R-Value
Resistance to heat flow through a material — higher means better insulation. Fiberglass batts deliver about R-3.2 per inch, closed-cell spray foam R-6.5. Attic targets run R-49 to R-60 in most US climate zones per DOE guidance.
Where this appears in real estimates
This term isn't trivia — it's a working variable. These tools use it directly:
- r-value calculator — Insulation depth needed to hit target R-value by material.…
- insulation calculator — Batts, rolls or blown bags from area and product coverage.…
- figure your btu numbers — Heating and cooling BTUs from room area, climate and insulation.…
Go deeper
- Metal Roof vs Asphalt Shingles — head-to-head decision guide
- Roof Replacement Walkthrough — full project walkthrough
- Roofing in New York — local pricing & climate
- Read the field guide on the blog — practitioner-level detail
- Related engineering article — from our licensed engineer
Reviewed: · Part of the CalculatorAsphalt Construction Glossary · Sources: see methodology & standards.