Household Hints & HELP!

Prevent Ice Dams on Roofs

submitted by Lorene Bartos, Extension Educator
This article appeared in the January 26, 2004 Lincoln Journal Star Newspaper.

Even though we’ve had a mild winter with little snow we know there is more snow to come. Being aware of possible problems when snow collects on roofs is important.

Ice dams occur when a snow-covered roof over the attic or room is warmer than the eaves, or overhang of a roof.

If the roof is warm, it will cause the snow to melt and run under snow along the roof. When the melted snow hits the cooler eaves, it freezes.

As ice builds up on eaves, it eventually traps water behind it. The water backs up under shingles and finds its way through seams in the building paper and roof decking to enter the attic and living area.

Wallpaper, plaster and paint surfaces may be damaged in the process. Fortunately, there are several ways to remedy the problem.

A cooler attic area will help decrease problems with ice dams.

Here are two ways to keep attics cool:

• Make sure the attic floor is well insulated to minimize the amount of heat rising through the attic from within the house. Increase insulation in the attic floor to at least 12 inches. Also, close any thermal shortcuts – openings that allow air to move from the heated part of the house into the attic. Chases around chimneys, plumbing vents, junction boxes for ceiling light fixtures, attic hatches and ceiling fan mounts are common thermal shortcuts.

• Create adequate attic ventilation to remove any heat that escapes into the attic. One square foot of free ventilation opening is recommended for every 150 square feet of attic space. Ventilation should be divided between eaves and the house ridge to take advantage of the fact warm air rises. When installing eave or soffit vents, be sure the opening isn't blocked by insulation. You can do that by installing a cardboard or plastic channel over the insulation lined up with each vent.

If there is an immediate problem with ice dams, remove the snow from the part of the roof directly above the ice dam. This limits the amount of water that can collect behind the dam.

Consider having the snow removed from your roof. If you must do it yourself, use safety precautions. Remove the snow using a roof rake, hoe or push broom. Roof rakes, available at hardware stores, have long handles that allow you to stay on the ground when clearing a single-story roof.

Avoid using sharp instruments, such as axes, to break channels through the ice, which is likely to cause roof and structure damage.

Just in case the snowy winter weather returns be sure to check your roof for problems that may cause damage and unwanted expense.

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