Insulation & energy estimator · Updated June 2026
Spray Foam Insulation Cost Calculator
Spray foam insulation typically costs $1,500 to $6,000 per project, averaging around $3,500. Pricing runs $1 to $4.50 per square foot depending on open-cell or closed-cell foam and thickness. Use our free calculator to get an instant estimate using the same board-foot method contractors use to quote real jobs.
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Enter the total wall, ceiling or floor area to be sprayed to calculate your instant cost estimate.
- Most spray foam projects cost $1,500–$6,000, averaging around $3,500
- Closed-cell foam costs roughly double open-cell per board foot
- Spray foam is priced by the "board foot" — area × thickness in inches
- Contractors typically have a $1,500–$2,000 minimum job charge
What affects spray foam insulation cost?
- Foam type — Closed-cell costs roughly double open-cell per board foot but offers a much higher R-value per inch.
- Thickness — Spray foam is priced by the board foot (area × thickness), so every added inch increases material cost directly.
- Application area — Open attics are cheaper to spray than existing walls, which require drilling and injection.
- Removal & prep — Removing old fiberglass or cellulose insulation adds labor and disposal cost.
- Code requirements — Ignition or thermal barrier coatings are often required in living spaces by local building code.
- State — Labor costs in California and the Northeast run 25–30% higher than Midwest and Southern states.
How much does spray foam insulation cost in 2026?
Spray foam insulation typically costs $1,500 to $6,000 per project, averaging around $3,500. On a per-square-foot basis, pricing runs $1 to $4.50 depending on foam type and thickness. Open-cell foam costs $0.40 to $0.75 per board foot, while closed-cell costs $1.00 to $1.65 per board foot. Use our free calculator above for an instant estimate using the same board-foot method professional installers use.
Spray foam insulation cost calculator — by project size
| Project size | Typical cost |
|---|---|
| Small (500 sq ft) | $1,500–$2,500 |
| Medium (1,200 sq ft) | $2,500–$4,000 |
| Large (2,500 sq ft) | $4,500–$6,000 |
Open-cell vs. closed-cell spray foam insulation cost
The choice between open-cell and closed-cell foam is the single biggest cost driver after project size. Closed-cell costs nearly double, but delivers a much higher R-value per inch and doubles as a moisture barrier.
| Foam type | Cost per board foot | R-value per inch | Best for |
|---|---|---|---|
| Open-cell | $0.40–$0.75 | R-3.5–3.8 | Interior walls, attics, soundproofing |
| Closed-cell | $1.00–$1.65 | R-5.6–7.0 | Roof decks, basements, exterior walls, moisture-prone areas |
Closed-cell spray foam insulation cost
Closed-cell spray foam costs $3.00 to $5.00 per square foot installed at standard wall thickness, roughly double the cost of open-cell for the same coverage. It's denser, rigid, and moisture-resistant, making it the standard choice for basements, crawl spaces, metal buildings, and roof decks where water resistance and structural rigidity matter. Because it delivers R-6 to R-7 per inch — nearly double open-cell — closed-cell foam often needs less thickness to hit the same R-value target, which can partially offset its higher per-board-foot price.
How spray foam is priced: the board foot explained
Unlike most insulation, spray foam isn't priced by square footage alone — it's priced by the board foot, a volume measurement equal to 1 square foot sprayed 1 inch thick. To calculate board feet, multiply your square footage by the thickness in inches: a 1,000 sq ft attic sprayed 6 inches thick equals 6,000 board feet. This matters because two quotes for the "same square footage" can differ enormously if one contractor is spraying 2 inches and another is spraying 6 — always confirm the thickness (and target R-value) behind any quote, not just the square footage.
Spray foam vs. fiberglass vs. blown-in insulation
| Insulation type | Cost per sq ft | Air sealing |
|---|---|---|
| Fiberglass batts | $0.30–$1.50 | Poor — leaves gaps |
| Blown-in | $1.00–$2.80 | Fair — fills cavities, no seal |
| Spray foam (open-cell) | $1.00–$2.60 | Excellent — full air seal |
| Spray foam (closed-cell) | $3.00–$5.00 | Excellent — air seal + moisture barrier |
Frequently asked questions
How do I estimate spray foam insulation cost?
Measure the total square footage to be sprayed, decide on open-cell or closed-cell foam, and determine your target thickness (which depends on your desired R-value). Multiply square footage by thickness in inches to get board feet, then multiply by the per-board-foot rate for your foam type. Our calculator does this automatically.
What is the cost of spray foam insulation per square foot?
Spray foam insulation costs $1.00 to $4.50 per square foot on average, with open-cell foam at the lower end ($1.00–$2.60) and closed-cell foam at the higher end ($3.00–$5.00) for a standard 3.5-inch wall cavity.
How accurate is this spray foam insulation cost calculator?
Our estimates are typically within 15–25% of contractor quotes for standard residential projects. Actual pricing depends on access difficulty, whether old insulation needs removal, and local code requirements for ignition barriers. Always get 3+ quotes from certified spray foam installers.
Is spray foam insulation worth the cost?
For most homeowners, yes. Spray foam can reduce heating and cooling costs by 30–50% compared to minimal or degraded insulation, often paying for itself within 3–5 years through energy savings, while also improving comfort and moisture control.
How thick does spray foam insulation need to be?
Thickness depends on your target R-value: reaching R-38 in an attic requires about 10 inches of open-cell foam or about 5.5 inches of closed-cell foam, since closed-cell delivers roughly double the R-value per inch.
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Disclaimer: All spray foam insulation cost estimates are for informational purposes only based on average 2026 US contractor rates. Actual costs vary based on access difficulty, existing insulation removal needs, local building codes and contractor availability. Always obtain multiple quotes from certified spray foam insulation contractors before proceeding with any project.