Ice Dam Prevention
"An
ice dam is formed when heat from the interior space of the structure, vents
up through the ceiling and exits the roof causing the snow to melt. This
melting snow then moves down the slope of the roof and contacts the cold
unheated overhang section of the roof and accumulates to form the ice dam.
Once this ice is formed, water is then pushed back up the roof where it
penetrates through seams, valleys and disturbed shingles. As water enters
though the seams it saturates the insulation and inner wall cavities. This
damage can happen over several seasons, before it eventually is observed
and noticed through staining the drywall, or dripping occurs. Ice dams
also become a danger to persons and property below. As the weather warms,
blocks of ice can suddenly release and fall to the ground. The weight of
this ice block can be substantial and can cause severe damage. Homeowners
typically need to be concerned where their vehicles are parked, that their
decks and other exterior amenities can be severely damaged, destroyed,
or worse, someone can be seriously injured. These two ice dam example photos
are excellet examples of typical ice dams." - Heated Roof Systems
Inc
This information was taken from www.Libertymutual.com and is a list of ways to prevent Ice dams
Make sure your gutters are clear of leaves and debris.
Check and seal places where warm air could leak from your house to the attic: vent pipes, exhaust fans, chimneys, attic hatches and light fixtures are all possibilities.
Inspect, or have your roof and attic inspected for proper ventilation and insulation.
Look for signs of inadequate ventilation: rust spots, rusty nails or a mildew smell are all signals that moisture has formed on the inside of your roof. (Condensation forms on the warmer of two back-to-back surfaces, thus on the outside of a glass of ice water, or on the inside of a roof in winter.)
If you have soffit vents in your eaves, make sure they are not blocked and insulation surrounding them is secured so that air can flow easily.
If you do not have soffit or ridge vents, you can have them installed or install them yourself fairly easily. There are a number of self-help books that explain how many vents you need, where they should be placed and how to install them.
Install one of the following, but recognize that these treat the symptoms,
not the disease itself. Only proper ventilation and insulation prevents
ice dams:
1) Install snow and ice slides. These are metal strips about 24" wide installed as a retrofit solution over the existing roof to prevent ice and snow from "bonding" to the lower roof.
2) Install a rubberized ice and water shield beneath the roof shingles for the first three to six feet from the eaves up.
3) Install heating cable along the eaves to melt ice. While generally effective, heat cables can cause pooling behind the ice if the snow pack is very heavy or if the cable is not turned on early enough.
