What are the dangers of not cleaning the snow off your roof in winter?

What is an ice dam?

In its simplest form, an ice dam is ice that freezes to the edge of your roof and prevents any melting runoff from draining.

How do ice dams form?

One way ice dams form is when the roof deck heats up. This is usually caused by poor insulation and a lack of sufficient ventilation in the attic.

Once it starts to heat up, the snow above it starts to melt. When the snow starts to melt, the water follows gravity down the roof. But since your gutters are already full of snow and possibly ice, there’s no where for the water to go.

So, it starts to pool, and as the temperature drops, it starts to freeze again. As this process continues throughout the winter, the ice dam gets bigger and bigger.

Are ice dams dangerous?

Yes, ice dams are dangerous. Not only can they potentially fall of the roof and injure someone, but they could also potentially cause damage to your home.

Water, as important yet destructive as it is, can find its way under the shingles and leak into your house. Not only will you have to repair your roof, but perhaps also you walls, ceilings, insulation and other integral structures.

How much do ice dams weight?

Obviously, the weight of an ice dam depends on how big it is.

But for reference, one cubic foot of ice weighs 57 pounds.

So, if your ice dam is 10 feet long by 2 feet wide by half a foot high, you’d be looking at 20 square feet, which would be an extra 1,140 lbs on your roof.

Minimizing the chance of your roof collapsing

As you just read, once an ice dam forms on your roof, the extra weight can be substantial.

If you live in an older house that hasn’t been upgraded in awhile, and you’re not sure about the integrity of your roof and internal structures, you might want to keep an eye out for ice dam formation.

Remember, heavy snow can be as much as 1.66 lbs per cubic foot.

We’ve all probably thought at one time or another, while driving down some Winnipeg street in winter, that the houses looked so beautiful with their snow-capped roofs.

What we probably didn’t think about was the extra weight the roofs were supporting.

To put it into perspective, one area of roof measuring 20 feet by 15 feet, with 1 foot of heavy snow on it, would have an extra weight of 747 lbs.

While that’s spread out over a fairly big area, add in some ice dams and you have a lot of weight pushing down on your roof.