Roof Materials - Green Roofs

Green Roofing Systems

Green Roof Construction

Extensive Green Roof

Intensive Green Roof

Taking the place of the usual shingles, tiles, metals, and membranes, the green roof is on the rise in popularity, as it proves to be an energy efficient, earth friendly alternative. The green roof covers traditional roofing materials with vegetation that provides many benefits to the structure and the environment. A green roof has a number of layers including a soil layer, as well as layers for drainage and waterproofing with the vegetation layer topping them all. Though it varies between green roof systems, the roof may even have an irrigation system installed for upkeep of the plants. However the plants typically used on these roof systems do not require much watering, since the installed plants are generally found in drought prone areas.

Green roofs are not only on the rise here in the United States , but are quite popular in different parts of Europe . In fact, Germany is considered to be at the top of green roof research and development partly due to the German public feeling a responsibility to use as little energy as possible.

Irrigation systems aren't necessary under most circumstances, but there are the few exceptions. When installing an irrigation system for your green roof, do not use surface watering systems such as a drip or spray system. You should install a system that delivers the water deep underneath the vegetation and straight to the roots. A drip system wastes water through evaporation, losing much of the needed water before it can get to the plant roots.

Green roofs come in two different types: extensive and intensive.

First, the extensive green roof, also referred to as an eco-roof , has fewer and thinner layers, making it much lighter. The lighter roof requires less additional bracing and support for the structure, thus making the extensive roof cheaper. Since they have less soil medium, extensive roofs ' plant selection is limited to mosses, succulents and grasses all low growing plants. These plants grow from 16 to 24 inches tall, creating a low profile roof. The extensive green roof is very low maintenance since most of the plants are drought tolerant.

The intensive green roof isn't as limited to the variety of plants because the soil medium depth is increased greatly. Therefore, an intensive roof will be much heavier, and may require additional bracing and support. The increased soil allows for taller plants that may require more maintenance. It is also possible to find waterfalls, gazebos, and other small structures atop an intensive green roof. Though intensive green roofs require additional maintenance and materials, they also provide the opportunity for an outdoor area that can be used recreationally or to grow food.

There are a number of advantages to having a green roof:

• A green roof reduces a lot of heat from the roofs surface, thus saving on air conditioning and energy costs for the building. This is especially good in urban areas with large buildings because many structures create what is called a heat island affect, making the inner city substantially hotter than surrounding areas.

   

• A green roof works as a good sound insulator, reducing the noise inside a building by up to 10 decibels.

   

• A green roof shields the roof membrane layer from absorbing heat from the sun, thus making the membrane last longer. Green roofs also retain water well, creating less storm water drainage, and run off from the building.

   

• Green roofs reduce the amount of pollutants that run off with rainwater from buildings. The Green roof retains much of the water in the soil and the plants will actually absorb some of the pollutants, purifying the water before it leaves the building.

   

• Green roofs also act as a natural air filter. The vegetation will absorb various airborne toxins, purifying the air.
• Intensive green roofs provide garden and yard space in tight living conditions, such as apartment buildings.

Summary:

Although green roofs are initially more expensive to install, they can save you time and money in the future and are good for the environment. For more information on green roofs check out the International Green Roof Association.

Green roof illustration from American Wick Drain