Repost from Landmark Exteriors Norwalk CT:

There’s nothing like a beautiful snowfall during the winter season! While it’s undoubtedly an incredible sight, lots of snow and ice falling on your roof with nowhere to go can be a nightmare. We’re here to help you be prepared before more snow falls, so you can ensure your roof is well-protected.
 
Take a look at all the ways snow and ice can negatively impact your roof and home, so you know to be cautious:
 
Roof Stress 
Snow and ice don’t run easily off of your roof like rain does. The added weight and pressure from built-up snow and ice, especially in back-to-back snow storms, can cause severe stress and potential damage to your roof.

Ice Dams 
Ice dams are created from ice and snow melting and flowing down off of the roof and then freezing again right at the edge. Not only can this cause water damage, but ice dams could also have the potential to destroy your gutters. 
 
Freeze and Thaw Cycle 
As the snow and ice thaw and then freeze, often in a repeated cycle, damage can happen quickly. The melted water seeps into any cracks, and then, when the water freezes, those cracks can widen causing more damage and possibly leading to mold and mildew developing in your living areas. 
 
Icicles 
While they may be pretty to look at, those icicles hanging off the sides of your roof can be hazardous. Not only do you have to worry about one falling on you unexpectedly, but forming icicles can be a sign that you have more significant problems at hand, including gutter blockages and roof damage.