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How to Spot and Prevent Ice Dams

Between COVID lockdowns, work-from-home arrangements, and bitterly cold weather, many of us have been cooped up inside more than usual this winter. Now that it’s warming up a bit, it’s time to make sure your home will make it through another winter okay – and that means checking for ice dams.

What’s an ice dam?

Ice dams are caused by snow melting and then freezing again. Snow becomes a layer of insulation on your roof, which warms up the air in your attic. The warm air causes the snow to melt and roll down to the edge of the roof and eavestroughs. If the melted snow can't drain properly, it will freeze and build up over time, creating an ice dam.

If this weather cycle keeps going and ice dams spread up your roof, past the water shield, water can eventually work its way under your shingles and get into your attic. The water can seep into your insulation, and down your walls.

Over time, wet surfaces attract mould, which causes breathing problems and makes repairs more expensive and labour-intensive.

This is a common problem in older homes, but even newer homes can potentially be at risk.

Signs to watch for

  1. Icicles on your roofline, showing your eavestroughs are full and the meltwater has nowhere to go.
  2. Discoloured icicles, caused by water coming into your attic, picking up dirt, and taking it back outside.
  3. New water stains on your ceilings, or water running down the inside of your walls and pooling in your basement.
  4. Uneven melt patterns on your roof.
  5. Hills or mounds of ice running along the bottom edge of your roof.

How to prevent ice damming

Keep the snow load down

Use a roof rake or hire a professional to clear away excess snow.

Give meltwater somewhere to go

Clean leaves out of your downspouts and eavestroughs in the fall, and then clear away ice, snow, and gunk regularly throughout the winter. Break off any icicles that develop around your roof.

Keep the air moving

Your attic needs good insulation and ventilation. Without it, the heat inside your home can leak into the attic and cause the snow on the roof to melt. We recommend bringing in a roofing contractor to make sure the airflow is working properly.

Seal it up

Many homes have exhaust fans, air ducts, chimneys, attic hatches, and pipes – and these are often vented into the attic. They're designed to move airflow properly, but if they aren't sealed well, extra air can escape around them. We recommend getting into your attic and checking the seals. If they need work, you can fix them yourself or hire a professional to take care of it. Good seals will also save you money by keeping your house warmer and preventing your furnace from working as hard to heat it.


SGI Canada

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