A roof gardening means a garden on the roof of a building. Besides the decorative benefit, roof plantings may provide food, temperature control, hydrological benefits, architectural enhancement, habitats or corridors for wildlife, recreational opportunities, and in large scale it may even have ecological benefits.
Humans have grown plants at top structures since the ziggurats of ancient Mesopotamia (4th millennium BC–600 BC) had plantings of trees and shrubs on above ground terraces. An example in Roman times was the Villa of Mysteries in Pompeii, which had an elevated terrace where plants were grown.
A roof garden has also been discovered around an audience hall in Roman-Byzantine Caesarea. The medieval Egyptian city of Fustat had a number of high rise buildings that Nasir Khusraw in the early 11th century described as rising up to 14 stories, with roof gardens on the top story complete with ox-drawn water wheels for irrigating them.
Types of Green Roofs
- Intensive – parks and gardens in Urban Agriculture.
- Semi-intensive – garden green roofs.
- Extensive – natural low maintenance green roofs.
- Blue-green roofs – that combing green roof and blue roof technologies to maximize water storage.
Purpose of a Green Roof
Green roofs sometimes referred to as ‘vegetated roofs’ or ‘eco-roofs’ consist of a waterproofing membrane, growing medium (soil) and vegetation (plants) overlying a traditional roof. Green roofs are used to achieve environmental benefits including reducing storm water runoff, energy use and to reduce heat effect.
There are two types of green roof: intensive roofs, which are thicker, with a minimum depth of 12.8 cm (5.0 in), and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are shallow, ranging in depth from 2 cm (0.79 in) to 12.7 cm (5.0 in), lighter than.
Green roofs help reduce the Urban Heat Island Effect, a condition in which urban environments absorb and trap heat. A green roof’s plants remove air particulates, produce oxygen and provide shade. Another important benefit of green roofs is their ability to reduce and slow storm water runoff in urban environments.
By lowering air conditioning demand, green roofs decrease the production of associated air pollution and greenhouse gas emissions. Green roofs help reduce the Urban Heat Island Effect, a condition in which urban environments absorb and trap heat.
Weight of roof garden
The saturated weight of a 3-inch deep system is about 20 pounds per square foot, including a mature plant cover. Mid-range, 5-inch, systems weigh approximately 34 pounds per square foot and are compatible with wood or steel decks. Heavier intensive green roofs generally require a concrete supporting deck.
They can improve storm water management by reducing runoff and improving water quality, conserve energy, mitigate the urban heat island, increase longevity of roofing membranes, reduce noise and air pollution, sequester carbon, increase urban biodiversity by providing habitat for wildlife, provide space for urban.
The initial costs of installing a green roof are much more expensive than the costs of other roofing methods. However, over time the benefits of a green roof could help save you money and help to protect the environment.
- Roof gardens substantially increase property values.
- A good roof garden can increase the life expectancy of your roof.
- A good roof garden insulates against heat and cold.
- Green roofs and roof gardens retain and manage storm water.
- Provide social benefits Improve air quality.
- Elevated gardens modify urban micro-climates.
- Roof gardens provide diverse habitats.
- Greater expense than traditional roofs.
- An increase in weight load.
- Requires extra maintenance.