What Are Ice Dams and How Can You Prevent Them?

We're expecting a lot of ice dam-related insurance claims in the next week as Oklahoma City gets hit with a cold blast of wintry weather. While icicles are pretty, ice dams are another thing.

What is an Ice Dam?

If you live in an area that experiences heavy snowfall most winters, then you are probably already familiar with the damage that an ice dam can cause. Houses and buildings with a sloping roof are the main targets for this often costly occurrence.

Damn Ice!

Ice dams generally form when snow accumulates on a sloping roof. As the snow begins to melt, the water runs underneath the insulating blanket above. As the meltwater reaches the freezing air, usually at the eaves, it begins to form a wall of ice creating a thick barrier.

This barrier (or dam) makes it difficult for new meltwater to drain, resulting in leaks through the roof. This can cause great damage to the home; the roof, ceilings, walls, carpets and insulation can be destroyed by the resulting leaks.

Uneven Heat

Ice dams are formed when a roof’s heat is unevenly distributed. When a higher area of a sloped roof is warmer than lower areas (including the edges), the meltwater moves down and begins to accumulate at the edges where it is cold enough to freeze.

A large barrier of ice forms that begins to trap the new water. The dam can grow as more water freezes - and the mere weight of the structure can cause damage itself. Large ice dams have been known to fall and take with them large parts of the roof. These large deposits can also hurt people as warmer temperatures begin to thaw the ice and send them hurtling below.

How to Prevent Ice Dams

Although there are some quick fixes, such as Deicing Cables, ice dams can be prevented by making a few improvements to your roof or attic, many of which are simple DIY projects - air sealing, insulation, and ventilation.

• Add Roof Insulation: By adding insulation to your roof, you can prevent the hot spots that cause the melting. The key is ensuring your roof keeps a consistent temperature, so any meltwater from a thaw will drain appropriately.
• Seal Roof Leaks: A leak in your roof will allow any warm air to escape, creating the warm spots that contribute to the formation of ice dams. If your attic and roof are well insulated, but you are still dealing with ice dams, a roof leak could be the cause.
• Seal Attic Floor: There could also be leaks in your ceiling/attic that are causing an accumulation of warm air underneath your roof's sheathing. Seal all leaks that you can find.
• Add Roof and Soffit Vents: Insufficient ventilation can cause moisture problems in the winter and poor energy efficiency in the warmer months, so it is good to look into a ventilation system regardless. However, attic ventilation is also good way to keep the roof temperature cool. Ventilation will draw in the cold air while releasing the warmer attic air, ensuring both the attic and roof stay a consistent temperature; keeping ice dams from forming.
• Quick Cleaning: After a heavy snowfall, the best way to make sure an ice dam doesn’t form is to clean the roof quickly. Depending on the snow cover, a broom, rake or special tool called a roof rake might be all that is needed to remove it before it begins to melt. Be mindful of the situation and call a professional if the snow cover is too deep – or the roof is simply too dangerous to maneuver.
• Install Ice Belt Panels: A band of metal roofing called an ice belt can help deter ice dams from forming. Installed at the eaves, these belt panels create a low-friction surface where the ice dams usually form.
• Make DIY Ice Melting Socks: Fill some nylon stockings with Calcium Chloride Ice Melt and place them along the edges of your roof or even in your gutters to prevent ice from building up there. Do NOT use rock salt!