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United States

U.S. Climate Zone 3B home maintenance

DOE uses El Paso to illustrate Zone 3B. Check the official PNNL county data to confirm the zone for your property.

Official profile

3BWarm–DryRepresentative: El Paso, Texas

Check the county first. In Zone 3B, ENERGY STAR compares an uninsulated attic with R49 and an attic with 3–4 inches with R38.

What the official table recommends

Official insulation comparison for U.S. Climate Zone 3B home maintenance
ConditionGuidanceScope
Uninsulated atticR49ENERGY STAR retrofit recommendation for Zone 3.
Existing 3–4 inchesR38Official 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

    Check exposed sealants, wood ends, and coating failure.

    Preparation depends on actual surface condition.

  2. Summer

    Inspect attic access, penetrations, and insulation coverage.

    Thin or displaced areas need a measured plan.

  3. Winter

    Review indoor moisture signs around envelope transitions.

    Visible condensation or staining should be diagnosed before covering.

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.