Ice Dams: What Your Gutters Have to Do With Them
Every January the calls start. Water coming in above a window or down an inside wall, and the first thing the homeowner says is "the gutters are full of ice." That's half right. The ice in the gutter is part of it. But the ice dam itself is a roof problem that the gutters make worse. Here's what's going on and what to do about it.
How an ice dam forms
Snow sits on the roof. Heat from inside the house leaks up into the attic and warms the roof deck. The snow on the warm part melts and runs down toward the edge. The edge hangs out past the warm attic, so it's cold, and the water freezes there. That ridge of ice is the dam. More melt water comes down, hits the dam, backs up, and goes the only direction it can: under the shingles and into the house. The gutter sits right at that cold edge, so it fills with ice first and makes the dam taller.
What a clogged gutter adds to it
A clean gutter is cold and empty when the first melt comes, so some of the water drains before it freezes. A gutter packed with wet leaves from the fall is already holding water. That freezes solid with the first cold snap, and now there's a block of ice at the roof edge before the snow even shows up. The dam has a head start. This is the biggest reason the fall cleaning matters. It's not about the leaves. It's about January.
Signs you've got one
- Icicles along the gutter line, especially big ones
- A ridge of ice sitting on the roof edge above the gutter
- Water stains on the ceiling near an outside wall
- Water dripping at a window frame when it's below freezing outside
- Ice forming behind the gutter, between it and the fascia
- Gutters sagging or pulling loose under the weight
What not to do
Don't chip at it with a hammer or a shovel. That puts holes in the roof and dents in the gutter, and the ice is back tomorrow. Don't put rock salt on it. It eats shingles and metal. And don't get on an icy roof. No ceiling is worth that.
What actually helps
The real fix is in the attic, not the gutter. Better insulation and ventilation keep the roof deck cold so the snow doesn't melt from underneath. That's a different trade. What a gutter company can do is make sure the gutters aren't adding to the problem. Clean gutters drain instead of freezing full. Properly pitched gutters don't hold standing water. Gutters hung with enough hangers don't tear off under ice weight. And gutter covers keep the leaves out in the fall so there's nothing in there to freeze in the first place.
If water is coming in right now, a roofer can steam the dam off safely. Calcium chloride in a sock laid across the dam will melt a channel through it in a pinch. That's a patch, not a fix.
Ice tore the gutter loose? That's the most common call in February. Sometimes it's a few hangers. Sometimes the weight pulled the fascia board out with it. Ozark Streams will come look and tell you which it is. If the gutter has to come down anyway, that's the time to go seamless and hang it right.