For most people, discussions on energy efficiency are academic. They only seriously think about it when paying their heating bills, when it is too late.
It’s during winter that energy inefficiency is most obvious. In fact, the enormous icicles and ice barrages that accumulate on roofs are flagrant proof of heat loss and an inefficient use of energy. I am always surprised to hear intelligent people say that this is typically normal for our Quebec winters – just like apple pie is American. What nonsense!
At the beginning of winter, heat loss through the eaves or the attic keeps the roof surface warm. As snow starts to accumulate, it stays, even on slanted roofs. After awhile, snow becomes the insulation and traps the air. The colder it gets, the more we heat the house and the more heat we lose, the more the eaves and roof surface warm up.
One day, the roof surface temperature reaches 0 degrees Celsius and the snow next to it softens and melts. This melting snow transforms into water which slides down towards the edges. As water accumulates at the roof edges and rain gutters, the water freezes as it contacts outside air which is colder than the roof surface. Over time, the result is the formation of spectacular icicles – some reach one storey and more! The greater the heat loss is, the greater the thickness of the ice barrages behind the icicles and the greater the length of the icicles.
When there’s a major thaw and rain with temperatures reaching at least +6 degrees Celsius, even in the Laurentians, infiltrations begin. Frequently though, these do not come from the roof as such, they occur horizontally, from the edges.
In fact, the weight of the accumulated ice in the gutters opens up a joint on the edge of the roof, on the ledge or in the soffit, and the water leaking under the accumulated snow and ice in the roof penetrates to the ceilings. To the greatest surprise of homeowners, even when ceilings have a slight slope, infiltrations can manifest themselves a good distance from the exterior wall.
It’s Raining in my Bed
To my greatest disappointment, this is what my family lived through at the summer cottage of my in-laws in the Laurentians, following a successful surprise party given for André Fauteux, editor of La maison du 21ième siècle. Water started dripping from the ceiling onto our beds in the middle of the night.
Unfortunately in such cases many homeowners mistakenly blame their roof while the origin of the problem is the house’s heat loss.
Roofers are called in by panicking homeowners, and repairs are scheduled, even if no one has determined what the real cause of the problem is. Redoing a roof when it is not necessary is a very costly additional energy loss.
Certain customers have told me that they have had their roof completely redone two or three times in 10 years but the problem has not disappeared. This is outright robbery by the roofers!
In fact, as unbelievable as it may seem, many Montreal eaves contain only from 0 to 4 inches of insulation. (Note: It is generally more advantageous to install from 12 to 14 inches for a thermal resistance of R-42 to R-49, if cellulose is used, it being the most economical insulation for attics.)
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