What is the purpose of an ice and water shield, and where is it typically applied?

• A. To prevent leaks from ice dams and wind-driven rain; applied at eaves, valleys, and around penetrations per manufacturer's instructions.
• B. To provide a decorative pattern on the roof.
• C. To insulate the attic from heat.
• D. To secure shingles during high winds.

Answer: (A)

An ice and water shield provides a reliable water barrier where a roof is most vulnerable to leaks. Ice dams can force meltwater to back up under shingles at the eaves, and wind-driven rain can infiltrate around roof penetrations. The shield uses a self-adhesive waterproof membrane that sticks to the roof deck, creating a continuous layer that stops water from seeping in even if the outer shingles are stressed or damaged. It’s typically applied at the eaves, in valleys, and around penetrations such as vents and chimneys, and then covered with the rest of the roofing material according to the manufacturer’s instructions. The other options describe decoration, insulation, or securing shingles—none of which directly protect against water intrusion in those critical areas.