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United States

U.S. Climate Zone 2B home maintenance

Tucson is an example of Zone 2B, not a shortcut for identifying your zone. Confirm the project county in the official PNNL data.

Official profile

2BHot–DryRepresentative: Tucson, Arizona

After the county lookup confirms Zone 2B, use R49 for the uninsulated-attic comparison or R38 when 3–4 inches remain. Similar weather to Tucson does not establish the zone.

What the official table recommends

Official insulation comparison for U.S. Climate Zone 2B home maintenance
ConditionGuidanceScope
Uninsulated atticR49ENERGY STAR retrofit recommendation for Zone 2.
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

    Inspect exterior sealant and coating transitions.

    Open joints and failed finishes should be scoped before cosmetic recoating.

  2. Summer

    Check the attic boundary and approved fixture clearances.

    Air-sealing work must preserve fire and electrical details.

  3. Fall

    Inspect roof drainage even when no leak is visible.

    Drainage defects can damage assemblies when water arrives.

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.