Spray Foam Insulation Cost Calculator
Get an instant free estimate for spray foam insulation based on area, thickness, and open-cell vs closed-cell foam.
Free Spray Foam Insulation Cost Calculator
Use this calculator to calculate the cost of spray foam insulation near you for free. Enter your ZIP code for a localized estimate.
Project Dimensions
Enter the total surface area to be sprayed.
Insulation Type:
Add-ons & Prep Work:
Estimates are instant and require no contact information.
Based on inputs, your Spray Foam Insulation project cost is approximately:
Note that the cost above is purely an estimate.
The actual cost may be higher or lower depending on the contractor's quote.
How Much Does Spray Foam Insulation Cost?
Spray foam is priced per board foot (one square foot, one inch thick): about $0.45-$0.75 for open-cell and $1.00-$1.50 for closed-cell. A typical job — an attic or a set of walls — runs roughly $1,500 to $4,000, with whole-home or thick closed-cell projects higher.
Three things set your number: the area you're covering, the thickness (which sets the R-value and the board-foot count), and open-cell vs. closed-cell — closed-cell can cost two to three times more for the same space. Then add the practical extras: removing old insulation, the code-required thermal/ignition barrier, vent baffles, and prep. Use the calculator above to localize your estimate, then read on for exactly what drives your quote.
Spray Foam Insulation Cost by Foam Type & Thickness
Open-Cell vs. Closed-Cell
| Foam Type | Per Board Foot | R-Value / Notes |
|---|---|---|
| Open-Cell | $0.45 - $0.75 | ~R-3.7/in; soundproofing, interior walls & attics |
| Closed-Cell | $1.00 - $1.50 | ~R-6.5/in; vapor barrier, rigid, crawlspaces & rim joists |
Source: Aggregated installer quote data across U.S. markets; labor anchored to U.S. Bureau of Labor Statistics data for Insulation Workers (SOC 47-2131). A board foot = 1 sq ft at 1 inch thick.
Typical Cost per Square Foot by Thickness
| Application | Thickness | Approx. $/sq ft |
|---|---|---|
| Flash coat (air-seal) | 1 in | $0.50 - $1.50 |
| Walls (open-cell) | 2-3 in | $1.00 - $2.25 |
| Walls/crawl (closed-cell) | 2-3 in | $3.00 - $4.50 |
| Attic roof deck (open-cell) | 5-6 in | $2.50 - $4.50 |
Source: Aggregated quote ranges from licensed insulation contractors, with regional pricing applied via the calculator above.
The 6 Factors That Drive Your Quote
1. Area to Cover
Spray foam is quoted by the board foot — one square foot covered one inch thick. So the total area you're insulating is the foundation of the price: a single attic ceiling, a few walls, a crawlspace, or a whole home are very different jobs. Bigger areas spread the contractor's setup and minimum charge over more surface, which is why a tiny patch can cost much more per square foot than a full attic.
2. Thickness & R-Value
How many inches you spray sets both the R-value and the board-foot count you pay for. A thin 1-inch 'flash coat' for air-sealing costs far less than a 4-5 inch fill that hits a high R-value for a cold climate. Because cost scales directly with thickness, knowing your target R-value (and your climate zone's recommendation) is the key to not over- or under-buying foam.
3. Open-Cell vs. Closed-Cell
This is the single biggest price lever. Open-cell foam is softer, expands more, and is cheaper per board foot (roughly $0.45-$0.75), with an R-value around 3.7 per inch. Closed-cell is denser and rigid, runs about $1.00-$1.50 per board foot, and delivers ~6.5 R per inch plus a built-in vapor barrier and added structural strength. For the same space, closed-cell can cost two to three times as much.
4. Where You're Spraying
The application affects access and prep. Open attics and new-construction walls are easy and efficient to spray; tight crawlspaces, rim joists, cathedral ceilings, and retrofits into closed walls take more time and masking. Retrofitting an occupied home — protecting finishes, moving belongings, and ventilating during cure — adds labor that a bare new-build doesn't, even for the same square footage and foam.
5. Prep & Old Insulation Removal
Foam needs a clean, dry surface to adhere and cure properly. If old batts or blown-in insulation have to come out first, that removal (around $1 per square foot) and the debris disposal are separate line items. Minor framing or prep work, masking off areas, and protecting HVAC and electrical also add to a retrofit. A clean cavity sprays faster and cheaper than one that needs to be cleared out first.
6. Code: Thermal Barrier & Venting
Building codes require exposed spray foam in living spaces and attics to be covered by a thermal or ignition barrier — often an intumescent paint coating — for fire safety, which is a per-square-foot add-on. Roof applications may also need vent baffles to maintain airflow. These aren't optional extras to skip: they're code, and a reputable installer will price them in so the job passes inspection.
Open-Cell vs. Closed-Cell — Which Do You Need?
The foam type sets the price and the performance. Match it to the space and your climate, not just the budget.
Choose open-cell if…
- You're insulating interior walls or an attic roof deck with room for thickness.
- You want soundproofing and the lowest cost per R-value.
- You're in a milder climate and don't need a vapor barrier from the foam itself.
Choose closed-cell if…
- You need maximum R-value in limited space (rim joists, thin wall cavities, vans/tiny homes).
- You want a built-in vapor/moisture barrier — crawlspaces, basements, humid or flood-prone areas.
- You want the foam to add structural rigidity to the assembly.
Many homes use both — closed-cell where moisture or tight space demands it, open-cell everywhere else to keep the cost down. Whichever you choose, hitting your climate zone's target R-value matters more than the number of inches.
How to Vet and Hire a Spray Foam Installer
Spray foam is only as good as the application — bad mixing or temperature leaves foam that never cures and can off-gas, so installer skill matters more than with most insulation:
- Confirm licensing & insurance and ask about manufacturer training/certification for the foam they use.
- Ask how they control the spray — chemical ratio, substrate temperature, and even thickness in passes.
- Confirm the code thermal/ignition barrier is included and the job will pass inspection.
- Check reviews and references, and ask about re-occupancy time (ventilation during cure).
What a complete quote should spell out
- The foam type (open/closed) and the thickness and target R-value per area.
- Board feet covered and any old-insulation removal and disposal.
- The thermal/ignition barrier and any vent baffles.
- Masking/protection, cleanup, cure/re-occupancy time, and the warranty.
Methodology & Sources
This calculator works in board feet — your area multiplied by the thicknessin inches — then applies the per-board-foot rate for open-cell or closed-cellfoam. Selected prep and code items (old-insulation removal, ignition barrier, vent baffles, disposal) are added, and the result is adjusted to your ZIP code's regional price level. In short: (Sq Ft × Thickness × Foam Rate) + Add-ons, × Regional Factor.
Data sources:
- ENERGY STAR / U.S. DOE — recommended R-values by region
- Spray Polyurethane Foam Alliance (SPFA)
- U.S. Bureau of Labor Statistics — Insulation Workers (SOC 47-2131)
For a full explanation of how every calculator on this site is built and localized, see our methodology page.
About the Reviewer
Licensed Mechanical (HVAC) Contractor
Mechanical contractor specializing in residential HVAC system sizing, replacement, and indoor air quality.
View full profile & credentials →Frequently Asked Questions
Spray foam is priced per board foot (one square foot, one inch thick): roughly $0.45-$0.75 for open-cell and $1.00-$1.50 for closed-cell. In practical terms, a typical job — an attic or a set of walls — runs about $1,500-$4,000, while whole-home or thick closed-cell projects run higher. Per square foot of surface, expect around $1.50-$2.25 for 3 inches of open-cell and $3-$4.50 for 2-3 inches of closed-cell. Removal, thermal barrier, and prep add to the total.
It depends on foam type and thickness, because spray foam is really priced per board foot. For open-cell at a common 3-inch attic depth, figure about $1.50-$2.25 per square foot of surface; closed-cell at 2-3 inches runs roughly $3-$4.50 per square foot. Thicker applications for higher R-value cost proportionally more. The calculator above multiplies your area by your chosen thickness to get board feet, then applies the open- or closed-cell rate, so you can see the per-square-foot result for your exact job.
Open-cell is lighter, expands more to fill gaps, dampens sound well, and is cheaper (~$0.45-$0.75/board foot) with an R-value near 3.7 per inch — great for interior walls and attics in milder climates. Closed-cell is dense and rigid (~$1.00-$1.50/board foot), gives ~6.5 R per inch, acts as its own vapor barrier, and adds structural rigidity — ideal for crawlspaces, rim joists, exterior applications, and tight spaces where you need high R-value per inch. Closed-cell costs roughly two to three times more for the same space.
Attic spray foam typically runs $1,500-$4,500, depending on the attic size, whether you insulate the flat ceiling or the underside of the roof deck, the foam type, and the thickness. Open-cell at 5-6 inches is common for attic roof decks in moderate climates; closed-cell is used where space is tight or a vapor barrier is needed, at higher cost. Encapsulating the whole attic (sealing the roofline) costs more than just the attic floor but turns the attic into conditioned space.
It depends on the assembly and your climate zone. Walls are often 2-3 inches; attic roof decks 5-6 inches of open-cell or 3-4 inches of closed-cell to reach recommended R-values. The U.S. Department of Energy publishes target R-values by region — for example, attics often call for R-38 to R-60. Since closed-cell delivers more R per inch, it reaches a target in less thickness, which partly offsets its higher per-inch cost. Tell your installer the R-value goal, not just inches.
Often, in the right spots. Closed-cell is worth it where you need maximum R-value in limited space, a built-in vapor/moisture barrier, or added structural strength — crawlspaces, rim joists, basement walls, and flood-prone or humid areas. For interior walls, sound control, or large attic decks in milder climates, open-cell delivers most of the benefit for far less money. Many homes use both: closed-cell where moisture or space demands it, open-cell elsewhere to control cost.
Usually, yes. Building codes require spray foam in living spaces and most attics and crawlspaces to be covered by a thermal barrier (like 1/2-inch drywall) or, in some unoccupied spaces, an ignition barrier — commonly an intumescent paint sprayed over the foam. This is a fire-safety requirement, not an upsell, and inspectors check for it. Budget for it as a per-square-foot add-on, and make sure your installer includes it so the job passes inspection.
Often it does, over time. Spray foam both insulates and air-seals, which can cut heating and cooling bills by 15-30% versus a leaky, under-insulated home, and it improves comfort and reduces drafts and moisture issues. Payback typically lands in the several-year range depending on your climate, energy prices, and how bad the old insulation was. It costs more upfront than batts or blown-in, but the air-sealing performance and longevity are what justify the premium for many homeowners.
Spray foam should go on a clean, dry surface, so existing batts or blown-in insulation in the cavity usually need to be removed first for the foam to adhere and perform — that removal and disposal is a separate cost. In some cases (like adding a flash coat in an open assembly) prep is minimal. Spraying foam over old, possibly damp or compressed insulation can trap moisture and reduce effectiveness, so a good installer will assess whether removal is needed rather than spraying over it.
DIY kits exist and can make sense for very small jobs — sealing a rim joist or a few gaps. But for attics, walls, or whole rooms, professional installation is usually worth it: pros control the chemical ratio and temperature (critical — bad mixing can leave foam that never fully cures and off-gasses), apply even thickness, and handle the code-required thermal barrier. DIY kits are also expensive per board foot, so for larger areas a contractor is often comparable in cost and far better in results.