It is important to rethink green space as more land is lost to construction. Green roofs—which incorporate plant life on a flat or slightly sloped waterproofed and layered substructure—offer a solution with many benefits.

Environmental Benefits

A major environmental benefit of green roofing is its impact on the urban heat island effect, which reduces the air temperature surrounding the building due to the foliage absorbing or reflecting most of the heat. The plant life also absorbs particles and dust in the air, as well as decreases the production of smog, thus helping control greenhouse emissions in the region.

Another benefit of eco-roofs is a reduction in waste from the building’s maintenance. Green roof waterproofing materials are protected from the elements, so these materials are replaced less often.

Lastly, the plants on the green roof can house many different species of birds and insects to create a natural wildlife habitat.

Construction Benefits

Green roofs can protect buildings from various natural elements, such as heavy rainfall, extreme heat and strong winds—extending the roof’s lifespan. An eco-roof also can help manage excessive stormwater runoff because the growth media and moisture retention mats absorb the rainwater and act as a buffer for the drainage systems, which reduces the load on the stormwater drainage system.

Along with stormwater, green roofs protect the building against the sun, wind and temperature fluctuations and can double or triple the longevity of the roof.

Corporate Benefits

Eco-roofs add marketing value to a building. They are associated with the environmental movement and give potential renters an incentive to use the building. Along with helping building owners recruit tenants or employees, eco-roofs help create jobs in manufacturing, plant growth, design, installation and maintenance fields in the growing green roof market.

Social Benefits

Green roofs regulate a building’s noise levels and create a visually appealing space. They provide excellent noise attenuation due to the plants, media and drainage layers acting as a noise insulation barrier. Plus, green roofs with plant life create a visually inviting area in an otherwise dull space to provide a better living or working environment and to add value to the building.

Systems and Maintenance

When looking at garden roofs, there are three main types of systems: intensive, extensive or modular trays. Intensive green roofs have a deeper soil level, which allow a deep-rooted plant landscape. In contrast, extensive and modular tray roofing systems have shallow soil levels and are limited with plants that will thrive in these conditions. When comparing the different green roof techniques, modular trays are typically the least expensive option with intensive green roofs being the premium choice.

When selecting materials, it is critical to choose native plants that have the best chance of survival and provide easy maintenance. The roof media should be blended to meet a certain usage and weight requirement to prevent an overloaded condition and increase the chances of plant success. Along with materials selection, irrigation is important for a roof garden project.

A green roof can incorporate many different elements to help the structure work efficiently. Stormwater detention tanks store rainwater and use it in the building’s water system for non-potable applications and irrigation. Thermal heat exchangers can be found on the roof, which warms the building’s water supply. Solar panels and a wind turbine also can be placed on a green roof to reduce the building’s electricity consumption.

When planning maintenance for a green roof, upkeep must be done on the landscaping each month during the first growing season, and then quarterly once the plants are established. Eco-roofs also must be monitored after significant weather events to check all components for damage.