Spray foam insulation cost dataset

The two products

The R per inch and the densities are the EPA’s, from EPA, Spray Polyurethane Foam Product Types (read 2026-08-25); the price bands are ours and carry their own uncertainty. ⚠️ The unit price is the comparison everybody makes and it is the wrong one — the table below makes the same comparison at equal R-value, which is what you are actually buying.

The same 1,000 square feet, at every depth

A factor of 8 separates the cheapest cell of this table from the dearest, and every one of them would be described as “1,000 square feet of spray foam”. ⚠️ That is the whole reason this page exists: the depth is half the quantity, and it is the number a quote per square foot is not telling you.

At the same R-value, and what fits

⚠️ No code R-value for walls appears anywhere on this page, deliberately: the figure the IRC asks for varies by climate zone and that text belongs to the ICC, not to us. What the arithmetic can say is what physically fits, and it is usually what decides the choice rather than the price. For attics and floors there is a public figure to aim at — ENERGY STAR, Recommended Home Insulation R-Values (read 2026-08-25) gives R-30 to R-60 for attics and R-13 to R-38 for floors depending on the zone.

Where it is sprayed, and what goes over it

Where it is sprayed moves the hours and never the material: a floor from underneath is the slowest surface on this page because the crew is on their back and everything that leaves the gun comes down. ⚠️ Read the two cheapest rows with the caveat attached: a foundation wall and a steel skin come out under a stud wall only because there is no cavity and so nothing to trim, and the reference job in this column is open-cell — which is the wrong product in both of those places for reasons that have nothing to do with price. Cheaper there is not a recommendation, and the calculator says so when you pick it. The barrier column is the line most quotes are missing — cured foam is a plastic and the code does not let it sit exposed where people are. And the last row is the question Google shows on this search: a 40 × 60 building is 2,800 sq ft of wall at a 14-foot eave plus 2,530 of roof at 4:12, both assumptions stated because the question does not give them.

Line items

66% of the reference total comes from estimated rather than official figures. The reference job is 1,000 square feet of open studs sprayed to 3.5″ of open-cell with nothing over it: 3,500 board-feet, R-12.3, 17 trade hours. Products and finishes that are not selected sit at zero quantity, so the table below is every path rather than one job.

The reasoning behind each figure

Open-cell, half-pound spray foam, chemical delivered to siteestimated, ±26%

• ⚠️ A board-foot is one square foot at one inch, and it is the only unit that scales with depth. This is why a price per square foot is not a price for spray foam: the same wall at six inches is three times the material of the same wall at two.
• Expands hard and dries soft, at R-3.5 per inch. It is an air barrier but not a vapour retarder, and it holds water rather than shedding it, so it does not belong below grade, against masonry or anywhere it can get wet. In a cavity it is normally sprayed to overfill and then trimmed flush, which is a real cost and one of the two places the two products stop being comparable.
• R-3.5 per inch and 0.5 lb per cubic foot are what the EPA publishes for this product type, not our estimate. The price band is ours: the two-component chemical, the blowing agent and the rig consumables, without the crew, which is priced separately below so that your metropolitan wage applies to it.

Closed-cell, two-pound spray foam, chemical delivered to siteestimated, ±26%

• ⚠️ A board-foot is one square foot at one inch, and it is the only unit that scales with depth. This is why a price per square foot is not a price for spray foam: the same wall at six inches is three times the material of the same wall at two.
• Expands less and dries rigid, at R-6.5 per inch — almost twice the R of the same inch of open-cell. At two inches or more it is also a vapour retarder and it adds racking strength to the frame. It is sprayed in lifts with cooling time between passes, which is why the crew hours per board-foot are higher even though there is nothing to trim.
• R-6.5 per inch and 2 lb per cubic foot are what the EPA publishes for this product type, not our estimate. The price band is ours: the two-component chemical, the blowing agent and the rig consumables, without the crew, which is priced separately below so that your metropolitan wage applies to it.

Spray crew: gun time at the surface

• Modelled at 2 trade hours per thousand board-feet of open-cell and 3.6 for closed-cell. Closed-cell is slower per board-foot because it goes on in lifts of about two inches with cooling time between passes; open-cell is one aggressive pass.
• Multiplied by where it is being sprayed: a wall in front of you is the baseline, a sloped ceiling is a third slower and a floor from underneath is more than half as slow again, because the crew is on their back and everything that leaves the gun comes down.
• The wage is official BLS data for insulation workers, adjusted to your metropolitan area. The hours are our estimate. BLS publishes this occupation in 135 of 530 areas; outside those the model falls back to the broader construction wage for your area rather than inventing one.

Rig mobilisation: truck, hose, generator and fuelestimated, ±42%

• ⚠️ The line that explains why small foam jobs feel outrageous. A rig has to arrive, the hose has to be run and heated, and the chemical has to come up to temperature whether you are spraying two hundred square feet or two thousand. On a small job it is most of the bill; on a large one it disappears.
• It is also why bundling matters: if a crew is coming for the walls, the rim joist and the crawl hatch cost almost nothing extra on the same visit and a great deal on their own.
• Priced as equipment rather than material or labour, because that is what it is: the truck and the plant, not the foam and not the hours.

Masking, sheeting and protecting everything nearby

• Cured spray foam does not come off glass, brick, finished floors or a car. Masking is not a nicety on this job, and a crew that skips it is a crew you will be arguing with later.
• Modelled at 0.004 trade hours per square foot of sprayed surface, on the same access factor as the spraying itself.

Trim the open-cell flush with the framing and bag the offcut

• Open-cell is sprayed to overfill the cavity and then cut back level with the studs or rafters, because drywall will not sit on a bulge. The offcut is bulky, light and goes in bags.
• ⚠️ This is one of the two reasons the two foams are not the same job. Closed-cell is applied to a measured depth and there is nothing to trim, so this line is zero for it. It applies only where there is a cavity to be flush with — not on a foundation wall or the underside of a steel roof.
• Modelled at 0.006 trade hours per square foot of cavity face.

Strip the old insulation out of the cavity

• Foam has to go against the substrate, so whatever is in the cavity comes out first. Batts pull; anything that has been wet has to be bagged rather than folded.
• Modelled at 0.008 trade hours per square foot, which is pulling and bagging rather than a careful strip-out.

Bags, haulage and tipping for the old insulationestimated, ±47%

• Old fibreglass is almost all air, so the cost here is volume and trips rather than weight.
• ⚠️ If the house is old enough that the insulation might be vermiculite, stop: that is an asbestos question and not an insulation one, and it is not priced anywhere on this site.

Intumescent ignition-barrier coating over the cured foamestimated, ±42%

• A coating applied over the foam where the code wants an ignition barrier and there will never be a finished surface — a crawl space, an unoccupied attic, a shop.
• ⚠️ Foam plastic is not allowed to sit exposed in most of the places people put it, and this line or the gypsum line below is the requirement being met. It is routinely missing from a spray foam quote, which is one of the ways two quotes for the same job differ by more than they look.

Spraying the ignition-barrier coating

• A second pass with a different gun, after the foam has cured. Modelled at 0.004 trade hours per square foot on the same access factor.

Half-inch gypsum board as the thermal barrierestimated, ±33%

• Board, screws, tape and compound over the foam. It is the barrier the code asks for in space people occupy.
• ⚠️ On a gut remodel this is not an extra: the wall was always going to be boarded, and counting it here would charge you twice. It is an extra on a basement wall, a garage ceiling or anywhere the plan was to leave the surface unfinished.

Hanging, taping and finishing the board

• A different trade from the foam crew and usually a different day. Modelled at 0.016 trade hours per square foot for hang, tape and a level-3 finish.
• Wages are official BLS data for drywall and ceiling tile installers in your metropolitan area.

Not included in this dataset

Opening the wall or the ceiling up

This page prices foam going into a cavity that is already open. Taking siding off, pulling plaster down or cutting a ceiling back is the job that comes first, and on a retrofit it is often larger than the insulation. ⚠️ It is also the reason foam is easy to specify in a new build and awkward in a finished house: high-pressure foam cannot be injected through a hole the way loose fill can.

Putting the room back together

Siding, plaster, paint and trim after the foam is in. The gypsum option on this page is the code barrier over the foam and nothing more: it is board, tape and compound, not a finished room.

Attics and crawl spaces, which are priced whole elsewhere

⚠️ Deliberately not modelled here, and it is a rule rather than an omission: one job, one model, one number. Open-cell at the roof deck is priced on our attic insulation page and closed-cell on crawl space walls on our crawl space encapsulation page, both including the parts of those jobs that are not foam. Two models of the same work drift apart, and a reader who compared the pages would be right to stop trusting both.

Staying somewhere else while it cures

⚠️ Not a line on any quote and it is a real cost. EPA guidance on the professional high-pressure system says some manufacturers recommend twenty-four hours before re-entry, that the recommended time varies, and that re-entry should wait until the product has cured and the building has been ventilated and cleaned. Ask your contractor for the figure for the specific product before the day, not after.

What it saves on the energy bill

No payback figure is published here, because an honest one needs your fuel price, your climate, how leaky the house is now and how you heat it. What this page can say is what the insulation costs and what R it buys, which is the half nobody gives you straight.

⚠️ One of those exclusions is not money and belongs here rather than in a footnote: spraying uses isocyanates, which OSHA, Isocyanates (read 2026-08-25) associates with occupational asthma and respiratory irritation, and EPA, Vacate and Safe Re-Entry Time for Spray Polyurethane Foam Application (read 2026-08-25) says re-entry should wait until the foam has cured and the building has been ventilated and cleaned — 24 hours being a figure some manufacturers recommend, and one the EPA says varies by product.