Ice and water shield is a self-adhesive membrane often installed under fiberglass shingles to protect roof areas prone to water infiltration caused by ice dams or wind-driven rain. It’s typically applied along roof edges, valleys, and around roof penetrations like chimneys and vents, where water backup is most common. The shield acts as a waterproof barrier, preventing damage to the roof decking and interior even if ice or water manages to seep beneath the shingles. Ice dams form when melting snow refreezes at the roof’s edge, causing water to pool and infiltrate beneath shingles. Since fiberglass shingles themselves are durable but not fully waterproof, the shield adds an essential extra layer of protection in vulnerable spots.
To safely check if ice and water shield is properly installed, you can inspect the attic for signs of moisture or water stains after heavy ice or rain events. From the roof, look for areas where shingles have been overlapped in places like valleys and edges; the presence of a slightly thicker underlayment there may indicate the shield. However, because this membrane is beneath the shingles, visual confirmation from your rooftop is limited. If you’re unsure or notice any water damage signs, call a professional roofer for a thorough inspection. When consulting a contractor, ask if they include ice and water shield in their installation and where they apply it, especially in colder regions. Also, inquire how their warranty addresses ice dam damage when the shield is or isn’t used. This ensures the job meets both roofing code requirements and provides lasting protection.