Blog · Cambridge

Ice in your gutters in Cambridge this winter: what to do, and what will only make it worse

If your Cambridge eavestroughs are full of ice, leave the ice alone, keep the downspout outlets clear of snow, pull snow off the lower roof edge from the ground if you can, and watch the ceilings below the eave for stains. The ice is a symptom of heat leaking into the attic, and the lasting fix is air sealing and insulation, with an empty gutter in November as the cheap first line of defence.

Last updated October 24, 2026 · Reviewed by the Cambridge Gutter Cleaning team

Why do gutters fill with ice in Cambridge?

Because the local winter is a freeze-thaw winter rather than a deep freeze. Environment Canada's 1981 to 2010 normals for the Region, measured at the airport, give December a mean daily high of 0.2 C and a mean low of -6.8 C, with March at 3.6 C over -5.6 C. Snow falls at about 160 cm a year, lies on the ground on roughly 95 days, and there is a low at or below freezing on about 158 days. That pattern melts the roof in the afternoon and freezes the eave at night, over and over, for three months.

Natural Resources Canada's housing guide describes the result: ice dams are large masses of ice that collect on the lower edge of a roof and in the gutters. As melting snow runs down the roof it meets the ice, backs up, and sometimes gets under the shingles and into the attic. The mechanism is heat loss. Snow insulates the roof; if the attic is above freezing it warms the sheathing and melts the snow in contact with it; the water runs to the overhang, which is below freezing because there is no heated space under it, and freezes. The guide adds that dark, south-facing siding warmed by the sun can push warm air up into the eave and cause the same thing.

What to do when you see ice in the gutter

Look inside first. Check the ceilings and the top of the walls on the side with the ice, especially in rooms under the eave, and look in the attic if you can reach it for frost on the underside of the roof or damp insulation. A brown ring on a bedroom ceiling in February is the dam, not the roof.
Keep the downspout outlets clear of snow. A downspout that is open at the bottom can at least drain the afternoon melt. One buried in a snowbank cannot, and the water freezes in the pipe.
Remove snow from the lower roof edge, from the ground. A roof rake on a pole, used from the lawn, takes the snow off the first metre or so above the eave so there is less to melt and refreeze. Pull straight down, stay away from the hydro service, and stop if you are reaching.
Let the ice melt. On most days it will, at least partly, and the gutter will drain what it can. Ice in a sound trough rarely does damage on its own; people attacking it do.
Book the attic look and the spring repair. The two things that will stop it happening next year are air sealing and insulation in the attic, and an eavestrough that is empty and draining before the first freeze.

What not to do

Do not chip, hammer or pry at the ice. Aluminum eavestrough dents, seams open, end caps pop off, and hangers pull. Most of the gutter repairs that follow a Cambridge winter were caused by a shovel, not by the ice.
Do not put a ladder on frozen ground or against an icy trough. Ontario's construction rules require fall protection for a worker who could fall more than three metres and a portable ladder set on a firm and level footing; a trained crew will not climb a ladder on ice, and neither should you.
Do not pour hot water into the trough. It refreezes within the hour, lower down, usually in the downspout, where expanding ice splits the elbow.
Do not throw rock salt into the gutter or use a torch or heat gun near the eave. Salt corrodes aluminum and steel and kills whatever the downspout drains onto.
Do not walk the roof. Not in winter, not for a gutter.

The real fix is in the attic

Natural Resources Canada is direct about it: the best prevention for ice damming is to seal all attic air leaks and insulate thoroughly. The guide suggests looking at the roof after the first heavy frost or a light snow and noting where the snow melts first, then finding out what is under that spot. The usual culprits are a bathroom fan ducted into the roof space, a plumbing vent, a skylight, a leaky attic hatch, and on a storey-and-a-half house the horizontal line where the short knee wall meets the ceiling. The guide notes that roofs with many valleys and dormers or a large overhang are more prone to dams, which describes a good share of the older housing in West Galt, Preston and old Hespeler.

The guide also notes that an uninsulated attic usually does not get ice dams, because the heat melts the snow as it lands, and a well-sealed, well-insulated attic does not either, because the roof stays cold. It is the half-done attic in between, warm enough to melt, cold enough at the eave to freeze, that builds a dam every winter. That is a job for an insulation contractor, not a gutter crew, but a gutter crew will tell you which side of the house to point them at.

What a clean gutter does and does not do

An empty, draining eavestrough does not prevent an ice dam. It does keep the dam smaller and later, because the melt that reaches the trough on a mild afternoon can run to the downspout and away instead of pooling on a bed of frozen leaves. It also protects the downspout: a downspout left part-blocked in November freezes into a solid column and splits at the seam or the elbow, which is the most common piece of winter damage a Cambridge gutter crew finds in April. The fall clean therefore wants to land in the second half of November, after the maples have dropped and before the first stretch of days that stay below zero.

When to call a pro

Call if you see water inside, if icicles are heavy enough to pull at the trough, or if a downspout is split or hanging. In midwinter the contractor we book for Cambridge will not clear a frozen trough from a ladder, but can look from the ground, advise on the melt and book the first open spring date for reseal and re-hang repairs. If you had a dam this year, a fall maintenance plan holds the late-November slot so the trough is empty before next winter. Planning ranges are on the Cambridge gutter cleaning cost page, or send a photo of the ice and you will get a straight answer on what to do now.

Sources

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