Seasonal

Ice Dams on Roofs: Why They Form and How to Stop Them

By Maple Grove Roof Repair · November 1, 2026 · 8 min read

Ice dams on roofs are one of the costliest winter problems a Maple Grove house can have. The first real snow usually lands here in the first half of November, and by the middle of December the same story repeats on street after street: water running down the inside of a window frame, or a brown ring spreading on a bedroom ceiling along an outside wall. That is an ice dam, and the damage it does inside often costs more than the roof repair.

Now is the useful week to read this. Once there is a foot of snow on the roof and the ridge of ice is already built at the gutter, your options shrink to paying someone to steam it off.

How ice dams on roofs form

An ice dam is a heat problem wearing a weather costume.

1. Warm air leaks out of the house into the attic — around can lights, the bath fan, the top plates of interior walls, the attic hatch, a chase around the furnace flue.
2. That warm air heats the underside of the roof deck over the heated part of the house.
3. Snow on that part of the roof melts, even at 15 degrees outside.
4. The meltwater runs down under the snowpack until it reaches the overhang, which hangs out past the warm wall and is the same temperature as the air.
5. It freezes there. Repeat for a week and you have a ridge of ice several inches thick at the eave.
6. The next round of meltwater backs up behind that ridge, sits in a pond, and works its way under the shingles. Shingles shed water going downhill. They are not waterproof standing still.

That is why a heavy snow year is not the real trigger. The trigger is a string of sunny days in the 20s, which Maple Grove gets all winter, and a leaky attic.

Where the water goes

By the time you see it, the water has usually been in the wall or the ceiling for a while. In a typical Maple Grove house, it shows up as:

• Stains on the ceiling within about two feet of an exterior wall
• Wet insulation over the top plate, which then holds moisture against the drywall
• Paint blistering on the inside of a soffit or a window head
• Frost or dark stains on the sheathing at the eave, visible from the attic
• Water running out of a can light — the fastest way to find out the light was not airtight

Mold can follow within a couple of weeks if the wet insulation and drywall are left alone. The interior repair is often more expensive than the roof repair.

What removal costs, and what not to do

If water is coming in now, the fix is to open a channel through the ice so the pond drains. Done properly that is low-pressure steam, not a hammer, not a chisel, and not a pressure washer.

Do not put salt pucks in a nylon stocking on an asphalt roof — the runoff eats aluminum gutters and stains siding. Do not chip. Every winter someone puts a hatchet through the decking, and now they have a hole under a foot of snow. And do not climb a ladder onto an iced roof edge; a fall from an icy ladder is a far bigger risk than the leak.

The page on ice dam roof repair in Maple Grove covers the emergency side. If water is actively coming in, call a local contractor before you climb.

Ice dam prevention starts in the attic

Removing the ice without fixing the attic is a rental, not a repair. The three things that actually end it:

• Air sealing. Foam and caulk every penetration between the house and the attic. This matters more than insulation depth, and it is the step most often skipped.
• Insulation. Get to a deep, even blanket across the whole attic floor, including over the top plates at the eaves, without blocking the soffit vents.
• Ventilation. Baffles at each rafter bay keep the soffit path open, and a continuous ridge vent lets that cold air out at the top. The goal is a roof deck that stays the same temperature as the outside air.

Xcel Energy and CenterPoint Energy have run rebates on attic air sealing and insulation for Minnesota homes; check current offers before you book the work. The attic insulation guide goes deeper on R-values and what a good attic looks like from the hatch.

Where heat cable fits

Heat cable, run in a zigzag at the eave and through the gutter and downspout, is a legitimate tool in two places: a north-facing eave over an entry where falling ice is a safety issue, and a roof section you cannot fix from the attic, like a vaulted ceiling over a family room or a dormer with no accessible bay. Installed, expect $12–$25 per foot, plus an exterior outlet if there is not one. Run it on a thermostat, not all winter.

What it is not is a substitute for insulation on a normal vented attic. It carves a drain channel. It does not stop the melting.

What to do in the next two weeks

• Pull a long-handled roof rake along the bottom three or four feet of the eaves after any storm over six inches, standing on the ground.
• Open the attic hatch on a cold morning and look for frost on the nail tips and daylight at the soffits.
• Check that the bath fans and the dryer vent exhaust outside, not into the attic. A fan dumping warm, wet air into the attic is one of the most common causes.
• If your eaves dammed last winter, book the attic work now — nobody is insulating in February.
• If a section of eave has dammed three winters running, the decking under it has been wet and frozen repeatedly, and a roof inspection should look at the sheathing before spring.

Common mistakes once the ice is there

• Waiting for a thaw to fix it. The thaw is when the pond behind the ridge is biggest, and when the water gets in.
• Raking from a ladder. Rake from the ground only. A roof rake on a ladder is how people get hurt.
• Raking the whole roof hard. Pull snow off the bottom few feet and leave the rest. Scraping down to the shingles strips granules.
• Paying for removal twice a winter and never fixing the attic. Steam clears this week's ice. Only the attic work keeps next winter's from forming.
• Skipping photos. Before anything is touched, photograph the ice, the stains and any wet insulation. Your insurance agent will ask.

Questions to ask whoever removes the ice

1. Will you use low-pressure steam, and nothing sharp?
2. Will you clear a channel only, or the full length of the eave?
3. Will you check the gutters and downspouts so the meltwater has somewhere to go?
4. Will you send photos of the shingles at the eave once the ice is off?

Common questions

Do heat cables stop ice dams?

Not on their own. Heat cable melts a drain path through the ice so water can escape, but the snow above it keeps melting for the same reason it did before: heat leaking out of the house. Use it for spots you cannot fix from the attic, like a vaulted ceiling or an entry eave, and fix the attic everywhere else.

Is ice dam damage covered by insurance in Minnesota?

It depends on the policy. Many homeowners policies treat sudden water damage inside the house differently from the cost of removing ice or fixing the cause, and some policies exclude damage from long-term neglect. Check with your insurance agent before you start repairs, and take photos of the ice, the stains and any wet insulation first.

Why do ice dams form on some houses and not others?

Two houses on the same street get the same snow, so the difference is almost always the attic. A house with leaky can lights, an open attic hatch, a bath fan venting into the attic or thin insulation over the outside walls warms the roof deck and melts the snow from below. Complicated rooflines with valleys and low eaves over heated rooms make it worse. A house with a cold, well-sealed attic can sit under the same snow all winter without a dam.