Green Roofs See Several Benefits

10/19/2022

Blue roof assemblies can be integrated with green (living) roofs and paver applications, allowing the roof component to become a usable space and contribute to the facility’s wellness strategies for the employees. Roof areas have been converted to usable spaces for decades in high-rise residential buildings, entertainment facilities, hotels, schools, and universities. Traditionally, roof areas have been commonly used as plaza decks, gardens, and recreational areas with pools, tennis courts, or basketball courts.   

In office buildings or manufacturing facilities, the roof areas adjacent to cafeteria/dining rooms or meeting/conference rooms can be utilized for outdoor dining, work breaks, or meeting places. They become extensions of indoor spaces that can be utilized when outdoor weather permits.  

The aesthetics of a building’s roof spaces can be enhanced through the addition of living plants/vegetation that can be set in planters or containers on the plaza deck surface (typically pavers). The installation of a living roof is another option. The application of living roofs has become more prominent in the last 20 years as technological advancements to living roof technology have provided many benefits which made these systems more economical. Installation of new living roof systems has a few benefits: 

• They are lightweight 
• They are easier to apply 
• They require minimal long-term maintenance 
• They provide instant green root with full grown plants 
• They have a proven performance track record 

One of the significant advancements that resulted from increased use of these systems is the development of the growing medium. Sedums are integrated into mats that make the systems both lightweight – no growing medium or soil is required – and immediately aesthetically pleasing, because vegetation is already fully grown and developed. Another advantage is the vegetation requires little maintenance. 

The living systems can be applied in mats or tray systems that are set over the roof membrane. The advantage of this method is that medium is supplied as a full assembly which includes the vegetation, the required protection mats, and drainage layers. In most application methods, the contractor simply sets the living system assembly over the completed membrane in a similar fashion as applying pavers. 

While the technological developments were primarily to the living surface, roof membrane design has also improved as well. The living roof applications have become roof surfacing – like pavers or ballast – that can be applied over virtually any type of roof membrane system. Most of the major low-slope membrane manufacturers on the U.S. market offer some type of living roof system as a surfacing option. 

Living roofs are environmentally friendly and add to the sustainability of the building. Application of these systems qualifies for LEED points for the facility. Some of the primary benefits of installing living roofs are: 

• Reduction in energy costs 
• Stormwater management, as they reduce water run-off from the roof system 
• Increases in the longevity of roof membrane, as they shield from UV exposure 
• Improvement in surrounding air quality, as they absorb pollutants 
• Additional esthetic quality to the building 
• Increases in green space available in urban environments 

Membrane installation 

Blue and green roof assemblies are typically installed over inverted or protected membrane systems. In these types of applications, the membrane is applied directly to the structural deck and covered with a protection board and filter fabric or the fabricated void component. The void for water retention is located directly under the final surfacing, such as living roof assembly, pavers, or ballast. It is strongly recommended that a true waterproofing membrane that can withstand continual standing water is applied in these types of applications. It is best practice to apply membranes that are not averse to standing or ponding water. Consult with the membrane manufacturer prior to application to determine the best material and application requirements for blue and green roof assemblies.  

John D'Annunzio, president of Paragon Consultants and Paragon Roofing Technology, Inc., has more than 20 years' experience as a consultant on projects around the world. D'Annunzio, a construction consultant specializing in roofing and waterproofing materials application and field performance, has written four books about roofing. He can be reached at john_paragon@ameritech.net.