Natural Resources Canada shows a recommended minimum roof/ceiling value of RSI 7.9 (R45) for Zone 4.
Official insulation comparison
| Condition | Guidance | Scope |
|---|---|---|
| Roof / ceiling target | R45 (RSI 7.9) recommended minimum roof/ceiling value | NRCan Table 2-1; inspect the actual assembly before choosing a top-up. |
This is a comparison value, not a bag count. Choose the applicable added R-value and a current named-product label before calculating material.
Seasonal priorities for this profile
- Spring
Inspect water entry and attic condition.
Repair moisture before insulation.
- Summer
Air-seal accessible ceiling penetrations.
NRCan places air/moisture control before top-up.
- Fall
Verify bag label coverage and settled depth.
Material count and thickness must follow the label.
Use the profile correctly
- Confirm the actual project zone using the cited official lookup or the authority that applies locally.
- Inspect existing material, moisture, air leakage, safe access, wiring, fixtures, and combustion equipment before top-up.
- Use the exact current product coverage card; do not transfer bag data between U.S. and Canadian products.
- Treat representative locations as classification examples, not local forecasts or code boundaries.
Sources and scope
Source links reviewed July 16, 2026. A review date is not the document's publication date.
- Natural Resources Canada: Keeping the Heat In — How your house worksCanada · government guide
Canadian guidance uses effective thermal resistance and climate-zone classifications.
- Natural Resources Canada: Keeping the Heat In — Roofs and atticsCanada · government guide
Follow product labels for bag count and settled depth; do not disturb suspected vermiculite.