Small, even icicles are usually harmless. Large icicles in one spot or thick ice on the roof edge can mean an ice dam, which can leak into the house.
Get My Free Estimate →Small, even icicles along a gutter are common in a Wisconsin winter and usually harmless. They form when sun or mild weather melts snow on the roof and the water refreezes as it drips off the cold edge.
Large icicles in one spot, a thick band of ice along the roof edge, or icicles forming behind the gutter are different. Those point to an ice dam, where heat escaping into the attic melts snow and the water refreezes at the eave.
Buckshot removes ice dams, repairs gutters and corrects attic ventilation through our ice dam removal, gutter repair and attic ventilation services. This guide shows how to read the icicles on your house and what to do about each pattern.
Why icicles form on gutters
Icicles form wherever meltwater reaches a cold edge and freezes before it can drain. The meltwater comes from snow melted by the sun, by mild daytime temperatures or by heat escaping from the house into the attic.
The roof edge and gutters sit over the overhang, outside the heated part of the house, so they stay colder than the roof above the rooms. Water running down a warmer roof refreezes when it reaches them.
What different icicle patterns mean
| What you see | What it usually means |
|---|---|
| Small, even icicles along the whole gutter after a sunny day | Normal melting and refreezing |
| Large icicles clustered in one spot | Heat escaping below that spot, or a blocked gutter or downspout |
| Thick ice on the roof edge with bare roof above it | An ice dam from heat escaping into the attic |
| Icicles forming behind the gutter or on the siding | Water getting behind the gutter, often backed up by ice |
| Icicles hanging from gutter guards | Snow and meltwater freezing on top of the guards |
A bare strip of shingles above the icicles, while the rest of the roof holds snow, is a strong sign of heat loss. Our guide to snow melting in patches explains that pattern, and our heated gutters guide includes a quick check from the yard.
When icicles mean an ice dam
An ice dam is a ridge of ice at the roof edge that traps meltwater behind it. The trapped water can back up under the shingles and leak into the attic, walls and ceilings.
- Thick ice on the roof edge itself, not only hanging from the gutter
- Water stains or drips on upstairs ceilings or exterior walls
- Icicles that come back in the same spot every cold spell
- Ice filling the gutter that does not melt on mild days
Our guide to ice dams in Wisconsin explains the causes and prevention in detail.
Why large icicles are a problem
Large icicles and gutter ice add weight to the gutters and hangers. Over a winter, that weight can bend the gutter or pull it away from the fascia, as our guide to gutters pulling away from the house explains.
Falling icicles can injure people and damage anything below them, so keep walkways and entries clear of large ones. Ice packed in the gutters and downspouts also blocks drainage, so the next thaw overflows behind the gutter or onto the foundation.
Gutter guards do not cause ice dams, but snow and meltwater can collect on top of them and freeze. That is why icicles often hang from the front edge of guarded gutters.
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What to do about icicles safely
Stay off the roof and off ladders when there is ice. Knock down small icicles only from a spot where nothing can fall on you, and leave large icicles and roof ice for a crew.
After heavy snow, a roof rake used from the ground can pull snow off the lower few feet of the roof, which reduces the meltwater feeding the icicles. Before winter, clear the gutters and downspouts so meltwater can drain, as our guide to cleaning gutters in Wisconsin explains.
For a heavy ice dam or an active leak, call for removal. Our ice dam removal crews remove ice safely, and the storm line is answered 24/7.
Seeing large icicles or ice along your roof edge? Our roof and attic inspection is free, and for an active leak the storm line at (608) 909-9109 is answered 24/7.
Free on-site inspection · Family-owned since 1979How the cause of recurring icicles is fixed
Icicles that return in the same places usually trace to heat escaping into the attic through air leaks and thin insulation, along with ventilation that cannot keep the roof deck cold. Fixing the cause means stopping that heat and keeping the underside of the roof cold.
Balanced attic ventilation brings cold air in at the soffits and lets it out near the ridge. Blocked soffit intake is a common problem, as our guide to vented vs solid soffit explains.
At the roof edge, ice and water shield under the shingles protects the deck if water backs up. It goes in during a roof replacement.
Heat cables in the gutters can keep a drainage path open, but they treat the ice, not the heat loss behind it. Gutters bent or loosened by ice are repaired or rehung through our gutter services.
If an ice dam has already caused a leak, our guide on whether homeowners insurance covers ice dams explains what policies usually cover.
Get your roof and attic checked before heavy snow
Buckshot Exteriors is family-owned, has served homeowners since 1979, and has offices in Madison, Wisconsin and Centerville, Iowa. We remove ice dams, repair gutters and balance attic ventilation, and our roof and attic inspection is free.
Call (608) 909-9109 to schedule your free inspection, or send us a message and we will set a time. If you would rather check first, compare your icicles with the table above after the next snow.
Get a straight answer on your Madison roof
Wisconsin storm season and insurance non-renewal letters do not wait. Get a free, no-obligation inspection and an honest assessment of exactly what your roof needs, even if the answer is to wait.