Spray Foam Insulation Cost Calculator & Price Guide

Spray foam goes on as a liquid and expands into a solid layer that fills gaps and seals air leaks. That is why it costs more than batts or blown-in insulation: you pay for a material that insulates and air-seals in one pass. The price depends on whether you choose open-cell or closed-cell foam, how thick the layer is, and how much area you need to cover.

The numbers below come from published guides with a check date of Oct 11, 2026. They are priced per square foot, by location, and by total area, so you can build your own estimate.

Closed-cell foam is denser, so it provides more insulating value per inch and adds rigidity. It also costs more per square foot at the same thickness.

Open-cell foam is softer and lighter and expands more. It costs less and works well for interior walls and attic roof decks where you want air sealing and sound dampening. It is not designed to resist moisture on its own.

Closed-cell foam is rigid and resists moisture better, so installers often use it in basements, crawl spaces, and below-grade or exposed areas. It costs more and uses more material for the same R-value in some applications. Ask which type your contractor recommends for each area, and why.

You can estimate a total yourself with three steps:

1. Measure the square footage of the surface you want to insulate (attic floor or roof deck, wall area, or basement walls).
2. Choose a foam type and thickness, then find the matching per-square-foot range in the tables above.
3. Multiply the area by the low and high ends of the range.

For example, the thickness you need depends on your climate and the R-value your local energy code requires. A contractor can tell you the target for your area. Treat the result as a ballpark, since accessible flat surfaces cost less than irregular framing, and the quote may add a minimum job charge, prep, and masking.

Attics and garages tend to run higher because of the surface area and the access. Basements and HVAC areas such as ducts and crawl spaces vary with the size of the space and how reachable it is.

The sources list ranges for each size. Total price rises with area. Ask whether the quote has a minimum job charge, since small areas can cost more per square foot.

The sources group their data differently. Some show per-square-foot prices at a given thickness, while others show job totals by area or room. Thickness assumptions, foam type, and whether removal of old insulation is counted can change the numbers.

• Foam type. Closed-cell costs more than open-cell.
• Thickness. Each added inch adds material and cost.
• Area. Larger surfaces cost more in total.
• Access. Tight attics and crawl spaces slow the crew.
• Existing insulation. Old material may need removal first.
• Surface prep. Dirty, damp, or cluttered surfaces need cleanup.
• Local labor rates and climate. Both affect the quote and the thickness required.
• Rebates. Some utilities and programs offer incentives. Ask your utility and your state energy office what applies to you.

Spray foam releases fumes while it cures, so the crew uses protective gear and the home should be vacated during application. Follow the contractor's re-entry instructions and the manufacturer's guidance. Poor installation can lead to curing problems or odors, so choose an installer with relevant training and references. This is a job for a professional. DIY kits exist, but mixing, temperature, and ventilation errors can ruin the foam and create health risks.

• Open-cell or closed-cell, and how thick, in each area?
• Is the price per square foot or a flat job total?
• Does the quote include prep, removal of old insulation, and cleanup?
• How long until we can re-enter the home?
• What warranty covers the product and the installation?

The higher cost buys air sealing and insulation in one step, which matters most in attics, rim joists, and crawl spaces with many gaps. In open wall cavities with few leaks, cheaper insulation may be enough. A home energy audit can show where air escapes and help you spend on the areas that matter most.