The article “The Concrete Advantage”, taken from the Green Rooftop webpage, provides readers with a deeper understanding of concrete green roofs. According to the article, concrete green roofs which incorporate “Permanent built in water-proofing”. This will lower construction costs and will not be damaged over time. The process of design, construction and maintenance will be shortened through the removal of membranes. The article states that with lesser exposure risk for owners and designers, concrete green roofs are more economical, which increase return on investment and project value. It is also more cost-effective for owners as there is no need for replacement of membranes, thus lowering life-cycle cost. The article also mentions that the usage of “hydrophobic technology” removes dangerous components, making fewer contact risks for anyone who owns the green roof. When there is crack on the green roof, a simple inoculation from the bottom side will mend it without disrupting growing mediums or plants. Leaks can also be detected easily with the waterproof concrete system as compared to a typical membrane system. From all the points listed above, one can understand that projects with a concrete green roof will have simpler design and lower life-cycle costs than typical green roof.
The first reason to support the above statement is by comparing typical green roof and concrete green roof. Concrete green roof does not require filter layer, drain layer and the waterproofing methods as all are permanently built-in. According to Wark and Wark (2003), a typical green roof consists of vegetation, growing medium, filter layer, drain layer, protective layer and waterproofing system. Filter layer is in between the growing medium and drain layer. It serves as a root barrier allowing water to flow through while retaining the growing medium. Similar to filter layer, the drain layer is in between the planting medium and roof membrane allowing water to flow from the green roof to the building’s drainage system. The article “Waterproofing green roofs”, taken from Growing Green Guide webpage, states that a strong waterproofing layer on the roof is essential to prevent water from slipping into the building. There are two types of waterproofing methods: liquid applied treatment and performed sheets. These waterproofing membranes must be protected from physical and chemical damage. Furthermore, these membranes are prone to wear and tear and will get brittle over time losing the ability to block off water due to environmental exposure.
The second supporting reason that concrete green roof is simpler and cheaper than typical green roof can be seen when designers and architects do not have to design and detail any waterproofing membrane and contractors do not have to wait for the concrete to dry before applying the membrane, these shortens project time and increases efficiency of team working on site. Leaks can be detected easily with the waterproof concrete system as it can only come from a crack or an improperly sealed penetration. However, in a typical waterproofing membrane system, they are difficult to trace and costly to repair. They can also cause damage to plants and growing mediums.
As demonstrated by the information in the above paragraphs, projects with concrete green roofs will provide owners, and project team with benefits in the long run. It is because of the simpler design as well as the lower life-cycle cost as compared to when using typical green roof.
Greenrooftops.org. (n.d.). The Concrete Advantage. Retrieved September 20, 2016 from http://www.greenrooftops.org/advantage.html
Wark C. G. & Wark W. W. (2003, August). Green roof specifications and standards: The construction specifier, Greenroofs.com, 56(8). Retrieved from http://www.greenroofs.com/pdfs/newslinks-803_construction_specifier.pdf
Growinggreenguide.org. (n.d.). Waterproofing green roofs. Retrieved September 25, 2016 from http://www.growinggreenguide.org/technical-guide/construction-and-installation/green-roofs/waterproofing/