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New Home Insulation Cost in Ontario (2026): The 2,000 sq ft House Priced in Wood Frame and in ICF, Line by Line, and What a Builder Budget Should Carry
Insulation & Air Sealing
Insulating a New House: $23,475 in Wood Frame, $7,325 in ICF, and Why Those Two Numbers Are Not Comparing the Same Thing
On a new house the insulation is not one trade; it is five trades and a roll of poly, and it shows up in a builder budget as a single line that nobody can check. This page takes a 2,000 sq ft two-storey, 36 by 28 ft with a full basement, and prices every piece of it the way a builder would: the walls, the attic, the basement, the rim, the under-slab and the air sealing, at October 2026 rates. Then it prices the same house in ICF, which is how I build, where the walls and the basement arrive insulated and the insulation line shrinks to the attic, the slab and the ceiling poly. The two totals are honest and they are not a like-for-like saving, and I will say why.
What each surface has to reach
The code does not ask for a product; it asks for a number, and the common Zone 1 prescriptive package in SB-12 gives one per surface: ceiling under an attic R-60, cathedral or flat roof R-31, exposed floor R-31, above-grade walls R-22 nominal or R-19 plus R-5 continuous, full-height basement walls R-20 effective from subfloor to slab, R-10 under a heated slab, windows about U-1.4 to 1.6, and an HRV. The packages trade one element against another, so a house with better windows can carry a little less wall, and the form your designer filed says which package you are on. The SB-12 page explains the packages; this page prices meeting them.
Effective R, not the number on the batt bag, is what the compliance form and the heat-loss calculation use. A 2×6 wall with R-22 batts is about R-17 effective once the studs are counted, which is why the batt-only wall sits at the bottom of the comparison table and the code lets it through anyway.
The wood-frame house, line by line
| Line | Quantity | Rate | Cost | Meets |
|---|---|---|---|---|
| Above-grade walls, R-22 fibreglass batts plus sealed 6 mil poly | 2,400 sq ft net | $1.50 + $0.50 | $4,800 | R-22 nominal, about R-17 effective |
| Attic, blown cellulose from bare joists to R-60 | 1,100 sq ft | $3.75 | $4,125 | R-60 |
| Basement walls, Assembly A: 2 in. XPS, 2×4 wall, R-14 batt, poly | 984 sq ft | $9.60 | $9,446 | about R-21 effective |
| Rim joists, 2 in. closed cell | 128 lf | $5.50 | $704 | R-12 and the air seal |
| Under-slab 2 in. Type II EPS with 6 mil poly | 1,000 sq ft | $2.00 | $2,000 | R-8 (R-10 if the slab is heated) |
| Whole-house air sealing package | 1 house | $2,400 | $2,400 | the SB-12 air-tightness credit, about 2.5 to 3.0 ACH50 |
| Total, before HST | $23,475 |
$11.74 a square foot of house. Upgrades that change it: mineral wool in the walls instead of fibreglass adds $0.90 a square foot, $2,160; 1 in. of continuous exterior foam over the sheathing takes the wall to about R-21.5 effective at the re-siding rate on the exterior insulation page; swapping the basement to Assembly B, 3 in. of closed cell and no poly, saves about $840 and gets the best air seal in the house.
The same house in ICF
An ICF wall is 2.5 in. of EPS on each face of a concrete core, from the footing to the roof, and nothing is added to it inside or out. A standard 6 in. core starts at about R-22 effective, R-24 on most manufacturer sheets, and it is continuous, so there is no stud to bridge it and no effective-versus-nominal haircut. The basement is the same wall; it does not get Assembly A or B or anything else. There is no poly on an ICF wall, because the foam is the vapour retarder and the concrete and foam together are the air barrier. The ICF R-value page has the numbers by core size.
So the insulation line on the ICF version of this house is the attic at $4,125, the under-slab at $2,000, and the ceiling poly with the air sealing of the attic plane and the penetrations, $1,200, because that is the only vapour barrier in the house and the only place the air barrier still has to be built by hand. $7,325 of separate insulation work against $23,475. The difference, $16,150, is not a saving; it is inside the ICF wall price, which is a different and larger number that belongs on the ICF home building pages. What you get for it is a wall at R-22 and up with no bridging, a basement with no studs and no poly to grow anything behind, and a house that tests under 2 ACH50 without anyone chasing leaks with a caulking gun. The houses we build at ICFhome.ca are all built that way; the wall assembly comparison calculator puts the four wall types side by side with the installed cost and the effective R.
What a builder budget should carry
- Insulation as six lines, not one. Walls, attic, basement, rim, under-slab, air sealing, each with a quantity, a rate and the R it meets. One line that says “insulation, $18,000” cannot be checked and cannot be changed.
- The blower door in the budget. $300 to $450 for a standalone test at drywall stage, before the ceiling poly is covered. The SB-12 air-tightness credit is only a credit if somebody measures it.
- The spray foam minimum, once. The rim joists, any cantilever, the garage ceiling under a bedroom and the attic hatch surround all want foam. Schedule them for the same visit, or the $900 mobilization is paid three times.
- R-10 under the slab if the floor is heated. SB-12 requires under-slab insulation under a heated slab, and R-10 is the number to carry; 2 in. of Type II EPS is R-8 and the upgrade is a few hundred dollars before the pour and impossible after it. The radiant floor pages have the rest.
- An allowance for the thermal barrier. Any foam left exposed in the finished space needs 1/2 in. drywall over it under OBC 9.10.17, or an intumescent coat at $1.25 to $2.00 a square foot. Mechanical rooms get missed.
- The heat-loss calculation after the envelope is decided, not before. The furnace or heat pump is sized from the effective R and the air-tightness target. Size it from a default and you buy equipment for a house you did not build. That stamped design is what OntarioHeatLoss.ca produces.
Where new-house insulation budgets go wrong
The commonest miss is the basement. A builder budget that says “basement unfinished” often carries no basement insulation at all, and then the homeowner finds out that SB-12 wants R-20 full height whether or not there is drywall over it. On a poured wall that is $9,446 the day the house is built or $9,446 plus the cost of working around a furnace two years later. On ICF it is zero either way, which is the quiet reason ICF basements price so well against poured ones once the insulation is counted.
The second miss is the air sealing. The code wants a continuous air barrier and the batts are not one; a sweater is not a windbreaker. Poly that is stapled up but not sealed at the plates, the boxes and the windows is a vapour barrier and nothing else. The $2,400 buys the acoustical sealant, the gaskets, the rim foam and the man who cares, and it is the cheapest $2,400 on the house.
The third is counting on the rebate. There is no new-house insulation rebate; the Home Renovation Savings program is for houses occupied more than six months. Budget the full number.
Questions people ask
How much does insulation cost for a new house in Ontario?
About $23,475 before HST for a 2,000 sq ft two-storey in conventional wood frame, roughly $11.75 a square foot of house, covering walls, attic, basement, rim joists, under-slab and air sealing to the SB-12 Zone 1 package. In ICF the separate insulation work drops to about $7,325 because the walls and basement are already insulated inside the wall price.
What R-value does a new house need in Ontario?
Under the common SB-12 Zone 1 package: attic R-60, cathedral roof R-31, above-grade walls R-22 or R-19 plus R-5 continuous, basement walls R-20 effective full height, R-10 under a heated slab, windows around U-1.4 to 1.6. Packages trade elements against each other; the SB-12 form for your house is the authority.
Does an ICF house need extra insulation?
No. A 6 in. core ICF wall is about R-22 to R-24 effective and continuous, above and below grade, with no poly. The insulation work left on an ICF house is the attic, the under-slab and the ceiling vapour barrier with the air sealing of the attic plane.
Is spray foam worth it in new construction?
At the rim joists, yes, every time, at about $5.50 a linear foot. Full-depth closed cell in a 2×6 wall is about $6.90 a square foot for about R-24 effective against $2.00 for batts and poly at R-17; it is a real upgrade and a big one, and a flash-and-batt at $3.60 gets most of the air seal for half the money.
Should the basement be insulated if it is not being finished?
Yes, the code wants R-20 full height on a new basement regardless of finish, and the inspector will look for it. It is far cheaper to do with the house empty than after the mechanicals go in.
Put the four walls side by side
The wall assembly comparison calculator runs your house four ways, 2×6 batt, batt plus exterior foam, flash and batt, and ICF, with the installed cost and the effective R for each, so the insulation line in the builder budget becomes a decision instead of a guess. If you have a builder quote with one insulation line on it, the $99 review will tell you what that line should contain.
Sources and further reading
- Ontario’s Building Code, Supplementary Standard SB-12: the energy-efficiency packages that set the R-values for attics, walls, basements and slabs in a new or renovated Ontario house.
- 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.
