R-value is the measure of thermal resistance — how well insulation resists the flow of heat. Higher R-value means better insulation performance. In many regions’s cold climate, R-value recommendations are significantly higher than in warmer Canadian regions, and many older your region homes are substantially under-insulated relative to current best practice.
“The R-value question I get most often is: what does my attic have, and how much should it have? The honest answer for most older your region homes is: probably R-12 to R-20, and it should be R-50 to R-60. That’s a big gap, and it’s where the biggest energy savings are. The good news is that filling that gap is one of the most straightforward and cost-effective home improvements available.”
— Priya Sundaram, certified insulation contractor and building envelope specialist with 16 years of experience in residential insulation and energy efficiency upgrades in the local area
Table of Contents
Recommended R-Values for your region (Climate Zone 6)
Most of your region falls within NRCan Climate Zone 6 — a cold climate zone with long, cold winters. The following are Natural Resources your country recommendations for existing homes being upgraded (not new construction minimums, which are lower):
| Location | Recommended R-value |
|---|---|
| Attic (flat ceiling below attic) | R-50 to R-60 |
| Cathedral ceiling / roof assembly | R-40 to R-50 |
| Exterior walls (above grade) | R-20 to R-24 |
| Basement walls (from interior) | R-12 to R-20 |
| Basement slab (floor) | R-10 |
| Rim joist | R-20 (closed-cell spray foam) |
| Crawlspace walls | R-12 to R-20 |
What Does Typical your region Housing Actually Have?
| Home era | Typical attic R-value | Typical wall R-value |
|---|---|---|
| Pre-1945 | R-0 to R-5 (if any insulation) | R-0 to R-4 |
| 1945–1965 | R-5 to R-12 | R-4 to R-8 |
| 1965–1980 | R-12 to R-20 | R-8 to R-12 |
| 1980–2000 | R-20 to R-32 | R-12 to R-20 |
| 2000–present | R-32 to R-50+ | R-20+ |
Even homes built in the 1990s often fall short of current recommendations for attic insulation — which is why attic top-ups are worthwhile in homes that are 20–30 years old.
Understanding R-Value in Common Materials
| Material | R-value per inch |
|---|---|
| Blown fibreglass | R-2.2 to R-2.9 |
| Blown cellulose | R-3.2 to R-3.8 |
| Fibreglass batt | R-3.0 to R-3.8 |
| Mineral wool batt | R-3.7 to R-4.2 |
| Open-cell spray foam | R-3.7 |
| Closed-cell spray foam | R-6.0 to R-7.0 |
| EPS rigid foam board | R-3.6 to R-4.0 |
| XPS rigid foam board | R-5.0 |
| Polyisocyanurate rigid board | R-6.0 to R-6.5 |
Why R-Value Alone Isn’t Enough
R-value measures resistance to conductive heat transfer — heat moving through a material. But homes also lose heat through:
Air infiltration (convective heat loss): Air moves through gaps, penetrations, and bypasses carrying conditioned air out and cold air in. This can represent 25–40% of a home’s total heat loss. R-value doesn’t measure or address this.
Thermal bridging: Where materials with poor insulation value (framing lumber, steel, concrete) create pathways for heat to bypass the insulation. This reduces the effective R-value of an assembly below the nominal value.
This is why air sealing alongside insulation is critical — and why a certified energy advisor and blower door test give a more complete picture of a home’s performance than R-value alone.
How to Know What Your Home Currently Has
Attic: Measure the depth of insulation in the attic and identify the type (loose-fill fibreglass or cellulose, batt fibreglass). Divide depth by R-value per inch for that material type.
Walls: Harder to assess without opening the wall. A certified energy advisor using blower door testing and thermal imaging can identify missing or insufficient wall insulation non-invasively.
Basement: Measure or assess the type and thickness of any visible insulation on walls. Many basements in older homes have no insulation on the walls.
Related Questions
- Questions to Ask an Insulation Contractor Before You Hire One
- Questions to Ask an Insulation Contractor About Attic Insulation
- How Much Does Insulation Cost ?
- Questions to Ask About Home Energy Audits and Rebates
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