How do I Keep Ice from Forming on a Roof?

Even in Ontario, you can keep ice from forming on a roof. Ice is the stuff of wintery wonderlands, mugs of cocoa, and romantic couples who skate in unison, one of whom does it backwards. It is an example of the natural beauties of our northern climate and, unfortunately, the first word in the phrase “ice dam.”

Causing damage to our roof and shingles, ice shows a different side of itself, causing justifiable worry all winter long. 


When ice damming occurs at the lower edge of our roofs, eavestroughs and facia can fail under the weight of the ice.


If you have roof ice as a homeowner in London, ON, you probably think the ice forming on the lower part of the roof (called ice damming) is expected in the winter. But it isn’t supposed to be there, and it is unpleasant for your house.

A healthy roof should bear its accumulated snow equally from top to bottom. During a sudden warm spell, the eavestroughs should allow melted snow to exit, ideally through downspouts and well away from your home’s foundation.

This is an idyllic winter roof, one you can achieve!

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Not every house has roof ice. What prevents roof ice/ how can you keep ice from forming on a roof?

During the construction of your house, the attic space is permeated only by the occasional vent pipe, chimney assembly, maybe a skylight (roofing contractors are the perfect professionals from whom to purchase and install skylights), and an attic hatch that allows the placement of insulation batts to seal the attic air from the main living areas. 

These entry holes are purposefully sealed around their edges with caulking, insulation, and insulative tape to prevent temperature-altered air entering the attic. 

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Vents, vents, vents.

Your roofing contractor ensures a well-sealed attic space circulates the hot air transferred into the attic from sun-heated shingles. Several types of vents are installed, all of which move the air inside your attic space. Roof vents, soffit vents, and gable vents circulate air from below and out through the vents. 

This way, the attic space remains almost the same temperature as the outdoors. Not too cool, and in the summer, not too hot. Hot air that does not ventilate creates an environment for mould or condensation in the attic. 

The attic remains a neutral temperature, creating an energy-efficient home, so you don’t spend money cooling the attic in the summer or warming it in the winter. 

Read more about our roofing services here.



What happens when someone installs recessed lighting or cuts more vent holes into the ceiling below the attic?

Renovations that do not include isolating the attic space are how ice forms on your roof. Holes are cut, allowing air exchange from the outdoors to the attic to the living space below and vice versa.

You must have the electrician (or a handyman who may provide the work at a lesser rate) seal, seal, seal. They must seal around the obvious holes of the recessed lighting. Someone must also seal or insulate with the proper material all around the recessed lighting fixture in the attic space because air infiltration is up through the fixture’s centre. 

The solution is a box made from rigid insulation installed around the fixture in the attic space. It must provide enough room for the heat produced from the fixture to disperse and cool within its box. That box is tightly sealed around its edges to the joists. 


But what makes roof ice occur if it is not a natural effect of winter and snowfall, and is it dangerous for the roof and eavestrough?

An attic not correctly insulated can damage your roofing plywood: If an attic is not adequately isolated from the heat of the living spaces, even adequate roof vents will not likely be able to expel the accumulated heat. When snow lands on a warm roof, the bottom layer of snow, therefore, melts first. Then, the melted moisture moves toward the warmth of the roofing plywood. If allowed to continue, it will rot the roofing plywood. 

A constantly wet roof causes problems not only to the roofing plywood but also the shingles: During the refreeze, the edges of the wet shingles curl, allowing more melted snow to accumulate. After each thaw, it refreezes, lifting the shingles even more. The repeated melted snow also runs down the roof. If it cannot exit the eavestrough, it accumulates, refreezing above and in it. 

If eavestroughs aren’t cleaned, this adds to the ice damming effect that extends up the roof and causes significant water problems at your foundation: Melted snow creates a solid wall of ice at the bottom of a roof, preventing any melted snow from going past. The weight of this ice dam is dangerous for the eaves troughing and the facia board. Continued ice damming year after year causes damage to your roof shingles and roofing plywood. This ice-sheet forces melted snow behind your facia, creating water concerns for your home’s exterior walls and foundation.



And lastly, how can you get rid of it? 

Ice dams are created when several things go wrong. Fixing the problems mentioned previously will keep your roof healthy, benefit your pocketbook, and bring you peace of mind. In turn, you can spend more time at an ice rink practicing your backward skating. 


Ask us at Forest City Roofing about eaves troughing, venting, and advice about your roof’s health. 

Contact us online or call our friendly staff at (519) 659 6937


November 17, 2021

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