Ice Damming Leaks: What Happened?

ICE DAMMING LEAKS: What happened? ANDREW AMOROSI, P.E., R.S., MASCE, PRINCIPAL- THE FALCON GROUP

It’s that time of year again – snow that is pretty for some is scary for others. If you have experienced, read or heard about ice damming then you are familiar with the damage this phenomenon can cause. Perhaps your association has spent thousands or over a million dollars on roofing improvements or replacements within the last few years. Why do you still have leaks from ice damming? Was the roof replacement installed or designed correctly? The answer is simple, with a properly designed and installed roof system – the possibility of damage resulting from ice damming should be significantly reduced.

The five (5) main causes of ice dams include: 1. Snow and ice buildup on the roof. 2.

Continuously warm and cold temperatures.

3.

An under-ventilated and poorly insulated attic (heat in attic).

4. Deficient roof installation (lack of ice and water shield, drip edge, insulation baffles, etc.) 5. Blocked or deficient underground roof leader collection systems.

A typical ice damming event occurs when the heat escapes from the living quarters into the attic and eventually warms the roof deck. The combination of the sun and the interior heat combine to accelerate and exacerbate this process. The melting water runs down the roof deck until it hits the area over the eaves and the gutter. This area remains cold because it is not over a heated space and thus the water begins to freeze and the ice dam forms. As the ice dam builds, it begins to trap more snowmelt, extending the height of the dam. The melting water begins to pool and backs up under the shingles. Severe problems begin when no ice and water shield is present and no drip edge is located behind the gutters, see illustration.

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