Spray foam calculators.
Installed cost and R-value for homeowners, ENERGY STAR savings and payback for your climate, and a board-foot, set and bid calculator for applicators.
Installed prices from this site’s 2026 cost guide (open ≈ $1.00–$1.50, closed ≈ $1.50–$3.50 per sq ft, at typical thicknesses). R-values use ≈R-3.7/in open and ≈R-6.9/in closed — check your product’s data sheet. Code-approved foam assemblies can differ from the ENERGY STAR table.
Savings use ENERGY STAR’s modeled average for air sealing plus insulating attics, floors over crawl spaces and rim joists in your climate zone (methodology). Costs use this site’s 2026 installed-price ranges. Your home will differ.
Default yields are typical starting points (open cell ≈ 16,000 BF/set, closed cell ≈ 4,500 BF/set). Real yield swings with product, temperature, substrate and technique — use your own numbers. Margin is calculated on the final price.
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Before you trust a number.
Calculators get you in the right neighborhood. A site visit gets you the address.
How much does spray foam insulation cost?
Most homeowners pay roughly $1.00 to $3.50 per square foot installed. Open cell usually lands around $1.00 to $1.50 and closed cell around $1.50 to $3.50, depending on thickness, access and your local labor rates. A small attic can be a couple thousand dollars; a whole-home retrofit with closed cell can run well past $10,000. Our cost calculator gives you a ballpark in seconds.
Open cell or closed cell — which one do I need?
Open cell is lighter, more affordable and great for sound, typically about R-3.5 to R-3.8 per inch. Closed cell is denser, roughly R-6 to R-7 per inch, adds rigidity and works as a vapor retarder at about 1.5 to 2 inches — which is why it is the usual pick for crawl spaces, rim joists, basements and metal buildings. Many homes use both.
How much can spray foam lower my energy bills?
ENERGY STAR estimates homeowners save an average of 15% on heating and cooling costs (about 11% of total energy costs) by air sealing and adding insulation in attics, floors over crawl spaces and accessible basement rim joists. Spray foam insulates and air-seals in one step. Results vary by home, climate and how leaky the house is today.
Is spray foam safe for my family?
Once fully cured, spray foam is an inert plastic. During spraying the chemicals are reactive, so occupants should stay out of the home while it is installed and for the re-entry period the manufacturer specifies — commonly around 24 hours. A good installer will tell you the product, the re-occupancy time and how they ventilate the space.
Can spray foam go over my existing insulation?
Usually not. Foam needs to bond directly to the framing, sheathing or roof deck to air-seal properly, so old batts or loose fill in the spray area are typically removed first. Your installer will look at what is there and quote any removal separately.
How long does a spray foam job take?
Many attics, crawl spaces and rim-joist jobs are finished in a single day. Whole-home projects often take one to three days depending on size, access and how much prep is needed.
How do I get quotes through Spray Foam Forum?
Answer a few quick questions on our free quote form. It takes about a minute, there is no obligation, and a spray foam specialist follows up to talk through your options.
I want to start spraying foam. Where do I begin?
Start with the equipment, training, chemistry supply, insurance and a plan for getting your first jobs. Our startup planner walks you through each piece and connects you with people who build rigs and train new applicators every day.
