Extensive and intensive green roof: all technical information. Stratigraphy, maintenance costs, set-up costs and differences between walkable and non-walkable green roof.
When it comes togreen roofwe refer to two main categories, that of the extensive green roof and the intensive green roof. The intensive green roofit can be walked on and requires a flat surface for its construction; theextensive green roofit cannot be walked on and can be made both on inclined surfaces and on flat surfaces. Let's see all the technical details together.
Extensive green roof
It is more suitable for large roofs. It lends itself well as a covergreenfor roofs that are difficult to access and cannot be walked on: the extensive green roof can only be walked on under certain circumstances. Keep all advantages of the green roof and it requires a very simple system.
Extensive green roof maintenance
To start aextensive green roofself-sufficient, which therefore does not require maintenance, it takes approximately one or two years from commissioning and fromplantingsome plants.
Theextensive green roofit does not require irrigation and when it comes to maintenance it requires one or at most two maintenance operations a year. The maintenance of theextensive green roofconsists of fertilization, weeding or mowing treatments in the case of very active plant species.
Maintenance is concentrated in the first year after installation, when the plants need more attention to ensure they take root.
Extensive green roof: which plants to choose
To lower the need for maintenance, plant species are used that have, at the same time, a limited development and low cultural needs such as those belonging to the genusSedum (succulent and rustic plants).
To mention the most used species we point out: album, cauticolum, floriferrum, hybridum, reflexum, sexangulare, spurium ... all of the genus Sedum.
Extensive green roof, weight and thickness
Thickness and weight depend on the plant varieties chosen. Generally the growing substrate has a very reduced thickness, just enough to allow the planting and the development of the root system of the chosen plant varieties. As a guideline, the thickness of theextensive green roofamounts to 15 - 20 cm.
The weight of thestratificationsshould be estimated at the moment of maximum water saturation (when the interstices in the ground are filled with water). The weight sees values between 75 and 250 kg per square meter.
There stratigraphy of the extensive green roof always starts with a heat-insulating layer.
Intensive green roof
It needs a lot of maintenance: it needs to be taken care of as you would a garden or vegetable garden! Theintensive green roofis alwayswalkableand can be called a realroof garden!
Plants for the intensive green roof
On theintensive green roofit is possible to set up avegetable gardenup to the seating area in the shade with evergreen trees. The plant species that can be grown on theintensive green roofthey are very numerous. The classic turf is just one of many options, it is possible to grow herbaceous perennials, bushes, shrubs and trees.
Intensive green roof maintenance
As stated, it requires frequent maintenance interventions that are not limited to an annual mowing work as indicated for the extensive green roof. Maintenance works are frequent: irrigation, pruning, mowing, weeding, fertilization ... for its care, an intensive green roof needs a gardener.
Intensive green roof: thickness and weight
The thickness of the earth, including the draining layer, is generally between 20 and 50 cm. Those who want to grow onroofof the most demanding shrub and tree species will have to set up a layer of soil that can reach up to 150 cm!
The growing medium depends on the nutritional needs of the plants to be grown. This is why for aintensive green roofit is more difficult to talk about thicknesses and above all about aweightfixed! Weight can fluctuate a lot. On average it ranges from 400 to 750 kg per square meter (always in conditions of maximum water saturation).
Extensive and intensive green roof, costs
Putting maintenance costs aside, the costimplementation of a green roof is difficult to estimate. Wanting to make an overall average, i costs of construction related to the installation of aextensive green roofoscillate between 40 and 80 euros per square meter while the cost for the realization of aintensive green roofstarts at 80 euros per square meter.