Ice Dam Prevention

Maintaining our homes in colder environments can be challenging. Accumulated snow on a roof is a concern unless precautions are taken to prevent ice dams and roof leaks. Ice dams form when one or more of the following occurs.



1. Heat from interior living spaces can penetrate insufficient insulation and will warm

the roofing material enough to melt the snow that rests upon it. The water drains

toward the unheated roof overhang and typically freezes at this point. An ice dam is

born.



2. Heat loss from interior spaces is allowed to accumulate within the attic, and warm the

roofing, because of poor attic ventilation.



3. A roof is exposed to the sun in the upper half, and in the shade in the lower half.



Removing ice dams, after they have formed, can cause damage to the roofing material

and be costly to do. Prevention is the best way to approach the issue. Once a prevention

technique is in place, ice dams will never be a problem again. Using one or more of the

following prevention methods will insure an ice free roof.



1. Preventing heat loss thru attic space insulation is possible, and involves adding

insulation to the original quantity. Insulation is measured in R values. For example,

a 6" wall should have an R-value of 19, or R-19. R values approaching 38 are

common for attic spaces, and are recommended. Insulation values above 38 are

referred to as being super-insulated and will reduce heat loss but are appropriate in

extreme climates.



2. Super-insulated or not, the key to eliminating ice dams is ventilation. A passive

method that works well involves placing vents in the soffit of the roof overhang

and vents in the ridge or upper quarter of the roof. The escaping heat rises thru the

insulation and exits thru the upper vents, while being replaced by outside air supplied

by the soffit vents. The circulation maintains a cold attic space, prevents snow melt

on the roof and ice dam formation.



3. Active methods use attic fans. The use of fans guarantees specific volumes of air will

be vented to the outside. Electric gable mount or wall mount fans have been the most

commonly used product. They require an electrical power source and can be costly

to operate on a regular basis. A more energy efficient fan is a solar attic fan. The solar

panel industry has produced small but effective solar panels suitable for solar attic .

fans. The fans are available in a variety of sizes and configurations, adapting to most

custom installations. The solar fans are easily installed and work well.



Winter months are not known to be the sunniest months and the solar cell does not generate electricity on cloudy days. U.S. Sunlight sells an accessory to their fans that allows the fan to be plugged in, and be operated on a timer, 8 minutes for every 30 minutes. This works well on cloudy days and at night, guaranteeing good ventilation all winter long.



Understanding ice dams is the first step to preventing them. Adding ventilation and insulation can mitigate most potentially damaging ice problems. .