Renovating Your Commercial Roof? 3 Reasons To Consider Going Green

When you're in need of a new roof for your commercial building, you have lots of choices. Many commercial roofs are made out of black tar, but metal and membrane roofs are also common choices. Green roofs – roofs made up of vegetation and growing medium installed over a drainage system and filter – are a less common choice, but they have surprising and often overlooked benefits for commercial property owners. Take a look at some of the advantages of topping your commercial building with a green roof.

Less Heat

Your roof is supposed to keep the external weather conditions out of the building, but most roofs allow at least some of the sun's heat in. Traditional roofs absorb the heat and transfer it into the building – that's why your summer cooling costs are so high. Certain types of roofs, like metal roofs and roofs coated with reflective white paint, are becoming more popular because they absorb less heat, and therefore allow less heat to penetrate the building.

Green roofs also absorb heat. However, they also absorb water from rainfall. The moisture in a green roof works to cool the heat before it can penetrate the roof and find its way into the building. That makes green roofs even more effective at reducing cooling costs than reflective roofs. This was demonstrated on the roof of Chicago's City Hall in 2012. The City Hall roof was divided into three parts. One part was black tar. Another part was painted white. A third part was covered with plants. On a hot summer day with temperatures in the 90s, the temperature of the black tar was 169 degrees. The white area was cooler – between 126 and 130 degrees. And the section covered with vegetation fluctuated between 91 and 119 degrees. Even at its hottest, the green roof was at least 50 degrees cooler than black tar, and at least seven degrees cooler than the white roof.

Green roofs do more than just lower your cooling costs – they help reduce the overall heat in the area. In crowded cities, a collection of overheated roofs can raise the temperature of the air in the area, driving everyone's cooling costs up and contributing to heat-related ailments. By installing a green roof, you're doing a good thing for the tenants of the buildings around you  and everyone using the nearby streets and sidewalks, as well as for yourself.

Better Water Management

It's a common misconception that green roofs are more prone to leakage than other types of roofs. But the truth is, if your building is located in an area where heavy rains are a problem, a green roof is one of the best ways to manage your storm water.

Studies have shown that green roofs are no more likely to leak than any other roof. On the contrary, the waterproofing membrane that every roof has may actually be better protected under a layer of vegetation than it is under traditional roof coverings. The plants and growing medium effectively protect the waterproofing barriers from elements that would weaken it, such as ultraviolet light.

When it comes to managing storm water, the way that a green roof works is simple. Instead of simply pooling on your roof, or running off through gutters to pool on the ground around your building, the vegetation and soil on your green roof absorbs the moisture. This significantly decreases the amount of runoff and of standing water on your roof or around your building. The plants on your roof slowly release the water they absorb through the natural transpiration process, and of course, excess water evaporates in the heat. That means that you actually have less water to deal with, and less chance of water damage.

Lower Maintenance Costs

Many property owners worry that a green roof will require a lot of extra care and maintenance. However, the amount of work that goes into a green roof depends largely on what kind of green roof you choose to install. An extensive green roof is composed mostly of grasses, and requires very little in the way of maintenance once it's established.

If you prefer a garden-like roof with flowers, vegetables, shrubs, and other varieties of plants, it will require more maintenance. You'll need to ensure that the plants stay healthy the same way that you would in a ground-level garden. However, the costs associated with maintaining an established garden are still likely to cost less than replacing roofing tiles or repairing storm damage, so chances are that you can choose a more elaborate green roof and still save on roofing maintenance costs.

If you haven't yet considered the possibility of adding a green roof, now is the time to think about it. Ask a commercial roofing contractor from a company like John Criner Roofing Inc to evaluate your building and decide whether it can support a green roof. 


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