Understanding Green Roofs and Their Benefits: A Comprehensive Guide

In the modern era, green initiatives are becoming increasingly popular as we strive to combat climate change and promote sustainability. One such initiative is the implementation of green roofs.

What is a Green Roof?

A green roof, also known as a living roof, is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems.

Note: Green roofs are typically installed atop flat or slightly sloped roofs.

In essence, a green roof is an outdoor garden space located on the top of a structure, featuring sedum or other succulents grown into low-level substrates.

Types of Green Roofs

Extensive Green Roofs

Extensive green roofs are lightweight and low-maintenance. They are often used on residential, commercial, and city buildings as they can be installed on a variety of structures. The sedum plants used are easy to manage and require minimal watering, making them ideal for areas that are difficult to access and maintain.

Modular Green Roofs

An innovative approach to green roofing is the modular green roof. This is a pre-grown roof that is developed in specially designed cassettes at a farm. These cassettes can be hand-carried and clicked together to form a seamless green roof.

The advantage of a modular green roof is that it provides an immediate green roof, reducing the time and disruption caused by traditional green roof installations. It also allows for easy access to the deck as they can be lifted into place and easily removed if necessary.

Advantages of Green Roofs

Green roofs offer a myriad of benefits:

1. Aesthetically Pleasing: They improve the look of buildings, providing a natural, calming environment in urban settings.
2. Temperature Regulation: They act as natural insulators, reducing the need for artificial cooling and heating.
3. Biodiversity: They create habitats for wildlife, promoting biodiversity.
4. Stormwater Management: They absorb rainwater, reducing runoff and mitigating flooding.
5. Air Quality: They filter pollutants and carbon dioxide out of the air, improving air quality.
6. Noise Reduction: They can help to reduce ambient noise.

Cost of Green Roofs

The cost of implementing a green roof varies depending on the type of green roof and the specific requirements of the project. For instance, the cost of an M-Tray®, a type of modular green roof, is approximately £88 per square metre.

Please note, prices are subject to change.

Components of a Green Roof

A green roof typically consists of several components:

1. Vegetation: The vegetation on a green roof is usually a mix of different types of sedum species. There may also be a mix of wildflowers and sedum available upon request.
2. Substrate: This is the growing medium for the plants. It’s specially mixed to provide optimum drainage.
3. Filter Membrane: This prevents the substrate from being washed away with the drainage water.
4. Drainage Layer: This ensures that excess water is removed from the roof.
5. Root Barrier: This prevents roots from penetrating the waterproof membrane.
6. Waterproofing Membrane: This is an essential component that protects the building from water seepage.

Maintenance of Green Roofs

Despite their many benefits, green roofs do require maintenance. The sedum on green roofs is very hardy and can tolerate extreme conditions. However, watering during extreme conditions is advisable. Regular removal of dead leaves and vegetation is also recommended.

In addition, the application of a slow-release fertiliser at certain times of the year can promote plant health and growth.

Additional Considerations

Before installing a green roof, there are several considerations to be aware of:

1. Load Capacity: The weight of the green roof must be considered. Consult an engineer to advise on loadings.
2. Light Requirements: While the plants on a green roof can tolerate partial shade, they do require some light to grow.
3. Fire Regulations: A hard border between vegetation and the walls of buildings is required by fire regulations.
4. Delivery and Installation: The green roof modules are delivered stacked onto pallets and must be unpacked within 24 hours of delivery. A crane and forklift may be needed to transfer pallets onto the roof.

Green roofs offer a unique combination of environmental benefits and aesthetic appeal. They represent a significant step towards more sustainable and environmentally-friendly urban environments. Whether you’re considering a green roof for your home or business, this guide provides a comprehensive overview of what you need to know.