How much does spray foam insulation cost per square foot?

Budget $1.35–$2.10 per square foot for closed-cell spray foam at 2" and $0.55–$0.90 for open-cell at 3.5" in the upper Midwest, installed, with most jobs also subject to a $1,200 minimum mobilization charge.

Spray foam pricing is moving in 2024-2025 because material costs are up roughly 8-12% year over year and crews in the upper Midwest are booked 2-4 weeks out in peak season. The price a homeowner actually pays depends on three things: the assembly depth, how hard it is to access, and whether old insulation has to be removed first.

• Closed-cell, 2": $1.35–$2.10/sq ft. R-13 to R-14, acts as a Class II vapor retarder at 1.5" and above.
• Open-cell, 3.5": $0.55–$0.90/sq ft. R-13. Vapor-open, so it needs a separate vapor strategy in Climate Zone 6.
• Rim joist only: $8–$14 per linear foot, usually a 1-day job.
• Minimum charge: most crews will not mobilize for less than $1,200.
• Access adder: crawlspaces, attic knee walls and tight rim joists add 15–25% to the per-square-foot rate.
• Removal adder: pulling old batts or degraded foam adds $0.35–$0.60/sq ft and often a full day.

The trade-off is upfront cost versus performance per inch. Closed-cell costs roughly 2.2x per R-unit compared with open-cell, but it is the only choice for unvented roof decks, below-grade walls and rim joists where moisture control matters. Open-cell is cheaper and damps sound better, yet it cannot stand alone in assemblies that need a vapor retarder.

Start by measuring the square footage and noting access issues, then request an itemized quote that breaks out foam type, depth, removal and minimums so the numbers can be compared line by line.