Spray Foam Insulation Cost Calculator

The cost depends on the type of foam and thickness.

• Open Cell Foam: Costs between $0.48 and $1.08 per board foot. For a standard 2x4 wall (3.5 inches thick), this equates to roughly $1.68 - $3.78 per square foot.
• Closed Cell Foam: Costs between $1.15 and $2.80 per board foot. For a 2-inch layer on a wall, expect to pay $2.30 - $5.60 per square foot.

Note: Professional contractors often have a minimum job charge of $1,000 - $2,000.

A "Board Foot" is the industry standard unit for measuring spray foam volume. It represents a volume of 1 foot x 1 foot x 1 inch thick.

To calculate it, multiply your total square footage by the thickness in inches. For example, 1,000 sq. ft. sprayed at 2 inches thick equals 2,000 board feet. Our calculator automatically handles this conversion for you.

The main differences are density, R-value, and moisture resistance:

• Open Cell: Light and sponge-like. It's cheaper and great for soundproofing interior walls, but it is not waterproof and has a lower R-value (~R-3.7/inch).
• Closed Cell: Dense and rigid. It acts as a vapor barrier (waterproof), adds structural strength, and has a very high R-value (~R-6.5/inch). It is ideal for basements, roofs, and exterior walls.

It depends on your local climate (Climate Zone) and building code:

• Walls (2x4): Typically need 3.5" of Open Cell or 2.0" of Closed Cell to meet R-13 standards.
• Attics/Roofs: Typically need 6" to 10" of Open Cell or 4" to 6" of Closed Cell to meet R-38 to R-49 standards.

Tip: Closed cell foam provides a higher R-value per inch, making it better for shallow wall cavities.

For small projects (under 600 board feet), such as a "Rim Joist" or a small van conversion, DIY kits (like Froth-Pak) are cheaper and convenient.

However, for large projects like a whole house or attic, hiring a professional is often cheaper. Contractors buy materials in bulk at a fraction of the cost of DIY kits. Plus, professionals have better equipment to ensure the foam expands correctly and safely.

Compare the quote against the total board feet, foam type, thickness, prep work, cleanup, and minimum job charge. A high quote may be reasonable if it includes old insulation removal, difficult access, ignition barrier coating, or multiple trips.

Use the quote checker in the calculator results to compare a contractor's price against the estimated range.

Yes. According to the U.S. Department of Energy, proper air sealing and insulation can save homeowners 15% to 50% on heating and cooling costs. Spray foam is unique because it insulates and seals air leaks simultaneously, making it more effective than fiberglass batts in reducing energy loss.