Ice Dam

[bintopo]

I have a L shaped roof that faces north and west. I'm located about an hour north of Toronto and in normal winter conditions everything is fine, no ice. However as soon as the sun comes out, water starts to drip and icicles start to form along with ice dams. The attic is properly insulated and I do not have any problems with melting on the south or east side.

The house is almost forty years old and about ten years ago I replaced the old plywood sofits with modern (perforated) vinyl ones and added a couple of turbine vents. I also added rafter vents to allow air to circulate.

I believe the main problem is the snow that builds in the valley on the north and west side can add up to a couple of feet. Keeping the attic cold only prevents heat that may escape from the interior from melting snow on the roof. The sun itself can also cause snow to melt.

Since it's a one story house I have a roof shovel that allows me to pull the snow off the roof. But I can't be here for every snowfall.

Am I right in that solar melting is the main problem? Is my only option to install heat cables or are there other alternatives?

Thanks
Brian

[HayZee518]

I have seen roofs with aluminum flashing going up about three feet from the roof edge. old offset printing plates work just fine. with sun on the snow the base heats up and things start sliding. when it meets the edge for some reason the sliding stops and it re-freezes. the aluminum flashing will keep the "glacier" moving!