Spray Foam vs. Fiberglass Batt Insulation: Which Is Right for Your Home?

If you’re planning to upgrade your home’s insulation, two options come up again and again: spray foam and fiberglass batt. Both can dramatically improve comfort and cut your heating and cooling bills, but they work differently, cost differently, and suit different parts of the house. Here’s an honest, Ontario-focused comparison to help you decide.

The quick answer

Neither material is universally “better.” The right choice depends on where you’re insulating, your budget, and whether air leakage is part of the problem. In many Ontario homes, the smartest solution is actually a combination — spray foam where air sealing matters most, and fiberglass batt where it’s the more cost-effective fit.

R-value per inch

R-value measures resistance to heat flow — higher is better. This is where the two materials differ most clearly.

• Fiberglass batt: roughly R-3.1 to R-3.4 per inch. To reach the R-60 now recommended for Ontario attics, you need a thick layer.
• Open-cell spray foam: around R-3.5 to R-3.9 per inch.
• Closed-cell spray foam: roughly R-6 to R-7 per inch — the highest of the three, so it delivers more insulating power in less space.

If space is tight — think rim joists, cathedral ceilings, or narrow wall cavities — closed-cell spray foam’s high R-value per inch is a real advantage.

Air sealing: the deciding factor for many homes

This is often more important than R-value alone. A large share of a home’s energy loss comes from air leaking through gaps, not just conducting through insulation.

Fiberglass batt resists heat flow, but air can still move around and through it. Spray foam expands to fill cracks and gaps, sealing air leaks as it insulates.

Closed-cell spray foam also acts as an air and vapour barrier, which is why it excels in basements, rim joists, and hard-to-seal areas. Fiberglass batt, on the other hand, needs a separate, well-installed air barrier to perform its best — and gaps or compression during installation can noticeably reduce its effectiveness.

Cost

Budget is usually where the two part ways.

• Fiberglass batt is the more affordable option per square foot, both in material and labour. It’s a proven, cost-effective choice for open, accessible areas.
• Spray foam costs more upfront — closed-cell most of all — because of the material and specialized equipment involved. The trade-off is superior air sealing and higher performance in less space.

The good news for Ontario homeowners: with available rebates and financing, most homes qualify for $0 upfront, which softens the cost difference considerably.

Best use cases

Where fiberglass batt shines

• Open, easily accessible attic floors and standard wall cavities
• Projects where budget is the primary driver
• Homes that already have a sound air barrier in place

For many Ontario attics, a proper top-up of fiberglass or blown-in insulation to R-60 is the most economical upgrade. Our attic insulation service often uses Owens Corning PINK NEXT GEN® materials for exactly this reason.

Where spray foam shines

• Rim joists and basement headers, where air leaks are common
• Cathedral ceilings and tight cavities with limited depth
• Crawl spaces and areas needing an integrated air and vapour barrier

If air leakage and moisture are your main concerns, our spray foam insulation service is usually the stronger fit.

Rebate eligibility

Both spray foam and fiberglass batt insulation can qualify for support under the Ontario Home Energy Rebate Program, provided the work meets the program’s requirements and is documented properly. Rebates are typically tied to the improvement in your home’s energy performance — often confirmed through a pre- and post-upgrade energy assessment — rather than to one specific material.

PolarCore Systems is certified for the program and an Owens Corning authorized installer, and we handle all the rebate paperwork for you. That means you get the right product for each part of your home without worrying about missing paperwork or deadlines.

So, which is right for you?

Choose fiberglass batt for open, accessible spaces where cost-effectiveness matters and a good air barrier already exists. Choose spray foam where air sealing, moisture control, or tight spaces demand more. And in plenty of Ontario homes, the best plan uses both — matched to each area’s needs.

The only way to know for certain is to have your home assessed. PolarCore Systems offers free assessments across Toronto, the GTA, and Ontario, and we’ll recommend the right approach for your home and budget — not a one-size-fits-all upsell. Book your free assessment online today, or call us at (647) 740-9246. With rebates handled and $0 upfront for most homes, a warmer, more efficient home is closer than you think.