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Attic Insulation Cost Calculator Ontario (2026): Existing R-Value to R-60, Blown Cellulose or Fibreglass, Air Sealing, Removal, Baffles, Hatch, HST and the Rebate Check
Insulation & Air SealingFree Calculator
What Should Attic Insulation Cost? Measured From What Is Up There Now, With the Air Sealing Priced Before the Fluff Goes On Top.
Existing depth to existing R, the top-up to R-50 or R-60 by the point of R added, air sealing, pot lights, hatch, baffles, removal when it is needed, HST. And a plain check of which rebate tier the attic falls in, if any. No email address required.
An attic quote is three numbers pretending to be one: the square feet, the R-value you start at, and the R-value you end at. The contractor who quotes “$2,400 to insulate the attic” without measuring what is there is guessing, and the one who leaves out the air sealing is selling you a sweater to wear in the wind. This calculator does the arithmetic the way a good crew does it: depth ruler first, R-points added second, air sealing as its own line, and the things people forget (the hatch, the pot lights, the baffles at the eave) priced so nobody finds them on the invoice.
Step-by-step
Attic Insulation Calculator (Ontario)
1
What is up there now
The footprint of the house under the attic, not the whole floor area. A 2,000 sq ft two-storey has about 1,000 to 1,200 sq ft of attic.
Not sure? The depth chart has photos of each.
Push a ruler down to the drywall in four or five places and average it. Old blown fibreglass is about R-2.7 per in., cellulose R-3.6, batts R-3.4.
2
The work under the insulation
The line that makes the insulation work. The leak list.
Airtight covers at $45 each. Non-IC lights cannot be buried; the cover is the fix.
Keeps the new insulation out of the soffit vents. Why the attic has to breathe.
Dense-pack cellulose from inside or outside at $4.25 per sq ft. Spray foam against the sheathing is priced on the foam calculator.
For the rebate check only.
3
Where is the house?
Material costs the same everywhere; labour does not, and insulation is mostly labour, a truck and two men in a crawlspace.
Used only to tell you whether the house is in our direct service area. Not stored.
Enter a postal code to see service coverage.
BuildersOntario.com
Your Attic Insulation Budget
Illustrative Ontario estimate
| Item | Estimate |
|---|
Estimated total with HST$0
Example only, using BuildersOntario budgeting rates checked October 2026 for blown cellulose or fibreglass installed by machine to the depth that gives the stated R-value with depth markers left in place, air sealing of the attic floor with foam, caulking and gaskets, airtight pot light covers, the hatch insulated and weatherstripped, soffit baffles, and removal by vacuum truck where selected. It does not include electrical work, replacing non-IC pot lights, bathroom fan ducting to the outside, roof or soffit repairs, mould remediation or vermiculite abatement, which are quoted after an inspection. The rebate check is an eligibility screen, not an approval; the program site governs. The contractor’s site measure governs the contract, not this page.
Request a Real Quotation
Your attic area, the insulation measured in it, the target R-value and the air-sealing list become a written scope an insulation crew can price without a ladder, so three of them price the same attic. It goes straight to our inbox, and a copy comes back to you; reply to that copy with two or three photos from the hatch (the insulation, the eaves, the hatch itself) and a photo of a ruler pushed into the insulation.
What this calculator does, and what it will not do!
It turns the depth you measure with a ruler into the R-value you have, prices the R-points you are adding instead of a flat “per attic” number, and puts the air sealing on its own line so you can see whether a quote has it. It also screens the attic against the rebate tiers, which depend on where you start, not where you end.
It cannot see the attic. It does not know that the bathroom fan dumps into the insulation, that the pot lights are the old non-IC kind, or that the back corner has been wet since the ice dam two winters ago. Those are the things a crew finds from the hatch, and the reason the scope asks them to report what they find before they bury it. This is a budget; the contractor’s measure is the quote.
A rule of thumb: in Ontario in 2026, a blown cellulose top-up from an old R-20 to R-60 is about $2.60 a square foot, air sealing about $1.00, and the hatch, pot lights and baffles another $700 to $900 on a normal house. A 1,200 sq ft attic comes to about $5,400 with HST; a bare attic in a new build to R-60 is about $3.75 a square foot for the insulation alone. If a quote is half that, ask what was left out; usually it is the air sealing and the depth.
How I price it
| Line | Rate | Notes |
|---|---|---|
| Blown top-up | $0.065 per sq ft per R-point | R-20 to R-60 is 40 points, $2.60. Minimum $1.50 for a thin settling top-up. Fibreglass +$0.25. |
| Bare attic to R-60 | $3.75 per sq ft | New build or after removal. R-50 is $3.25. |
| Air sealing | $1.00 per sq ft | Minimum $600. Top plates, stacks, wires, duct boots, chimney chase. Done before the insulation, never after. |
| Pot light covers | $45 each | Airtight, fire-rated covers so the insulation can go over them. Non-IC lights without a cover are a fire hazard under insulation. |
| Hatch | $200 to $350 | Insulated and weatherstripped, or a box over a pull-down stair. The hatch is a hole in the attic floor the size of a small window. |
| Baffles | $300 | Every rafter bay at the eave, so the soffit keeps breathing after the insulation goes deeper than the joists. |
| Removal | $2.00 to $3.00 per sq ft | Vacuum truck for blown, hand-bagging for batts, plus $300 to fog a rodent attic. Wet or mouldy is quoted after inspection. |
| Vermiculite | Test first | $100 to $200 a sample; licensed abatement $2,000 to $5,000 if positive. No price without the test. |
| Cathedral or flat roof | $4.25 per sq ft | Dense-pack cellulose. Foam against the sheathing is on the foam calculator. |
| Minimum job | $900 | The truck and the hose come for a small attic too. |
Checked against Ontario insulation crews each month. Attic insulation costs has three houses worked through; the rebate page has the tiers and the catch.
Where homeowners go wrong
- Buying R-value without air sealing. Blown insulation slows heat; it does not stop air. The warm wet air from the kitchen goes up through the pot lights and the top plates and freezes on the sheathing. Seal first. The leak list.
- Letting the crew bury the soffit. No baffles and the new insulation fills the eave, the attic stops breathing and the shingles cook. Attic ventilation.
- Accepting “R-60” with no depth. R-60 in cellulose is about 17 in. Ask for depth markers and the bag count on the invoice; the bag label says how many bags make R-60 over your area. What to check from the hatch.
- Insulating over a problem. Wet insulation, a bath fan venting into the attic, a roof leak, vermiculite. Each one gets fixed first or the new insulation is money on top of a mistake. The bath fan.
- Counting the rebate before it is approved. The tier depends on what is up there now, the contractor has to be on the list, and the program can close early. Price the job as if there were no rebate; take the cheque as a bonus.
Questions people ask
How much does attic insulation cost per square foot in Ontario?
A blown top-up is $1.50 to $3.50 a square foot in 2026 depending on how many R-points you are adding; from R-20 to R-60 is about $2.60. A bare attic to R-60 is about $3.75. Air sealing adds about $1.00, and the hatch, pot light covers and baffles add $700 to $900 on a normal house. A 1,200 sq ft attic done properly is $4,500 to $6,000 with HST.
How do I know what R-value my attic has now?
Measure the depth with a ruler in four or five places and multiply: old blown fibreglass about R-2.7 per inch, cellulose R-3.6, batts R-3.4. Six inches of old pink fluff is about R-16. The depth chart does the arithmetic for every product.
Do I have to remove the old insulation before adding more?
No, not if it is dry, clean and lying flat. Top it up. You remove it when it is wet, mouldy, full of rodent droppings, or when it is vermiculite, which is a different job with a lab test first. Removal.
Is R-60 worth it over R-50?
The last ten points cost about $0.65 a square foot and save a few dollars a month. R-50 is where the rebate tiers start and where most of the saving is. If the budget is tight, R-50 with air sealing beats R-60 without it every time.
Can I get the attic rebate without an energy audit?
Yes, that is the standalone attic stream: no assessment, up to $1,250 if the attic starts at R-12 or less, $1,000 up to R-25, $800 up to R-35, taken to R-50 or better by a contractor on the program’s list. The list is closed to new contractors, so ask before you sign. The rebate page.
Foam in a cathedral ceiling or a rim joist?
The Spray Foam Cost Calculator prices foam by the board foot, surface by surface, with the masking, the backing and the minimum charge the truck brings. If you already have attic quotes, the $99 quote review puts them on one grid and tells you which one measured the attic.
