Short Answer
Ice-and-water protection is a self-adhering membrane designed for vulnerable roof areas. It can be particularly important around eaves, valleys, roof-to-wall transitions, penetrations, chimneys, and skylights. Exact application requirements depend on the roof design, product specifications and applicable code.
Detailed Explanation
Ice and water shield is a rubberized, self-adhering membrane that sticks directly to the roof deck and seals around nails when shingles are fastened through it. Unlike regular underlayment, which sheds water that flows over it, ice and water shield actually seals against water that might back up under shingles — which is exactly what happens during ice dams or wind-driven rain. It's installed in the areas most vulnerable to water intrusion: along the eaves (where ice dams form), in valleys (where water concentrates), around chimneys and skylights (where transitions create vulnerability), and at roof-to-wall intersections. In cold-climate regions like New Jersey, ice and water protection along the eaves is particularly important for preventing ice-dam water from entering the home.
Why It Matters
Ice and water shield is the component that prevents water from entering during ice dams and wind-driven rain. Its absence or insufficient coverage is a common cause of winter leaks.
Questions to Ask Your Contractor
- ?Where will ice and water shield be installed?
- ?How far up the roof from the eave will it extend?
- ?Will it be used in valleys and around penetrations?
- ?What product is being used?
Code & Manufacturer Considerations
Building codes in cold-climate regions may require ice-and-water membrane along eaves to a specified distance. Manufacturer installation instructions also specify minimum coverage areas.
Building codes and permit requirements can change. Always verify the current requirements applicable to your municipality and project.