To help prevent or reduce the speed of global warming, adding a green open space with a garden on the roof of houses, buildings, hotels and offices is one of the effective ways. Although the conditions of the urban region largely filled by multi-storey buildings, the designers had to create a green open space to add plants that have been taken over when the building was built. By creating a garden on the roof, high-rise buildings can still have a green open space, because there is space efficiency. Garden on the roof or roof garden is as an alternative reforestation to improve the quality big city environmental health. Currently, only some five-star hotel in Jakarta which has a garden on the roof or roof garden.
Making the garden on the roof or roof garden is not cheap and need structure and specific roof construction. Even for optimal results, the construction of a roof for the park in the design from the beginning, before the building was constructed. However, this investment can come back in a few years later, because the cost of electricity is reduced air conditioning, as well as building economic value added.
A private hospital in Singapore managed to reduce electricity consumption by 50 percent, after a garden on the roof or roof garden. Although the roof garden was just a tomato plant, which is placed in the pot to cover the entire roof. Another advantage, the hospital did not have to buy tomatoes again.
In addition to the shade, garden on the roof or roof garden can also be used to absorb toxic gases. For example, bamboo or palm can absorb formaldehyde gas and gasoline. While the lily plant, in addition to absorbing the formaldehyde gas and gasoline, as well as alcohol and acetone produced paint and so on. Vines also serves to absorb gases acetate, ammonia, and other gases. Because of this function, the vines have been used for a garden on the roof or roof garden in foreign countries like Singapore and Japan.
How to build a garden above roof
Before making a rooftop garden, first consider the construction of the roof of the building. Is it designed to support the burden of growing media such as land and trees will be planted on it or not. Because the garden on the roof or roof garden. must be supported structure and strong roof construction.
The existence of a garden on the roof or roof garden will cause increasing burden. Heaps of soil and plants will increase the dead load, wind load, and the additional burden of water on the roof of the building. The building must have a drainage system that works well.
If the types of shrubs to be planted, he takes into account the load of the roof will add approximately 650 Kg / m2. Plus more for live load according to activity on the roof garden. For example, 400 Kg / m2 for sports, 500 Kg / m2 to party and dance, as well as 250 Kg / m2 for restaurants.
To plant a large tree, the location of the floor slab should be supported concrete structural columns so that plates do not collapse. In addition, retaining wall needs to be made because the trees require adequate soil thickness, or make a hole in the roof of a building, under a tree.
Construction leak-prone roofs, so it must be equipped with drainage channels. Drainage layer such as gravel, sand, pumice and should be added so that water easily flows into the drain hole. Filters are made of geo-textile or fibers serves to drain water down but retains granular soil from clogging the drain.
To prevent damage to the waterproof coating or water proof layer, a barrier layer must be added to the plant roots do not damage the waterproof coating and the concrete underneath. Because the plants on the roof exposed to direct sunlight and the wind faster, watering should be done regularly. So it needs water spraying can be done manually or automatically.
For the planting medium, the formula should be light but have the ability to provide nutrients and moisture. For example, by mixing sand with wood shavings plus a layer of pine bark and manure. Depth of planting medium for grass requires 20 to 30 centimeters, as well as cover crops. Meanwhile, shrubs and small trees require a depth of 60-105 centimeters. Big trees need a depth of almost 2 meters.