Winter Ice Damming – What To Know

October 21, 2020
ice damming

An Ice Dam is a hump of ice that forms at the edge of a roof under certain wintertime conditions. An ice dam can damage both your roof and the inside of your home. It will put gutters and downspouts at risk too. Ice Dams are a common sight during winter in Nebraska. There are several things you can do to avoid getting an ice dam or to reduce the risk of damage after one has formed, but there’s really only one cure: a combination of better sealing, insulation, and venting in the attic and eaves.

WINTER ICE DAMMING

HOW DO ICE DAMS FORM?

An ice dam forms when the roof over the attic gets warm enough to melt the snow. The underside of the layer of snow on the roof melts, causing water to trickle down between the layer of snow and the shingles until it reaches the edge of the roof’s surface. This part of the roof stays cold because it extends beyond the side of the house. There, the water freezes, gradually growing into a mound of ice.

The flatter the pitch of the roof, the easier it is for an ice dam to form. Gutters at the eaves can also trap snow and ice. If snow and ice build-up high enough in the gutter, it can provide a foundation for an ice dam.

WHAT DAMAGE DO ICE DAMS CAUSE?

When an ice dam gets big enough, melted water backs up behind it and seeps underneath the shingles. Eventually, it will drip into the insulation and down into the ceilings and exterior walls beneath the eave, ruining sheetrock and paint. If the ice breaks free, it can pull shingles and gutters off with it, and it will damage anything it falls on: shrubs, windowsills, cars, pets, and people. If the roof sheathing stays wet, it can form mildew and start to rot.

DEALING WITH EXISTING ICE DAMS

  1. Remove the ice dam by breaking it free in small chucks. Do NOT use an ax or other sharp tool! You’ll cut through the shingles. Instead, tap lightly with a blunt mallet. This is slow, dangerous work, so hire someone experienced at roofing. Even if you do it safely, the chunks of ice can take pieces of shingle with them.
  2. Clear out gutters and downspouts. This is ladder work and an easy way to damage either plastic or metal gutters and spouts.
  3. Melt vertical strips through the ice dam with calcium chloride ice melter. Do NOT use rock salt! It will damage paint, metals, and plants beneath the eave and wherever the salty water drains.

PREVENTING ICE DAMS

You can scrape snow from the roof whenever it falls, using a snow rake from below or a broom or plastic shovel from above. BE CAREFUL: The first method can bury you in snow, while the second can send you slipping off the roof. Hire someone who knows how to use a safety line.

You can replace your shingle roof with a standing seam or other metal roofs. Or you can replace the bottom three feet or so of your shingle roof with a wide metal drip edge. Whatever you do, install a water-repellent membrane under any new roofing.

THE PERMANENT SOLUTION

All of these methods treat the symptoms, not the underlying problem, which is the warm roof, caused by poor insulation and venting of the space under the roof. We have found that the only way to cure an ice dam – and prevent one in the first place – is to:

  1. Seal all points where warm air leaks from the living space into the spaces immediately below the roof sheathing.
  2. Insulate the living space well enough to prevent conduction and convection of heat through the ceiling.
  3. Vent the space between the insulation and the roof sheathing, so any heat that does leak through is carried away.

CONTACT MCKINNIS TODAY

If you are in the greater Omaha, Lincoln, Blair areas, and have concerns about ice damming in the winter months, the McKinnis team is ready to assist! We offer both commercial and residential services. You can call us at 402.426.2644 or fill out our contact form. We look forward to hearing from you and assisting with all your roofing and exterior needs!