Roof Insulation Calculator
Insulation R-value and thickness from energy code.
Inputs
%
Results
Required Thickness (in)
5.5
Achieved R-Value31.4
U-Factor (BTU/hr·ft²·°F)0.03
Number of Layers2
Insulation Boards (4×8)198
Cover Boards (4×8)99
Calculated Thickness (in)5.26
Est. Material Cost ($)$15,259
Layer Thicknesses3, 2.5
How to Use This Calculator
- Enter total roof area (sqft) and target R-value.
- Select insulation type (polyiso, EPS, XPS, or mineral wool) and set waste factor (%).
- Review insulation thickness (in), achieved R-value, U-factor, number of layers, and board count.
- Confirm achieved R-value meets local energy code minimums (ASHRAE 90.1 or IECC requirements).
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