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Installing a Green Roof
5 components of a successful green roof
Green roofs are installed on top of conventional roofs and have been found to outlast their non-green counterparts because the plant material protects the roof’s surface from harmful UV rays. Special consideration must be taken to plan for waterproofing, drainage and environmental challenges.
1. Root-resistant layer – a root barrier deters roots from penetrating or damaging the roof membrane.
2. Drainage layer – drainage mats are used to remove excess water from the growing medium and channel it to drains.
3. Filter layer – a textile material prevents fine particles from being washed out of the growing medium and impacting stormwater quality.
4. Growing medium – the mineral-based growing medium has the basic physical, chemical and biological properties needed for plant growth requiring minimal long-term maintenance.
5. Vegetative layer – plants that can be sustained in a very shallow growing medium which will endure the stresses of a rooftop environment.
NATS recommends two choices for your green roof
Now that you know the basics, you can decide which type of installation best suits your project needs, budget and long-term objectives.
1. Plant in Place System
This type of green roof involves planting vegetation directly into the growing medium of a roof once all of the roofing components (waterproof membrane, drainage and filter layers and growing medium) have been installed. This method can be very cost effective in the short run, but specialized knowledge is required during the planting and maintenance stages to ensure that plants survive and thrive. In addition, plant in place roofs tend to be mostly brown (dirt) for their first year or more as the plants take root and grow to size. The establishment stage can consume a large amount of time and resources and requires regular rooftop access. NATS Nursery grows a wide variety of plants for plant in place installations. Visit the plants for green roofs section to find out more.
2. Modular System
Modular systems are compact modules that house growing medium and vegetation that are applied in a grid pattern over the roof. Because they are modular, they allow for easy access to the rooftop if needed for repairs, or if you would like to alter the design of your roof (adding a pathway for example). Modules have the advantageous option of being planted and grown offsite and transported to the rooftop when they are grown to size. NATS Nursery is please to offer the LiveRoof modular green roof system to our customers. Our modules are grown to 95% coverage at our nursery and are delivered to your rooftop for the installation stage, giving you an instant green roof. We believe it to be the best modular system on the market because if its unique design which ensures that the plastic edging of the modules is never visible when the roof is installed, even during dormancy.