Zone 8 is DOE’s Subarctic classification represented by Fairbanks, Alaska; ENERGY STAR shows R60 for an uninsulated attic and R49 with 3–4 inches existing.
Official insulation comparison
| Condition | Guidance | Scope |
|---|---|---|
| Uninsulated attic | R60 | ENERGY STAR retrofit recommendation for Zones 7 and 8. |
| Existing 3–4 inches | R49 | Official retrofit table condition |
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
Document roof and attic moisture or structural findings.
Unsafe or wet conditions need qualified repair.
- Summer
Use the accessible period for inspection, sealing, and label-based top-up planning.
Deep insulation should not bury unresolved defects.
- Fall
Recheck access, penetrations, and equipment clearances.
Continuity and safety both matter.
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.
- U.S. Department of Energy: Prototype Building Models — Climate Zone RepresentativesUnited States · government standard
Representative locations classify a zone; they are not a substitute for local weather or code data.
- Pacific Northwest National Laboratory: Guide to Determining Climate Zones by CountyUnited States · government standard
Use the county files for a project address; representative cities are examples rather than boundaries.
- ENERGY STAR: Recommended Home Insulation R-ValuesUnited States · government guide
Recommendations are presented by ENERGY STAR using 2021 IECC climate zones.
- ENERGY STAR: DIY Checks and InspectionsUnited States · government guide
Do not disturb suspected vermiculite insulation; obtain qualified guidance before work.