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Spray Foam Insulation Cost in Ontario (2026): Board Feet Explained, Closed vs Open Cell Per Board Foot, What Moves the Rate, Masking, Backing, Minimum Charges and Three Jobs Priced
Insulation & Air Sealing
Spray Foam Cost in Ontario: Board Feet, Closed vs Open Cell, What Moves the Rate, and the Minimum Charge That Eats Small Jobs
Spray foam is sold by the board foot, one square foot of surface one inch thick, and that unit is where most of the confusion starts. With the crews I use, closed cell runs $1.00 to $1.50 a board foot in October 2026 and open cell $0.90 to $1.20. Where a job lands in that range is not the foam. It is the masking, the backing where the bays are open, and how easy the walls are to reach. Then add a minimum charge of $900 to $1,500 that makes a 400 sq ft job not worth anyone’s diesel, and the price per board foot stops meaning much on its own. When you see $2.00 or $2.50 a board foot quoted, that is usually a small job carrying the truck.
The numbers
$1.25closed cell, per board foot ($1.00 to $1.50)
$1.05open cell, per board foot ($0.90 to $1.20)
$300masking on a normal job
$900+minimum charge per visit
| Line | Rate | R-value | Notes |
|---|---|---|---|
| Closed cell, 2 lb | $1.00 to $1.50 per bf, default $1.25 | R-6 per in. nominal, R-5.6 aged | 2 in. = R-12, 3 in. = R-18, 3.5 in. = R-20. Air barrier at 1 in., vapour retarder at 2 in. |
| Closed cell, low end | about $1.00 per bf | same foam | Open framing, nothing to mask, the rig runs all day. The top of the range is small bays, crawlspaces and occupied houses. |
| Open cell, 0.5 lb | $0.90 to $1.20 per bf, default $1.05 | R-3.7 per in. | Not below grade or against sheathing without a vapour retarder. |
| Masking and protection | $150 to $500 per job, default $300 | Poly over windows, floors, the furnace, the panel. | |
| Backing | $1.50 to $3.00 per sq ft, default $2.00 | Cardboard or OSB behind open joist bays, the rim from below, knee walls. | |
| Minimum charge or mobilization | $900 to $1,500 | Two men, a truck and the rig, whatever the job is. | |
| Rim joist, 2 in. closed cell | $4 to $7 per lf, default $5.50 | R-12 | Rims alone: $900 to $1,800 because of the minimum. |
| Thermal barrier over exposed foam | drywall rate, or $1.25 to $2.00 per sq ft | 1/2 in. drywall under OBC 9.10.17, or an intumescent coating. Ignition barrier in a crawlspace or attic $1.25. |
These are the lines the spray foam cost calculator runs surface by surface. Which foam goes where is on the closed vs open cell page; this page is about the money.
A board foot, explained once
One board foot is 12 in. by 12 in. by 1 in. thick. A 100 sq ft wall sprayed 2 in. thick is 200 board feet; sprayed the full 5.5 in. depth of a 2×6 bay, 550. That is the whole of the arithmetic, and it is why two quotes for the same wall can look nothing alike: one contractor prices per square foot at a stated thickness, the other per board foot, and a third writes “R-20 closed cell” with no thickness at all.
Convert everything to board feet and inches before you compare. Closed cell is R-6 an inch on the data sheet and about R-5.6 after it has aged, so 3 in. is an honest R-18 and 3.5 in. is the honest R-20. A quote that calls 3 in. “R-20” is rounding in its own favour. Open cell is R-3.7 an inch, so the same 5.5 in. bay comes out at R-20 nominal. At the prices I see, that is not cheaper per R than 3.5 in. of closed cell; open cell earns its place in interior walls for sound, in vented roofs, and with crews that only carry it.
What moves the price inside the range
On my own jobs, with the subs I use, closed cell has been running $1.00 to $1.50 a board foot and open cell $0.90 to $1.20. The price, in the words of the man who sprays it, “depends on how much masking is included and if they have to put backing.” On a new house the framing is open, there is nothing in the rooms to protect, and the crew does the rims, the garage ceiling and the cathedral in one visit with the rig running from eight until four. That is a good day for a foam company, and it is the bottom of the range.
A homeowner calling for one job is a different day. Two men, a truck and a trailer with a proportioner come for a half day, mask a finished basement, spray 800 board feet, clean the gun and drive home. That lands at the top of the range, or on the minimum charge, and it is where the $2.00 and $2.50 quotes you see online come from. If your job is big and clean, a whole unfinished basement with nothing in it, say so when you ask for the price; it should be near the bottom.
Masking, backing and the minimum
Masking is poly and tape over everything the overspray could land on: windows, the floor, the furnace, the electrical panel, the stairs. Overspray on a window is there for the life of the window. $150 to $500 per job, $300 on most houses.
Backing is what the foam sticks to where there is nothing there. The underside of a floor over a garage with open bays, the rim joist seen from below with no sheathing behind it, a knee wall with the attic on the other side: each wants cardboard or OSB cut and fastened into the bay before anyone sprays. $1.50 to $3.00 per square foot of backing, $2.00 is typical, and it is the line most likely to be missing from a low quote and to appear as an extra on day one.
The minimum is the one that surprises people. “They have to mobilize at least two guys, truck and equipment. It is not worth going out for 400 sq ft of wall.” Expect $900 to $1,500 before a single board foot is counted. A rim joist job on its own lands on that minimum and feels expensive per foot because it is. The fix is to bundle: do the rims the same day as the basement walls, or the garage ceiling with the cathedral, so the truck earns its trip.
Three jobs priced
Job 1: rim joists only, 36 x 28 ft house. The perimeter is 128 lf. At $5.50 a linear foot for 2 in. of closed cell over the rim, the top of the wall and the joist ends, that is $704 of work. The foam in it is about 1.67 board feet per foot, 214 board feet at $1.25, or $268; the rest is crawling along the top of a foundation wall with a gun. But $704 is under the minimum, so the invoice reads $900 to $1,500 depending on who rolls the truck. Rims alone: $900 to $1,800, and the cure is bundling.
Job 2: 1,000 sq ft of wall at 2 in. closed cell. 2,000 board feet at $1.25 is $2,500. Masking $300. $2,800 before HST, $364 of HST, $3,164 with. At the bottom of the range, $1.00 on a wide-open wall, the foam is $2,000; at the top, $1.50 for awkward access, it is $3,000. The same 2 in. is the flash coat in a flash-and-batt wall, with an R-14 batt at $1.10 going over it.
Job 3: a 2×6 wall, 1,000 sq ft, filled full depth. Open cell at 5.5 in. is 5,500 board feet at $1.05, $5,775, plus masking $300, $6,075, for R-20 nominal. Closed cell full depth is 5.5 in. at $1.25, about $6.90 a square foot, $6,875 plus masking, $7,175, for R-31 nominal and about R-24 effective because the studs still bridge. The same wall with an R-22 batt and poly is $2.00 a square foot, $2,000, at about R-17 effective. Whether the tighter wall is worth $5,000 on 1,000 sq ft is the question the wall assembly calculator is for.
Where the quote goes wrong
- No thickness on the paper. “R-20 closed cell” is a hope, not a specification. Inches, net square feet, board feet, product name. All four, or send it back.
- Gross area. Windows and doors come off the count; nobody sprays a window.
- Masking “included” and backing not mentioned. One of those turns into a change order. Ask for both as lines, even if a line reads zero.
- No thermal barrier. Foam exposed in a living space needs 1/2 in. drywall or an intumescent coating, and that is not the foam company’s line, so nobody prices it. The thermal barrier rule.
- No card, no sheet. The product is certified to CAN/ULC S705.1 and the installation to S705.2. The installer should carry a CUFCA photo ID and leave a daily work sheet with lift thickness and density. Ask for both. What goes wrong when they do not is on the installation problems page.
Questions people ask
How much does spray foam cost per board foot in Ontario?
Closed cell, installed, $1.00 to $1.50 a board foot in October 2026, with $1.25 usual on a normal job. Open cell $0.90 to $1.20. Small jobs get quoted higher because the minimum charge is spread over a few hundred board feet.
How much is spray foam per square foot at 2 inches?
Two board feet per square foot, so $2.50 at $1.25, before masking and the minimum. At 3 in. it is $3.75, at 3.5 in. for an honest R-20 it is about $4.40.
What is the minimum charge for spray foam?
$900 to $1,500 for the visit, which covers two installers, the truck and the rig. Jobs under about 1,000 board feet land on the minimum. Rim joists alone run $900 to $1,800 for that reason.
Why do two foam quotes for the same wall differ so much?
Open framing, nothing to mask, nothing to back and a full day for the rig is the bottom of the range. A one-off job in an occupied house is a half day of setup for a few hundred board feet, and that is the top of it, or the minimum. Then check the thickness: 2 in. and 3 in. are 50% apart before anything else.
Does spray foam need to be covered?
Inside a living space, yes: 1/2 in. drywall or a tested intumescent coating under OBC 9.10.17. In an attic or crawlspace entered only for service an ignition barrier coat at about $1.25 a square foot is the usual answer.
Price it surface by surface
The spray foam cost calculator takes each surface at its own thickness, counts the board feet, adds masking and backing and applies the minimum so a rim-joist-only job shows what it will really cost. If you already have quotes and none of them say how thick, the $99 review will work it out from the board feet and tell you which contractor is rounding R-18 up to R-20.
Sources and further reading
- CUFCA Quality Assurance Program: Canadian Urethane Foam Contractors Association: certified installers with photo ID, licensed contractors, daily work sheets and the CAN/ULC S705 standards a spray foam job is held to.
- Ontario’s Building Code: the official page with the current regulation; vapour barriers are 9.25, attic ventilation 9.19, thermal barriers over foam 9.10.17, radon 9.13.
- ICFhome.ca: where I build the ICF houses these insulation numbers come from.
