How long does ice and water shield last?
Why covered membrane lasts
The biggest enemy of a self-adhered membrane is ultraviolet light. Under shingles or metal it stays in the dark, at temperatures it was designed for, bonded tightly to the deck. In that environment the rubberized asphalt stays flexible and keeps sealing around the nails driven through it.
What shortens its life
- Excess heat. A standard membrane under metal roofing can soften and flow. High temperature versions exist for that reason.
- Long exposure before covering. Weeks in the sun beyond the product's limit degrade it before the roof is even finished.
- Poor installation. Wrinkles, fishmouths at laps, and membrane applied over dust or a wet deck can let water in early.
- Chemical incompatibility. Some sealants and materials are not compatible with asphalt-based membranes, so manufacturers list what can contact them.
How it fails, when it does
Failures usually show up as a valley or wall leak with shingles that look fine. Often the cause is not the membrane itself but a reversed lap, a missing piece around a penetration, or flashing that sends water behind it. An attic inspection after heavy rain can point to the spot.
At the next replacement
Because it bonds to the wood, the membrane rarely comes off cleanly, and some deck sheets may need replacing. New membrane goes on with the new roof. For how long the roof above it lasts, see how long a roof lasts in Georgia, and for where membrane belongs, ice and water shield in Georgia.