Ice Dam Season is Upon Us and Prevention is Key

With the tumultuous winter climate that we experience here in Canada, there is a good chance that ice will develop on your roof at some point this season. That being said, if the ice on your roof starts to grow thicker than a couple of inches, this is considered an ice dam and leaks are likely to follow.

Ice damming
Severe ice damming.

What is An Ice Dam?

When ice build up in this manner, it is generally referred to as an ‘ice dam’. This is because as the ice grows, it literally forms a dam that prevents any water behind it from flowing freely down the roof. Ice dams are a problem because as this water pools behind it, it may be able to seep under the shingles through the roof deck and into the attic. Unfortunately, once a leak has occurred a water migration pathway will have been opened.

A water migration pathway is a pathway that water uses to find its way into the home. Once this pathway has been created, even if a repair is made to one area on the roof, water leaking through another area on the roof will work its way through the same spot on the roof deck and into the home because it will follow the path of least resistance.

Consistent ice dam formations can also cause irreparable damage to your shingles, roof deck, and eavestrough system.

Eavestrough damage caused by ice damming.
Eavestrough damages caused by ice damming.

How Do Ice Dams Develop?

While every roof will inevitably develop some amount of ice on its surface, some roofs develop a great deal more ice around the eavestrough and roof edge, than others. There is usually a good reason for this.

The temperature of the surface of your roof plays a large role in how much ice build up you will see. If there is a lack of insulation and vapour barrier, or an inadequate amount of attic ventilation this will cause the temperature within the attic to rise dramatically. When the temperature of your attic space rises, so will the temperature of your roof deck and the outer surface of the roof. This will cause the snow in these areas to melt, before running down the roof and refreezing along the edge, and in the trough area where the surface temperature is colder. The weather patterns in your specific area, along with the structural design of your roof will also contribute to the size and frequency of the ice dams that you experience.

Ice damming at the roofs edge.
Significant ice damming at the roofs edge. The ice is also blocking the downpipe.

How to Prevent Ice Dams in the Future.

There are a couple of tried and true ways to stop the current ice dam problem, and prevent them in the future.

  1. Ensure that your attic space has sufficient attic insulation, and adequate ventilation. When this is completed, be sure that any protrusion such as pot lights or plumbing pipes are properly sealed. This will prevent heat loss from the living space, that can also contribute to the rising temperature within your attic space. When these upgrades are completed, the surface of your roof should remain colder, preventing damaging ice dams.
  2. Unfortunately, some homes are not designed well and this makes it very hard to insulate and ventilate the attic space properly. In these situations, it may be impossible to keep your roof deck cool enough to prevent ice dams. In these cases, installing electric heating cables in the problem areas may help. While the cables will not prevent the ice dams from forming completely, they should help to melt them before significant issues can arise.

It is important to note that not all icicle build up is cause for concern. Small icicles developing on your eavestrough system are usually harmless, and a regular part of life in Canada. However, if you are experiencing a leak, or if you are noticing ice build-up where it shouldn’t be: along the edges of the roof, through your soffit, or behind the gutters professional help may be needed. Contact a reputable roofing & insulation contractor to discuss your options for ice dam prevention.