How to Remove Ice Dams Safely

Should you remove an ice dam yourself?

You can safely relieve a small ice dam yourself only if every step happens from the ground; anything that requires a ladder or standing on the roof belongs to a professional. Icy roofs and ladders on frozen ground are dangerous, and falls from them cause serious injuries every winter. It also helps to set the goal correctly. You don't need to remove the whole dam. You need to stop more meltwater from feeding it and open a path so trapped water can drain. Raking snow from the lower roof and melting a channel through the ice usually does that. If water is already coming through a ceiling, if the dam is thick and long, or if the roof is steep or two or more stories up, call a contractor who handles ice dam removal rather than improvising.

How do you use a roof rake safely?

Use a roof rake by standing on the ground, reaching up with the extension pole, and pulling snow down the slope in short strokes, starting at the edge and working upward only as far as you can reach comfortably. Clearing the lower several feet of snow takes away the meltwater that feeds the dam and lightens the load at the eave. A few precautions matter. Look up before you start and stay well clear of overhead power and service lines, especially with aluminum poles, which conduct electricity. Snow and ice can let go suddenly, so stand to the side of where it will land and keep others back. Don't scrape down to the roofing; leaving a thin layer of snow avoids scuffing shingles or finishes. A rake with rollers or a guard that keeps the blade off the surface is gentler on the roof. On large or steep roofs, a rake from the ground may not reach far enough, and that is a job for a pro.

How does the calcium chloride method work?

The calcium chloride method works by melting a narrow channel through the ice so trapped water can drain off the roof. Fill a fabric sleeve, such as an old pantyhose leg or long sock, with calcium chloride ice melt and tie it closed. From the ground, ease it onto the roof with the rake so it lies across the dam, running up the slope and hanging slightly over the gutter or edge. Over several hours, the chemical cuts down through the ice and opens a path for water. Several sleeves spaced along a long dam work better than one. Use calcium chloride, not rock salt: rock salt works poorly in deep cold and can damage plants, lawns and roofing materials. Expect some runoff onto beds and shrubs below the eave, so cover or rinse sensitive plantings when you can.

What should you never do to an ice dam?

Never chip, hammer, axe or pry at an ice dam, and never climb onto an icy roof to deal with one. The ice is often bonded to the roofing, so striking it can crack shingles, dent or puncture metal, tear flashing and break gutters, turning a possible leak into a certain one. Avoid pressure washers, which can force water under roofing and strip surfaces. Don't use open flames, heat guns or torches anywhere on a roof. Don't pile rock salt on the roof or in gutters. Don't pull down large icicles while standing beneath them; they are heavy, sharp and can bring sections of gutter with them. And don't walk on a snow-covered roof, where snow can hide ice, skylights and soft spots. These shortcuts often cause more damage than the ice dam itself.

When should you call a professional?

Call a professional when water is leaking into the house, when the dam is large or runs along much of the roof, or when the roof is steep, high or otherwise unsafe to work near. Experienced ice dam crews typically use low-pressure steam, which melts ice off the roof without the force that damages roofing. A pressure washer spraying hot water is a different tool and can do harm. When you hire, ask for proof of insurance. In Massachusetts, check that the contractor holds Home Improvement Contractor registration where the work requires it; Connecticut and Rhode Island run their own contractor registration programs. After big storms, demand for these crews rises fast, so it helps to have a name before you need one. Take photos of the dam and any interior damage first, in case you contact your insurer.

What should you do after the ice dam is gone?

After the ice dam is gone, deal with the heat loss that caused it, or the same dam will be back with the next storm. Check the attic for wet insulation, stained sheathing and frost, and dry out or replace anything that got soaked. Look at ceilings and walls below the eave for stains that may point to hidden moisture. Then plan the real fix: air-seal the top-floor ceiling, bring insulation up to a level suited to a cold climate, and confirm soffit-to-ridge ventilation is open and balanced. If the roof is due for replacement, make sure the new installation includes an ice barrier membrane at the eaves and valleys. A new roof, metal or otherwise, does not stop ice dams on its own; our article on preventing ice dams covers the order of work in more detail.

Step by step

1. Stay on the ground and keep people and pets away from the eaves and hanging icicles.
2. Look up for power and service lines, then rake snow from the lower several feet of the roof, pulling down the slope.
3. Fill a fabric sleeve, such as an old pantyhose leg or tube sock, with calcium chloride ice melt and tie it closed.
4. Ease the sleeve onto the roof with the rake so it lies across the dam and hangs slightly over the edge.
5. Catch any drips inside with towels and containers, and photograph the damage.
6. Call an ice dam professional for active leaks, large dams or steep and high roofs.
7. When winter ends, fix the attic heat loss that caused the dam.

Common questions