Green Roofs and Water Mitigation

With more and more people turning towards eco-friendly living and making changes to their structures to accommodate such trends, we couldn’t help ourselves but to write about the Green Roof. Also known by other names, including eco-roofs, oikosteges, vegetated roofs and living roofs, this environmentally friendly roof is gaining some new popularity even though it is long rooted in history.
First off, what exactly is a Green Roof? It is a roof partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It is an extension of an above grade roof, built on top of a human-made structure, that allows vegetation to grow in a growing medium and which is designed, constructed and maintained in accordance with a Construction Standard. The assembly includes, as a minimum, a root repellent system, a drainage system, a filtering layer, a growing medium and plants. There are three types of Green Roofs: intensive, semi-intensive, or extensive, with extensive being self-sustaining for the most part.
The benefits of a vegetated roof are many and include absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperatures. In addition, they provide excellent insulation and this help reduce the need for heating and energy consumption during winter months, as well as cooling in the summer – both by 26%! Also, an eco-roof can help reduce stormwater run off while filtering pollutants and heavy metals out of rainwater. In addition, these roofs are great for soundproofing! With the many layers that are produced by green roofing, sound waves are absorbed, reflected or deflected. This is beneficial to the noise and sound from cars, trains and people in a populated city.
As mentioned above, eco-roofs have a long history and “sod roofs” have been around in Scandinavia for centuries. Germany modernized the sod roof in the 1960’s and since then, this style of roofing has spread to many countries. Green Roofs are becoming increasingly popular in the United States, although they are not as common as in Europe. In Europe, Germany, Switzerland, the Netherlands, Norway, Italy, Austria, Hungary, Sweden, the UK, and Greece are the top European countries promoting eco-roofs. The City of Linz in Austria has been paying developers to install vegetated roofing since 1983 and in Switzerland it has been a federal law since the late 1990s.
In the USA, Green Roofs are making their appearance in Chicago, Atlanta, Portland, San Francisco, New York City as well as other cities. These types of environmentally conscious roofs are encouraged to be built in cities where Urban Heat-Island effect is a problem. The Urban Heat-Island effect describes the phenomenon when temperatures within a city are warmer than the surrounding suburban/rural areas, primarily due to the urban development being built by materials which effectively retain heat. Urban Heat-Island effect decreases air quality by increasing the production of pollutants such as ozone, and decreases water quality as warmer waters flow into area streams, which stresses their ecosystems.
As mentioned above, Green Roofs are great for water mitigation as they lessen the impacts of stormwater runoff. Vegetated roofing systems can retain around 60-100% of the rain water they receive which is amazing! In areas with combined sewer-stormwater systems, heavy storms can overload the wastewater system and cause it to flood. Flood damage is bad enough let alone when the flood water carries raw sewage and deposits it into local waterways. Thus, eco-roofs are an effective way to mitigate water.
For homeowners, Green Roofs help prevent flooding and water damage by decreasing the total amount of runoff from rainfall and slow the rate of runoff from the roof. It has been found that they can retain up to 75% of rainwater, gradually releasing it back into the atmosphere via condensation and transpiration. Also, Eco-roofs are a financial benefit as they increase roof life span dramatically. roof repair toms river nj 
Regarding disadvantages of vegetated roofs, a higher initial cost of $15-$20 per square foot is probably the main disadvantage. Depending on what kind of Green Roof it is, the maintenance costs could be higher, but some types of eco-roofing have little or no ongoing cost. Living roofs also place higher demands on the waterproofing system of the structure both because water is retained on the roof and due to the possibility of roots penetrating the waterproof membrane. It is true that installing adequate waterproofing systems and root barriers can increase the initial cost of the roof; however, due to the fact that this type of roofing protects the waterproofing membrane from the elements, particularly UV light, the life expectancy of the membranes is doubled or even tripled, leading to recovered initial cost differentials.
So what about living roofs and Florida? Currently, the largest live roof is located in Pensacola Florida at the Escambia County One Stop Permitting Center. The roof is more of the intensive type, compartmentalized by plant species. Further to that, Green Roofs are making more and more of an appearance in Florida.
In sum, eco-friendly roofs are not only aesthetically pleasing to look at but also provide huge benefits for homeowners and the environment. With these roof choices passing even hurricane wind stress tests, they are definitely providing property owners with a roofing choice worth considering!

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