Open-cell vs. closed-cell: the biggest cost driver
Spray foam comes in two main types, and material choice is usually the biggest factor in your final number.
Open-cell spray foam
Softer, lighter, lower density. Great for interior walls, attics, and sound-dampening. Typically $0.45–$0.75 per board foot.
Closed-cell spray foam
Dense, rigid, higher R-value per inch, and acts as a moisture barrier. Ideal for rim joists, basements, pole barns, and metal buildings. Typically $1.00–$2.00 per board foot.
A "board foot" is one square foot at one inch thick. Most homes use a mix of both products depending on where the foam is going.
Project size and square footage
Larger jobs spread the cost of mobilization, setup, and crew time across more area, so the per-square-foot price often drops on bigger projects. Small jobs (a single rim joist, a bonus room over a garage) carry a minimum because the truck, rig, and crew still have to show up.
- Attic (1,500 sq ft, blown-in or hybrid): typically $1,500–$4,500
- Rim joist & basement band board: typically $600–$1,800
- Pole barn (1,200 sq ft, closed-cell): typically $4,500–$9,000
- Whole-home new construction package: highly project-specific — request a quote
Ranges are general national estimates. Real pricing requires an on-site inspection to measure cavity depth, accessibility, and prep work.
Labor, access, and prep
Labor is the other major piece. Tight crawlspaces, vaulted ceilings, two-story walls, and retrofits all take longer per square foot than open new-construction cavities. Removing old insulation, masking finished surfaces, and protecting flooring also add cost — but skipping prep almost always costs more later.
What lowers your overall cost
- Bundle areas during one mobilization (attic + rim joist together).
- Use closed-cell only where you need its strength and R-value; pair with blown-in fiberglass elsewhere.
- Insulate during the framing stage of new construction — no demo, faster install.
- Get a real quote instead of a phone estimate, so you don't overpay for guess-work.
Why an inspection is the only real number
No reputable spray foam contractor can give you an exact price over the phone. Two homes with identical square footage can quote thousands apart based on cavity depth, framing, existing insulation, and access. Use the ranges above for budgeting, then schedule a quote so we can measure and recommend the right system for your project.