Costs & R-Value
Spray Foam Insulation Cost
Spray foam is priced per board foot — one square foot at one inch thick. Knowing that unit makes every quote comparable.
Updated January 2026 · about 7 min read
Price per board foot (2026)
Open-cell installed: $0.45–$0.75 per board foot. Closed-cell installed: $1.00–$1.75. DIY two-part kits: $0.85–$1.40 per board foot before waste, and real-world yield usually comes in 10–20% under the printed figure.
Typical job totals
Rim joists in an average basement (2 inches closed-cell, ~200 board feet): $350–$700. Crawl space walls (1,000 board feet): $1,100–$1,900. Unvented attic roof deck on a 1,500 sq ft footprint with open-cell at 5.5 inches: $4,500–$8,500. Whole new-construction house: $9,000–$22,000.
Gear for this job
Great Stuff Gaps and Cracks Insulating Foam Sealant,12 Ounce - Case of 12
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BEEST FullStop Spray Foam Insulation Kit - 240 Board ft/sq.ft. Fire Rated Spray Insulation Foam for Walls & Attics with Thermal & Soundproofing - Includes 12x Cans, 1 Cleaner, Pro X Gun, Safety Gear
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BEEST FullStop Fire-Rated Spray Foam Insulation for Walls & Attics - 240 Board ft/sq.ft - High Density Expanding Spray Insulation Foam Sealant for Thermal & Soundproofing - 12 Pack (12x26.8 oz)
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Magic Chems Spray Foam Insulation, Expanding Sealant, 2 Pack-25.4 oz | Closed Cell; High Density; Covers up to 40 sq ft; Cans Only, No Gun Included
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DIY kit math
Kits are sold by advertised board feet (200, 600, 1,000). Calculate area × inches, add 15–20% for overspray and yield loss, and buy the next size up. Temperature matters: below 60°F substrate temperature, yield and adhesion both fall off.
Getting a fair quote
Ask for board feet and installed thickness in writing, not just 'spray the attic'. Confirm the product name and data sheet, the ignition barrier plan, and the re-entry period. Compare bids on board feet, because thickness is where quotes quietly differ.
Run the numbers
Frequently asked questions
- How much does spray foam cost per square foot?
- At 2 inches, closed-cell runs about $1.75–$3.50 per square foot installed, and open-cell about $1.20–$2.20 at 3.5 inches.
- Are DIY spray foam kits cheaper?
- For small areas like rim joists, yes. For large jobs the per-board-foot cost of kits approaches professional pricing without the equipment control.
- Why do spray foam quotes vary so much?
- Different installed thicknesses. Always compare board feet at a stated inch depth, not lump sums.
Insulation gear worth owning
The tools and materials that show up on almost every insulation job.
BEEST FullStop Spray Foam Insulation Kit - 240 Board ft/sq.ft. Fire Rated Spray Insulation Foam for Walls & Attics with Thermal & Soundproofing - Includes 12x Cans, 1 Cleaner, Pro X Gun, Safety Gear
Check price on Amazon
Great Stuff Gaps and Cracks Insulating Foam Sealant,12 Ounce - Case of 12
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Respirator Mask with Filters set - Reusable Respirator Mask for Chemicals, Painting, Spraying, Epoxy Resin, Dust, DIY etc
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Andes Hazmat Suit, Disposable Paint Suit, Lab Coverall
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