Definition
R-Value
A measure of insulation's resistance to heat flow — the higher the R-value, the better the insulating performance.
The Full Picture
R-value measures thermal resistance — how well a material resists the transfer of heat. It's expressed as a number: R-13 fiberglass batts, R-38 blown-in cellulose, R-49 code minimum for attics in cold climates. R-values are additive — two layers of R-13 insulation provide R-26. Different insulation materials achieve different R-values per inch of thickness: fiberglass batts are about R-3.2 per inch, cellulose is R-3.5, closed-cell spray foam is R-6.5. Building energy codes specify minimum R-values for walls, ceilings, floors, and foundations based on climate zone.
Why It Matters
Why field professionals need to document this
R-value is how energy auditors, home inspectors, and builders communicate insulation performance. Measuring existing insulation R-value and comparing it to current code requirements is a core part of energy audits and home inspections. Low R-values in attics and walls are among the most common and cost-effective upgrade recommendations. Documenting R-values by location creates the baseline for improvement recommendations with ROI estimates.
In a Report
How this shows up in findings
Here's how a r-value finding looks in a professional field report generated by ReportWalk:
Attic: blown-in fiberglass measured at R-15, code minimum is R-49 — upgrade recommended
Walls: 2x4 with fiberglass batts, approximately R-11 — below R-13 minimum
Rim joist: uninsulated (R-0) — highest priority for spray foam or rigid board application
Relevant For
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