Ice Damming can be a bad problem. Ice damming in Calgary is common because of the freeze-thaw cycles. It can be caused by many factors, I’ll list some common questions and answers below.
What is ice damming
An ice dam is caused by snow above the heated space of your roof melting when it’s cold out. After it melts it travels down the roof surface to the eave above the soffits(overhand of the roof) this area is colder causing the melted snow to freeze and turn to ice. The dam will slowly build up until the water has nowhere’s to go but inside your house.
What causes ice damming
First, you need to asses the situation, do you have enough attic insulation? The minimum recommended amount is R40. If you don’t have enough attic insulation the heat from your house could be escaping through the attic floor, warming the underside of your roof sheathing and causing snow to melt and then freeze when it hits the eave (unheated space). The trick is to try and keep the underside of your roof sheathing below freezing. If the snow on your roof is melting but then freezing when it hits the eave of the roof(where roof hangs over and there is no heat below) this causes an ice damming.
Another problem could be insufficient attic ventilation. This comes right back to keeping the underside of your roof sheathing cool. If the warm air from your attic is not expelling the warm air that has risen from your house fast enough the warm air causes the snow in your roof melt and then it freezes when it hits the eave.
The tricky thing is that the ice dam is a result of the problem. The actual problem is the snow on your roof and has melted at different temperatures. If the snow on the eave melts at the same time as the snow on the roof above the heated space you won’t have the problem. As it melts it will fall into the gutter and out the downspouts like it should.
So the basic fixes for ice damming are added insulation, ensure the roof is vented properly and if all else fails you can go to heat traced wires to prevent future damming.
If you have any questions about ice damming please call me at 4036165041