Attic Ventilation Systems: Protecting your Home from Canada’s Temperature-Tantrums
Did you break the rules when you were a kid? If you did, even just occasionally, you probably heard your parents say something like: “As long as you’re under my roof, you’ll follow my rules!” Or how about this one: “You’re lucky to have food on the table and a roof over your head!” (something I heard a few times when I’d asked for expensive things that no ten year old really needs- remember Poo-Chi the robot dog??).
As adults, we all understand our parents’ fixation with roofs, and their need to remind us how lucky we were to have one. Your roof keeps you warm, dry, and out of the elements, and not inexpensively. Roof replacements and repairs are a huge cost to homeowners. Our temperamental Canadian climate doesn’t help matters; a shingle that is advertised to last 25 years is lucky to last 15 with our sweltering summers and unforgiving winters. It’s no wonder our clients are asking:
“How can I extend the life of my roof?”
The answer: ventilation. Improper ventilation will cause ice buildup in the winter and extreme heat in the summer, both of which will drastically reduce the lifespan of an asphalt shingle.
Check out the image above. This is a properly ventilated attic. Here’s how it works:
Soffit Vents: We cut holes in your soffits to draw outside air into your attic. We cover these holes with perforated aluminum, which will keep out any critters looking for a place to nest. Our friends at Gentek can match virtually any aluminum or siding colour, so these new soffits will never look out of place
Moore Vents: Moore Vents are made of a lightweight Styrofoam and are installed between the rafters to create channels within your attic that direct airflow. How many Moore Vents do you need? Well, the Ontario Building Code requires at least one vent every 32 inches (which is typically one every other rafter cavity). This will create an acceptable amount of airflow. A better system will have one Moore Vent every 16 inches (every rafter cavity). If your roof is trussed, most builders will install one every 24 inches. The best systems in trussed roofs will have two every 24 inches.
The vents extend up past the insulation, which is crucial in keeping your soffit vents from becoming blocked. The best part about Moore Vents is that the materials are cheap! The difference between installing one every 24 inches and installing two every 24 inches is just a few dollars!
Roof vents: Roof vents are installed as close to the ridgeline as possible. This is how the air drawn into your attic is exhausted. The most recognizable roof vents are “whirly birds,” and they stand about 18 inches off of the roof. The spinning top is very effective at keeping out rain and snow. The problem with these is that, if they aren’t spinning (if there’s no wind or if built up snow holds it stationary), all of that rain and snow is coming right into your attic.
A better system will have ridge venting. A ridge vent lifts the top ridge of your roof by an inch and a half and allows air to escape along the entire run. These are the best for exhausting air during the summer months. The drawback is that, 3-5 months of the year, our roofs are covered in snow. As soon as snow builds up on your roof these vents are covered, and the air in your attic becomes trapped.
The best system for Canadian homes is one that uses a stationary ventilator, similar to a whirly bird, but without the need for a spinning component. Our favourite product is the Duraflo Pro Ventilator, which is effective and attractive. It sits off the roof 18 - 24 inches (high enough to sit above the snow) and blocks rain and snow from entering your attic.
Insulation: Insulation is the last piece of your attic system. Having insulation with an adequate R rating (click here to find out all about R ratings and insulation quality) will keep the cool attic air that protects your roof from changing the temperature in your home!
With a proper attic ventilation system you can reduce ice build-up and heat damage
In the winter, having a proper attic ventilation system will keep your attic cool, which will prevent ice buildup. Think of an unvented attic like one big air bubble. Ice problems (including icicles forming on your eves) are caused by the warm air from your house rising up and warming that bubble. A warm bubble will inevitably heat up the roof above it, melting the snow sitting on top. That melted snow doesn’t stay melted for long; the cold air and wind quickly refreeze it, but this time instead of fluffy snow it takes the form of ice. That ice will continue to build, creating dangerous icicles and damaging your shingles. A good ventilation system will draw in the cold winter air, create channels that keep that air moving, and maintain the outside temperature below your shingles, thus preventing buildup and protecting your roof. All the while, the happy homeowners are protected and toasty warm below the insulation layer!
In the summer, that same system will keep your shingles cool and your A/C bill low. Remember that warm air bubble in the unvented attic? In the summer it can easily reach 60°C, and will climb much higher in a heat wave. Asphalt shingles are comprised of a fibreglass mat, coated in stone granules and held together by tar. At these extreme summer temperatures the tar in your shingles will begin to evaporate, causing the tiny pebbles to wash away the next time it rains. The airflow from your ventilation system will help to keep your roof from reaching shingle-damaging temperatures. Have you noticed little granules sitting loose on your roof? If so, it may be time to inspect your attic ventilation system.
Give us a call to book your attic inspection and add years of life to your roof!