Ice & Water Shield Calculator

Enter your eave length, valley length, and penetration count to estimate how many rolls of ice and water shield you need — and compare standard vs wide roll costs.

Eave Protection

Eave Length (ft)

Eave Coverage Width (ft)

Valley Protection

Valley Length (ft)

Valley Width per Side (ft)

Penetrations / Skylights

Waste Factor (%)

Pricing (edit to match local rates)

Standard Roll ($/roll)

Wide Roll ($/roll)

Total Coverage Area

399 sq ft

Eave 360 + Valley 0 + Penetrations 20 sq ft (incl. 5% waste)

Recommended Buy

Wide Roll (150 ft)

1 rolls · $175.00

Purchase Option	Quantity	Est. Cost
Standard Roll (75 ft)	2 rolls	$190.00
Wide Roll (150 ft)Best value	1 rolls	$175.00

Best value: Wide Roll (150 ft) at $175.00IRC Section R905.1.2 requires ice barrier underlayment (ice & water shield) in areas where the average daily temperature in January is 25°F or less. The membrane must extend from the eave edge to at least 24 inches past the interior face of the exterior wall. Most roofers use a 3-foot coverage width to ensure compliance with comfortable margin.

Don't forget valleysRoof valleys are high-flow areas where ice dams commonly form. If your roof has valleys, add their total length above for a more accurate estimate. Valley protection typically extends 3 feet on each side of the valley centerline (6 feet total width).

Wide rolls reduce wasteFor this coverage area, wide rolls (150 ft) are more cost-effective because you need fewer rolls, which also means fewer seams and less material waste on the roof.

This is a material estimate only. Actual coverage may vary based on roll overlap, roof geometry, and local code requirements. Always verify IRC requirements for your climate zone and consult local building codes.