Home & Construction
Attic Insulation Calculator - Calculate insulation needed for attic energy efficiency
Calculate insulation needed for attic energy efficiency
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
What R-value do I need?
Depends on climate zone: Zone 1-2: R30-49, Zone 3-4: R38-60, Zone 5-8: R49-60.
Can I add over existing insulation?
Yes, if existing is dry and not compressed. Remove vapor barrier from new layer.
Blown vs batts?
Blown fills gaps better and is faster for large areas. Batts work well for standard joist spacing.
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About this tool
This Attic Insulation Calculator turns your inputs into practical results. Provide Current R-Value, Target R-Value, and Attic Floor Area to calculate Additional R-Value Needed and Total Coverage.
Adjust values to compare scenarios and see how sensitive the result is. The calculation uses the numbers as entered, so double-check units and expect small differences from rounding in the displayed totals.