What is an ice dam?
An ice dam is a buildup of ice that forms at the edge of a roof and prevents melting snow from draining off the roof properly. The water builds up and can cause a leak that damages your walls, insultation, ceilings, and other areas.
How does an ice dam form?
A combination of prolonged outside temps at 32 degrees, snow on the roof, and a warmer temperature on the upper portion of the roof will cause the upper portion of the snow to melt, trickle down the roof, and refreeze again.
How can a roof have different temperatures?
He rises and can escape the home in various ways. Inadequate insultation is a big contributing factor. The top later of insulation closes to the roof will be warmer, as heat rises through a process referred to as conduction. By adding more insultation, you will make the upper level of insultation closer to attic temps.
How to deal with an ice dam
Remove the snow from your roof first and foremost. The easiest way to do this is with a broom, but be careful in doing so.
Seal any leakage in your attic and ceiling and increase insultation.
Roof ventilation will be the biggest assistance in creating a uniformed roof temperature. This prevents heat from backing up in your attic in the summer (which can cause curling of your shingles) and will reduce the humidity in your attic as well. By creating an effective air barrier you won't have unnecessary air leakage!
WARNING: Anyone attempting to perform work on a roof in the winter will risk personal injury and home damage. Always contact a professional roofer.