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Roof Eave Ice Dam Protection Membrane Footprint

Calculate the ice-and-water-shield membrane area required at eaves per IRC cold-climate requirements.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
65.62 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Ice dam membrane area needed

243 ft²

High confidence
Membrane width (along slope)
3.7 ft

Running these inputs gives 22.6 m² as the ice dam membrane area needed. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • IRC R905.1.2: self-adhering ice barrier membrane must extend from the eave edge to at least 24in inside the building's exterior wall line, measured along the roof slope

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Frequently asked questions

Why does the membrane width need to be measured along the slope, not horizontally?
The overhang and required interior coverage are both horizontal distances, but the membrane itself lies along the sloped roof surface, so the horizontal distance must be scaled up by the slope factor (from the roof pitch) to get the actual membrane width needed.
Where does the 24in requirement come from?
IRC R905.1.2 requires self-adhering ice barrier membrane to extend from the eave edge to at least 24in inside the building's exterior wall line, measured along the roof slope, in areas with a history of ice forming along the eaves.
Does this calculator include the overhang itself in the required coverage?
Yes — the membrane width combines the horizontal overhang distance plus the required interior coverage distance, then converts that total horizontal run to an along-slope width using the roof pitch.