Attic Insulation Upgrade Payback Calculator

Fourier conduction through your ceiling — see how jumping to code-level R-values shrinks BTU loss and pays back the install quote.

Attic & HVAC Setup

Attic footprint / ceiling area (sq ft)

Existing insulation material

Current insulation depth 4 in · R-12

Current attic R-value: R-12.4 (4 in fiberglass)

Target upgrade level (building code)

Targets below your current R-value are disabled.

Primary home heating source

Insulation project quote ($)

Electricity ($/kWh)

Natural gas ($/therm)

Thermal Transfer & Payback

Projected annual cash savings

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Winter heating + summer cooling load reduction.

Break-even timeline

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Annual thermal transfer through ceiling (BTU contraction)

Current configuration—

Before

After upgrade—

After

BTUs saved / yr

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Transfer reduction

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Winter ΔT

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Summer ΔT

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Practical tips & common mistakes

Air seal before you blow

Insulation stops conduction, not airflow. Seal penetrations, chase ways, and top plates first — otherwise R-60 still leaks.

Blocking soffit vents

Baffles must keep intake paths open. Insulation packed against roof deck causes ice dams and rot — worse than thin insulation.

Target depth, not bag count

Blown cellulose settles 10–15%. Install to settled depth on the ruler, not bag label "coverage" at fluffy blow density.

Knee wall attics

Finished attic rooms need wall and roof insulation too — floor-only R-value models miss hybrid assembly paths.

Note: Hourly conduction uses a 70°F living-space setpoint vs vented-attic seasonal extremes (winter ~28°F, summer ~118°F) over typical runtime hours. Assumes uniform depth and no air sealing. Actual payback varies by climate zone, installation quality, and thermostat setbacks.