Published | 05-19-2020

Finding the Green in Green Roofs

The aesthetic benefits of green roofs are visibly obvious, but what about the functional benefits? It takes both aesthetic appeal and measurable advantages to make the investment in a green roof beneficial for building owners, tenants, and the surrounding community. Fortunately, the facts make an effective case.

Positively Impacting Energy Consumption

Buildings consume a staggering 41% of the energy used in the United States.[1] With the average cost of utilities in a commercial building at $2.10 per square foot, annual utility costs really add up.[2] “Customers are looking for buildings that have a good chance of operational efficiency to reduce their operating costs,” noted Jeannie Renne-Malone, Vice President for ESG, Prologis.[3] In that context, a green roof is an ideal solution.

Green roofs effectively add a thick layer of insulation to the roof structure. This additional insulation makes the building more energy efficient, requiring less heat in the winter and less cooling in the summer. In summer months, the amount of solar radiation on the building is reduced; in the winter, less heat escapes the building through the roof. For tenants, the temperature in interior spaces is regulated, requiring less adjustment to remain comfortable. The cooling effect from plant transpiration lowers the temperature above the roof, making rooftop HVAC units operate more efficiently.

Extending Roof Life

The additional layer of insulation on the roof also extends the life of your roof by protecting the roof membrane. The lifetime of a roof membrane is largely responsible for the longevity of a roof. According to architect Andrew Franz, “The membrane is not exposed to sun, UV rays, hailstorms, or other deterioration. You’re basically putting another membrane and soil above it, so it really does extend the life of most roofs as long as everything is installed correctly.”

The U.S. General Services Assembly reports that green roofs, when properly installed, “more than double the number of years required before a roof needs to be replaced, as compared with conventional and white counterparts.”[4]

Properly designed green roofs normally include a cover board like DensDeck® Prime Roof Board on top of the roof deck and insulation, just beneath the roof membrane. The cover board provides a durable substrate for the roof membrane and protects the thermal insulation from mechanical damage. Most importantly, a high-performance cover board also helps the roof assembly support the green roof’s additional weight.





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Managing Stormwater Where It Falls

The large expanse of commercial roofs contribute significant stormwater runoff, which causes erosion, pollution, habitat elimination, and potentially damaging flooding. A green roof manages runoff by slowing its flow and by retaining it in the soil for plant usage. It is the only method of addressing stormwater at its source, making it an efficient stormwater manager. State and municipality regulations are increasingly requiring management of a percentage of stormwater runoff onsite. In urban areas where land is expensive and availability is limited, solutions like stormwater ponds aren’t feasible. A green roof is an optimal solution.

A New Source of Cool and Quiet

The additional insulation a green roof provides reduces the heat island effect. According to the Environmental Protection Agency, cities can be up to 22°F warmer after sunset than less-developed areas.[1] On a summer day, roofs and paved surfaces can be 50-90°F warmer than the air temperature, increasing energy demands. Green roofs reduce the heat island effect by absorbing solar heat and using plant transpiration to lower the temperature over the roof. In addition, the extra insulation a green roof provides delivers enhanced sound insulation for interior spaces, as well as absorbing some of the sound that would otherwise deflect off the roof.

Maximizing Space, Maximizing Benefits

The functional benefits of a green roof, coupled with the aesthetic attributes, are reason enough to install green roofs. But there are additional financial perks, too. Government incentives can help offset initial costs, making the advantages of a green roof even more appealing. And with more cities like New York passing mandatory green roof legislation, including green roofs in your development planning is a timely move.

Learn more about how DensDeck Prime Roof Boards can help ensure a strong support for your building’s green roof space at


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Want to learn more about cover boards? Have a new roof construction project? Need assistance on a roof remodel?


Want to learn more about cover boards? Have a new roof construction project? Need assistance on a roof remodel?