Green roofs have become an increasingly popular solution for those wanting to live a more sustainable life, and especially for those living in urban areas, in attempt to offset the grey, the concrete, and the smog-filled environment. With a worrying lack of green spaces, green roofs serve not only to improve the aesthetics, the landscape, and to make up for the lack of greenery, but they also, and more importantly, benefit the climate and the general air quality by providing clean oxygen and fresh air, as well as create new habitat for wildlife.
You can leave it to professional roofers to design and build your new green roof, but if you feel capable and confident enough, you can also do it yourself. It is not a very complicated task. Here are some of the most important things to take into consideration and a guide on what to do and how to do it.
First things first – is your roof suitable?
Before going into anything and starting work, it is important to first make sure your roof can handle a green roof. Some of the important characteristic to check are durability and slope.
Green Roof, Credited by Fordingbridge
When it comes to durability, you have to keep in mind that a green roof adds certain weight to it. You have to consider the plants’ weight and calculate how much added weight they will bring when they grow in the future. Consider how many layers you will need when making your green roof, as well as rain and snow which will undoubtedly saturate it and add more weight sometimes. Your roof needs to be sturdy, durable enough and waterproof. It is always best to consult with a structural engineer and have them assess it.
The slope or the angle of the roof should also be considered. Green roofs can be built on both flat and pitched roofs. Ideal slope is up to 10°, but it can also be more, in which case you might need to build and install a frame to prevent your green roof from slipping (you would usually need it if the slope is over 20°).
After the roof’s inspection and assessment, the first thing to do is check your drainage system and install one if you don’t already have it. We are talking about a simple gutter system. Make sure you have it all around the roof, as well as a downspout on its lowest part so that the water can go into it and off the roof.
Sustainable green roof, Credited by Wikimedia
There are a couple of layers to a green roof, and the first, bottom one is a waterproof layer. It needs to go over the entire roof – some type of waterproof sheet (bitumen felt or rubber pond liner) covering the whole surface. On top of this layer you have put at least one more which will function as a part of the drainage system – it will help the excess water go into the gutters. It can be made of mulch, pumice, polymers, clay, etc.
For soil you need some lightweight substrate which will not add too much weight on the roof. It should also be low in organic material and nutrients so that you don’t have any unwanted vegetation springing up. In this case it is best to avoid topsoil, and use a soil mix where there is more than half of inorganic content.
Finally, adding your plants
Of course, you want your new roof to look nice and colorful so that you can enjoy it aesthetically as well. But if you want your roof to last and your plants to survive, choose your plants carefully, not only the ones that look good. It is recommended to plant native and resilient plants because they are already accustomed to the climate in your area and will withstand extreme weather conditions. You can choose from different types of succulents, sedums and wildflowers (for example yarrow or aster), or lavender and daylilies which will add some color to your roof and are also tolerant.