Green Roof FAQ


1. What is Green Roofs?

Green Roofs are roofs that covered with living plants like vegetable and a growing medium, planted over a waterproofing membrane. It may also include additional layer such a root barrier and drainage and irrigation systems.


2. What Types does Green Roof Have?

  • Expansion-type green roof
  • Half Intensive Roof Garden
  • Intensive Green Roof


3. What is the Function of Green Roof?

  • Reduce the indoor temperature
  • Weaken the urban noise
  • Increase air humidity, clean the water
  • Improve the utilization of land resources
  • Reduce air pollution and atmospheric dust, clean the air
  • Protect the top of the building, extend roof materials service life
  • Improve the environment of urban, the quality of people's living and working environment

4. What is the Advantage of Green Roof?

A. Energy Saving

  • Thermal insulation 5-70C, up to 30% saving electricity; 
  • Absorb lots of dust in the air, reduce atmospheric haze; 
  • Release fresh oxygen, absorb carbon dioxide, reduce carbon dioxide emissions;
  • Collect natural rainfall, reduce water leakage on the roof alluvial ground, reduce pressure on urban drainage.

B. Green and Beautification

Do not take any land area to greatly increase the green area, improve the green coverage, reduce the cost of roof greening, landscape unit of the landscaping, improve air quality, improve he ecological environment


C. Roof Protection

Insulation roof exposed affected by the sun, rain, wind, frost, snow and other natural factors directly, the excellent ecological thermal insulation properties, effective in reducing the thermal expansion and contraction of the roof structural damage, especially extend the life of the waterproof layer.

5. What Matters Need to Attention for Green Roof System?

A. Leakage-proof Processing
Putting soil and growing vegetation on the roof can protect the roof from summer sun exposure and baking, thus obviously reduce the temperature of roof, however, acid and alkaline from watering and fertilization will erode the waterproofing layer, which will lower its waterproof properties. The solution is before construction daub one 1.5cm - 2.0cm layer of ash Portland cement mortar in the original roof waterproofing layer, which can improve the water resistance, corrosion resistance and penetration-proof quality and finally enhance the waterproofing capability with the joint action of green system. The key technology of the waterproof layer is to protecting the roof, but waterproofing and drainage are a problem in two aspects, thus we should take care of roof drainage system. In the construction and design of green roof, planting pool, water pool and road should be designed according to the roof drainage system to avoid blocking up or isolating the original outfall, don't change slop at will. Especially, drainage pipeline of drainage layer in large growing pool should coordinate with the outfall of the roof, In order to make sure the extra water is easy for drain from the growing pool, please pay attention to the relevant elevation difference.

B. Bearing Problem
Bearing capability also should be taken into consideration, because it is related to safe issues. The bearing capacity of the buildings is subject to bearing ability of beam slab column and foundation under roof garden. Because the bearing capacity of housing structure affects the cost directly, so the allowing load of the roof is subject to the cost. In order to solve the problem, should take matrix cultivation. For example, use specialized roof greening soil-less lawn, adjust matrix dosage according to need when product soil-less lawn to substitute the loam layer with the same thickness, which is needed by the green roof, thereby reducing roof bearing significantly.

C. Bad Environment will Cause Plants Survival Problem
Bad environment will cause plants survival difficult problem should be into green roof consideration. Medicinal plants growing on the roof is not easy. Because environmental factors roof obviously different with the ground, light, temperature, humidity, wind, etc. With the increase of story showed different changes. For example: Roof solar radiation, warming fast, violent storms of cold heat, the temperature difference between day and night, and so on. Therefore, various types of plant growth characteristics need to select the suitable environment for the growth of plants. The plants should be resist cold, heat, drought, lean, vigorous flowers and trees. Bags containing flowers and trees are the best choice for seedlings to ensure survival.

4. Design Problem
The last problem should be take into green roof's consideration is design problem. First, design should consider the special requirements of green roof, like load-bearing roof, roof leak, lighting, water supply and drainage, leakage, etc. Second, local conditions should be counted be consideration when design the roof garden. Roof garden area is small, within the limited roof area should combine sculptures, road, lighting, pools, fountains, flowers, trees, pavilions sketches, architectural style together.

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