Find exactly how many rolls or bags of insulation you need to hit your target R-value.
Check EnergyStar.gov for your specific climate zone recommendation.
🏗️ Pro Tip: R-value per inch varies dramatically by type — closed-cell spray foam (R-6.5/in) delivers more than twice the insulation of fiberglass batts (R-3.2/in) in the same space. In 2×4 walls with limited cavity depth, spray foam or rigid foam boards let you hit code R-values that fiberglass simply can't reach. Check your local energy code before buying materials.