Do you live in a duplex, triplex, or townhouse with a flat roof? Natural light is often lacking in central rooms, especially in adjoining buildings where side windows are impossible. A skylight can radically change this space and improve your daily comfort.
This article explains what to choose, what to avoid, and why this type of installation should always be entrusted to a professional.
Key points to remember
- A skylight on a flat roof can provide up to five times more light than a wall window of the same size.
- Two main types exist : the conventional well (fixed or opening) and the tubular well.
- Watertightness is the most critical point : a bad installation causes infiltrations.
- In Quebec, positioning and implementation must be adapted to the climate, snow, frost and thaw cycles included.
- Professional installation is the only way to ensure sustainability and compliance.
What exactly is a skylight on a flat roof?
One skylights, also called skylight in Quebec, is a window installed directly in the roof. On a flat roof, it usually takes the form of a dome or pyramid made of glass or polycarbonate, mounted on a raised frame.
They are more common in urban areas, where adjoining buildings limit lateral openings. It's the most effective solution for lighting central rooms of a plex or a Montreal townhouse.
There are two main types. The classic well (fixed or opening) creates a glass opening with a direct view of the sky, often motorized to allow ventilation. The tubular well, on the other hand, directs light from the roof to the room via a reflective duct, without requiring a large structural opening — an option well suited to corridors or small spaces.
What are the real benefits for your home?
Natural light has measurable effects on comfort and health. According to a Laval University Research, Quebecers would only be exposed to about 30 minutes of natural light per day in winter. A skylight doesn't solve everything, but it helps to reduce this deficit without leaving home.
Less need for artificial lighting during the day, so a Reduced electricity bill. The opening models allow to evacuate moisture in kitchens and bathrooms. And a well-installed skylight is usually perceived positively during a resale : it is a visible, functional addition that gives character to the property.
What risks do you need to know before taking action?
Flat roofs pose challenges that sloped roofs don't have. Water stagnates, snow accumulates, and membranes are more stressed. This is precisely why the installation cannot be improvised.
A well improperly positioned or improperly sealed may result in infiltrations in the walls or ceiling, condensation caused by insufficient glazing, or Overheating in summer if the orientation has not been planned. The basic rule : the well should be placed near the parapet, never in the center of the roof where water and snow accumulate. It relies on a frame that is raised at least two feet above the membrane, a technical requirement that requires the eye of a certified roofer.
Which model should you choose according to your situation?
Why entrust this project to a professional?
Installing a skylight directly affects the integrity of your roof. A single sealing error can result in costly damage to the interior of the property, and that damage isn't always visible right away.
A professional roofer ensures that The membrane is well assembled and folded around the frame, that the flashings are adapted to the type of roof (elastomer, TPO, etc.), and that the location chosen is optimal for your structure. The work must also respect the standards of the Quebec Building Code.
The certified roofers install skylights on flat roofs with a watertightness guarantee. They also offer maintenance and repair services if your existing well has infiltration or performance issues.
The best way to extend the life of your skylight
A well-maintained skylight can last between 20 and 30 years. A few reflexes are enough to maintain its performance over time.
An annual inspection, ideally in autumn, allows you to check the joints, the sealant, the membrane and the glazing before winter starts. Cleaning the dome or the glazing prevents the accumulation of debris that reduces the supply of light and accelerates wear. After the extreme cold, a A look at the gaskets is still useful : freeze-thaw cycles end up weakening them over the seasons.
A project worth doing well
A skylight is above all an opening in your roof. What comes in from above — light, air, heat — should be kept under control. The right model, the right location, perfect watertightness: none of this can be improvised, especially on a flat roof exposed to Quebec winters.
Entrusting this project to a professional means ensuring that the installation lasts — not just the first summer.
Do you want to add a skylight to your flat roof? Our team can assess your situation, recommend the right model, and ensure a watertight installation.
Contact us for a non-binding quote.
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