Ice on a roof: when it is normal and when it is an ice dam
A little ice on the roof is normal. A thick band at the eave is not. Here is how to tell them apart.
Ice on a roof comes in two kinds. A thin glaze after freezing rain melts off by itself and does little harm. A thick ridge of ice along the eave is an ice dam, and it can push water under your shingles. The place and the thickness tell you which one you have.
The harmless kind
A light coat of ice across the whole roof is usually weather, not a defect. It forms when rain or sleet freezes on a cold surface. It tends to be even, thin and spread over the full slope.
It melts as the day warms up, and it leaves no wall behind. You can watch it from the yard. If the roof is evenly covered and the eaves look just like the rest, you most likely have nothing to fix.
The kind that matters
An ice dam is different. It sits low, at the eave and in the gutter, while the upper roof may be bare or lightly snowed. It looks like a thick, lumpy rim, often with icicles hanging off it.
That pattern means the upper roof is warm. Heat from the house is melting the snow, and the water refreezes where the roof edge is cold. Read more in what causes ice dams.
How to check from the ground
Stay on the ground with binoculars. Compare the eave to the middle of the roof. Look for these signs:
- A thick band of ice only at the lower edge.
- Icicles of different lengths, with some very long ones.
- Bare patches high up while snow stays at the eave.
- Ice pushing up the first row of shingles.
Icicles on their own are covered in icicles on gutters.
Why not to go up and clear it
Walking on an icy roof is how people get hurt, and banging at ice cracks shingles. We do not publish steps for clearing ice from the roof. If you think a dam is forming, call a roofer who has fall protection and the right tools.
What to do if it is a dam
Watch the ceilings under the eaves for new stains. If you see one, follow the steps in what to do about an ice dam leak right now. The lasting fix is in the attic: seal air leaks, even out insulation and keep the soffit vents open.
If the ice is the thin kind, do nothing yet. Check again after the next thaw and see whether it left a rim behind.
When to bring in help
Hire a roofing contractor for removal and inspection of the roof edge. For the cause, an insulation or weatherization contractor can test for air leaks in the attic.
Frequently asked questions
Is ice on my roof always a problem?
No. A thin, even glaze from freezing rain usually melts off with no harm. A thick band of ice at the eave is the one to worry about.
How do I know if the ice on my roof is an ice dam?
Look at where it sits. An ice dam builds up along the lower edge and in the gutter, often with long icicles, while the upper roof is bare or lightly covered.
Can I remove roof ice myself?
We do not recommend it. Working on an icy roof is dangerous, and chipping can damage the shingles. A roofer has the equipment to do it safely.
Will the ice come back every winter?
If the attic is losing heat, yes. Sealing air leaks and improving insulation is what stops the cycle.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- NOAA / National Weather Service. Winter — National Weather Service safety hub
- NOAA / National Weather Service. What To Do If You're Caught in a Winter Storm