional installers charge roughly $0.44 to $4.90 per square foot, or $50-$100 per hour in some markets, because the equipment and mixing process require training and the foam has to be applied correctly the first time (Fixr, Bob Vila, HomeAdvisor). Retrofitting an existing home also costs more than insulating during new construction, since existing walls need extra prep and access work (Fixr).
What affects the cost of spray foam insulation?
Foam type is the first major variable. Open-cell foam installs for about $1-$4 per square foot, while closed-cell foam - denser and delivering a higher R-value per inch - runs closer to $1-$5 per square foot (HomeAdvisor). Thickness compounds that: per-square-foot pricing roughly doubles going from 1 inch to 3 inches of coverage, since more material and labor time are needed to hit a given R-value target (This Old House, HomeAdvisor).
Where the foam goes matters too. Attic jobs, crawl spaces, basement walls, and garages each carry their own typical price bands, and whole-house or roof-deck projects scale well past a single-area job (Fixr, HomeAdvisor, Bob Vila). New construction is generally cheaper than an existing-home retrofit, since retrofits require cutting into finished walls or working around existing framing (Fixr). Finally, add-on work - removing old insulation, mold remediation ($1,125-$3,345), or drywall repair ($300-$920) - can push a project above the base estimate (Bob Vila, HomeAdvisor).
How to lower your spray foam insulation cost
- Match the foam type to the job. Open-cell foam is cheaper per board foot and fine for interior walls and sound-dampening; save pricier closed-cell foam for areas that need higher R-value per inch or moisture resistance, like rim joists or exterior applications (Fixr, Bob Vila).
- Only insulate to the R-value you need. Since cost scales with thickness, get a professional to confirm the R-value target for your climate zone rather than over-specifying depth.
- Bundle areas into one visit. Contractors often have minimum job costs, so combining an attic, crawl space, and rim joist job into a single appointment spreads the equipment setup and travel cost across more square footage.
- Handle prep work yourself where safe to do so. Clearing an attic or crawl space of stored items before the crew arrives can shave labor hours off the bill.
- Get multiple quotes. With installed pricing spanning roughly $1-$7.50 per square foot across sources depending on foam type and whether it’s new construction or a retrofit, local quotes can vary significantly - compare at least two or three before committing (Fixr, This Old House, HomeAdvisor).
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Frequently asked questions
How much does spray foam insulation cost on average?+
Most homeowners pay $1,400 to $4,300 for a spray foam insulation project, with a national average around $2,800 (HomeAdvisor, Bob Vila). Larger whole-house or roof-deck jobs covering more square footage can run well beyond that range.
How much does spray foam insulation cost per square foot?+
Installed spray foam typically runs $1 to $4 per square foot for open-cell foam and $1 to $5 per square foot for closed-cell foam. Thin, 1-inch applications can price as low as $0.44 per sq ft, while thicker coverage on existing walls can reach $7.50 per sq ft (HomeAdvisor, This Old House, Fixr).
Is open-cell or closed-cell spray foam cheaper?+
Open-cell foam material costs less per board foot ($0.44-$0.65) than closed-cell foam ($1.00-$1.50), but closed-cell needs less thickness to reach the same R-value, so installed per-square-foot pricing ends up closer than the raw material cost suggests (Fixr, Bob Vila).
Does spray foam cost more in a new build or an existing home?+
Yes. Fixr reports $2.75-$6.50 per sq ft for new construction versus $3.15-$7.50 per sq ft for existing homes, since retrofits require extra labor to access and prep walls that new builds don't.
How much does it cost to spray foam an attic?+
Attic spray foam jobs range from roughly $1,500 to $9,000 depending on the source and attic size, with typical single-attic projects landing in the $2,500-$4,450 range (Bob Vila, HomeAdvisor, Fixr).
What drives spray foam insulation pricing up or down?+
The biggest factors are foam type (open-cell vs. closed-cell), thickness/R-value target, project location (attic, crawl space, walls, whole house), labor rates, and whether it's new construction or a retrofit that needs extra prep work (Fixr, HomeAdvisor, Bob Vila, This Old House).
Sources
Figures synthesized and cross-checked across these sources (retrieved 2026-07-24):
- Fixr — National average $20,000; average range $10,000-$30,000 (full range $7,000-$40,000). Installed cost: new construction $2.75-$6.50/sq ft, existing walls $3.15-$7.50/sq ft. Material only per board foot: open cell $0.44-$0.65, closed cell $1.00-$1.50. By project location: crawl space $1,000-$5,900; basement $2,400-$8,400; attic $2,500-$12,000; garage $3,600-$8,600 (new) / $4,000-$8,600 (existing); entire house $8,000-$25,000 (new) / $10,000-$30,000 (existing). Labor $50-$100/hour; for a 2,000 sq ft home labor is $1,200-$4,800 of the $20,000 total.
- This Old House — Overall range $1-$4.50 per sq ft; average $1.25-$1.50 per sq ft. Closed-cell $1.25-$1.50/sq ft; open-cell closer to $1.50/sq ft. By thickness: 1 inch open-cell $0.44-$1.50, closed-cell $1.25-$2.90; 2 inches open-cell $0.88-$3.00, closed-cell $2.50-$5.80; 3 inches open-cell $1.30-$4.50, closed-cell $3.75-$8.70. Labor $0.44-$1.55 per sq ft. 1,500 sq ft home: new construction $4,125-$9,750, existing home $4,725-$11,250. Attic (avg. $4,450) $1,500-$7,400; basement (avg. $3,550) $1,500-$5,600; garage (avg. $4,500) $2,500-$6,500; HVAC (avg. $2,150) $1,000-$3,300.
- Bob Vila — National average $2,756; cost range $1,409-$4,145. Material only per board foot: open-cell $0.44-$0.65, closed-cell $1.00-$1.50. Labor $1.50-$4.90 per sq ft. By project: 100 sq ft $44-$150; 2,000 sq ft $880-$3,000; garage $930-$2,100; attic $1,500-$3,500; basement interior walls $500-$3,000; crawl space $1,000-$5,900; 30x50 ft metal building $1,600-$2,400. Mold remediation $1,125-$3,345; drywall removal $293-$875; drywall repair $300-$920.
- HomeAdvisor — Average cost $2,889; normal range $1,455-$4,338 (smaller jobs near $670, whole-house projects up to $8,000). By thickness per sq ft: 1 inch $0.44-$1.50; 2 inches $0.88-$3.00; 3 inches $1.32-$4.50; 4 inches $1.76-$6.00. By foam type installed per board foot: open-cell $0.60-$1.60, closed-cell $1.30-$3.10; per sq ft installed: open-cell $0.88-$3.85, closed-cell $1.44-$4.70. Labor $0.44-$3.30 per sq ft. By location: attic $1,100-$9,000; basement walls $1,500-$6,200; crawl space $1,200-$6,900; roof $1,500-$7,000; rim joists $2,000-$2,300; garage $1,500-$9,400; pole barn/detached building $8,000-$30,000. New construction $1-$4/sq ft; existing homes $3-$5/sq ft. 1,500 sq ft house: $1,500-$7,500.
The $2,800 national average and $1,400-$4,300 range are CostGuideHQ synthesized figures, not a verbatim quote from a single source: they reflect whole-project figures from Bob Vila (national average $2,756, range $1,409-$4,145) and HomeAdvisor (average $2,889, normal range $1,455-$4,338), which closely agree; these average to about $2,800 with a combined typical range of roughly $1,400-$4,300. Fixr's headline figure ($20,000 average, $10,000-$30,000 typical range) reflects larger whole-house/roof-deck scope rather than a single-room job and is not used in the main average, but its per-sq-ft and per-area figures are consistent with the other sources and are cited in cost_factors and sources below. Per-square-foot pricing is reported inconsistently across sources: some quote installed cost per square foot ($1-$7.50 depending on foam type, thickness, and new vs. existing construction), others quote material-only cost per board foot (a foam-industry unit equal to 1 sq ft at 1 inch thick: roughly $0.44-$0.65/board ft for open-cell, $1.00-$1.50/board ft for closed-cell material). The by_type figures above use installed per-sq-ft numbers from HomeAdvisor to avoid mixing units. Figures generally include material and standard installation labor; removal of old insulation, mold remediation, and drywall repair are typically quoted as separate add-ons.