Structural & systems · Glossary
R-value
R-value is the measure of an insulation material's resistance to heat flow. Higher R-value means better insulation. Building codes set minimum R-values per climate zone for walls (R-13 to R-21), ceilings (R-30 to R-49), and floors. ADU permits in California typically require R-19 walls and R-30 ceilings minimum.
Why this matters for renovation projects
R-value shows up on permits, contracts, or estimates that Renology covers across LA, San Diego, San Francisco, Seattle, Portland, and Denver. Most homeowners encounter the term once a project is already mid-flight, when there is no time to learn its mechanics without slowing the contractor. Knowing what it means before signing the contract is the difference between a clean project and an avoidable surprise. For how Renology calibrates cost ranges against permit valuations and contractor invoices, see the methodology.