Long icicles hanging from roof could mean an ice dam; here’s how to treat and prevent one

Long icicles hanging from roof could mean an ice dam; here’s how to treat and prevent one
A graphic illustration showing how ice dams form and function. MATT HANEY/THE WORLD-HERALD

If the icicles hanging off your roof are an inch or longer, you probably have an ice dam on your hands.

When snow accumulates on a rooftop, an unevenly heated attic can melt pockets of snow high on the roof. That moisture then trickles down the roof into the gutter, where it refreezes, creating a dense clog of ice.

Given all the snow the Omaha metro has seen recently, houses across the region are seeing footlong icicles and thick ice dams. By understanding what causes this phenomenon, homeowners can take steps to prevent them from forming.

Most of the time, ice dams are nothing to fret over. But when a large chunk of ice falls on something or someone or an imperfect roof lets water in, an ice dam can be costly.

“If they’re an inch or bigger or they’re all over the place and could fall and hurt somebody, they’re too big,” said Jake Hansen, vice president of White Castle Roofing in Omaha.

The most common way ice dams form is by poor heat distribution in an attic. They also can form when gutters or downspouts are clogged with debris, not allowing the gutters to drain properly.

When a roof has an ice dam, water can find its way into imperfections in a roof. In roofs that don’t have a weather shield or have cracks or open nail holes, water can seep in and freeze, expand and cause damage. Eventually, that water can leak into your house and cause further mayhem.

Ice dams aren’t all bad news. They can be a useful diagnostic tool.

Mark Loscutoff, president of Omaha Home Energy Analysis and Testing, said the melting and freezing patterns on your roof are clues that tell you where you’re losing heat.

“If you have a nice, even covering of snow but there are some depressed spots as the snow melts, those depressions are specific points of heat loss that are melting the snow,” he said. “If it’s more of an even melting going on, it may be a shortage of insulation in the attic or it could be a lack of attic ventilation.”

Companies like Loscutoff’s generally charge about $200 for a diagnosis of a home’s heat-loss issues. From there, costs vary depending on the severity of the issue and what needs fixing.

During extended periods of snowfall, like this month, new companies can arrive in the metro, offering to remove people’s ice dams. Loscutoff warned against chipping away ice, since it risks damaging your roof, gutters and fascia. Instead, he advised buying a snow rake to remove excess snow before it melts and freezes.

According to Hansen, Omaha’s city code calls for roofers to install two layers of ice and weather shield, so roofs built to code shouldn’t be prone to damage from an ice dam.

To prevent ice dams, Elkhorn’s Absolute Roofing recommends keeping gutters clear, checking for proper attic insulation, checking exterior ventilation and confirming that your roof has an ice and water shield.

Hansen said it’s not worth risking a fall to try and break up an ice dam once it has formed. Instead, he recommends buying a heat cable, which is a long cable that feeds through a pipe, drain or gutter. If you can feed it through your gutter safely, go for it, otherwise try wrapping it around the gutter or waiting until the next thaw to install it.

“It keeps the entire gutter, and more importantly your downspout, from freezing up,” he said.

But even then, snow falls. It melts. And it gets cold again and freezes. That’s nature.

“Because of our climate, it’s going to naturally occur,” Hansen said. “If your downspout is clear and your attic is properly ventilated, that’s all you can really do.”