Roof membrane roll estimator

Ice and Water Shield Calculator

Estimate ice and water shield rolls from total eave length, valley length, membrane width, roll coverage, waste, and roll cost. Use it before roofing underlayment, drip edge, shingles, or metal panels go on.

Units

Total eave length (ft)Valley or critical length (ft)Membrane width (ft)Coverage per roll (ft²)Lap / waste (%)Cost per roll ($)

Membrane rolls

Protected area

Protected length

Rough cost

Ice barrier rules depend on climate and code

This calculator estimates membrane quantity only. Ice-dam code, roof slope, eave overhang, heated-wall line, valley details, laps, penetrations, drip-edge sequence, product width, and manufacturer instructions can change coverage.

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Roof Underlayment Calculator

Estimate field underlayment rolls for the rest of the roof.

Drip Edge Calculator

Estimate eave and rake metal around the same edge.

Roof Shingle Calculator

Estimate shingle bundles after membrane and underlayment.

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Ice and water shield formula

Protected length = eave length + valley length

Protected area = protected length × membrane width

Order area = protected area × (1 + waste %)

Rolls = order area ÷ roll coverage

Sample takeoff

A roof with 120 ft of eaves, 30 ft of valleys, 3 ft membrane width, 200 ft² roll coverage, and 10% waste needs about three rolls.A roof with 36 m of eaves, 9 m of valleys, 0.9 m membrane width, 18.6 m² roll coverage, and 10% waste needs about three rolls.

Ice and Water Shield Calculator FAQ

How do I calculate ice and water shield rolls?+

Add the eave and valley lengths you plan to protect, multiply by membrane width, add lap waste, then divide by the roll coverage.Add the eave and valley lengths you plan to protect, multiply by membrane width, add lap waste, then divide by the roll coverage.

How far up the roof should ice barrier go?+

That depends on local code, roof slope, overhang, climate, and the heated-wall line. This calculator estimates quantity after that coverage width is chosen.That depends on local code, roof slope, overhang, climate, and the heated-wall line. This calculator estimates quantity after that coverage width is chosen.

Is this the same as roof underlayment?+

No. Ice and water shield is a self-adhered membrane used in vulnerable areas. Field underlayment often uses a separate product and coverage calculation.No. Ice and water shield is a self-adhered membrane used in vulnerable areas. Field underlayment often uses a separate product and coverage calculation.