Green Roofs – Good, Bad or Fad?
By Shelly, Apr 26 2016 09:21AM
These days, green roofs are becoming a much more common sight, especially as more and more buildings are designed and built with the environment in mind.
A green roof or living roof is a roof that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. They can also include additional layers such as a root barrier and drainage and irrigation systems.
Green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife and helping to lower urban air temperatures and mitigate the heat island effect. They effectively utilise the natural functions of plants to filter water and treat air in urban and suburban landscapes.
There are two types of green roof:
- Intensive roofs
- Extensive roofs.
The former are thicker and can support a wider variety of plants but are heavier and require more maintenance. Whereas the latter are more shallow and, therefore, lighter than intensive green roofs, requiring minimal maintenance
So, is a green roof really worth considering?
Well, as usual, that depends on the reasons for considering the green roof in the first place, but now, more than ever they have become a very viable roofing option.
Firstly, looking at costs, a basic green roof can cost around £10 per sq foot to install. Obviously, installation is easier on a flat roof, but that doesn’t mean you can’t have one on a typical sloping roof. The only issue is that, the steeper the roof slopes, the more expensive it is to install.
When it comes to the question of fitness for purpose, a green roof is no different to any normal roof. As long as it’s installed properly, by an expert, and is correctly waterproofed, then it should be every bit as good as a normal roof and it’s not uncommon, according to research, for green roofs to last for double or triple the time of a more traditional roof.
In terms of energy efficiency, it is thought that a green roof can only have a positive impact in the reduction of energy use, by improving the roofs thermal energy performance, as it insulates the building better than a traditional roof, so there’s less cost in heating (or cooling) a property and, therefore, has a positive effect on emissions from a house or building.
By absorbing more water than any traditional roof can, this means that less water runs off into drains and people with green roofs could even see a saving in their water bills, as potential savings for utility companies are passed on to the consumer.
So, there you have it. Interestingly, green roofs are not a new concept! They’ve been in use for years and years across Europe, in some form or another. But now, technological advancements have put green roofs into a position to be a viable option for new builds and even as retrofits to existing properties.
Maybe it is time to go green!
Until next time….