It's difficult to say exactly how long green roofs have been in: they fluctuate between eco-fantasy and eco-solution, but apparently surprising and environmentally friendly green roofs have always existed in Europe and North America. But I remember a very special design and special technology, a dreamlike miracle built in 2008 on top of the San Francisco California Academy of Sciences. A while has passed since then and green roof design has evolved.
Green roofshave proven to be a natural fit and quite appropriate for many public buildings, thanks to their great ecological and financial advantages such as energy efficiency, storm and water safety, and noise insulation. In this order, we must not forget the birds and other small, harmless creatures that live on the green roofs. That is why there are now established rules for “extensive” environmentally friendly roof greening projects: the vegetation should grow in a flat (7.5 cm to 15 cm) layer of light soil in a special assembly system, over a waterproof membrane. Such projects are good for the environment, they add a lot to the beauty of our local surroundings and stimulate more interest in gardening. When implementing them, you have more design freedom even with reduced financial resources and for this reason, with a growing number of green roofs, there are surprises, innovative ideas and a wonderful feeling of experimentation and lots of fun!
Would you like to take a look at a few examples?
Here they are selected especially for you: In Phoenix, for example, landscape architect Steve Martino created a playful concept. Prickly pear cactus on 7.5 cm thick soil of native granite, on a low, flat, steel roof. And in the woods of Washington's Olympic Peninsula, architect Roy Hellwig of Sequim also worked with local materials. This is actually a departure from typical earthbound plants. He roofed his apartment with mosses, lichens and ferns. These are largely epiphytes (air plants) that require soil soils. The lightweight roof requires minimal maintenance and looks as if it is connected to the earth, like in the films “Hobbits Homes” and “The Lord of the Rings”. For those who want a similar look, Hellwig has designed an easy-to-install mat, connected to the epiphytic ecosystem that clings to almost any roof or wall. He is currently busy working on a similar system for subtropical climates.
For your own house
Many designers use another possible working method when it comes to green roofs. They take different types of plants and mix the palette of plants on the roofs. In Sonoma County, California, is one such example, designed by Kevin Falkerson and Kerrie Lee Cole. This roof design displays a surprising variety of plants. On the house's 300-square-foot roof, they used nine types of sedum, plant species that attract butterflies—perennial carnations (Dianthus) and phlox—all visible from the upper floors of the house.
Architect Michael Van Valkenburgh's roof garden on top of his Washington apartment can serve as a model for green roof design. The living space covers 270 square meters and is located on two levels. At one level, low plants (especially Sedum species) were used; the other level contains a mix of sedum species with taller, drought-resistant grasses and perennials that require a deeper soil base. After six years, measurable results are already evident: the green roofs retained 77 percent of the rainfall that fell during the first data collection period, and temperatures were, amazingly, an average of 14 degrees lower than traditional black roofs on neighboring buildings.
Green roofs are complicated and expensive to install
If you want to opt for a green roof on your home, then you should definitely consult a landscape architect or designer. You need someone who specializes in the field, someone who knows well the construction requirements, mounting systems, drainage rules, local conditions, plant types and maintenance.
The cost of a green roof is approximately two to four times higher than that of building a standard roof. Before you start a construction project, you need to carefully calculate your finances.
Select plants for the green roof
The choice of plants for green roofs obviously depends on the local conditions. In general, roof systems need to be weatherproof; it can be hot, dry and very windy up there. The seeds could be blown away by wind and could still be infested by birds. Irrigation needs are stronger in southern regions. Ed Snodgrass - an outstanding American garden designer has already gained a lot of experience with green roofs; he has already "greened" over 100 residential buildings. He primarily chooses low-growing sedum species because they are hardy and well suited to a green roof. He says: “Sedums lose only a quarter of the amount of water compared to other plants.” He also recommends other hardy succulents such as roofwort (Sempervivum), Talinum, fringed housewort (Jovibarba) and Delosperma. For pops of color or varied texture and height, try perennials such as carnations (Dianthus), phlox (Phlox), bluebells, silvery cinquefoil (Potentilla), yarrow (Achillea), and violets (Viola), or small bulbous plants such as muskrat hyacinth ( Muscari) and crocus. Vegetables obviously cannot grow well on the roof because they require too much water and rich, deep soil.
Would you like to install a green roof? Start small
Do you also want to explore the possibilities of green roofs? Ed Snodgrass suggests starting with a doghouse or birdhouse.” This will be a good first step in learning the limitations and opportunities of growing plants in such a shallow root zone,” he says. And then there is no turning back, the only way is up, to the roof!
Roof terrace with garden
Buildings with flat roofs are ideal for this
Industrial buildings, former factories and even residential buildings are now being planted
Even pitched roofs can be planted without any problem
Environmentally friendly alternative – park on the roof
