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ICE DAMS

One of the biggest problems facing Ottawa area homeowners every winter is the dangerous build-up of snow and ice on your roof. Without professional roof snow removal your roof could leak from an ice dam or worse, buckle under the heavy ice and snow accumulation. This may lead to significant damage to your roof or even to the interior of your home in the event of a collapsed roof. If you wait too long to remove the snow on your roof, it can turn to ice and the cost to remove it will at least triple in price compared to snow removal.

What are ice dams?

An ice dam is a ridge of ice that often forms at the edge of a roof and prevents melting snow (water) from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation, and other areas.

Dealing with ice dams and leaks.

Immediate action:

Remove snow from the roof. This eliminates one of the ingredients necessary for the formation of an ice dam. A “roof rake” and push broom can be used to remove snow, but may damage the roofing materials. Best to call a roofing professional for this job. OHE does not offer this service.

What causes ice dams?

There is a complex interaction among the amount of heat loss from a house, snow cover and outside temperatures that leads to ice dam formation. For ice dams to form there must be snow on the roof and at the same time, higher portions of the roofs outside surface must be above 0°C while lower portions of the roof surfaces are below 0°C.

The snow on a roof surface that is above 0°C will melt. As water flows down the roof it reaches the portion of the roof that is below 0°C and freezes causing an ice dam. So the water above backs up behind the ice dam and remains a liquid. This water finds cracks and openings in the exterior roof covering and flows into the attic space. From the attic it could flow into exterior walls or through the ceiling insulation and stain the ceiling finish.

What causes different roof surface temperatures?

Since most ice dams form at the edge of the roof, there is obviously a heat source warming the roof elsewhere. This heat is primarily coming from within the house although solar heat gain may also be a cause. Unusually high heat loss on a roof will cause both an ice dam and icicles.

Ice dam prevention.

Ice dams can be prevented/reduced by controlling the heat loss from the home as follows:

  1. Increase the ceiling/roof insulation.
  2. Proper attic ventilation. Are your roof and soffit vents adequate?
  3. Seal attic air leaks. Air leaks are passageways for warmed air to enter in to the attic space and traditional insulation won’t fix this.

The most common sources of air leaks are:

i) The space around the furnace and / or water heater vents.

ii) Where plumbing vents enter in to the attic.

iii) The space around masonry chimneys.

iv) Gaps in drywall.

If you have these types of leaks in your attic, Ottawa Home Exteriors recommendation is to have an insulation contractor seal the air leaks. They’ll know where to look and how to seal them properly.

  1. Use GAF’s Deck Armour and Weather Watch or Storm Guard (often referred as ice & water shield) products for a better seal when having your roof redone. Yes, it adds a little more cost to the installation of a new roof but it reduces the risk of having roof leaks due to ice damming.
  2. Consider installing a heating cable in problem areas.
  3. Remove snow from the roof periodically. Best to call a roofing professional for this job. OHE does not offer this service.

Preventative maintenance with roof snow & ice removal

To avoid water intrusion or an unnecessary strain on your roof, your best course of action is to periodically remove the excess snow accumulation. Professional snow and ice removal services will help avoid the risk of personal injury as well as damage to your shingles and building structure.