Spray Foam Insulation Cost: How to Price Open-Cell and Closed-Cell Jobs

Spray foam is priced by the board foot (one square foot at one inch thick) or by the square foot at a stated thickness, and the biggest swing factors are open-cell versus closed-cell foam, the thickness needed for the target R-value, and how hard the area is to work in. Published 2026 ranges are roughly $1.50 to $3.00 per square foot for open-cell and $3.50 to $5.25 or more for closed-cell in a standard wall cavity.

Open-cell vs. closed-cell: how do prices differ?

Open-cell foam is lighter, cheaper and expands more, and it is common in interior walls and attic roof decks where a vapor barrier is not required. Closed-cell is denser, adds structural rigidity and a vapor barrier, and has a higher R-value per inch, so it costs roughly two to three times as much per board foot. It is common in crawl spaces, basements, rim joists and areas exposed to moisture.

How should you price by area?

• Exterior walls: quote by square foot at the thickness that fills the cavity or hits the code R-value.
• Attic roof deck: larger surface area than the floor plan suggests because of roof pitch — measure the deck, not the ceiling.
• Crawl space and rim joist: small areas, but access and prep drive labor, so charge by the linear foot or a flat area price.
• Retrofit vs. new construction: open studs are fast; existing walls need drilling or removal, which adds cost.

What prep and extras should be separate lines?

Masking and protection, removing old insulation, ventilation or baffles, ignition barriers or thermal barriers where code requires them, and clean-up are all real costs. Add a job minimum: mobilizing a rig for a small area can cost as much as a small job earns, so many contractors set a minimum charge.

Include a re-occupancy note. Homeowners and pets often need to stay out of the space during and after application for a period set by the product manufacturer, and a clear note prevents surprises.

How do you protect yourself on the estimate?

State the foam type, the thickness in inches, the resulting R-value, and the areas covered. Note that you are not responsible for existing conditions such as moisture, mold, knob-and-tube wiring or improperly sealed recessed lights that must be corrected before foaming.

Frequently asked questions

What is a board foot?

One square foot of foam sprayed one inch thick. A 2,000 square foot area at 3 inches is 6,000 board feet.

Is spray foam worth the extra cost over batts?

It air-seals as well as insulates, which is why many homeowners choose it for leaky attics and rim joists. Explain the trade-off honestly and let the customer choose.

Should I offer a job minimum?

Yes. Small jobs still require mobilization, setup and clean-up, and a minimum keeps them worth taking.

Price it faster and more consistently

Photograph the attic, walls and rim joist, and Fast Snap Pro helps you build an itemized quote with the area, thickness and prep spelled out.