What are They?
Ice dams refer to a common and harmful winter roofing problem which is caused by a combination of an inadequate roof or attic ventilation and a warm attic space. Formally, ice dams is an accumulation of ice at the edge of the roof which causes water to pool behind it rather than flow off the roof. Clogged or poorly draining gutter system promote the forming of ice dams. Ice dams can and do cause considerable damage to your roof, paint, gutters, insulation and interior drywall.
How They Form
Ice dams form when the snow melts on the upper warmer section on the roof. This is because the underside of the roof in the attic is above 32 degrees Fahrenheit, thus warming the exterior surface to a point that the snow actually melts. The warm water flows down toward the cooler eave and refreezes back to ice.
Harmful Effects of Ice Dams
As the ice accumulates, it can back up under the roof singles, melting again. This soaks the roof sheathing and leaks into the attic. Once in the attic, it soaks the insulation, making it much less effective, and can eventually leak through the drywall of the ceiling right into your living space. Mold may also start to grow.
Large ice dams may even damage your gutters and present a safety hazard for people passing below.
How to Prevent Ice Dams
Proper Insulation and ventilation
The most effective and long-term solution for ice dams is to keep heat out of your attic (through proper insulation) and to promote ventilation under the roof deck so that you may keep it as cold as possible. Your roof’s underside temperature should be kept close to that of the exterior.
Ventilation provides for continuous airflow from the underside of the roof eave to the peak, or ridge of the roof.
Reduce Heat Sources in the attic
Proper ventilation alone is not enough to prevent ice dams if you have active heat injection into your attic. Heat originating from uninsulated or leaky can lights in the room below add heat to the attic. This allows heated air from the living space to escape into your attic. Uninsulated ductwork and improperly vented bathroom exhaust fans are also potential heat sources.
Clean Your Gutters
Sweep all the leaves falling on the gutters before the snow comes. Make sure the downspouts are functioning properly. When the snow melts, it has nowhere to flow if your gutters are clogged.
Heat Tape Installation
In limited situations of light snow, electric heat tape can be useful. Proper installation is also important. The tape should serpentine along the roof edge and run inside the gutter and down into the downspout.
Snow Removal During Winter
Ice dams are the farthest thing in our minds during summer. Most of us deal with ice dams during winter. Snow removal can prevent ice damming. You should use a roof rake to remove at least the lower 4 feet of snow from the roof edge. A roof rake is similar to a shovel that is turned on its side with a very long handle. It allows you to safely pull snow off from your roof while you are on the ground. It is a bad idea to go up your roof to remove snow.
You may use an ice melting product such as calcium chloride to make it melt faster.
Removing Ice Dams
You should never try to chip away at the ice on the roof as this damages the shingles. The safest and by far the most effective way of getting rid of ice dams is using steam which melts the ice without damaging the roof, shingles or gutters.
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High Performance Restoration LLC
6500 Preston Rd #201
Frisco, TX 75034