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United States

U.S. Climate Zone 5C home maintenance

Port Angeles is DOE’s example for Zone 5C. Check your address against the official county file.

Official profile

5CCool–MarineRepresentative: Port Angeles, Washington

ENERGY STAR’s Zone 5C comparison is R60 for an uninsulated attic and R49 where 3–4 inches remain. Port Angeles is a model location only.

What the official table recommends

Official insulation comparison for U.S. Climate Zone 5C home maintenance
ConditionGuidanceScope
Uninsulated atticR60ENERGY STAR retrofit recommendation for the Zone 4C/5/6 group.
Existing 3–4 inchesR49Official retrofit table condition

This table compares attic R-values. It does not calculate bags or measure the gap in performance. Assess the existing insulation first, then match the required added R-value to a current product label.

Estimate insulation bags

What to check through the year

  1. Spring

    Inspect for roof leakage and wet insulation.

    Insulation condition matters alongside nominal depth.

  2. Summer

    Repair accessible boundary defects.

    Air and moisture control precede top-up.

  3. Fall

    Inspect exterior wood and finish compatibility.

    Exposure and preparation guide the finish system.

Before you plan the work

  • 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 coverage chart on the current product label; 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 notes

Source links reviewed July 16, 2026. A review date is not the document's publication date.

  1. 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.

  2. 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.

  3. ENERGY STAR: Recommended Home Insulation R-ValuesUnited States · government guide

    Recommendations are presented by ENERGY STAR using 2021 IECC climate zones.

  4. ENERGY STAR: DIY Checks and InspectionsUnited States · government guide

    Do not disturb suspected vermiculite insulation; obtain qualified guidance before work.