The Three Types, Straight Up
Blown-In Fiberglass
Cost installed: $1.50-$2.50 per square foot, or roughly $1,800-$3,200 for a typical 1,500-square-foot attic. R-value: about R-2.5 per inch. Best for: open, accessible attics with no obstructions.
The default choice for a straightforward attic top-up. It's cheap, fast to install in a few hours, and doesn't settle much over time. It doesn't seal air leaks on its own, so a contractor who skips air sealing before blowing in fiberglass is leaving performance on the table.
Blown-In Cellulose
Cost installed: $1.75-$3.00 per square foot, or roughly $2,100-$3,800 for the same attic. R-value: about R-3.5 per inch. Best for: attics where you want higher density and better sound dampening for a modest premium over fiberglass.
Made from recycled paper treated with borate for fire and pest resistance. It packs denser than fiberglass, which cuts air movement through the insulation layer itself, but it can settle 15-20% over the first few years, so installers should account for that in the initial depth.
Spray Foam (Closed-Cell)
Cost installed: $4.50-$8.00 per square foot for closed-cell, so a full attic runs $6,000-$12,000, though most BC jobs use it selectively rather than whole-attic. R-value: about R-6.5 per inch. Best for: rim joists, crawlspaces, cathedral ceilings, and irregular framing where air sealing is the real problem.
Foam seals and insulates in one step, which matters in spots where blown-in material can't reach or would just fall through gaps. For a standard open attic it's overkill — you're paying three to four times the price for R-value you can get cheaper with fiberglass or cellulose plus separate air sealing.
| Type | Cost (1,500 sq ft attic) | R-value per inch | Best use |
|---|---|---|---|
| Blown-in fiberglass | $1,800-$3,200 | ~R-2.5 | Open attic top-up |
| Blown-in cellulose | $2,100-$3,800 | ~R-3.5 | Denser fill, sound dampening |
| Spray foam | $6,000-$12,000 (full) / spot-priced | ~R-6.5 | Rim joists, crawlspaces, air sealing |
How the BC Rebate Applies
BC Hydro and CleanBC offer up to $5,500 for insulation, depending on your income and how much of your home you're upgrading. A single-measure job — just the attic, say — usually lands in the $1,000-$3,000 range. Whole-home retrofits that add insulation alongside air sealing and other upgrades can push toward the $5,500 ceiling, and stacking with the federal Canada Greener Homes Loan has pushed some homeowners' combined savings to $11,350.
The rebate amount is set provincially, so it's the same whether you're in Abbotsford, Kelowna, or Victoria — check your BC city page for the local installer list, but the rebate math doesn't change by city.
Rebates typically cover 30-50% of project cost, which means the type you choose has a direct effect on your out-of-pocket total: fiberglass or cellulose at $2,000-$3,000 might come down to $1,000-$1,800 after rebate, while a full spray-foam job at $8,000 still leaves you paying $4,500-$6,500 even after the maximum rebate.
What to Check Before You Buy
- Current attic depth: Most BC building code calls for R-40 to R-50 in attics. Have the installer measure your existing depth before quoting — many homes only need a top-up, not a full removal and replace.
- Air sealing first: Insulation without air sealing is like a winter coat with the zipper open. Ask whether the quote includes sealing around pot lights, the attic hatch, and top plates before insulation goes in.
- Ventilation: Blocking soffit vents with insulation causes moisture problems. Confirm baffles are installed to keep airflow open at the eaves.
- Vapor barrier condition: If your attic has an old or damaged vapor barrier, ask how the installer plans to handle it — insulating over a compromised barrier can trap moisture in the roof structure.
What to Ask Before You Sign
- "What R-value am I at now, and what will I be at after?"
- "Does this quote include air sealing, or just the insulation material?"
- "Will you file the BC Hydro/CleanBC rebate claim, or do I need to?"
- "What's the installed cost after rebate, not before?"
- "Are soffit vents baffled so airflow stays open?"
The One Number That Matters
Topping up an under-insulated BC attic from R-20 to R-50 typically cuts heating costs by 10-15%, which on an average BC Hydro electric heating bill works out to roughly $150-$300 a year. Combined with the rebate, most single-measure attic jobs pay back their remaining out-of-pocket cost in under five years.