How and when should you use ice and water shield?
Short answer. Use ice and water shield wherever water concentrates or moves slowly on a roof: valleys, low-slope sections, around chimneys, skylights and pipes, along roof-to-wall joints, and at the eaves in ice-prone areas. To use it, apply it directly to a clean, dry deck, press it down firmly, lap it shingle-fashion, and cover it with the finished roofing.
When to use it beyond a new roof
- Valley repairs. When a leaking valley is opened up, new membrane goes in before the valley is rebuilt.
- Chimney reflashing. Membrane on the deck around the chimney backs up the new step and counterflashing.
- Skylight replacement. Many skylight makers specify membrane around the curb before their flashing kit goes on.
- Room additions and porch tie-ins. Where a new roof meets an old one, membrane bridges the transition.
- Low-slope porch roofs. Shingled porch roofs near the minimum slope benefit from full coverage.
Handling tips
- Store rolls out of direct sun until use, and in cold weather keep them warm so the adhesive grabs.
- Cut on a scrap board, liner side up, with a sharp utility knife.
- Use a primer on masonry, metal or dusty surfaces if the manufacturer calls for it.
- Press and roll every edge and lap.
Common mistakes
- Installing over a wet, dusty or frosty deck.
- Reversing laps so water runs into a seam.
- Leaving it as a long-term exposed roof surface.
- Smearing caulk at the top edge instead of lapping underlayment over it.
- Using a standard membrane under metal roofing where a high temperature version belongs.
Where leaks usually start, and so where membrane helps most, is covered in common causes of roof leaks. The Georgia-specific guide is ice and water shield in Georgia.