Planting Trees on Roofs & Using Deep Systems
Posted in Blog, green roof, Jobsite Photos, Trees on June 15, 2017
Green roofs are a worldwide megatrend in architecture. As the green roof industry has matured, green roof designs are changing from rather simple extensive green roof systems to very complex urban landscapes on structure. Leading designers and landscape architects are envisioning and creating ever more sophisticated green roofs on top of buildings.
Trees are an essential part of these landscapes on structure providing an additional dimension for green roof design, function, and value. And when trees are included on a green roof, they are typically a central piece of the design. They are highly visible – from the roof and even the ground – and they are almost always used on green roofs that will be accessible amenities, such as plaza decks, roof gardens, and healing gardens, providing a dynamic and unique space on a rooftop.
Ensuring that trees on green roofs have long-term success is an absolute essential to protect the investment into the green roof and achieve the aesthetic vision. But it’s not as simple as transferring common at-grade garden designs to roofs. When you move trees to rooftops, the technical requirements change dramatically.
Because trees are larger and heavier than other plants, they need a much deeper soil system for their roots. And with limited depth on a roof, it’s critical to use the right green roof media to have trees that thrive. On a rooftop, engineered lightweight soil systems replace natural at grade soil horizons and optimize the long-term performance of the growth media.
Skyland USA, which produces rooflite, is the only company in the industry to offer a unique soil system for rooftop trees. This soil system has a well-designed root zone with a perfect balance of water retention and aeration along with adjusted nutrient levels to allow for long-term healthy root growth. Our soil system is lightweight and structurally stable, so you can rely on it to perform long-term.
This multi-layer soil system, made up of four rooflite products, mimics and improves on natural soil horizons. It recreates soil conditions at grade but optimized for on-structure installations – with a granular drainage layer, a filter layer, an innovative base layer, and an organic, rich intensive top layer.
Because our deep soil system for trees has been engineered to be structurally stable and not to lose volume over time, trees will thrive for many years. Structural stability is essential to create and maintain a well-aerated root environment for healthy long term growth.
With our deep, rooftop trees soil system, we successfully manage water in two ways. Our soil system is free draining so that water doesn’t build up on the roof structure, but it also retains the necessary water to nourish the trees. It’s a delicate balance that we’ve perfected over many years.
Finally, our rooftop trees soil system is designed to be flexible for your specific rooftop trees project. It can easily be adjusted from a minimum depth of 20 inches to build-ups of several feet. We also offer the products that make up our rooftop trees soil system in a variety of weight classes, depending on your region. This allows you to take your requirements and combine them with our weight classes to have a solution that works best for your project.