INTERIOR
Spray Foam Insulation Cost: Per Square Foot in 2026
Estimate spray foam insulation cost per square foot — with the free insulation calculator.
Spray foam is the best-performing insulation on the market — and the most expensive per square foot. Whether it's worth it depends on your climate and project. Here's the real 2026 cost.
THE SHORT ANSWER
The short answer
Spray foam runs $1–$4.50 per sq ft installed in 2026 (closed-cell $2.50–$8). A 1,000 sq ft attic runs $1,800–$4,500. DIY kits run $0.75–$2 per sq ft. Open-cell is cheaper; closed-cell is stronger and pricier.
Open-cell vs closed-cell
Open-cell foam runs $1–$3 per sq ft — softer, cheaper, good for interior walls. Closed-cell runs $2.50–$8 per sq ft — denser, waterproof, structural, and doubles as a vapor barrier. Attics and basements use closed-cell; walls can use either.
- Open-cell: $1–$3 per sq ft
- Closed-cell: $2.50–$8 per sq ft
- 1,000 sq ft attic: $1,800–$4,500
- DIY kits: $0.75–$2 per sq ft
Spray foam vs batts
Batts cost $0.30–$0.75 per sq ft — a third of the price. But spray foam seals air leaks, doubles R-value per inch and never settles. Payback is 2-4 years in heating and cooling savings in most climates.
Try the insulation calculator
Enter the area and material cost per sq ft to estimate the project.