Author – Nellia Melnyk
There is a rising trend for installing green roofs atop buildings as welcome break from the concrete jungle we are living in. A green roof is a sustainable roofing system with vegetation grown on top. Proponents claim green roofing your building can offer environmental and social benefits by providing energy efficiency, reduced water runoff, and improved air quality. They improve the ecological footprint of buildings and are low maintenance as well.
Advantages of Green Roofing
So let’s consider and evaluate the numerous advantages of green roofing that are offered over conventional roofing systems:
Combat the ‘urban heat island’ effect: Ambient temperature in urban areas can rise up to 10 degrees higher (fahrenheit) than in nearby rural areas due to the absorption and retention of solar radiation by traditional roofs. Green roofing systems absorb much less solar radiation and cool the air through photosynthesis and evapo-transpiration, which can help to mitigate the heat.
Improve air quality: Through photosynthesis, green roofs absorb carbon dioxide and other harmful air pollutants and replace them with clean oxygen, thereby improving the quality of the local atmosphere. This can help to mitigate the negative impacts of air pollution on human health and the environment. Further, studies have shown that green roofs with a dense vegetation layer consisting of large-leaf plants can capture up to 84% of airborne particulate matter.
Mitigate stormwater runoff: During storm seasons, traditional roofs direct stormwater runoff to the gutter systems, which then transports the water away from your property. This process can overwhelm the city’s stormwater management systems and lead to flooding and water quality issues, especially if the gutters aren’t maintained properly. Green roofs, however, can absorb and filter rainwater before it reaches the ground, which can help to reduce the volume and impact of stormwater runoff in your community.
Enhance energy efficiency: By providing natural insulation and reducing solar heat gain, green roofs can help reduce the need for air conditioning during warm weather. This can lead to significant energy savings and reduce a building’s carbon footprint.
Increase biodiversity in urban areas: The vegetation on green roofs can provide habitats for birds, insects, and other wildlife, which can help to support local ecosystems and promote biodiversity. However, this depends on the uniqueness of plants that you have integrated into your green roof.
Extend the lifespan of the roof membrane: By protecting the roof from direct exposure to elements, green roofs can help to prevent damage and deterioration of the roof membrane. This can reduce maintenance costs and increase the roof’s overall lifespan.
Different Types of Green Roofs
Before you get started and install a green roof on your property, it’s important to consider the various types that are available. Each type of green roofing system is suited to different climates, building types, and aesthetic preferences. Here are three common types of green roofs to consider:
Extensive Green Roofs
Extensive green roofs are lightweight and low-maintenance systems. They are typically built with shallow soil depths of 2-6 inches and are designed to support drought-tolerant plants. They are more suitable for arid climates where water conservation is a concern.
Intensive Green Roofs
Intensive green roofs, on the other hand, are more complex systems that require a more substantial structure to support varied plant species. The soil depth for these roofs can range from 12-24 inches, allowing for a wider range of plant varieties. Intensive green roofs are ideal for larger flat roofs on commercial buildings that can benefit from the added green space.
Semi-Intensive Green Roofs
Semi-intensive green roofs combine elements of both extensive and intensive green roofs to blend functionality and environmental needs. These systems are designed to support a medium-depth soil layer of 6-12 inches, allowing for a mix of shallow-rooted and deep-rooted plants. Semi-intensive green roofs require moderate maintenance and are suitable for buildings where access is relatively easy.
Components of a Green Roof System
While each type of living roof is different, each system relies on the same components to properly function:
- Waterproofing membrane: This layer is the bottommost layer of the green roof system that is placed right on top of your structural deck. This membrane is designed to protect the building structure from water damage.
- Root barrier: On top of the membrane, a root barrier is placed to prevent the growing roots from breaking the membrane and expanding into other areas of your roof.
- Drainage layer: This element is placed on top of the root barrier and allows excess water to divert away from the green roof system, preventing water buildup that can damage the roof and cause plant death. It is connected to your gutter system to allow proper drainage and prevent water stagnation.
- Filter fabric: Above the drainage layer, you’ll find the filter fabric that acts as a barrier to prevent fine soil particles from clogging the drainage layer and impeding water flow. Typically this layer is a geotextile fabric that helps prevent soil erosion for optimal performance.
- Growing medium: Also known as the substrate layer, the growing medium such as compost or coco peat provides nutrients to your plants.
- Irrigation: Proper irrigation is needed to help your plants grow and thrive. This system is typically integrated into the middle of the growing medium or on top.
- Vegetation (plants): Plant selection can vary based on climate, building location, and the intended aesthetic or functional purpose of the green roof.
All these elements work together to create a sustainable roofing system that benefits the environment and building occupants alike.
Space and Water Flow Considerations
How much of your roofing system do you want to dedicate to your new green system? How do you intend it to be used? Will employees visit the space regularly? Will it be used to grow vegetables? Or is its purpose more for the environmental benefits than your workforce? These questions are essential when calculating the surface area of your green roof and determining the appropriate water flow management system for it.
A proper water flow management system helps handle rainfall, prevent waterlogging, and promote efficient drainage on the roof. Water management is critical to the success of green roofs as it can prevent water damage to the roof and the building interior, so make sure you think through these considerations with a certified roofing professional.
Social Benefits of Green Roofs
Green roofs offer some unbeatable environmental and social benefits, enhancing well-being and fostering community engagement. They provide recreational spaces and easy access to nature for employees. Improve urban life with aesthetically pleasing environments.
Author’s BIO: Nellia Melnyk is a writer who writes engaging and informative content on the latest trends in the roofing industry including roof repair and maintenance.
