The main structural layer of the roof greening: the construction layer from the bottom to the top is mainly composed of protective layer, drainage (storage) layer, filter layer, substrate layer and vegetation layer. In the actual process of roof greening construction, more than a few basic structure is indispensable, each step is related to the growth of plants after the whole roof.
Protective layer
The protective layer includes a waterproof layer and root proof layer, sometimes both be made one. Protective layer for two main effects, waterproof and prevent root penetration, and sometimes to prevent root layer and the waterproof layer, sometimes combined. For the protection level, in addition to prevent rain water and irrigation water infiltration, but also requires a waterproof layer can be a long time to resist the penetration of plant roots.
Protective layer generally have alloy, rubber, PE (polyethylene) and HDPE (high density polyethylene) and other material types, for the prevention of plant root penetration protection layer. These materials have very strong workability and root stability, and the tensile strength is high, the bearing capacity is strong, is a very good roof greening protection materials.
(drain)
(storage) the drainage layer generally includes (storage) drainage plate, Tao Li (load permit) and drainage pipe (roof drainage slope is relatively large), and other different (storage) drainage form, used to improve the matrix ventilation, rapid discharge of excess water, effectively relieve the instantaneous pressure, and can save a small amount of water.
Some suitable for the drainage layer of the material, its characteristics are also suitable for the protection layer, there is no need to add a protective layer under the drainage layer. At present, there are many products in the market. However, some materials such as sand, gravel, perlite, ceramsite, should additional layer of protection. Some formed by the combination of minerals such as broken expanded clay and shale expansion, from the demolition of buildings of concrete, brick or tile and expanded the old glass foam glass, very suitable for storing drainage layer.
Filter layer
The filter layer is blocked by the matrix into the drain. Filter layer to ensure that the function of the drainage, in addition, but also to prevent the role of the drainage pipe sediment deposition. In general use of both permeable and can filter the polyester fiber non-woven fabrics and other materials.
Matrix layer
The substrate layer is a light material layer that satisfies the plant growth conditions, has a certain permeability, water storage capacity and space stability.
It is necessary to have three basic conditions for the cultivation of the roof greening. It has a certain capacity of water conservation and protection, good ventilation, and a certain chemical buffer capacity. Fourth, the weight is light, the ideal matrix bulk density should be 0.1 ~ 0.8T/m3, preferably in 0.5T/m3.
The matrix mainly includes two types of modified soil and ultra light weight matrix. Modified soil is made from the mixture of field soil, drainage material, lightweight aggregate and fertilizer, and the super light weight matrix is composed of three parts, which are the surface covering layer, the cultivation layer and the drainage water.
Planting layer
The choice of green roof plants is a very important part in the process of roof greening.
Principles of plant selection: in low shrubs, lawn and ground cover plants and climbing plants and so on, as far as possible without large trees and a small amount of planting drought tolerant small trees; developed fibrous plant selection, should not use plant with strong root system puncture, prevent plant roots to penetrate the building waterproof layer; easy to transplant, cut resistant, resistant to extensive management, slow growth of plant selection; lag selection, anti dust, pollution resistant, drought resistant, high temperature resistant, cold resistant, salinity, disease and pest resistance plants.
Because of Sedum plants with drought, cold, high temperature, shallow root system, plant is low, Yi Chenghuo, the four seasons can enjoy many properties, is often used in roof greening, especially for vegetation roofing. Wood and perennial flowers small irrigation can also according to the substrate thickness or have no choice and application of irrigation. Vine plant varieties, big green quantity, extensive management, to the roof of the equipment and the advertisement frame of green coverage, unique role.
In addition, Japan and Europe have used the moss to carry on the roof greening, the moss does not need the soil, only depends on the sun and the rain to be able to grow. The water level in the moss insurable weight about 20 times. The moss sand, Hypnum moss resistant to drought, on the formation of general plant growth layer of biological difficult high-rise building roof, slope steep sloping roofs can be used. The soil, sand and straw and waste paper and moss sand and balanced Hypnum moss together, not to use any chemical synthetic materials. On the fixed roof can be good. And the cost is low, do not need to maintain.