Measure and MendStart measuring

Insulation

Attic insulation inspection

ENERGY STAR publishes estimated R-value per inch for common loose-fill materials and batts. The estimate can support a first check, but mixed, compressed, wet, disturbed, or unknown insulation needs more care than one depth reading.

First answer

Identify the insulation, measure depth at several representative points without compressing it, note uneven or wet areas, and use the official estimated R-per-inch value only as a screening estimate.

Formula or decision rule

screening R estimate = representative settled depth in inches × official estimated R per inch
  • Loose fiberglass: 2.5 R/in; rock wool: 2.8; cellulose: 3.7; vermiculite/perlite: 2.7; fiberglass batts: 3.2.
  • Do not apply the estimate when material identification is uncertain.
  • Compare the screen with the correct U.S. or Canadian official zone table.

ENERGY STAR screening estimates

ENERGY STAR screening estimates
InsulationEstimated R/inInspection note
Loose fiberglass2.5measure settled depth
Rock wool2.8identify before use
Cellulose3.7check settling/coverage
Vermiculite or perlite2.7do not disturb suspected vermiculite
Fiberglass batts3.2do not compress

Work through the project

  1. Screen access first

    Look for unsafe flooring, exposed wiring, heat-producing equipment, pests, moisture, and suspect material before entering.

  2. Measure a pattern

    Take representative depth observations across accessible areas and record thin, compressed, displaced, or wet locations separately.

  3. Compare condition and zone

    Use the official table for both climate zone and existing insulation condition; do not turn one depth into a false precision claim.

Safety and scope

  • ENERGY STAR warns not to disturb vermiculite insulation because it may contain asbestos.
  • Avoid stepping between framing members and keep clear of electrical and combustion hazards.

Sources and scope

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

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

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

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

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

  3. 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.