Bob Dillon, President, Unique Home Solutions explains why interior water damage from ice dams is very common after heavy snow followed by frequent periods of melting.
Ice dams occur because the eaves (the overhangs at the edge of your roof) tend to be colder than the rest of the roof. When water melts off the main part of the roof and reaches the eaves, it may re-freeze there and create a dam that prevents water from draining off the roof. The water can then back up underneath the roof shingles and make its way inside your home. Structural damage can also occur when the weight of snow and ice exceeds the load-bearing capacity of your roof. This is most often the case with flat roofs, older buildings, or structures whose integrity may already be compromised.
So, how do I know if there is too much snow and ice on my roof? The answer depends on a number of factors, including the roof type, construction technique, and age and condition of the structure. As a rule of thumb, if there is more than a foot of heavy, wet snow and ice on your roof, you should try to have it removed.
If you have a flat roof that is easily reached from an interior stairway, you may want to shovel the roof. Remember to put safety first any time you are on a roof, especially one that is covered in snow and ice. If you have any doubt, leave it to the professionals.
If you have a sloped roof, it may be possible to remove the snow and ice using a roof rake, a long-handled tool designed specifically for this purpose. Stand on the ground and pull as much of the snow off the eaves as you can safely reach. It is not necessary to remove all the snow; removing the first three to four feet of snow closest to the gutters will help alleviate these issues.