Icicles and Mouldiness – Drummond House Plans Blog

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.

Monster Icicles

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.)

Fungus and Baseboard Heaters

Another very visible sign of energy inefficiency is the accumulation of mould in the form of dark stains on the ceilings and corners of walls of houses heated by electric baseboard heaters.  A great many Montreal rental properties – in Rosemount, the Mount Royal Plateau, in Ville LaSalle and in Ahuntsic were not designed or built to be heated in this fashion, but with radiators or other types of central heating offering a more even heat distribution.

When these were replaced by electric baseboard heaters, each with their own individual thermostat so that tenants could pay for their energy consumption and the addition of insulation in the ceilings was forgotten or neglected for financial reasons.

That’s a shame because today tenants turn down or even turn off heating in some rooms in order to reduce their electric bill.  The problem is that these rental properties have a relatively high humidity rate because, typically, bathrooms and kitchens are not ventilated towards the exterior.

When the temperature of a room falls, the relative humidity goes up, not because the absolute humidity has changed but because cold air cannot hold as much steam as the warmer air.  Results: humidity condensates on badly insulated walls, ceilings and junctions (joists, corners, etc.) and which allow air to infiltrate.  This is when mould and mildew start to proliferate.

As winter advances, the problem worsens.  Wet insulation loses its insulating capacity.  If windows have been replaced and do not permit air to infiltrate (condensation will often freeze them shut as well), the level of carbon bioxyde (CO2) easily surpasses 1000 parts per million – and more than 2000 ppm if people smoke.

Symptoms of the Sick House

Headaches, dizziness and other illnesses follow.  If we let the situation degenerate, the elevated concentration of toxic mould will sooner or later take its toll on the health of the occupants – at the immunity, neurological levels…

What started as a search for a way of saving energy has transformed into a disaster for the health of the occupants.  Moreover, a building shell which condenses and retains humidity is even more difficult and costly to heat.  Know that the presence of mould and mildew is due to a lack of energy efficiency and of ventilation.

Unfortunately, mouldy walls are also a part of Quebec folklore, just like the act of placing a towel at the foot of the entrance door, instead of weather stripping, in order to prevent an exchange of air, which is ironically necessary.

To sum up, the essential is to insulate the roof if we want to change the heating system in favour of electric baseboards and, to save energy, although this type of heating loses much more heat through ascending convection than a radiant heating system.

This problem would not exist if our homes were better designed and built, particularly with regards to insulation, water-tightness and ventilation.

Morris Charney inspects all types of buildings full time now for more than 25 years.  With a diploma from prestigious Harvard University, he founded and for a long time gave a Building Inspection course at McGill University and the Architects’ Guild of Quebec (Ordre des Architectes du Québec) Moreover, he has also accomplished, as architect, over 1000 renovation designs.


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