Ice dam leaking? What to do

1 Nov 20264 min readD1 Construction Group

If an ice dam is leaking into the house, deal with the water inside first, then get the snow off the roof safely. Once the weather turns, fix the attic air leaks that caused it.

An ice dam is a ridge of ice along the edge of a roof. Snow higher up melts, the water runs down to the cold edge and freezes there, and the meltwater behind it backs up under the shingles and into the house. The Minnesota Department of Commerce puts the cause plainly: heat from inside the house gets into the attic and melts the underside of the snow on the roof.

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1. Warm air leaks into the attic. Heat escapes around ceiling lights and other gaps and warms the underside of the roof.
2. Snow melts from below. The meltwater runs down the roof under the snow.
3. The ice dam. At the cold eave, past the outside wall, the water freezes again into a ridge of ice.
4. Water backs up. Meltwater trapped behind the ice works under the shingles and into the top of the wall.
5. The leak. It shows on the top-floor ceiling near the outside wall, often a few feet from where it got in.

Where it shows up inside

Ice dam leaks usually show on top-floor ceilings and at the tops of exterior walls: a stain or drip near an outside wall, water at the top of a window, a damp patch inside a closet on an outside wall. The water often travels before it shows, so the stain isn’t always right under the leak.

Inside: deal with the water first

• Catch drips with buckets and towels, and move furniture, electronics and anything valuable out of the way.
• Keep people out from under a ceiling that is sagging with water.
• Stay clear of water near light fixtures, outlets or anything electrical. Switch that circuit off at the panel if you can reach it from somewhere dry.
• Photograph the stains, the drips and the ice on the roof edge before anything is cleaned up or removed.
• Start drying straight away. The EPA’s guidance is to dry water-damaged areas within 24 to 48 hours. Wet insulation is usually removed and replaced; drywall can sometimes be dried in place if it isn’t swollen and the seams are intact.

On the roof: clear it safely, or have it cleared

Taking the snow off the roof is the short-term fix. The Department of Commerce suggests a roof rake used from the ground, or hiring a professional snow remover, and says to put safety first. An icy roof is no place to be.

• If water is already coming in, Commerce recommends a professional ice dam removal service that uses steamers.
• Don’t remove ice with chippers, chemicals or heat. They can damage shingles, gutters and other parts of the building.
• Don’t install heating cables as the fix. Commerce’s advice is that they shorten the life of the roof and add to energy costs.

After the thaw: fix the cause

Ice dams come back every winter until the heat stops getting into the attic. In the Department of Commerce’s words, “Ice dams are not caused by roofing, ventilation or gutter problems, as often believed.” The real problem is a house that is leaking warm air.

• Start with a home energy assessment, an energy audit, to find where warm air is getting into the attic.
• Seal those leaks. Commerce suggests caulking or expanding spray foam, with attic insulation brought up to at least R-50 where there is room.
• Don’t add roof vents, including powered vents. Commerce says they won’t eliminate ice dams and often make the problem worse.
• Get bids from at least two licensed contractors for the work.

What we handle

The inside. We find where the water went, dry what can be dried, take out the wet insulation and drywall that can’t be, and rebuild the ceilings and walls. Clearing the roof and air sealing the attic are separate jobs; get them done before next winter, so the repair isn’t undone by the next ice dam. Our water damage restoration page covers how a job runs.

Common questions

Will insurance cover ice dam damage?

It depends on your policy and on how the damage happened. Call your insurer early, and keep the photos you took before cleanup.

Are heat cables a good fix?

The Minnesota Department of Commerce advises against installing them: they shorten the life of the roof and add to energy costs.

Should I add more roof vents?

Commerce advises against it, powered vents included. Sealing the air leaks into the attic and adding insulation deals with the cause.

Can I knock the ice off myself?

Chipping, chemicals and heat can damage shingles and gutters, and an icy roof is a dangerous place to work. Rake the snow from the ground or hire it out.

Sources

• Minnesota Department of Commerce, Got ice dams? Learn what to do and how to prevent them to save energy (February 25, 2019)
• U.S. EPA, A Brief Guide to Mold, Moisture and Your Home