Poor Attic Insulation Or Air Leaks Cause Roof Ice Damming—not Gutters

Nov. 11, 2011 - PRLog -- We are weeks away from the official start of winter but one of the most common problems we hear about every year is ice damming or icicles brought on when it snows.  Contrary to popular opinion, gutters do not cause ice dams. According to a recent University of Minnesota study, the real cause of ice damming is a warm sunny winter day when the runoff water from melting snow runs down to the edge of the roof where it refreezes, forming an ice dam or ridge of ice.  As more snow melts end becomes water, it runs down the roof and the ice dam grows, sometimes creating icicles.
What  causes the snow to melt and refreeze creating  ice dams? Poor attic insulation or air leaks inside the home that allow warm air to get into the attic, notes the Minnesota study. Warm air rises and raises the temperature of the underside of the roof, making the snow melt. The melted snow runs down the warmed roof until it reaches the roof overhang that is not warm and is the same temperature as the outside air. The water freezes there, creating the ridge or ice dam. An ice dam can extend from the edge of the roof into a gutter under certain weather conditions. And if the gutter’s already clogged with leaves and debris, you may have an issue.
Eventually the runoff water can back up under the shingles or through cracks in the roof.
What can you do to stop it?  It depends on what’s causing the underside of the roof to warm up, the university study notes. Either more insulation or more ventilation in your home can help prevent heat buildup. You’re probably going to need a professional to tell you what’s causing the problem and what’s required in terms of insulation or venting changes to fix it.  
Some people suggest roof mounted heating cables to form a path for the melted snow to travel through an ice dam. But you’ve got to remember to turn them on.  You can’t leave them running all the time or they might short out and if the electrical power goes in a storm, you may be out of luck.
Some people suggest a snow rake to remove the rooftop snow and slow down the ice dam growth. Others suggest using a hose to cut channels through the ice dam. But it’s not  recommended that homeowners  get up on ladders in the winter to rake off or hose down the roof. And besides, both would only be temporary solutions.  Homeowners may wish to contact an energy specialist who can do an evaluation using diagnostic equipment to isolate the problem,  the University of Minnesota study suggests.
Do so, and you’ll not only find out where the problem is under your roof but you’ll also probably learn if other parts of your home are simply  leaking hot air and wasting your money.