What Causes an Ice Dam on my Roof?

An ice dam is a wall of ice that forms at the eave of the roof, above the plate line of the exterior wall. The snow on your roof melts from the loss of heat from your home. The melted snow reaches the soffit and cannot drain into the gutter due to the ice dam, eventually causing a leak.  

Problem: Water flows to the eave area and cannot shed off the roof:

  • The gutters and roof line above the soffit ice up & an ice dam is created.
  • The ice dam prevents the water, produced from melted snow, from shedding off the roof.
  • Roofs are water resistant, not waterproof. Standing water will eventually cause a leak.

Solution: Three things are required for the ice dam to form: snow, cold, and heat. You can’t control the snow or the cold. You can help control the amount of melting of the snow from the heat of your home.

  • Ventilate the attic with balanced intake and outtake ventilation.
  • Insulate the attic floor, preventing heat from melting the snow on the roof.
  • Install Ice and Water shield on the roof 2 feet inside of the exterior wall.

Conclusion: Ice dams are likely to occur in our area due to our climate. The leaks that are caused by ice dams can be mitigated and even completely eliminated by taking the steps outlined above. If your contractor does not know about ice dams, or how to eliminate them, you may find yourself in a precarious position the first winter after your roof is replaced.