Quick quiz: how insulation works
Ten questions on the technology. Tap an answer to see why.
Short answer: Seal the air leaks in your attic floor first, then add insulation. In cold places (most of Canada and the northern US), aim for about R-60 total, per ENERGY STAR. Blown-in insulation is the usual choice for topping up. You can often do it yourself, but hire a pro if you see vermiculite, old knob-and-tube wiring, mould, or if your rebate requires a certified contractor.
Step 1: Check what you have now
Pop the attic hatch with a flashlight. Don't step between the joists: the ceiling below won't hold you. Look for:
- How deep the insulation is. Measure in a few spots. If you can see the tops of the joists, you almost surely need more.
- What kind it is. Fluffy pink, yellow or white is fibreglass. Grey, shredded paper is cellulose. Pebbly, grey-brown or gold granules may be vermiculite. Don't touch it (see safety below).
- Signs of moisture. Dark stains or frost on the roof boards, damp or matted insulation, or rusty nails mean warm, moist air is leaking up. Fix that before adding insulation.
- Air leak spots. Dirty, dark patches in the insulation often mark where house air is leaking through and leaving dust behind.
How much attic insulation do you need? (R-values by climate)
R-value measures how well insulation slows heat. Higher is better. Here is what ENERGY STAR recommends for attics:
| Climate | Attic with little or no insulation | Attic with 3 to 4 inches now |
|---|---|---|
| Hot (US zone 1) | Bring to R-30 | Add R-25 |
| Warm (US zones 2 and 3) | Bring to R-49 | Add R-38 |
| Mixed to very cold (US zones 4 to 8; most of Canada) | Bring to R-60 | Add R-49 |
Canada doesn't use the US zones, but most Canadian homes are in climates as cold as or colder than zones 5 to 7. So R-50 to R-60 is a good target in most of Canada. Your provincial building code sets the minimum for new work. Each bag of insulation has a coverage chart that shows how deep to blow it to reach each R-value. Follow that, not a guess.
Canada: attic R-value targets by climate zone
Natural Resources Canada's Keeping the Heat In guide recommends attic insulation by climate zone, measured in heating degree-days (HDD), a count of how cold a place is over the year. Colder zones need more. Find your zone, then check your local building code, which may set a different minimum.
| Zone | Heating degree-days | BC examples | Recommended attic |
|---|---|---|---|
| 4 | Under 3,000 | Vancouver, Victoria, Surrey, Burnaby | R-45 (RSI 7.9) |
| 5 | 3,000 to 3,999 | Kamloops, Kelowna, Nanaimo, Vernon | R-55 (RSI 9.7) |
| 6 | 4,000 to 4,999 | Prince George, Cranbrook, Whistler | R-60 (RSI 10.6) |
| 7a to 8 | 5,000 and above | Fort St. John, Dawson Creek, Fort Nelson | R-80 (RSI 14.1) |
Sources: Natural Resources Canada, Table 2-1 · Better Homes BC climate zones. Checked September 29, 2026. These are guidelines, not code.
- Rebates may stop short of the guideline. Ontario's and Nova Scotia's attic rebates are for insulating up to R-50, which is below the guideline for zones 5 and up. You can add more at your own cost.
- Adding over old insulation with a plastic vapour barrier? Natural Resources Canada says to put at least twice the insulating value above the barrier as below it (its example: R-12 below means at least R-24 on top). That keeps moisture from getting trapped.
- Not in BC? Look up your town's heating degree-days and match it to the zone above.
Why air sealing comes first
Insulation slows heat moving through it. It does not stop air. Warm, moist house air leaking into the attic carries heat with it and can condense on the cold roof boards. Adding insulation makes the attic colder, which makes that worse. Natural Resources Canada is clear: don't count on insulation to do the job of air sealing.
Before you add any insulation, seal these spots on the attic floor:
- Holes around plumbing stacks and vent pipes (use flexible gaskets or sealant)
- Electrical boxes and wire holes
- Duct joints and ceiling registers (foil tape or mastic)
- The tops of inside walls, where the wall meets the attic floor
- Around chimneys, using non-combustible materials only
- The attic hatch: weatherstrip it and insulate the top of the lid
Keep the attic vented
Air should flow in at the soffits (under the eaves) and out near the peak. Put baffles between the rafters at the eaves so new insulation can't block the soffit vents. NRCan suggests leaving 1.5 to 2 inches of air space between the top of the insulation and the roof boards there.
Blown-in vs batts vs spray foam
- Blown-in (loose-fill) fibreglass or cellulose: fills around wires and odd framing well. Best for topping up an existing attic. You can rent a blower at many hardware stores.
- Batts: cheaper and cleaner to handle in tight spots. Lay a second layer across the first so it covers the tops of the joists.
- Spray foam: seals and insulates in one step, but it costs more and is a pro-only job. Mostly used on roof slopes, not on open attic floors.
Safety checks before you start
- Vermiculite: may contain asbestos. Don't disturb it. Get it tested and removed by a pro first.
- Old wiring: knob-and-tube or frayed wires need an electrician before you cover them.
- Pot lights: older recessed lights can overheat under insulation. Replace them with airtight, insulation-contact (IC) rated fixtures, or box them in with the clearance the maker requires.
- Chimneys and flues: keep insulation at least 3 inches away using a non-combustible barrier.
- Animal droppings: large amounts can carry mould and bacteria. Call a pro.
DIY vs hiring a pro
DIY can make sense if your attic is easy to reach, dry, has room to move, and none of the safety issues above apply. Wear a good mask, goggles, gloves and long sleeves, and put boards across the joists to walk on.
Hire a pro if the attic is tight or low, you find any of the safety issues, you want the air sealing done properly, or your rebate requires a certified contractor. Get a written quote that lists the R-value added, the square footage, the air sealing work, baffles, and hatch sealing.
We don't list typical prices here because they vary widely by region, attic size and access. Get two or three quotes that spell out the same scope so you can compare them fairly.
Attic insulation rebates
- BC, electrically heated homes (BC Hydro): $0.02 per square foot for each R-value point added, up to $900 for an attic. You must add at least R-12, use a Home Performance Contractor Network (HPCN) member, and follow BC Hydro's air sealing best-practice guide. DIY doesn't qualify.
- BC, gas-heated homes: check FortisBC's insulation rebates.
- United States: the federal 25C tax credit for insulation ended on December 31, 2025. State and utility programs vary.
- Elsewhere: see your city's page for what's open now.
Doing a heat pump too? Insulate and air seal first. A tighter home needs a smaller heat pump. Read why insulation comes first.
Attic insulation rebates by region
| Where | Attic rebate | Key rule |
|---|---|---|
| BC (BC Hydro) | $0.02 per sq ft per R added, up to $900 | Electric heat, HPCN contractor, at least R-12 added |
| Ontario | Up to $1,250 without an assessment; to R-50 with one: $1,500, $1,200 or $900 | Assessment before and after for the larger amounts |
| Nova Scotia | To R-50, up to $750 | Through a Home Energy Assessment |
| Massachusetts | 75% to 100% off insulation and air sealing | Start with the free Mass Save assessment |
| New York | $2,500 or $3,000 seal-and-insulate package | Comfort Home contractors, participating counties |
| California (SMUD) | Up to $3,000 for air sealing, attic insulation and ducts | SMUD Contractor Network |
See every program, with sources and more regions, on the insulation rebates by province and state page.
What to do next
- Look in your attic and note the depth, type and any warning signs.
- Check your rebates before you start. Some require a pro or a pre-work energy assessment.
- Air seal, add baffles, then insulate to your target R-value.
- Keep your receipts and before/after photos.
FAQ
How much attic insulation do I need?
ENERGY STAR recommends R-49 to R-60 for most attics in cold climates (US zones 4 to 8), and R-30 to R-49 in warm ones. Most of Canada is as cold as or colder than those cold zones, so R-50 to R-60 is a sensible target. Check your local building code too.
Should I air seal before adding attic insulation?
Yes. Insulation slows heat, but it does not stop air. Natural Resources Canada says not to rely on batt, blown-in or loose-fill insulation in place of proper air sealing. Seal around pipes, wires, light boxes, the hatch and the tops of walls first.
Can I insulate my attic myself?
Many people can, if the attic is easy to reach, dry, and free of vermiculite, knob-and-tube wiring or animal droppings. Many rebates require a pro, though. In BC, the BC Hydro attic insulation rebate requires a Home Performance Contractor Network (HPCN) member, so DIY work does not qualify.
Is blown-in or batt insulation better for an attic?
Blown-in (loose-fill) fills odd spaces and gaps around wires and framing more easily. Batts are cheaper to buy and cleaner to handle in tight spaces. For topping up an existing attic, blown-in is the most common choice.
What if my attic has vermiculite insulation?
Don't touch it. Vermiculite may contain asbestos. Natural Resources Canada says not to disturb it. Have it tested and, if needed, removed by a qualified abatement company before any other work.
Is there a rebate for attic insulation in BC?
Yes, for electrically heated homes. BC Hydro pays $0.02 per square foot for each R-value point you add, up to $900 for an attic, with at least R-12 added and an HPCN contractor. Gas-heated homes should check FortisBC. See your city's page for other programs.
Related reading
- Why insulation first: the best order for a home retrofit
- What happens in an energy audit
- Home energy assessment: questions to ask
Sources, checked September 26, 2026: ENERGY STAR recommended R-values · NRCan Keeping the Heat In: roofs and attics · BC Hydro insulation rebates · FortisBC insulation rebates · IRS 25C credit
