Is ice and water shield necessary on a Georgia roof?
Short answer. Rarely by code in most of Georgia, but usually in practice. The eave ice barrier is required only where local officials designate ice damming as a hazard, yet manufacturers' system warranties and good roofing practice call for self-adhered membrane in valleys and around chimneys, skylights, pipes and walls.
Required by code
- Eaves, in designated areas. Where the jurisdiction has a history of ice forming at the eaves, an ice barrier must run from the edge to at least 24 inches inside the exterior wall line. Uncommon in most of Georgia; ask in the mountain counties.
- Low slopes. Shingles from 2/12 up to 4/12 need a double underlayment application, and many roofers use self-adhered membrane on these shallow sections.
- Valley linings. The code lists acceptable valley linings, and self-adhered membrane meeting ASTM D1970 is among them.
Required for some warranties
Shingle makers' enhanced system warranties often require their own leak barrier in specified locations. Check the warranty you are paying for.
Strongly recommended
- Valleys, especially under pine straw and leaf debris.
- Around chimneys, skylights and pipe boots.
- Roof-to-wall joints.
- Under metal roofs, in a high-temperature version.
Usually unnecessary
Covering the entire field of a steep, simple shingle roof in membrane adds cost and makes the deck nearly vapor-tight, which puts more pressure on attic ventilation. Full coverage makes more sense on low slopes, under metal, or in high-wind specifications that call for a sealed deck.
See ice and water shield in Georgia and roof flashing explained.