Though homeowners have recently begun to really understand and celebrate the benefits of having a green roof, it's not a new concept. In fact, it can be traced back to the 1940s in Germany. Regardless, the green movement has continued to gain momentum, making it an increasingly popular choice for homeowners. Below, we've outlined some helpful tips and step-by-step instructions for you to make one of your own. Plus, learn about sustainable roof systems here.
How to choose the right green roof
Green roofs consist of several layers, which include a growing medium—allowing plants to grow on the rooftop. The first step is to take into consideration whether you'll be able to maintain your green roof frequently or just leave it be so that nature can take its course. There are three types of green roof systems to choose from. We've outlined them below.
There are three different types of green roofs
1) Intensive green roof
If you want your roof to function as a garden and have large plants and even water features, then the intensive green roof is for you. With this type of roof, planting mediums are much deeper, which can be between seven and 24 inches, and can consist of lawn, shrubs, trees, and perennials (for example). Make sure the roof is easily accessible, since frequent maintenance will be needed. Adding a walkway makes it easy to maintain, while adding some benches and tables can give you the opportunity to relax in your own personal piece of nature.
2) Extensive green roof
With an extensive green roof, vegetation is thinner (1.6 to five inches thick) and lighter—with appropriate plants that will make them low-maintenance and self-sustaining. Any large slope or flat roof that's hard to reach makes a great area for this kind of vegetation, as nature will take care of itself. Plants that are used often with this treatment are ones that are tolerant to droughts, including certain sedums, succulents, a few types of grass, and mosses.
3) Semi-intensive (or hybrid) green roof
With this treatment, choices in vegetation are much broader than with an extensive green roof. Plus, not much maintenance is required. This green roof can be described as a combination of an extensive and intensive roof, and therefore is also called a hybrid roof. A variety of plants that grow well in a soil depth of five to seven inches are good to use, including certain perennials, ornamental grasses, herbs, shrubs, and sedums. Because irrigation is only needed from time to time and it requires a medium amount of maintenance, most rooftops can benefit from a semi-intensive green roof.
Step-by-step directions for your DIY green roof
Professionals can examine your roof to ensure that it will be strong enough for the green roof of your choice. Whether you're choosing to go with an extensive or intensive treatment, the primary layers of the green roof will remain the same.
The first layer should consist of a water- and root-proof membrane. A single sheet can be used to cover the whole area and keep the water and roots from reaching the roof. A heavy-duty pond liner from your local garden center can be applied with an adhesive. Make sure to mark all outlets in order to ensure proper drainage.
Cut into the containment frame, which will allow the water to run into the gutter. To keep the outlets clear, use pebbles and a layer of stones or rocks. This will avoid blockages and unwanted vegetation from gathering around the edges of the roof.
The next step is to add a substrate layer, which is usually 70 to 200 millimeters thick, but it can vary depending on the type of vegetation. By using a substrate mixture of 70-percent inorganic material and 30-percent organic material, it will be light enough, and you'll avoid undesired vegetation growth.
The last layer is what makes your roof green. You can choose between a green roof seed mixture, plug plants, plant cuttings, or pre-vegetated green roof mats or blankets.
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