Monster icicles might be pretty to look at but are often a symptom of a bigger issue

By Andrea Prazmowski – 

Before the February thaw there were plenty of prize-winning icicles sparkling in the sun throughout Kitchissippi. Pretty as they may be, they’re like neon signs flashing out an announcement: this roof is leaking heat and money.

“Basically, you’ve got a hot roof,” explains Greg Furlong, Senior Energy Analyst with Ottawa’s non-profit EnviroCentre. “Attics are supposed to be cold in winter. If you have a cold attic and a perfect roof, the snow will pile up but will not melt. If you have a warm roof, the snow melts and when it hits the cold eaves, it freezes and forms a long icicle – over time it can become a monster icicle.”

“It’s a typical problem in this neighbourhood,” observes Owen Mahaffy who lives on Mayfair Avenue and is Director of Communications and Public Affairs with Hydro Ottawa. He says dealing with that heat loss offers “significant benefits for saving you energy in both winter and summer.”

When looking at ways to keep the heat in and conserve energy, the attic is the best place to start, explains Owen. “Up to 60% of your heat loss is through the roof.”

To tackle the problem, get an inspection done first to find out what’s in your attic, he advises. “There may be some surprises, especially in this neighbourhood, like critters who’ve taken up residence.” There may also be condensation and other signs of issues to be addressed.

After that, the essential first piece of work, says Greg, is to seal any gaps between the attic and the living space, to prevent warm air from entering the attic. The attic hatch, the chimney, plumbing and wiring are likely places where heated air can rise into the attic.

The next step is to install adequate insulation in the floor of the attic, to slow the flow of heat from the living space. “In older homes the insulation was woefully inadequate,” says Owen. Adding additional insulation is “not all that expensive” and “the payback is very quick.”

The third step is to ventilate the air space above the insulation. Older homes also often don’t have adequate attic ventilation. By allowing outside air to flow in, it helps to keep the attic cold and reduce moisture build-up.

Icicles usually team up with their troublemaking partners: ice dams. This build-up of ice along the edge of the roof prevents the melted snow from flowing off, so that water may back up under the shingles. Damage from ice dams drastically shortens the life of your shingles and can cause your roof to leak, says Greg. He doesn’t advocate the use of heating cables to melt the dams. The melted ice “just falls off the edge and creates a skating rink below, and the other drawback is they consume more electricity. Instead, I like to see if you can go to the root of the problem.”

And it’s not only a winter issue, adds Owen. A properly sealed, insulated and ventilated attic stays cooler in the summer, so air conditioning systems don’t work as hard.

Greg recommends reading “Keeping the Heat In,” a publication by the National Research Council that can be found online at

Learn about EnviroCentre’s energy saving programs online at

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