What is an Ice Dam?

January 2, 2018

Significant snow events can often result in dangerous and destructive ice dams.

Ice damming occurs when water from melting snow runs down the surface of a roof and re-freezes. The melted snow is caused by warm air in the attic space that heats the underside of a roof. Fluctuating temperatures can also play a role in creating snowmelt.

As the melted snow makes its way down the roof, it eventually comes in contact with the deck over the eaves, which is not exposed to heat from the attic. This is where the ice generally begins to form.

As the water re-freezes, ice builds up and blocks the subsequent run-off, creating a "dam." Some of the pooled water then finds its way under shingles, which are designed to shed water, not handle pooled water. It then re-freezes, lifting the shingles from the roof deck and giving water an opportunity to enter.

Pre-season prevention measures such as a roofing underlayment that specifically protects against rain and ice dams or heating strips in drains and downspouts can significantly reduce this risk.

Recognizing Ice Dams

There are several signs that may indicate the presence of an ice dam. Be on the lookout for the following warnings, and always be sure to have excess snow cleared off your roof as soon as possible following a storm. 

Signs of an Ice Dam

Responding to Ice Dams

If you recognize an ice dam on your home, monitor the spaces directly under your roof for signs of water intrusion. A professional can assist you in removing ice dams with steamers or ice melt.

If you would like assistance locating a qualified vendor in your area, contact a PURE Member Advocate® at 888.813.7873 or memberadvocate@pureinsurance.com, and we will do our best to help you.