Problem: Rotting of structural members and sheathing materials.
Cause: Water leakage due to ice damming.
Inadequate eave protection under the roofing can also lead to wet roof sheathing and premature deterioration. Ice dams can trap melt water on the roof above the point where the eave protection ends.
Ice dams are built-up ice at the edge of the roof. Heat escaping from the house melts the snow on the roof until it reaches the outer edge of the eave over the unheated soffit, where it freezes, creating an ice dam. As the ice dam builds up, it stops the flow of melted water from reaching the eave. This melted water can back up past the eave protection, wetting the roof sheathing and structural members and leading to rotting.
Solutions: Install adequate eave protection under roofing materials.
- Install eave protection, an impervious roofing strip, at eaves and in valley intersections, to stop water from leaking through the shingles behind ice dams as shown in Figure 21.
Figure 21 - Ice damming
- Complicated roof systems that have other roofs draining onto one roof or have direct sun exposure require special attention. Installing an ice and water shield on the roof and under flashing is recommended.
Additional information on roofs and roofing