Green roofs are an increasingly popular roofing finish, as they can transform a plain roof into a thriving garden and offer numerous benefits for both the environment and homeowners. On this post, we’ll take a closer look at green roofs, their benefits, and things to consider. We’ll also take a look at some of our projects where we have used them.
Sedum Roof on our project at Undercroft
What are Green Roofs?
Green roofs are vegetated roofs that are designed to support plant life. They can be divided into two main types: extensive and intensive. Extensive green roofs are lightweight, shallow and typically have a depth of 10-20cm. They are designed to be relatively low maintenance and require minimal watering and fertilisation. Intensive green roofs, on the other hand, are deeper, require more soil and maintenance and can support a wider variety of plants, including shrubs and trees. When considering domestic projects, we will typically be looking at extensive green roof systems
Benefits of Green Roofs
Green roofs offer a range of benefits for both the environment and building owners. Here are some of the key advantages:
- Improved air quality: Plants absorb pollutants and carbon dioxide from the air, which can help to improve air quality in urban areas.
- Increased biodiversity: Green roofs provide a habitat for birds, insects and other wildlife, helping to increase biodiversity in urban areas.
- Improved insulation: Green roofs can help to reduce heating and cooling costs by providing extra insulation for buildings. This is hard to quantify as it will vary through the year depending on the water saturation of the growing medium, but it does have some insulant properties.
- Aesthetics: A green roof can add an attractive feature to a home, providing a unique look and creating a relaxing space for homeowners.
- Water attenuation: Sedum green roofs have excellent water absorption, which can help to reduce surface water runoff.
Considerations for Green Roofs on Domestic Extensions
When an architect is looking to design and specify a green roof on a domestic extension, there are several factors to consider. Firstly, it’s essential to ensure the roof can support the weight of a green roof.
Green roofs can be installed using different systems, including pre-grown mats, plug plants, or seed mixes. The system used will depend on the type of plants selected, the desired aesthetic and the size of the roof.
It’s also important to select the right plants for the roof, as this then affects the type of build up. The two main types are Sedum and Wildflower which we will discuss below.
Sedum Roofs vs Wildflower Roofs
Two types of green roofs that we would typically specify are sedum green roofs and wildflower green roofs. Both types of green roofs offer similar benefits, but they differ in terms of their appearance, maintenance, and biodiversity.
Sedum Green Roofs
Sedum green roofs consist of a layer of low-growing succulent plants. Sedum is a hardy plant that is well-suited to green roofs due to its ability to store water and withstand drought conditions. The plants grow to a height of 10-15cm, forming a carpet-like covering over the roof. They are typically low maintenance and require minimal watering and fertilisation.
Sedum Roof on our project at Dunvegan
Wildflower Green Roofs
Wildflower green roofs consist of a mixture of native wildflowers and grasses. Wildflowers are an important part of the UK’s biodiversity, and their use on green roofs can help to support local wildlife and pollinators. They require a deeper growing medium, but produce taller flowering plants. They also require more maintenance than sedum roofs, as they will require watering in dry weather and annual removal of dead growth.
Wildflower Roof on our project at Howard Street