Green Roofs: What Are They And What Benefits Do They Provide?

Have you ever considered a roof made entirely out of plants, grass, flowers and shrubs? This might sound like something straight out of a cartoon world; but these great Canadian roofing options, called green roofs, exist all over the world. If you have never heard of green roofs you might be wondering what they are, what they are composed of and how they benefit the environment.

What is a Green Roof Exactly?

A green roof, which is also sometimes called a living roof, is a roof that consists of vegetation of multiple types. Green roofs can be completely covered with various vegetation, but sometimes they are only partially covered. The base of the roof consists of a waterproof membrane, to ensure that any moisture drained off of the green roof doesn't enter and damage a home.

There are two main types of green roofs that are used for buildings, intensive and extensive.

  • Extensive Green Roofs - This type of green roof has a soil depth that is more shallow than that of intensive green roofs. They also have less layers of soil. Extensive green roofs are less heavy than intensive green roofs, meaning they need less complicated structural support.

           They tend to be easier to maintain and more inexpensive to install. Vegetation for an extensive green roof is usually limited to flowers, grass, small shrubs, and small plants.

  • Intensive Green Roofs - Intensive green roofs are composed of many layers of deep soil. Intensive green roofs have large structural support which allows for the heavy soil. The depth of the soil, as well as the intricate structural support, allow for large trees, larger plants, and even walkways and benches.

           These roofs may be completely inaccessible, only used for positive environmental impact, or they might function as a public rooftop park.

What Are the Components of Green Roofs?

In order to function properly and maintain stability, there are a number of components that must be present in a green roof. The first component of a green roof is structural support, the roof's skeleton. The skeleton is often times made from metal for the best support.

 From there a layer of insulation is added to keep the structure energy efficient. On top of the insulation lies the waterproof membrane base. This is important to prevent moisture damage or leaks to a structure. The drainage layer, usually small pebbles, rocks, or sand, is placed on top of the waterproof membrane. The soil then rests on top, where plants can be grown and flourish.

On top of this basic layout, irrigation, additional drainage, and structural membranes for added support might be present in a green roof.

What are the Benefits of Green Roofs?

A green roof is not just something pretty to look at. It has many environmental benefits, as well:

  • Reduced Heating Needs - Studies have shown that green roofs reduce heat loss during cold winter months. Less heat loss means less energy needed to heat your home.
  • Reduction in Water Usage - Green roofs retain moisture from rain or snow. Instead of excess water being wasted on watering, green roofs are naturally watered by the rain. This means less water consumption.
  • Green Roofs Create Habitats - Anywhere there is a large section of vegetation, small natural habitats will start to spring up.
  • Reduced Air Pollution - Having a large amount of vegetation spread throughout cities reduces the air pollution by the vegetation's photosynthesis process.

You might not think that a green roof is a viable option for your new roof, but green roofs can be found on homes in large cities as well as on homes in small towns. Green roofs take some time to install, but are easy to maintain once they have been initially built. If you think a green roof might be right for you, talk to experienced roofing contractors or people in your area with green roofs about their experience with this interesting, unique roof.


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