Ice Dams: Why Omaha Gutters Grow Icicles and How to Stop Them

A thick row of icicles along the gutter line looks like a Hallmark card, but it's usually the visible edge of an ice dam: a ridge of ice that traps melting snow on the roof and forces water backward, under the shingles, and into your walls and ceilings. In Omaha's freeze-thaw winters, they're one of the most common causes of winter water damage.

How an ice dam forms

Heat escaping from the house warms the middle of the roof and melts the snow sitting on it. That meltwater runs down to the cold overhang at the eaves, where it refreezes. Repeat for a week of 20-degree days and you get a growing wall of ice at the gutter line with a pond of trapped water behind it. Shingles are built to shed water downhill, not hold a pond, so the water finds nail holes and seams and shows up as a stain on the ceiling below.

The fixes, ranked by cost

• Free: rake snow off the first few feet of roof after storms with a roof rake, standing on the ground, never a ladder
• $100 – $180: clean the gutters in late fall, because leaf-packed gutters freeze solid and give the dam a head start
• Cheap: seal attic air leaks around can lights, bath fans and the attic hatch, which is where most of the heat escapes
• $1,500 – $3,500: top up attic insulation, the fix that addresses the actual cause and pays back every winter in heating bills
• Last resort: heat cables along the eaves, which manage the symptom when a tricky roofline can't be fully fixed

What not to do

Don't chip at the ice with a hammer or hatchet, which destroys shingles, and don't throw rock salt on the roof, which corrodes it and kills whatever's planted below. If water is already coming in, a roofer can steam the dam off safely, and a restoration crew should look at any ceiling that's stained or sagging.

An afternoon of prevention in October and November beats a February afternoon watching a brown stain spread across the dining room ceiling.