If you've lived through a Minnesota winter, you've seen it. A thick ridge of ice along the gutters, icicles hanging off the front, and sometimes a brown stain spreading across a ceiling inside. That ridge is an ice dam, and the stain is what happens when it starts doing its job a little too well.
How an ice dam forms
It starts inside the house. Heat rises into the attic and warms the underside of the roof. The snow sitting on that warm part of the roof melts, even when it's well below freezing outside.
The meltwater runs downhill toward the edge of the roof. But the edge, the eave, hangs out past the walls of the house. Nothing is heating it. So when the water gets there, it freezes again.
Day after day, that refreezing water builds up into a wall of ice. That wall is the dam.
Why it leaks into the house
Shingles are made to shed water running downhill. They are not made to hold back a pond. Once the dam is tall enough, new meltwater has nowhere to go. It pools behind the ice and backs up under the shingles.
From there, it soaks into the roof deck, drips into the attic insulation and finds its way down inside the walls. That's why ice dam leaks usually show up near outside walls, around windows, and on ceilings close to the edge of the house.
Signs you have an ice dam
- A thick ridge of ice along the gutters or roof edge
- Heavy icicles, especially in the same spots every year
- Brown stains or bubbling paint on ceilings near outside walls
- Water in window frames or running down an inside wall
- Ice coming out of soffits or behind siding
- Gutters bending or pulling away from the house
What to do if it's leaking right now
First, call someone who removes ice dams. Then take care of the inside. Move furniture and electronics away from the wet area, put down towels, and set a bucket under any drips. If water is near a ceiling light, turn off that circuit.
Don't climb onto the roof, and don't chip at the ice. Frozen shingles crack easily, and a slip off a ladder on icy ground is a much bigger problem than a leak.
How a pro removes an ice dam
We use low-pressure steam. It melts the ice in place without hitting or scraping the roof. On a leaking house, we cut drainage channels through the dam first, so the trapped water can run off and the leak slows down. Then we take the rest of the dam off down to the shingles and clear the gutters.
If there's still a lot of snow on the lower roof, we'll usually recommend clearing it too. That snow is the fuel for the next dam.
Why they keep coming back
If the same corners of your house ice up every winter, the same heat is escaping in the same places. Common causes are warm air leaking into the attic, thin insulation, blocked ventilation and gutters that hold ice. Fixing those is the long-term answer. Removing the dam and clearing roof snow is the answer for this winter.
The short version
An ice dam is a wall of ice at the cold edge of your roof, built by heat from inside your house. It leaks because water backs up behind it and under your shingles. Get it off safely, get the snow off the lower roof, and figure out where the heat is coming from. If you're in Minnesota or the snow belt, call us at 320-760-7280 or use the quote form.