Shopping mall roof garden drainage system

Laying geocomposite drainage sheets at the roof garden of a shopping mall construction. Special attention should be given to to direction of overlap considereng the backfill direction.

Design of green roofs (inverted roof)

Another typical cross section of a green roof design.

• Vegetation
• Substrate
• Drainage-, filter- and protection- layer Enkadrain
• Roof sealing layer
• Separating fleece
• Heat insulation
• Vapour barrier
• House top / fabric

Typical roof garden sections

Below 2 typical roof garden sections. These are only to give an idea. Of course the designs change depending on the needs in the project.

The upper with conventional design. For drainage 2 nonwoven geotextile (filter fabric) layer and gravel in between were used on top of the waterproofing layer. (mineral drainage layer) Heavy and cost more to take the gravel to the roof. Bigger load on the concrete.

The below is with a geocomposite drainage layer, lightweight and easy to use. The drainage layer is only between 0.5- 1 kg depending on the material. ıt is factory made and tested material. The access water from the vegetation and soil comes to drainage layer and carried to channels.

Roof Gardens and Green roofs

Two systems - Two purposes

Roof gardens:

• To be used as a garden
• with rich vegetation on a thick layer of soil
• requires maintenance
  

Green Roofs:

• environment-friendly roof with a thin vegetal cover
• not to be used as garden
• low maintenance vegetation (mosses,
  sedums, herbs) on a thin layer of
  lightweight substrate

Roof garden tips

Now it is spring and you may want to prepare a green roof. You know roof garden does not mean a garden on the roof only. It may be top of an underground garage or top of a underground structure.

An important thing is not to forget the drainage core of the drainage sheets or layers with a nonwoven (may be woven but non woven is cheaper) filter fabric.

The ready made drainage products already have filter on them. But you have to wrap filter on the drainage core. Otherwise the soil, gravel or etc may go inside the drainage layer and block the drainage or at least decrease the amount of water to be drained.

Drainage sheets are used to remove excess water.

On the drainage layers you may use a water retention layer depending on where you live.

For more information on green roof solutions check our roof garden section for all posts of this subject.

Roof garden system

In the design of roof gardens designers should choose the design system depending on the local weather and plant conditions. Because the climate and the plants are different in al the world. Especially the drainage layer is important for the plants.

Below another roof garden design is shown.

On the concrete substrate there is a waterproofing membrane and a root barrier on it. But in some designs it is possible to lay a nonwoven geotextile to protect the waterproofing layer and a protection concrete could be casted. So, the root barrier may not be used depending on the type of plants.

For the drain layer a geocomposite drainage layer can be used. Because it is made of light materials. Otherwise you should use gravel for drainage and it will cause a load of about 150 kg/m2 on the building. So, it is much better to use a composite drainage layer.

The drainage layer should have a good filter layer to prevent clogging.

On the drainage layer landscaping architects may use a water retention layer.

You can use a prevegetated mat and soil as growth medium on the top.

This system may be used as a good drainage system.

Parking deck- drainage

Dealing with the ever increasing number of cars requires both a creative and practical solution to growing parking problems. The construction of parking areas on the roofs of buildings proves to be an efficient option. This system should cover the primary objectives: prevent infiltration of rain water, protect the waterproof layer and provide a sufficient stability allowing vehicles to drive and park. Also aspects of aesthetics, maintenance and repair costs need to be considered. Securing a well designed drainage system is a major function that can be fulfilled by geocomposites. Due to the expected traffic loads, high compression resistance is one of the main factors to be taken into account in the choice of a suitable product.

Drainage mats, which have all proven themselves in the past and provide outstanding performance in many parking deck projects worldwide. As the number of applications has grown, so has the number of criteria for selecting drainage mats. From a combination of pressure resistance, water discharge capacity, slope, filter stability and other factors, can effect to choose the right product for each specific project. For more information on drainage mats like Enkadrain and their applications.
Typical roof construction
1. Concrete roof
2. Protection layer
3. Impermeable layer
4. drainage material (mat)
5. Sand/gravel 2-7 mm, 6-15 cm
6. Pavement layer, 6-12 cm
7. Interlock improvement by sand

long planters-drainage

If you have long planters, or some green areas in your balcony or terraces you may need a drainage layer in your planter to drain or to direct the water to drainage pipes. For this purposes you may use some prefabricated drains made of a drainage layer and filtre covered around it.

Even you may use the prefabricated vertical drains like colbonddrain horizontally.

Geocomposites - Drainage of roof gardens

For many years now, green roofs are well accepted as a visually attractive and cost-effective method of roof construction, and are becoming increasingly used on account of their advantages in terms of aesthetics, ecology and physical characteristics. Due to their added value related to energy efficiency, the improvement of the microclimate and cutting the peaks of rainstorm runoffs, many city authorities and councils are more and more promoting the use of green roofs. Green roofs can give architects and building engineers more scope for aesthetic design and environmental improvement by reducing the number of hard surfaces in built–up areas.
Green roofs retain anything up to 50% of precipitation, spreading the runoff over much longer periods of time. As a result, green roofs can reduce the need for expensive drainage extension works, this helps to the civil engineer cut back construction costs significantly.
Roof Garden of Grand Azur Hotel with Enkadrain, a multifunctional layer for the drainage of surplus water, protection and filtration without the risk of clogging. The nonwoven filter layer serves both to protect the sealing layer and as a separator from the substrate. The choice of the right Enkadrain product type depends on the specific roof structure and use. The Enkadrain product range covers a large number of different drainage mats, each designed for a specific purpose. Certain types of Enkadrain are designed for use in extensive or intensive green roofs; others offer effective solutions for construction projects where roof gardens are intended to take vehicular traffic or other heavy loads, making compression resistance essential.
Enkadrain could be used also to drain long planters