Roofing Services
Ice Dam Removal and Prevention
At a Glance
- Ice dams come from a warm attic, not from cold weather
- Steam removal is safe. Hammers and salt are not
- The permanent fix is insulation and ventilation
- The same three houses on a street get one every year
Every January the same handful of houses on a Davenport block grow a wall of ice along the gutter line. Their neighbors, in the same weather, on the same street, do not. The difference is not the roof. It is what is happening under it.
How an Ice Dam Forms
- Heat leaks out of the living space into the attic
- The attic warms the underside of the roof deck
- Snow on the warm part of the roof melts, even in freezing weather
- The water runs down to the eave, which hangs over open air and is cold
- It refreezes there and builds a ridge of ice
- The next meltwater backs up behind that ridge and sits
- Standing water works uphill under the shingles and into the house
Shingles shed water running downhill. They are not built to hold back a pond, and that is what an ice dam makes.
Getting It Off Safely
Steam is the only method we use on a roof with a finished ceiling under it. Low pressure steam melts a channel through the ice without touching the shingles.
- Never a hammer or a chisel. That breaks shingles under the ice
- Never a pressure washer. That strips granules and drives water in
- Never rock salt in a sock, which stains the roof and eats the metal
- Calcium chloride is a stopgap only and not a plan
The Fix That Ends It
Removing the ice treats today. The house will do it again next month unless the attic changes. Three things, in this order.
- Seal the air leaks. Around light fixtures, the attic hatch, bathroom fans and any chase
- Add insulation, so less heat reaches the deck
- Ventilate, so what does get up there leaves through the ridge instead of warming the roof
Done together, the roof deck stays close to outside temperature and snow sits on it instead of melting. That is the whole trick, and it lowers the heating bill on the way past. More in Ice Dams, Start to Finish.
Questions About Ice Dam Removal
Are icicles the same as an ice dam?
Not always, but they are the warning. Icicles mean meltwater is reaching a cold eave. A thick ridge of ice behind them is the dam.
Will heat cable fix it?
Heat cable cuts a channel so water can escape. It treats the symptom, uses electricity all winter and does nothing about the heat loss causing it. Useful in a few hard cases, not a substitute for insulation.
The ice is already there and my ceiling is wet. What now?
Call. That is an emergency and it gets a steam crew, not a schedule slot.
Does a metal roof stop ice dams?
It helps, because snow slides off it, and it does not remove the cause. A warm attic under a metal roof is still a warm attic.
Get It Looked At First
No sales call. A roofer looks at the roof and tells you what it needs.