Botanical Traditions - Roof Top Gardens

A green roof is a roof of a building that is covered with vegetation.  Green roofs serve many different purposes such as providing insulation for heat and sound, creating habitat for animals, reducing the heat island effect, reducing carbon dioxide levels,  reducing air pollution, increasing the roof life span, reducing stormwater run off,  increasing the value of the building and creating more open outdoor and social spaces for humans.  In fire prone areas they may help insulate against heat and slow the rate at which the fire spreads.  In addition to this they can also be designed to include solar power and solar hot water collectors as well as to harvest rainwater.

There are a number of different kinds of green roofs and they can consist of lawns, vegetables and productive plants, trees or a combination of these.  In Australia, many people also consider balcony gardens and roof top gardens that are not purely aesthetic and where containers are used as a type of green roof.  You also have green walls which are internal or external vertical building elements.

Green roofs are not a new phenomenon.  We have all heard of the Hanging Gardens of Babylon which were built around 600BC by king Nebuchadnezzar II. Sod roofs were used by the Vikings and are still seen today in places such as Iceland and Tanzania.  Frank Lloyd Wright used green roofs as early as 1910 as a tool to help buildings integrate into the landscape.  Le Corbusier encouraged the use of green roofs for their social aspects and to compensate for the loss of green spaces in the 1930’s with his small residential projects as well as his high rise developments.  In the 1960’s there was a rapid increase in concern about the degraded quality of urban environments and the rapid decline in green spaces in urban areas.  This lead to a new interest in green roofs. 

The development of the contemporary approach to green roof technology began in urban areas of Germany over 30 years ago.  In 1975, the German Landscape Research, Development and Construction Society was created. This organization was one of the first to formally study green roof technology, and its potential.  They studied urban ecology and the creation of urban habitats, energy balance, water proofing systems, root repelling agents, drainage, plant stability and effective design and planning.  Today it is estimated that 15% of roofs in Germany can be considered as ‘green roofs’ and this is set to increase with the Government making available financial incentives along with 75 other European municipalities.

Australian examples of green roofs are far less common and climatic conditions in all Australian cities are very different to those in Germany. However, overseas examples prove that green roofs are particularly effective in denser, more urban environments where they help to insulate buildings against heat and where they can compensate for the loss of green open spaces at ground level.  There is also no reason why green roofs can not be used in suburban settings or on sheds and garages.  After all, every square meter of barren rooftop is a wasted opportunity and reserved for exhausts and air conditioner units.

The growing interest and Australian research into the area has encouraged an increase in availability of technologies which make green roof construction easier and more economical than before.

The design and implementation of a green roof is relatively straight forward provided a number of site and horticultural issues are addressed.

All green roofs consist of the same basic components. These include a roofing layer, waterproofing layer, light weight growing media and a vegetation layer.

 

Botanical Traditions has designed an award winning roof top and been involved in a number of different balcony and roof top garden projects.