ice dam & interior water damage with a metal roof

Guest User
7/27/2011
We installed a metal roof on the north-facing side of our home to prevent snow build-up & ice-dam issues we had experienced during the winter of 2008/09. This past winter, 2010/11, was horrendous in terms of snow & ice accumulation & unfortunately the ice backed up under the metal panels & came into the house, not only through the window casement as it had before, but at a wall joint above the window as well. This north-facing roofline has a long converging valley that gets no sunlight during the winter months. The metal roof was supposed to eliminate this seasonal problem, but it certainly didn't work out for us last winter. Any suggestions?
Todd Miller
Isaiah Industries, Inc.
7/27/2011
Thanks Shelley. Unfortunately some folks sell metal roofing as a cure for ending ice dams. I have to be honest -- that really isn't necessarily the case. Metal will often shed ice and snow more quickly than other roofing materials and that shedding will play a role in avoiding ice dams. However, during certain weather conditions, the snow does not shed and ice can result if the home does not have good attic floor insulation and ventilation. Generally, ice dams are the result of heat that gets into the attic from the home creating "hot spots" on the roof surface. That melts the snow which then runs down the roof, re-forming as ice over the home's cold overhangs. Is there any way to increase insulation or ventilation in the attic?
Eric Novotny
An informed customer is the Best Customer!
7/28/2011
Todd is 100% correct in this case (actually he always is but this is somewhat up my alley as it pertains more to building efficiency than it does a roofing issue). Ice damns (the cause of them at least) are building issue and not a roofing issue. You can certainly mitigate the contributing factors with additional insulation, however, the root cause of ice damns are heat loss. Where these are most problematic and difficult to address is those instances where you have a hot roof deck (i.e. you insulation layer and roof structure are the same) and cannot properly air seal or add enough R-Value to the roof. What is the structure (i.e. layout of the attic) of the home?

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