Green roofs have been around for a long time and are now gaining a lot of traction in the building world. The term green roof could mean one of two things: that the roof is covered in vegetation or that the roof uses ‘green’ technology like solar photovoltaic systems or wind turbines.

A vegetative roof means that it is partially or fully covered with soil and vegetation over a waterproof membrane. The vegetation could be any type of grass or bush and there may be additional layers to this system that are responsible for irrigation and drainage. Green vegetative roofs serve several purposes and can greatly add to the value of the building. During hot summer days the roof can cool down the building, thereby reducing the load on cooling systems. This not only provides more comfort for building occupants, but also saves electricity and cuts down on cost as well. In times of intense rain the roof acts as a natural irrigation and drainage system, absorbing water that would normally be runoff. This saves on stormwater system costs and helps make the building more resilient to changes in weather.

There are tradeoffs with this sort of system however. The cost compared to a traditional flat roof may go up due to a need for increased support. The soil, vegetation and membrane will add more weight that would otherwise be non-existent on the building. Make sure to plan ahead when constructing your building. If it is an existing building, check with your architect or a structural engineer to see if the roof needs additional work in order to support your green idea. In addition to this there are higher maintenance costs with a green roof system and it is not applicable in all areas.