Ice and water shield is a self-adhering waterproof membrane typically installed under asphalt shingles in areas prone to ice dams and water infiltration. It works by creating a sealed barrier along roof edges, valleys, and other vulnerable spots to prevent water from backing up under the shingles due to ice buildup or heavy rain. Ice dams form when heat from the house melts snow on the roof, and that water refreezes at the colder eaves, causing a dam that traps water behind it. Without a proper barrier, this trapped water can leak through shingles and damage the roof deck or interior ceilings. Simple diagnostics include inspecting your roof edges and valleys for peeled-back shingles or water stains inside the attic after winter storms. A safe DIY check is to look for signs of ice buildup along the eaves during cold weather and verify that gutters are clean to allow proper drainage.
While ice and water shield is a common requirement in many building codes for colder climates, it’s worth knowing the warranty implications when installing or replacing shingles. Improper installation of the shield or shingles can void manufacturer warranties, so it’s best to follow product instructions or hire a roofer knowledgeable in both local codes and shingle warranty specifics. If you notice frequent or worsening leaks near roof edges or valleys, it’s time to call a professional. When discussing the project with your contractor, consider asking, “Which areas of my roof need ice and water shield, and why?” and “Can you show me how the ice and water shield overlaps with shingles to ensure a waterproof seal?” These questions help clarify the coverage plan and ensure a lasting waterproof barrier.