Before

After

Ice Dam Damage is Preventable

An ice dam is formed when snow melts unevenly on a roof and refreezes into a dam at the edge of the roof, near the eaves. This dam prevents any further snowmelt from draining off of the roof. This standing water can back up under shingles, leak into a home, and cause significant water damage to ceilings, walls, and other areas. Ice dams can also tear off gutters and loosen shingles.

To prevent ice dams: 

The key to preventing ice dams is to keep your attic and roof cold. After a snowfall, a cold roof will have a thick blanket of snow. A warmer roof, however, will soon have clear spots where the snow has melted off, and may well have icicles hanging from the eaves.

To keep your roof cold, follow these three steps:

1. Stop warm air from reaching your attic and roof. This typically stems from air leaks through your ceiling into your attic.  Most of that comes from air leaks caused by gaps in the drywall, cracks around light fixtures, unblocked walls, plumbing pipes, chimneys, and access hatches.  These can be hard to fix but can be done through the attic by plugging leaks with foam and caulk.
2. Go into your attic and check the depth of your attic insulation. Building codes require about 12 to 14 in. of fiberglass or cellulose. Add more if you have less than 8 in and have had ice dam problems in the past. 
3. Attic ventilation draws in cold outdoor air and flushes out warmer attic air, cooling the attic and the roof in the process. If you don’t have enough ventilation in your attic this could be causing ice dams and you might want to look into adding come ventilation vents.