Official sources checked on October 23, 2026: Home Renovation Savings attic insulation page, its terms and conditions (attic stream requirements, version January 2026) and Natural Resources Canada, Keeping the Heat In, Table 3-1.
This attic insulation rebate calculator estimates what the Ontario Home Renovation Savings program pays for insulating your roof. The rebate is 50% of your after-tax insulation cost, up to $1,250 for an attic (when it starts at R-12 or less) and up to $750 for a cathedral ceiling or flat roof. Example: an attic at R-12 with a $3,000 invoice gets $1,250, because half the invoice is above the cap. The work must be completed by November 30, 2026.
Looking for the price of the work rather than the rebate? This page only estimates the Ontario rebate; for the project budget, use our attic insulation cost calculator (currently based on Québec prices).
What next? Rules, the contractor list and the steps to apply are explained in our Ontario attic insulation rebate guide. To compare the attic with other upgrades, see the complete Home Renovation Savings guide. Pre-register on the program website before any work starts.
In this guide
How the attic insulation rebate calculator works
The calculator reads three things: the part of the roof you are insulating, the insulation level your contractor finds at the in-home visit, and, if you want an exact figure, the after-tax cost of the work. The program pays half of that cost, up to the maximum for your starting level. Without a cost, the calculator shows the maximum you can get. It also shows the level you must reach and the invoice needed to collect the full amount, which is twice the maximum.
The starting level is the one measured at the in-home visit, not the one you think is there. If your home has both an attic and a cathedral ceiling or flat roof, run the calculator once for each part and add the two rebates: the program calculates them separately.
Home Renovation Savings attic amounts in 2026
| Roof part | Insulation at the in-home visit | Level you must reach | Maximum rebate |
|---|---|---|---|
| Attic | R-12 or less | R-50 | $1,250 |
| Attic | Over R-12, up to R-25 | R-50 | $1,000 |
| Attic | Over R-25, up to R-35 | R-50 | $800 |
| Cathedral ceiling or flat roof | R-12 or less | R-20 | $650 |
| Cathedral ceiling or flat roof | R-25 or less | R-28 | $750 |
The rebate is the lower of the maximum and 50% of the after-tax insulation cost. Attics already above R-35 are not in the table and do not qualify in this stream. For your whole roof assembly, 100% of the area must be insulated, and new insulation goes where the old insulation is.
Examples
- Attic at R-12, $3,000 after tax: half is $1,500, the cap is $1,250, so the rebate is $1,250 and you pay $1,750.
- Attic at R-12, $2,000 after tax: half is $1,000, below the cap, so the rebate is $1,000 and you pay $1,000.
- Attic between R-12 and R-25, $1,400 after tax (program example): half is $700, below the $1,000 cap, so the rebate is $700.
- Cathedral ceiling at R-12 or less, $1,600 after tax (program example): half is $800, above the $650 cap, so the rebate is $650. With the $700 attic rebate above, the two parts add up to $1,350.
How much insulation do you need to add?
For an attic, the program requires R-50 in total. The table shows how many inches you would add with each material, using the design values in Natural Resources Canada’s Table 3-1 (settled thickness). The R-value printed on your contractor’s quote or label is the one that counts, so use these figures only as a rough guide.
| Material | R per inch (design value) | R-12 to R-50 (add 38) | R-25 to R-50 (add 25) | R-35 to R-50 (add 15) |
|---|---|---|---|---|
| Blown glass fibre (loose fill) | R-2.9 | 13.1 in. | 8.6 in. | 5.2 in. |
| Blown cellulose | R-3.6 | 10.6 in. | 6.9 in. | 4.2 in. |
| Blown mineral fibre (loose fill) | R-3.0 | 12.7 in. | 8.3 in. | 5.0 in. |
| Glass fibre batt | R-3.2 | 11.9 in. | 7.8 in. | 4.7 in. |
Not sure what you have now? As a rough guide, about 4 in. of old loose-fill fibreglass is R-12, 8 in. is R-23 and 12 in. is R-35, at R-2.9 per inch. Compressed or damp insulation gives less.
When the calculator shows “Not eligible in this stream”
The attic stream has no rebate for an attic already above R-35, or for a cathedral ceiling or flat roof already above R-25. In those cases the calculator shows “Not eligible in this stream” and leaves the level and the cost blank.
What the calculator does not check
- You must own the home (a landlord can apply for a rented home) and it must be occupied for at least six months. Tenants cannot apply.
- The home must be a detached or semi-detached house, a row house, a townhome that is not stacked, or a mobile home on a permanent foundation, heated with Enbridge natural gas or on the Ontario electricity grid.
- The work must be done by a contractor on the program’s participating list, after the in-home visit, and finished by November 30, 2026. The program says registrations for new contractors are closed.
- A home that already received an attic rebate from an Enbridge Gas or Save on Energy program cannot receive a second one for the attic.
- For cathedral ceilings and flat roofs the program lists “R-12 or less” ($650, reach R-20) and “R-25 or less” ($750, reach R-28). The calculator reads the second row as “over R-12, up to R-25”.
- Funding is limited and the program can change amounts before your work is finished. The amount that applies is the one in effect when the work is completed.
In short
- The rebate is 50% of the after-tax cost, up to $1,250 for an attic and $750 for a cathedral ceiling or flat roof.
- The maximum depends on the insulation level found at the in-home visit, and the new total must reach R-50 (attic), R-20 or R-28.
- No energy assessment is needed, but a participating contractor is mandatory and the work must be finished by November 30, 2026.
- Only the program decides the amount you receive.
To estimate the cost of the work itself, use our attic insulation cost calculator (area and target R-value).
Frequently asked questions
How much is the Ontario attic insulation rebate?
50% of your after-tax cost, up to $1,250 for an attic and up to $750 for a cathedral ceiling or flat roof. The maximum depends on your starting insulation level.
What R-value do I need to reach for the attic rebate?
R-50 for an attic. For a cathedral ceiling or flat roof, R-20 if you start at R-12 or less, or R-28 if you start at R-25 or less.
Do I need an energy assessment for the attic insulation rebate?
No. The attic stream does not require a home energy assessment, but you must pre-register and use a participating contractor.
How do I know my current insulation level?
The contractor measures it at the in-home visit, and that measurement sets your maximum. As a rough guide, 4 in. of loose-fill fibreglass is about R-12.
What is the deadline for the Ontario attic insulation rebate?
The insulation must be installed by November 30, 2026, and the contractor must enter your file in the program system by December 31, 2026.
Can I use the calculator for both an attic and a cathedral ceiling?
Yes. Run it once for each roof part and add the two rebates, using the cost of each part.
Sources
- Home Renovation Savings – Attic insulation (Save on Energy and Enbridge Gas), checked October 23, 2026.
- Home Renovation Savings – Terms and conditions (Attic Program Stream Additional Program Eligibility Requirements, version January 2026), checked October 23, 2026.
- Natural Resources Canada – Keeping the Heat In, Section 3, Table 3-1 (insulation values), page modified January 31, 2025, checked October 23, 2026.
