R-50 or R-60? The right R-value for your attic
What R-value to target in Quebec, the matching thickness, and why air sealing matters just as much.
What is the "R-value"?
The R-value measures the thermal resistance of an insulant: the higher the R, the more the insulant slows heat loss. For an attic, it's the number that matters. In Quebec, the modern target for the roof/attic is between R-50 and R-60.
R-50 or R-60: which to choose?
Most programs and recent codes target R-60 for the attic in Quebec. R-50 is still a worthwhile improvement in some cases (limited space, tight budget), but if access allows, aiming for R-60 offers the best comfort and the best grant eligibility.
| R-value | Approx. thickness (blown insulation) | Relevance |
|---|---|---|
| R-40 | ~28 cm | Below current standards — should be upgraded |
| R-50 | ~35 cm | A good improvement |
| R-60 | ~42 cm | Recommended target in Quebec |
Should you always aim for the highest R possible?
No. Beyond a certain point, each extra inch of insulation brings smaller and smaller gains while the cost keeps rising. R-60 is the sweet spot for most Quebec attics: excellent performance without needless extra cost.
Thickness isn't everything
An R-60 attic with poor sealing performs worse than an R-50 with good air sealing. Warm air leaking through the ceiling cancels out part of the insulation. That's why effective insulation combines thickness (R-value) AND caulking — and it's exactly that combination that unlocks the LogisVert grant.
How do you find your current R-value?
Our R-value calculator helps you estimate the existing insulation and the target to reach. Then our pricing tool gives you the cost to upgrade to R-60.
What R-value for your attic?
Estimate your current R-value, then your price to reach R-60.
Get my estimate →