Where does ice and water shield go?
Ice and water shield is installed at specific high-risk locations on the roof deck, not across the entire surface:
- Eaves: The bottom 3–6 feet of every eave — where ice dams form and back up water. Code minimum in Ohio is 24 inches inside the exterior wall line. Atlas Roofing installs a minimum of 3 feet at all eaves.
- Valleys: Where two roof planes meet — water concentrates heavily in valleys, making them a primary leak risk.
- Penetrations: Around chimneys, skylights, and pipe boots in some applications.
- Rakes: In high-wind areas, extended coverage along rake edges reduces wind-driven rain infiltration.
How does it work?
Ice and water shield has two key properties that standard underlayment lacks: it is self-adhering (sticks directly to the decking, creating a continuous seal with no gaps), and it is self-sealing around fasteners (rubber seals around every nail hole so water cannot track down the fastener into the structure). Standard felt paper or synthetic underlayment, while water-resistant, is not waterproof and cannot seal around nail penetrations.
Why is it especially important in Ohio?
Ice dams — a product of Northeast Ohio's repeated freeze-thaw cycles — force liquid water up under shingles at eaves. Standard shingles and underlayment are designed to shed downward-flowing water. They are not designed to resist water that is backing up from below under pressure. Ice and water shield handles exactly this scenario. Without it, ice dam events that are common in our climate cause structural damage that wouldn't occur with proper installation.
Standard vs. premium ice and water shield
| Product | Best for | Key feature |
|---|---|---|
| GAF WeatherWatch (standard) | Most residential applications | Granular surface, mineral-surfaced for walkability |
| Grace Vycor Pro (premium) | Homes with ice dam history | Higher elongation, superior cold-weather adhesion |
Atlas Roofing installs GAF WeatherWatch as our standard ice and water shield. For homes with a history of significant ice dam damage or particularly vulnerable eave geometry, we offer Grace Vycor Pro as an upgrade.
How to check if your current roof has ice and water shield: If your home was built before the mid-1990s or was last re-roofed before modern installation standards, it may not have ice and water shield. The only way to know for certain is to inspect the eave area during a tear-off — a good reason to confirm this with your contractor before any re-roofing project.