Spray Foam Insulation Cost Calculator
Enter your area and desired thickness, pick open-cell or closed-cell foam, and get board feet plus installed cost instantly.
Last updated: June 2026
Most common application. Open-cell typical for attic floor.
Spray Foam Estimate
Price data sources: HomeAdvisor 2026 Spray Foam Cost · Angi 2026 Insulation Cost · Homewyse May 2026 Spray Foam Installation
Last verified: June 2026
Prices per board foot. 1 board foot = 1 sq ft × 1 inch thick.
How Spray Foam Pricing Works
Spray foam is priced per board foot — 1 square foot of area at 1 inch of thickness. To calculate board feet: multiply your area (sq ft) by thickness (inches). Example: 1,000 sq ft attic × 6 inches = 6,000 board feet.
The calculator does this automatically. Change the thickness or area and the board feet update instantly, along with the cost estimate.
Open-Cell vs Closed-Cell: Which to Choose?
| Type | $/board ft | R/inch | Best for |
|---|---|---|---|
| Open-Cell Spray Foam | $0.44-$0.65 | 3.6 | Cheaper |
| Closed-Cell Spray Foam | $1-$1.5 | 6.5 | Highest R-value |
Cost Breakdown
| Component | % of Total | What it covers |
|---|---|---|
| Materials (foam kits / bulk) | 55-65% | Spray foam resin + hardener, either DIY kits or bulk delivery |
| Labor (certified installer) | 30-40% | Surface prep, application, trimming, cleanup |
| Equipment & travel | 5-10% | Spray rig, hoses, PPE, ventilation setup |
How Location Affects Your Cost
| Region | Labor | Materials |
|---|---|---|
| Midwest | 1x | 1x |
| Southeast | 0.9x | 0.95x |
| Southwest | 1.05x | 1.1x |
| Northeast | 1.3x | 1.2x |
| West Coast | 1.4x | 1.25x |
To adjust: multiply the calculator's total by your region's average multiplier. Source: Remodeling Magazine 2026 Cost vs Value Report regional indexing + HomeAdvisor 2026 Regional Cost Index.
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Try JobTread FreeHow Insulation Contractors Price Jobs
The standard approach: measure area, determine required thickness for target R-value, calculate board feet, multiply by per-board-foot rate. Most contractors price at $0.50-$0.60/board ft for open-cell and $1.10-$1.30 for closed-cell (including labor).
Minimum job size: most pros have a $1,500-$2,500 minimum because spray rig setup and cleanup is fixed cost regardless of job size. Small jobs (under 1,000 board feet) cost disproportionately more per board foot.
The upsell that works: show homeowners the energy payback calculation. A $5,000 attic insulation job that saves $400/year pays back in 12.5 years — but the comfort improvement (no drafts, quieter home, consistent temperatures) is immediate. About 70% of homeowners upgrade from fiberglass to spray foam once they see the numbers.
Frequently Asked Questions
How much does spray foam insulation cost per square foot?
Spray foam costs $0.44-$1.50 per board foot (1 board foot = 1 sq ft × 1 inch thick) in 2026. Open-cell foam runs $0.44-$0.65/board ft. Closed-cell foam runs $1.00-$1.50/board ft. For a typical attic (1,000 sq ft at 6 inches thick = 6,000 board feet), open-cell costs $2,640-$3,900 and closed-cell costs $6,000-$9,000. The calculator above converts your area and thickness to board feet automatically.
What is the difference between open-cell and closed-cell spray foam?
Open-cell foam is softer, lighter, and expands more (fills gaps better). It has an R-value of ~3.6 per inch and costs about half as much as closed-cell. But it absorbs moisture, so it can't be used in damp areas. Closed-cell foam is dense, rigid, moisture-proof, and has a higher R-value (~6.5 per inch). It also adds structural strength to walls. Choose open-cell for dry indoor areas (attics, interior walls). Choose closed-cell for basements, crawlspaces, exterior walls, and anywhere moisture is a concern.
How thick should spray foam insulation be?
Recommended thickness depends on area and foam type. Attics: 6-10 inches open-cell (R-21 to R-36) or 3-5 inches closed-cell (R-19 to R-32). Exterior 2x4 walls: 3 inches closed-cell (R-19, fills the cavity). 2x6 walls: 5.5 inches open-cell (R-20) or 3 inches closed-cell (R-19). Basements/crawlspaces: 2 inches closed-cell minimum (R-13, code compliant in most areas). Going thicker than cavity depth wastes money — foam can't exceed stud depth.
Is spray foam worth the cost?
For most homes, yes — spray foam pays back in 5-10 years through energy savings. A typical $4,000-$8,000 attic insulation job saves $200-$600/year on heating/cooling (Department of Energy data). Beyond energy savings, spray foam also: (1) seals air leaks (eliminates drafts), (2) reduces outside noise, (3) blocks moisture and mold, (4) improves indoor air quality. Fiberglass and cellulose are cheaper upfront ($1-$3/sq ft) but don't air-seal and settle over time.
Can I spray foam insulation myself?
DIY spray foam kits (Froth-Pak, Tiger Foam) cost $300-$600 for 200-600 board feet — cheaper than pro install. But DIY has major drawbacks: (1) inconsistent application creates voids and weak spots; (2) improper mixing causes the foam not to cure (toxic off-gassing); (3) no warranty; (4) you must wear full PPE (respirator, suit, gloves); (5) overspray is extremely difficult to remove. For jobs over 500 board feet, professional installation is almost always cheaper and definitely better quality.
Does spray foam insulation add resale value to my home?
Yes — spray foam is one of the few insulation upgrades that appraisers recognize. A properly insulated attic with spray foam can increase home value by 3-5% in energy-conscious markets (Pacific Northwest, Northeast). The energy audit documentation (pre/post utility bills) strengthens the value proposition. Most real estate agents in 2026 list spray foam insulation as a selling feature in markets where buyers prioritize energy efficiency.
What is the R-value of spray foam insulation?
Open-cell spray foam has an R-value of approximately 3.6 per inch. Closed-cell spray foam has an R-value of approximately 6.5 per inch — nearly double. For a typical 6-inch attic application: open-cell achieves R-21.6, closed-cell achieves R-39. Building code (IRC 2024) requires R-49 for attics in most US climate zones, which means 14 inches of open-cell or 7.5 inches of closed-cell. The calculator above shows your total R-value based on selected thickness.
Real Project Example
Open-Cell Spray Foam — 1,200 sq ft Attic
Seattle, WA · 2026
Sprayed 6 in of open-cell foam on the underside of the roof deck to create an unvented, conditioned attic.
How It Went Down
Prep and masking
Covered HVAC equipment, masked can lights, sealed all penetrations from below
Open-cell expands 100x — anything not covered gets embedded. Spent 3 hr on prep vs 2 hr spraying
Spray day
Two-man crew, one spraying and one monitoring temperature and humidity
Seattle dampness meant we ran a dehumidifier 24 hr before — foam won't cure right above 70% RH
Trim and seal
Shaved foam flush at rafters, applied ignition barrier over foam per code
Open-cell requires a thermal barrier — we used intumescent paint, $200 extra but satisfies IRC R316.5
Ventilation change
Sealed all soffit and ridge vents, the attic is now inside the building envelope
HVAC ducts in the attic now sit in conditioned space — homeowner's heating bill dropped 30%
What we learned: Moving the attic inside the conditioned envelope cut HVAC load by 30%. The ducts that ran through a 130F attic in summer now sit in a 75F space. The $4,200 foam job pays back faster than any other insulation upgrade we've measured.
EstimatorSuite contractor interviews, 2026
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