Ice and Water Membrane
A self-adhering, rubberized asphalt membrane applied to vulnerable areas of the roof deck before shingle installation, providing a waterproof seal around nail penetrations. Required by code in eave areas, valleys, and around penetrations in cold climates.
What Is Ice and Water Membrane
Ice and water membrane is a self-adhering, rubberized asphalt sheet applied directly to the roof deck that seals around every nail penetration to create a fully waterproof layer beneath the shingles in the most vulnerable areas of the roof. Unlike standard underlayment, which is water-resistant but not waterproof, ice and water membrane bonds to the deck and self-seals around nail shanks driven through it. This makes it the primary defense against water infiltration from ice dams, wind-driven rain, and valley flooding.
Where It Is Required
The International Building Code requires ice and water membrane along eaves in regions where the average January temperature is 25 degrees or below, extending from the eave edge to at least 24 inches past the interior wall line. It is also required in valleys, around roof penetrations, and at roof-to-wall intersections. Even in warm climates, shingle manufacturers often require it in valleys for warranty compliance.
Ice and Water Membrane in Estimates
In Xactimate, ice and water membrane carries a separate line item with a higher per-square cost than synthetic underlayment. The coverage area should be calculated based on code requirements and the specific roof geometry. Adjusters sometimes scope only standard underlayment across the entire roof, omitting the more expensive ice and water membrane in areas where code requires it. This is a documentable supplement opportunity based on local building code and manufacturer warranty requirements.
Frequently asked questions
Building codes in cold climates require ice and water membrane from the eave edge to at least 24 inches past the interior wall line. It is also required in valleys and around penetrations. Even in warmer climates, manufacturers and codes often mandate it in valleys and at roof-to-wall transitions.
Yes. Ice and water membrane is a distinct line item from synthetic or felt underlayment in Xactimate, with a higher unit cost per square. It should be itemized separately in every estimate where it is required by code or manufacturer specification.
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