Ice Dams: A Case Study
Several factors contributed to problem roofing area in the above photo. Even though the shingles were in good condition and installed properly, leaks were occurring due to ice dams. To remedy the situation, the homeowner installed an electrical device to melt the ice in this area.
What caused the leaks in this area?
1. Poor Design – Both the valley and downspout (from the upper gutters) empty large amounts of water into this small area.
2. Weather conditions – During the winter months, this roof area is always in the shade. As the sun shines on the upper roof areas, the snow and ice melt and refreeze in the lower (shaded) roof.
3. Poor ventilation – Soffit vents were not installed at this area. In the winter months, soffit vents allow cold air to enter the attic. If the interior and exterior sides of the roof sheathing are similar temperatures, a freeze-thaw process is unlikely to occur.
4. Gutter Flashing was not installed. The picture below shows the 1 ½ gap between the fascia board and the roof sheathing. When an ice dam occurs, it is very easy for moisture to back up from the gutter and enter the living space through this gap.
What did Deer Park Roofing do to stop the leaks?
1. All roofing materials and the electrical devices were removed from this area. Owens Corning ice and water guard was applied in 36 inch strips directly to the roof deck. Felt paper and 30 year shingles were then applied.
2. Soffit vents and a continuous ridge vent were installed to ensure proper rooftop ventilation.
3. A 2 inch by 3 inch aluminum gutter apron was installed to divert water into the gutters and prevent water backup into the house.
4. The downspout from the upper gutter was rerouted to empty directly into the lower gutter.
5. A new metal pan was installed at the base of the valley to prevent leakage at this area. The valley metal and pan were soldered together and new counter flashings were installed.
