Green roofs are an innovative and eco-friendly solution that combines vegetation and building structures to create a sustainable and aesthetically pleasing environment. In this post, we will explore the different types of green roofs, their advantages in terms of sustainability and blending into the local environment, the materials required for installation, retrofitting possibilities, insulation benefits, flood prevention capabilities, and the importance of regular maintenance.
Types of Green Roofs
Green roofs come in various types, including extensive and intensive green roofs, as well as brown roofs. Extensive green roofs typically feature substrate depths ranging from 100-40mm and are suitable for wildflowers or sedum. On the other hand, intensive green roofs, requiring substrate depths exceeding 200mm, can support larger shrubs and trees. Brown roofs, which rely on locally found substrates, allow nature to take its course, often supplemented with scattered wildflower seeds.
Advantages in Terms of Sustainability
One of the key advantages of green roofs is their positive impact on biodiversity. Upon installation, green roofs attract bees and butterflies, instantly enhancing the surrounding ecosystem. Additionally, green roofs contribute to the overall sustainability of a building. However, it is crucial to consider the ongoing maintenance required when evaluating their sustainable benefits.
Blending into the Local Environment
Green roofs are frequently incorporated into building designs to harmonise with the local environment. This integration enhances the views from neighbouring structures, demonstrating a considerate and respectful approach while providing a beautiful outlook.
Materials Required for Green Roof Installation
The installation of a green roof involves several essential materials. Typically, above the waterproof membrane, a specialised drainage and/or water retention layer is installed, accompanied by a root protection barrier. The specific specification may vary based on the roof pitch, usually designed with a maximum inclination of 15 degrees. A lightweight growing medium is placed on top of these layers, along with a chosen sedum blanket, wildflower turf, or a blend of both. Additionally, considering an irrigation system is advisable.
Installation Possibilities: Original Build or Retrofitting
Green roofs can be installed both during the original construction of a new home or retrofitted onto existing structures. In the case of retrofitting, it is crucial to assess the structural capacity of the roof and seek calculations from a structural engineer. Consideration must also be given to roof edges, drainage, and future safety and access for maintenance. Specifically designed lightweight crate systems can be utilised for retrofitting purposes, incorporating drainage, water retention, root barrier, substrate, sedum, and wildflower components.
Insulation Benefits of Green Roofs
While green roofs may provide some insulation benefits, their impact is generally marginal. Keeping the building or roof cooler during the summer months is one of the notable advantages, but insulation should not be the primary consideration when designing green roofs.
Flood Prevention
Green roofs act as sponges, reducing rainwater run-off during periods of heavy rainfall. By absorbing water, they mitigate the risk of flooding to some extent. However, it’s important to note that once saturated, the sponge effect diminishes, and run-off flow increases. Nevertheless, green roofs can significantly contribute to reducing the likelihood of flooding.
Maintenance Considerations
Maintaining a green roof involves two options: allowing nature to take its course or performing regular weeding. Since sedum substrates typically have a depth of 40-60mm, the growth of unwanted trees is usually not a concern as saplings quickly wither away. Wildflower roofs, on the other hand, benefit from an annual trim to eliminate dead growth and promote seed distribution. While indigenous wind-blown growth may go unnoticed, it is essential to maintain borders and drainage channels/outlets to ensure proper water flow. To mitigate the risk of accidents, it is advisable to design roof access points specifically for maintenance purposes.
Including a green roof in a new build home offers a myriad of benefits, such as enhancing sustainability, promoting biodiversity, improving the aesthetics of the building by blending it harmoniously with the environment, providing insulation and thermal regulation, reducing energy costs, mitigating stormwater runoff and flooding risks, and creating a peaceful and eco-friendly oasis right on top of the house. It not only adds value to the property but also demonstrates a commitment to environmental stewardship and sustainable living.
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