DIY Green Roofs

Guest post by Matt, writer and editor at Georgia Roof Pro

“Going green” and being eco-friendly is both environmentally and financially favorable, so it is no wonder green roofs are becoming more and more popular. A sustainable, green roof is partially or completely covered with vegetation. It protects the building from moisture, leaks and water runoff. It significantly decreases energy consumption, has a longer service life, and therefore requires less overall maintenance. It is both environmentally and economically more beneficial.

You can build your own green roof, and here is how.

Photo credit: denisbin via Visual hunt /  CC BY-ND

Photo credit: denisbin via Visual hunt /  CC BY-ND

1. Is your roof suitable for a green roof?

First, the most important thing to do before starting any work on your roof is to check whether it is even possible. There are a few aspects to take into consideration and certain characteristics your roof must have:

  • durability – your roof has to be strong enough to endure the weight of an entire garden on top of it. Consider how much plant life you will put on it and everything else that goes with it: there are at least three layers in a green roof. The overall weight of the roof can vary and it is best to consult with a structural engineer who can give you a professional assessment.
  • slope – it is very important that the slope is just right. If it is a flat roof, or has a small slope, it can retain too much water, and if the slope is too steep it can slip off. The ideal slope is up to 40 degrees.

2. Add drainage

When you have inspected your roof, and all of the required aspects and characteristics are in check, you can get to work. The first thing to do is to install a proper drainage system, if you don’t already have it installed. This is nothing complicated. You just need to make sure to have gutters all around the roof, and a downspout on the lowest part of the roof, so that the excess water can flow into it and escape.

3. Waterproof your roof

You will need to put a waterproof layer all across the roof. It was mentioned before that a green roof has several layers, and this one has to be the first one (the bottom one). Ideally, it will be a single waterproof sheet covering the whole surface. On top of that one, you should put another layer that will function as drainage, and that will allow the water to go into the gutters. You can use different materials for this, but if you are not sure, you can always ask professional roofers for advice. Some commonly used ones are pumice, clay, mulch, polymers etc.

Photo credit: 416style via VisualHunt /  CC BY

Photo credit: 416style via VisualHunt /  CC BY

4. Add soil

The soil for green roofs needs to be a little different than the one you would normally put in a garden. Since it is on the roof, it needs to be lightweight, low in nutrients and low in organic content in order to prevent unwanted vegetation. Considering this, you should avoid topsoil and peat. The best thing to do is to mix organic and inorganic materials (crushed brick, clay), so that there is more than half of inorganic materials in the mix.

5. Choose and add plants

Make sure to choose tolerant and resistant plants that can endure extreme weather conditions. Not every plant would survive the extreme exposure to the elements on the rooftop. Some of your best options are succulents (such as cacti), sedums (such as biting stonecrop), or some wildflowers (aster, yarrow, or sea thrift). And if you want to add more color, you can also plant daylilies and lavender.

6. Watering the roof

In the beginning, while they’re still growing, the plants will need to be watered a bit more frequently. But later, when they are fully grown, you will not have to worry about them as much. The rain will do most of the watering work. Just make sure none of your gutters are blocked in any way, and that the drainage is functioning properly. Otherwise, you can have some serious water retention problems and damage to your house.


This article was written by Matt, a writer and an editor for Georgia Roof Pro. He covers local topics, housing, sustainability and roof technology themes.