Ice Dams on Your Roof? Fill a Pantyhose With This $4 Hardware Store Item and Throw It Up There
Ice dams form when heat escapes through your roof, melts the bottom layer of snow, and the water refreezes at the cold eaves. The ice builds up, blocks drainage, and water backs up under your shingles — into your ceiling, down your walls, onto your floor. I know this because it happened to me. I had a brown water stain spreading across the bedroom ceiling in February.
The proper fix involves insulation and ventilation upgrades that cost thousands. The emergency fix — the one that stops the dam right now — costs about four dollars.
The Pantyhose Trick
Fill the leg of an old pair of pantyhose with calcium chloride ice melt — not rock salt. Rock salt damages shingles and kills plants. Calcium chloride is safe for roofing materials and works at much lower temperatures.
Tie off the end and lay the filled pantyhose across the ice dam so it straddles the edge of the roof — half on the dam, half hanging over the gutter. The calcium chloride slowly melts a channel through the ice. Water trapped behind the dam drains through the channel instead of backing up under your shingles.
You do not need to climb onto the roof. A long pole, a rake, or even a well-aimed toss from a stepladder can position it. The pantyhose keeps the ice melt concentrated in one spot instead of scattering uselessly across the whole roof.
What Not to Do
Do not chip at the ice with a hammer or shovel. You will destroy your shingles. Shingles are brittle in cold weather — they crack, not flex. Every impact damages them whether you can see it or not.
Do not use rock salt or sodium chloride. It corrodes metal flashing, gutters, and downspouts. And when it washes into the soil below, it kills whatever is planted there.
Do not ignore it hoping it melts on its own. Water behind an ice dam can sit against your roof sheathing for weeks. By the time you see a stain on the ceiling, the damage inside the wall cavity is already significant.
Prevention for Next Winter
After the ceiling stain incident, I bought a roof rake — a long-handled tool with a plastic blade that pulls snow off the bottom few feet of roof. Removing snow from the eaves prevents the freeze-thaw cycle that creates dams in the first place. It costs thirty dollars and takes ten minutes after each snowfall. Cheapest insurance I have ever bought.
Quick Summary: Fill pantyhose with calcium chloride ice melt and lay it across the ice dam to create a drainage channel — no climbing required, costs under five dollars, and prevents water from backing up under shingles.