What is R-Value?

What Is R-Value?

R-Value measures how well a material resists heat flow. In simple terms, the higher the R-value, the better the insulation. It's a critical factor in keeping your home, building, or barn warm in the winter and cool in the summer.

Why R-Value Matters?

Insulation’s job is to slow the movement of heat. If your insulation has a low R-value, heat will pass through more easily leading to energy loss, higher bills, and uneven indoor temperatures. Different areas of a building require different R-values based on:

• Climate zone - e.g., Alberta requires higher R-values than coastal BC
• Part of the structure  - attic vs. walls vs. basement
• Local building codes

Comparing Insulation Types by R-Value:

Here’s how common insulation materials stack up - Insulation Type R-Value Per Inch (Approx.)

• Closed-Cell Spray Foam: R-6.0 to R-7.0
• Open-Cell Spray Foam: R-3.5 to R-4.0
• Fiberglass Batts: R-2.9 to R-3.8
• Blown-In Cellulose: R-3.2 to R-3.8
• Rigid Foam Board: R-4.5 to R-6.5

Why Spray Foam Stands Out:

Because spray foam has a much higher R-value per inch, you need less of it to achieve the same or better thermal performance compared to traditional materials.

For example:

• To reach R-20 in a wall, you’d need just 3 inches of closed-cell spray foam, but up to 6–7 inches of fiberglass.
• In tight spaces, spray foam delivers superior performance without needing extra thickness or structure modifications.

How Much R-Value Do You Need?

Here are common recommendations for Western Canada (subject to local codes):

• Attics: R-40 to R-60
• Walls: R-20 to R-25
• Basements: R-12 to R-20
• Garages & Additions: R-12 to R-20

Keep in mind that spray foam acts as both an air seal and moisture barrier, while other materials might need separate vapour barriers or sealing.