3 ways you can prevent roofing ice dams from damaging your roof

Through the right combination of snow removal, roof modification and insulation, you can completely eliminate roofing ice dams in your home.

Roofing ice dams occur when snow melts and freezes in between the shingles of your roof. Over time, the shingles are forced apart and water can back up and freeze into these spaces. Then, when the water melts, it causes leaks in your ceiling and walls. There are several options to prevent these leaks before they occur, but the one you choose will likely depend on your budget and the time of year.

If you've already had an ice dam this winter, but no time to fix the underlying cause, manually removing the snow should prevent further leaks. Removing the snow from your roof can be dangerous, so you should hire an expert as they'll also be able to remove icicles that can be a safety hazard. Some homeowners prefer to use a snow rake and do it themselves, but there's a risk that the snow could quickly slide off of the roof and bury anyone in its path.

The best way to prevent any ice dams from forming is to add insulation, ventilation and a moisture barrier if necessary. By insulating your attic, you'll prevent the warmth from travelling into the attic that causes the ice dam to form. An R-value of 49, which is approximately 38 centimetres of blown in insulation or 50 centimetres of fibreglass insulation, is recommended. To further reduce warm air from travelling into the attic, any holes between the ceiling and attic should be sealed. These holes include openings for electrical wires or vent stacks.

You should also make sure that the attic is properly ventilated to prevent condensation and rot within the space. A moisture barrier may also need to be installed, which when done properly, should completely eliminate most ice dams. However, it is also the most expensive option. If your attic needs substantial work, you may want to consider a standing seam metal roof to eliminate all ice dam occurrences.

If you have cathedral ceilings, it's unlikely that you'll be able to adequately insulate the roof. Adding some extra blown-in insulation may help, but boosting the R-value significantly will be difficult. In these cases, modifying the existing roof is the best option. A wide piece of metal flashing can be installed over the areas that are prone to ice dams.

A less expensive, less effective option is installing heat cables along the edges of the roof. These cables are installed in a zigzag pattern along the edge of the roof. When the cables are on, they melt the snow around them and prevent an ice dam from forming. Unfortunately, they're not always effective during extremely low overnight temperatures or when there are large amounts of snowfall.