Spray Foam vs Blown-In Insulation: A Canadian Homeowner's Guide

If you are insulating a Canadian home, two names come up again and again: spray foam and blown-in insulation. They sound similar, they both fill gaps that batts cannot, and they are both far better than the bare cavities found in many older houses. But they are very different products, with different costs, different R-values, different health and safety considerations, and very different best uses. This guide compares them honestly, with Canadian pricing and the climate realities of Atlantic Canada and British Columbia in mind, so you can choose the right one for each part of your home.

Greenfoot installs several types of insulation, including spray foam and blown-in, so this is not a sales pitch for one product. The honest answer is that the best choice depends on where the insulation is going, what your budget is, and what problem you are trying to solve.

What is the difference between spray foam and blown-in insulation?

The simplest way to understand the difference is how each product is delivered and what it does once it is in place. Spray foam arrives as two liquid chemicals that are mixed at the nozzle and sprayed onto a surface, where they expand and harden into a solid plastic. It both insulates and air seals in one step. Blown-in insulation is loose material, usually cellulose or fibreglass, that is blown through a hose into attics or wall cavities, where it settles into a thick, fluffy layer. It insulates very well but does not air seal on its own.

That single distinction, air sealing built in versus air sealing separate, drives most of the differences in price, performance, and where each one belongs.

How does spray foam insulation work?

Spray foam is a two-part polyurethane product. When the two parts combine, they react and expand to many times their liquid volume, flowing into cracks and gaps before they cure into a rigid or semi-rigid plastic. Because it bonds to the surface and seals air leaks as it expands, spray foam delivers both insulation and an air barrier at the same time. There are two main types.

Open-cell spray foam

Open-cell foam is lighter and softer, with an R-value of roughly R-3.6 to R-3.9 per inch. The cells are not fully closed, so it stays flexible and lets some vapour through. It is a good choice for interior walls and ceilings where sound control and a moderate budget matter. It is not a vapour barrier on its own.

Closed-cell spray foam

Closed-cell foam is denser and harder, with an R-value of roughly R-6 to R-7 per inch, the highest of any common insulation. The closed cells block both air and moisture, so it acts as an air barrier and a vapour retarder in one product. That makes it the go-to for rim joists, crawl spaces, basements, and anywhere moisture is a concern, which matters a great deal in coastal Atlantic Canada and damp parts of BC. The trade-off is cost: closed-cell foam is the most expensive insulation per square foot.

How does blown-in insulation work?

Blown-in insulation, also called loose-fill, is installed with a machine that fluffs up loose material and blows it through a long hose. In an attic, the crew simply covers the floor with an even blanket to the target depth. In walls, the drill and fill method packs the material into closed cavities under pressure. There are two common materials.

Cellulose

Cellulose is made from recycled paper treated with borate for fire and pest resistance. It has an R-value of about R-3.5 to R-3.7 per inch, packs densely, and fills around wires and obstructions well, which reduces air movement inside the cavity. It is a popular, lower-carbon choice for attics and for retrofitting older Canadian walls.

Fibreglass

Loose-fill fibreglass is spun glass fibre with an R-value of about R-2.5 to R-3.5 per inch. It is light, will not absorb water, and is often the lowest-cost option for open attics. In very cold attics, low-density fibreglass can lose some performance through convection unless it is installed deep enough, so attic depth and density matter.

Spray foam vs blown-in: R-value and performance compared

R-value measures resistance to heat flow, and higher is better. Here is how the common products stack up per inch of thickness:

• Closed-cell spray foam: about R-6 to R-7 per inch, plus a built-in air and vapour barrier
• Open-cell spray foam: about R-3.6 to R-3.9 per inch, plus a built-in air barrier
• Cellulose blown-in: about R-3.5 to R-3.7 per inch
• Fibreglass blown-in: about R-2.5 to R-3.5 per inch

But R-value per inch is only half the story. The other half is air leakage. Natural Resources Canada notes that uncontrolled air movement can account for a large share of a home's heat loss. Blown-in insulation slows heat conduction but does little to stop air leaks, so it is usually paired with separate air sealing. Spray foam stops the air leak and insulates in the same pass. That is why a wall with a lower nominal R-value of closed-cell foam can sometimes outperform a higher nominal R-value of loose-fill that is leaking air.

Which insulation is best for each part of your home?

This is where the honest answer lives. Different areas call for different products.

Attics

Open, accessible attics are the classic home for blown-in insulation. You can reach a deep, high R-value at a reasonable cost by simply piling on cellulose or fibreglass to R-50 or R-60. For most Canadian attics, blown-in is the smart spend. See our guide to the best attic insulation for cold climates.

Walls

In existing walls, blown-in cellulose installed by drill and fill is the standard retrofit. In new construction or major renovations, closed-cell spray foam can deliver more R-value in a thin wall, but it costs more. Knowing when spray foam is worth it saves money.

Basements, crawl spaces and rim joists

These damp, leaky areas are where closed-cell spray foam shines. It seals air, resists moisture, and works in tight, irregular spaces where loose-fill would settle or absorb water. In coastal Atlantic Canada and the wetter parts of BC, moisture control here is critical.

How much does each one cost in Canada?

As a rule, blown-in insulation is the most affordable per square foot, open-cell foam sits in the middle, and closed-cell foam is the premium option. Final pricing depends on the area, the depth, and access. We walk through real Canadian numbers, including attic and wall examples, in the full cost comparison. The good news is that insulation rebates in Atlantic Canada and BC can offset a meaningful share of either choice.

What about health, air quality and safety?

This is a common worry, and a fair one. Properly installed and fully cured spray foam is inert and safe, but it must be installed by trained pros at the correct ratio and temperature, and the space must be ventilated during curing. Cellulose and fibreglass are stable once in place. We cover the full picture, including off-gassing concerns and why some homeowners reconsider foam, in the healthiest insulation for a home and why some people remove spray foam.

Does insulation type affect building code and resale?

Yes to both. Spray foam in particular has specific code requirements in Canada, including thermal barrier and installer certification rules under CAN/ULC standards. We explain them in the spray foam building code guide. On resale, well-documented professional insulation is an asset, while a poor foam job can become a liability, which we cover in does spray foam affect resale value. Before you sign with anyone, read what to ask an insulation contractor.

So which insulation should you choose?

Here is the short version for a Canadian home in Atlantic Canada or BC:

• Open, accessible attic: blown-in cellulose or fibreglass to R-50 or R-60. Best value.
• Older walls with no insulation: drill and fill with dense-pack cellulose.
• Rim joist, crawl space, damp basement: closed-cell spray foam for air sealing and moisture control.
• Tight new wall where every inch of R-value counts: closed-cell spray foam, if the budget allows.
• Sound control on interior walls: open-cell spray foam.

Most homes do best with a combination, matched to each area. The wrong question is "foam or blown-in for the whole house." The right question is "what does this part of the house actually need," and that is exactly what a Greenfoot assessment answers.