On the Necessity of New Type Roof Assembly Greening Technology
- 2019-05-14-

The new roof- mounted greening technology is a new technology for roofing gardens. Shangjia Green believes that the assembly-type greening technology mainly explains from four aspects: thinning of planting layer, new technology of drainage layer, improvement of drainage and waterproofing of building roofing. Layer protection, etc., through these analysis introductions, illustrates the necessity of new roof-mounted greening technology.

1. Planting layer assembly greening lightweight technology

In order to try to reduce the weight and thickness of the roof green planting layer, we have developed technology from two aspects.

1) Development of artificial light culture soil for roof greening (GT-I type)

Analyze the characteristics of a large number of natural materials, and select several kinds of organic matter and various trace elements which are prepared by modern scientific methods in an optimal ratio, which are rich in plant growth, and do not contain any common soil and livestock manure components. A new type of high quality soilless culture substrate. Tested by the Soil and Fertilizer Institute of the Guangdong Academy of Agricultural Sciences, its dry weight is less than one quarter (24%) of ordinary soil (compared to soil samples), and the wet bulk density is less than half of that of ordinary soil (compared to soil samples) (43%). ) is an excellent light culture soil; its water holding capacity and cation substitution amount were detected to be 57.31% and 7.16cmol/kg, respectively, which is 3.2 times (18.14%) and 2.1 times that of common soil (compared soil sample). (3.34 cmol/kg), it is a soilless culture substrate with excellent water retention capacity and fertilizer retention capacity.

The inorganic natural material in the GT-I artificial culture soil accounts for more than 70% (volume ratio), and does not decompose and absorb the organic matter, and the root layer is gradually thinned due to the decomposition and absorption of organic matter. Bare phenomenon, root exposure can affect the growth of flower plants. Its texture is loose, not suitable for lamination, and has excellent drainage and gas permeability. It can be used as a substrate for roof greening and can also be used as a soil conditioner in combination with local common soil (such as a ratio of 2:1 or 1:1), which greatly improves the water retention capacity of ordinary soil and prevents it. Soil compaction, enhanced drainage and venting characteristics, can also save on material costs.

The artificial culture soil is composed of pure natural materials and does not contain any chemical synthetic components. It is an environmentally friendly light culture medium that can be used for many times for a long time. When the roof garden is used up, it can be used as a soil conditioner for Daejeon. It will not pollute the environment and cause waste. It should be noted that due to the light weight of the artificial culture, it is easy to be blown away by the wind in the dry state. The roots of the turf and other ground plants can protect it from being blown by the wind. When the shrubs and the roots of the trees are bare, they can be covered. ~3cm thick GT-CL surface covering material (a specially treated pine bark granule with a particle size of 5-15mm) can also directly cover ordinary soil of 2~3cm thick. It can prevent the culture soil particles from being blown up by the wind and beautify the surface layer. At the same time, it can maintain the surface moisture and prevent the water in the plant layer from evaporating too quickly.

2) Apply a lightweight thin drainage board that replaces the ceramsite (or gravel) drainage layer

Our self-developed lightweight thin-layer overhead drainage board GT-DP-M28 has been awarded a patent certificate by the National Patent Office. Its structure adopts a honeycomb design, which guarantees the maximum overhead drainage space (about 25 liters/m2) and achieves high-efficiency and rapid drainage. It has superior resistance to pressing strength (tested, its compressive strength is about normal temperature) 150 tons / square meter). Each unit is small in size (290x330mm) for easy transportation. The unit can be connected to each other. It can be easily and quickly connected to the integrated overhead drainage layer according to the shape and size of the site at the construction site to prevent possible Shift. Its thickness is only 28mm, and the weight per square meter is only about 3kg, which realizes thin layering and weight reduction of the drainage layer. If a ceramsite drainage layer of 100 to 150 mm is used, only the drainage layer itself has a wetting weight of 80 to 120 kg/m 2 .

The overhead drainage board separates the wet green planting layer from the roofing surface, and forms a thin layer of air under the planting layer. The thin layer of air is evenly distributed under the culture medium of the whole planting layer, on the one hand, the roof can be avoided for a long time. The over-wet state, on the other hand, can effectively promote the respiration of flower plant roots and is conducive to plant growth. The overhead drainage board can be easily cut to meet the requirements of the shape of the site as needed, and has good construction convenience. At the same time, the drainage board can be set horizontally or tilted or vertically to meet the needs of various construction sites. Made of lightweight plastic, the used drainage board can also be recycled as waste plastics without polluting the environment.

2. Roof-mounted green drainage

Drainage of green roofs is a very important issue that must be given enough attention. When we are treating drainage, we have an overhead drainage layer at the bottom of the whole planting layer to ensure that the rainwater or greening sprinkler that penetrates through the planting layer can quickly enter the overhead layer of the drainage board, and the drainage slope of the roof flows to the roof collecting port and drains into the drainage. Riser. There are two ways to handle the water collection. The left side is the recommended water collection treatment method. The feature is that the roof greening adopts a flower-tank layout independent of the building's daughter wall, and the maintenance passage is reserved between the daughter wall and the flower bed wall. Check and clean the water collection regularly to prevent it from being blocked by foreign matter such as leaves and garbage. At least two drains should be provided for each flower bed. If it is not possible to use independent flower planting, roof greening needs to place the roof water collecting hole in the planting area. It is recommended to use the method of checking the well at the water collecting port shown on the right side of Figure 4. The inspection cover can be opened for regular inspection and cleaning. The water collection port prevents the foreign matter from being blocked by leaves and garbage, ensuring smooth drainage.

3. Protection of building roof and waterproof layer

We know that plant roots have a strong penetrating power, so roof greening must try to protect the building roof and waterproof layer. Once the damage caused by the waterproof layer causes the roof to leak, it will cause great trouble to the work or life of the top-level users, and the maintenance work is very complicated. Because the roof has leak marks, it is not necessarily the place where the waterproof layer is damaged, so the roof needs to be greened. Remove all the holes and look for the damaged position of the waterproof layer to repair or re-waterproof. From this point of view, roof greening must be technically considered to protect building roofing and waterproofing. We have a layer of anti-root layer on top of the building roof and below the overhead drainage board to prevent the root from damaging the roof and the waterproof layer. At present, the latest roof greening technology in foreign countries adopts high-quality and high-performance anti-root layer, and the green planting layer is directly placed on the building waterproof layer, eliminating the roof insulation layer and concrete protection surface layer, which can save about 80-140. The kg/m2 roof load increases the allowable weight of the green planting layer, enabling the planting of varied plants and building a beautiful “roof garden”. If the roof is greened directly on the building waterproof layer, the waterproof layer must be made of a waterproof layer with high safety and long service life. It is recommended to lay two layers of anti-root layer on the building waterproof layer to provide sufficient safety protection.

4. Comparison of roof-mounted greening methods and traditional roof greening methods

We compared the roof-mounted greening method with the traditional roof greening method. It can be seen that the thickness of the planting substrate layer can be reduced by more than half due to the use of light artificial culture soil with excellent water retention and fertilizer retention performance; since the wet density of artificial culture soil is about 1/2 of that of ordinary soil, the substrate layer is simply planted. The weight can be reduced to less than a quarter. Secondly, since the tarpaulin drainage layer is replaced by an overhead drainage plate, the weight of the drainage layer can be reduced from about 100 kg/m2 to 3 kg/m2, and the thickness is reduced from about 100 to 150 mm to 28 mm. Once again, the double-layer anti-root penetration protection layer can save the roof insulation layer and concrete protection surface layer, and save about 80-140kg/m2 roof load. In this way, if the thickness of the planting layer is 1240mm and the weight is 1540kg/m2, the thickness of the planting layer is reduced to 430mm and the weight is reduced to 235kg/m2 by using the roof-mounted greening technology. (Note: the weight of the figure does not include planting plants. Partial weight) has successfully achieved the thinning and lightweighting of the green roof we are pursuing.

In summary, the roof-mounted greening technology is not only suitable for new buildings, but also for existing buildings. Shangjia Green believes that if the roof-mounted greening technology is used, these existing buildings can be easily covered with “green clothes”, which greatly expands the scope of promotion and popularization of roof greening, and opens up new possibilities for urban ecological environment construction. And a wider space.