Green roofing, also known as a vegetated roof, is quickly gaining popularity in Quebec, in both institutional and commercial projects. And it is more than just a trend: a vegetated roof can improve comfort, reduce certain operating costs, extend the lifespan of the membrane, and contribute to better stormwater management.
If you are considering a project, start with a roof inspection to validate the condition of the membrane, drainage, and structural feasibility, especially during roof restoration.
What is a green roof?
A green roof is a roofing system on which a layer of vegetation is added above a waterproofing membrane. The system generally includes:
- a waterproofing membrane, often with a root barrier
- protection and a drainage layer
- a geotextile filter
- a substrate, such as lightweight engineered growing medium
- vegetation, such as sedums, grasses, perennials, etc.
In many cases, the choice of membrane, such as TPO, EPDM, elastomeric membrane, etc., influences long-term performance. If needed, consult our roofing membrane options.
Types of green roofs: extensive vs. intensive
Extensive green roof, the most common option
- low-growing vegetation, often sedum
- minimal maintenance
- lighter weight
- ideal for: commercial, industrial, multi-residential, school, and office buildings
Very popular for commercial roofing projects, as it offers a good balance between performance, maintenance, and cost.
Intensive green roof, rooftop garden style
- more varied vegetation, such as shrubs, vegetable gardens, and landscaping
- more extensive maintenance, including watering, fertilizing, and pruning
- much heavier weight
Often integrated into rooftop terrace projects, or buildings where the roof is accessible. Discover our green roof projects.
Benefits of a vegetated roof in Quebec
1) Extend the lifespan of the membrane
A green roof protects the membrane from UV rays and extreme temperature fluctuations. During renovation, it is a good time to plan a roof restoration adapted to a vegetated system.
2) Better manage stormwater
The substrate retains part of the water and releases it gradually. In some cities, this can help meet water management requirements or qualify for assistance programs.
A roof inspection also makes it possible to verify whether the existing drainage is sufficient, including drains, slopes, and protection elements.
3) Thermal comfort and energy performance
A green roof helps stabilize the roof temperature. The effect depends on the building, but the benefit is often more noticeable in buildings that are highly exposed to the sun or air-conditioned.
4) Reduction of heat islands
In urban areas, mineral surfaces accumulate heat. A vegetated roof helps reduce this phenomenon at the neighbourhood level.
5) Brand image, ESG, and attractiveness
For many companies, a green roof is a concrete action within an environmental approach, and sometimes even a marketing or HR argument.
Technical points to validate before choosing a green roof
Structural capacity
This is the number one point: even an extensive system adds weight, including substrate, water, and the system itself. During roof restoration, the structural analysis is often combined with a properly planned roof restoration project.
Slope, drainage, and details
The success of a vegetated roof depends on a flawless membrane, properly executed upstands, and protected drainage.
Maintenance and safe access
Even when maintenance is considered “minimal,” it still exists: inspection, weeding, and drain checks. Some companies choose annual monitoring through a roof maintenance service.
How much does a green roof cost in Quebec?
The cost depends on the surface area, the type of green roof, access, building height, and details such as penetrations, mechanical units, drains, etc.
In practice, the cost is often analyzed as a total cost:
- standard roof restoration + maintenance + lifespan
vs. - adapted roof restoration + vegetated system + benefits, such as durability, water management, and brand image
To obtain a realistic estimate, the best step is to request a quote for your roof.
Subsidies and assistance programs in Quebec
Programs related to green roofs are often:
- municipal, depending on the city
- related to stormwater management
- integrated into greening or climate adaptation programs
Good reflex:
- Check with your municipality
- Confirm whether your building is commercial or institutional
- Keep plans, invoices, technical data sheets, and photos, as they are often required
If you are in the planning phase, our team can guide you through the technical prerequisites with a roof inspection or consultation.
Is it the right choice for your building?
A green roof is particularly interesting if:
- you are planning a roof restoration and want to maximize the lifespan of the membrane
- your building is in an urban area, where runoff and heat islands are concerns
- you are looking for a sustainable solution for a commercial roof
It is less relevant if:
- the structure cannot support the load, or if the adaptation is too costly
- roof access makes maintenance unrealistic
How can LK Toitures help you?
A green roof project is not simply about “adding greenery to a roof.” It requires a complete approach:
- assessment of the roof’s condition
- planning and membrane selection
- execution of details and waterproofing, which are key to durability
- support during roof restoration
- maintenance plan
📞 Do you have a vegetated roof project? Contact us for a quote.
