Quick answer: Most Ontario attics benefit from being topped up to at least R-50, which takes roughly 14 inches of cellulose or about 17–20 inches of blown fiberglass. Ontario’s Home Renovation Savings Program currently pays 50% of the after-tax insulation cost, up to $1,250, on the standalone attic path, with no energy assessment needed. The program is currently scheduled to run until March 31, 2027, and amounts can change. The 40 answers below cover basics, rebates, materials, process, safety and what happens after the job.
Updated November 2026
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Key takeaways
- R-50 is the target to qualify for the standalone attic rebate; the Ontario Building Code targets about R-60 for new homes.
- The rebate is 50% of the after-tax insulation cost, up to a tier cap of up to $1,250. See current rebates.
- Any insulation type qualifies if the target R-value is met and a participating contractor installs it.
- Air sealing matters as much as depth in older homes.
- Never disturb loose, pebbly grey-brown or gold fill. It could be vermiculite.
Basics
These answers cover what attic insulation does, how R-value works and how much an Ontario home needs.
What does attic insulation do?
Attic insulation slows heat moving through your ceiling. In winter it keeps heat in your living space, and in summer it keeps attic heat out. It works best when air leaks into the attic are sealed too. Together, insulation and air sealing help keep upstairs rooms closer to the temperature you set.
What is R-value?
R-value measures how well a material resists heat flow. The higher the number, the better it insulates. Heat flow through the insulation layer is roughly proportional to 1 divided by R, so doubling R-value roughly halves conductive heat flow (simplified).
How much attic insulation does an Ontario home need?
The Ontario Building Code (SB-12) targets about R-60 for attic ceilings in new homes in most of Ontario. Existing homes are not required to upgrade, and many older attics sit well below that. To qualify for the standalone attic rebate, you need to reach at least R-50, or R-28 / R-20 for cathedral and flat roofs.
How many inches of insulation is R-50?
It depends on the material. Blown cellulose at about R-3.5 per inch needs about 14.3 inches (50 ÷ 3.5). Blown fiberglass at about R-2.5 to R-3 per inch needs about 17 to 20 inches. If you already have some insulation, you only need to add the difference.
How do I know if my attic needs more insulation?
Common signs include seeing the tops of the ceiling joists, uneven room temperatures, ice dams and rising heating use. Our list of 12 signs your attic needs insulation covers them all, with what to do for each. If two or more apply, it is worth measuring your attic.
How do I check my attic insulation level?
Look in from the hatch, identify the material, and measure the depth with a ruler. Multiply the inches by the R-value per inch, and do not step between the joists. Our step-by-step guide on how to check attic insulation R-value includes safety tips and worked examples.
Does an older home need more attic insulation than a newer one?
Often, yes. Older homes were usually built with much less attic insulation, and it settles over time. In Ontario, nearly 1.2 million residential properties were built in 1960 or earlier (Statistics Canada). See more in our Ontario insulation statistics.
Cost & rebates
Rebate amounts below are from the Home Renovation Savings Program. They are “up to” amounts, the program is first-come, first-served, and amounts can change.
How much does attic insulation cost in Ontario?
The cost depends on attic size, how much depth you need to add, the material, access, and whether old insulation must be removed first. Air sealing and hatch work add to the scope. The best way to get a real number is a written quote based on a measured attic. Remember to compare the net price after the rebate, not just the headline price.
What attic insulation rebate is available in Ontario right now?
The Home Renovation Savings Program, run by Enbridge Gas and Save on Energy with backing from the Government of Ontario, offers a standalone attic rebate. It pays 50% of the after-tax insulation cost, up to $1,250 depending on your starting level. Amounts can change; see our Ontario attic insulation rebate page.
What are the attic rebate tiers?
On the standalone path: R-12 or less to R-50 is up to $1,250; above R-12 to R-25 to R-50 is up to $1,000; and above R-25 to R-35 to R-50 is up to $800. Cathedral or flat roofs get up to $750 (R-25 or less to R-28) or up to $650 (R-12 or less to R-20). Amounts can change, so confirm the current figures on our rebates page.
How is the rebate amount calculated?
It is 50% of your after-tax insulation cost, capped at your tier maximum. For example (numbers only), a $2,000 after-tax cost gives 50% = $1,000, which is under a $1,250 cap, so the rebate would be $1,000. Our quote comparison template shows more examples.
Do I need an energy assessment for the attic rebate?
Not on the standalone attic path. The bundle path does require a home energy assessment before and after the work, plus two or more upgrades. On the bundle path, the assessment itself has $600 back. The assessments are done by a registered energy advisor, and work done before the first assessment does not count.
What is the difference between the standalone attic path and the bundle path?
The standalone path is attic only, no assessment, with rebates up to $1,250. The bundle path needs an assessment and two or more upgrades, and offers attic rebates up to $1,500 plus rebates for walls, basements, air sealing and more. You cannot combine an attic rebate from both paths. Read more on our rebates hub.
Who qualifies for the Home Renovation Savings Program?
You must own the home and heat it with Enbridge natural gas, or with electricity, oil, propane or wood on the IESO grid. Single-detached, semi-detached, townhouses and some other dwelling types can qualify. Cottages and seasonal homes can qualify for the attic path if they meet the requirements.
How long will the rebate program last?
It is currently scheduled to run until March 31, 2027, after being extended in October 2026. The terms allow it to change or end early, and funding is first-come, first-served. If you are considering the work, it makes sense not to wait too long.
Can I get the rebate if I already got one before?
Homes that already received an attic rebate from Enbridge, Save on Energy or the Home Renovation Savings Program may not qualify again. If you are unsure, check your records before booking. A participating contractor can help you confirm.
How long does it take to get the rebate cheque?
Rebate cheques typically arrive within a few months after the submission is approved. Keep your invoice and paperwork until it arrives. Our guide on how to claim the attic insulation rebate explains each step.
Materials
All R-values per inch below are general industry figures. Actual values vary by product and installation.
What is the best insulation for an Ontario attic?
For most open attics, blown cellulose or blown fiberglass is the practical, lower-cost choice. Spray foam suits cathedral ceilings, flat roofs and tight spaces where depth is limited. The right choice depends on your attic, not on a single product. Our cellulose vs fiberglass vs spray foam comparison walks through each.
Is cellulose better than fiberglass?
Cellulose has a higher R-value per inch (about R-3.5 versus about R-2.5 to R-3), so you need less depth. Fiberglass is lighter and does not absorb water. Both are good choices when installed properly. The quality of the installation usually matters more than the choice between them.
When does spray foam make sense in an attic?
Spray foam makes sense where you need air sealing and high R-value in little space, such as cathedral ceilings, flat roofs and rim joists. Closed-cell foam gives about R-6 to R-7 per inch. On a big open attic floor, loose fill usually reaches R-50 for less. See our spray foam insulation service.
Does insulation type affect my rebate?
No. The standalone attic rebate allows any insulation type as long as you reach the target R-value and use a participating contractor.
Can new insulation go on top of old insulation?
Yes, if the old insulation is dry, clean and not vermiculite. Add the R-value of each layer to get your total. If the old material is damp, mouldy or soiled, it should come out first. See our insulation removal service.
Does blown-in insulation settle?
Loose fill settles some over time, cellulose more than fiberglass. A good installer blows enough to reach the target depth after settling. Spray foam does not settle. Depth markers let you check the depth later.
What is dense-pack insulation?
Dense-pack is cellulose blown tightly into closed cavities such as walls or enclosed ceilings. It is useful where there is no open attic to blow loose fill into. Learn more about dense-pack wall and ceiling insulation.
Process
Here is what to expect from the first visit to the day the crew packs up.
What happens during an attic assessment?
The installer checks your current depth and material, looks for air leaks, ventilation, moisture and pests, and confirms your roof type. That sets your likely rebate tier and the scope. You should get the target R-value and depth in writing. A free assessment carries no obligation to book.
How long does attic insulation take to install?
A straightforward top-up on a typical attic is often done in a day. Jobs that need removal, extensive air sealing or pest clean-up take longer. Your quote should list a timeline. Ask about start dates early, since busy seasons fill up.
Why does air sealing matter if I am adding insulation?
Loose fill slows heat, but it does not stop air. Air leakage represents about 20–30% of heat lost from an older home (Natural Resources Canada). Sealing first lets the insulation do its job. See our air sealing service.
What are attic baffles?
Baffles are channels installed at the eaves that keep insulation from blocking soffit vents. They let outside air flow along the underside of the roof. Without them, insulation can choke ventilation and trap moisture. Ask whether they are included in your quote.
Should the attic hatch be insulated?
Yes. The hatch is often one of the leakiest spots in the ceiling. It should be insulated on top and weatherstripped around the edge so it closes tightly. It is a small item that is easy to miss on a quote.
Do I need to be home during the installation?
Usually you need to be home to let the crew in and confirm the scope, but you can carry on with your day. Clear a path to the hatch and keep pets and children away from the work area.
How do I compare insulation quotes?
Put them side by side on the same rows: target R-value, material, depth, air sealing, baffles, hatch, removal, rebate handling, after-tax price, rebate estimate and net price. Our insulation quote comparison template and attic insulation checklist make this easy.
Problems & safety
Some attic problems need to be dealt with before any new insulation goes in. If you are unsure, stop and ask.
What does vermiculite look like, and is it dangerous?
Vermiculite is loose, pebbly fill, usually grey-brown or gold. Some vermiculite, such as Zonolite Attic Insulation from the Libby mine in Montana, may contain asbestos. Health Canada advises not disturbing it, keeping children out of the attic, and using qualified professionals for testing and removal. See vermiculite and asbestos removal.
Can I insulate over vermiculite?
Do not disturb it or add insulation over it until it has been tested. Not all vermiculite contains asbestos, but it should be treated as if it does until tested. Testing tells you what your safe options are. Keep children out of the attic in the meantime.
What causes ice dams?
Ice dams usually form when heat leaks into the attic and warms the roof, melting snow that refreezes at the cold eaves. Low insulation and air leaks together are the usual cause. The fix normally includes air sealing and more insulation. Chipping ice off the roof can damage shingles, so focus on the cause instead.
What if I find mould in my attic?
Dark staining or fuzzy spots on the roof sheathing often point to warm, moist air leaking into the attic. One small air leak can let in 100 times more moisture than diffusion through the same area (Natural Resources Canada). Have it assessed, fix the air leaks, and see our mould removal and sanitation service.
What should I do about animal droppings in the insulation?
First make sure the animals are gone and entry points are closed. Soiled insulation should be removed and the area sanitized rather than covered over. See our animal and insect feces removal service.
Is it safe to walk in my attic?
Only on boards or framing that can hold your weight. Drywall between the joists will not support you, and stepping on it can put your foot through the ceiling. Be careful around wiring and do not touch loose pebbly fill. For most checks, staying at the hatch is enough.
After the job
A few simple checks and good records make the rebate and any future work easier.
How can I check the insulation was installed properly?
Look at the depth markers from the hatch and compare them to the depth in your quote. Make sure baffles are at the eaves and the hatch is insulated and weatherstripped. Take photos for your records. If something does not match, ask the contractor to come back before the rebate is submitted.
What paperwork should I keep after the job?
Keep the quote, final invoice with the material, final R-value and after-tax insulation cost, any rebate forms, your warranty and your before-and-after photos. These help with your rebate and with any future home sale. Store paper and digital copies together.
How much will my heating bill drop?
It depends on your home, air leaks, heating system and weather, so no one can give you an exact figure. What we can say is that going from R-12 to R-50 cuts conductive heat flow through the insulation layer by about 76% (1 − 12/50), simplified. That is not the same as a bill saving. See our Ontario attic rebate study for more.
How long does attic insulation last?
Well-installed insulation that stays dry and undisturbed can last for decades. Loose fill can settle or get crushed over time, and pests or roof leaks can damage it. Check it from the hatch every few years. Top it up if the depth has dropped.
Quick reference: depth, R-value and rebate tiers
Use these two tables alongside the answers above. Inches are worked out as target R-value ÷ R-value per inch.
| Material | R-value per inch (approx.) | Inches for R-50 | Inches for R-60 |
|---|---|---|---|
| Blown fiberglass | about R-2.5 to R-3 | about 17 to 20 | about 20 to 24 |
| Blown cellulose | about R-3.5 | about 14.3 | about 17.1 |
| Open-cell spray foam | about R-3.5 to R-3.7 | about 13.5 to 14.3 | about 16.2 to 17.1 |
| Closed-cell spray foam | about R-6 to R-7 | about 7.1 to 8.3 | about 8.6 to 10 |
| Attic before upgrade | Upgrade to at least | Maximum rebate (standalone path) |
|---|---|---|
| R-12 or less | R-50 | up to $1,250 |
| Above R-12 to R-25 | R-50 | up to $1,000 |
| Above R-25 to R-35 | R-50 | up to $800 |
| Cathedral/flat roof, R-25 or less | R-28 | up to $750 |
| Cathedral/flat roof, R-12 or less | R-20 | up to $650 |
The rebate is 50% of the after-tax insulation cost, up to the tier maximum, and requires a participating contractor. For the bigger picture, see the Home Renovation Savings Program page and our Ontario attic rebate study.
Get a free attic assessment
Have a question that is not answered here? Pro Home Insulation has more than 10 years of experience insulating attics across Toronto, the GTA and nearby Southern Ontario, including Toronto, Richmond Hill and Burlington. We will measure your attic and explain your rebate tier. Call (647) 250-0606 or Book online.