Green Roofs — Coming to a Building Near You.

3 Aug 2010

One of the largest in the world - the 10.4 acre green roof of the Dearborn Truck Plant. Photo credit: Scott_Monty @ Flickr

An aerial view of a typical urban area reveals a sea of rooftops covered in asphalt, black tar and gravel.  Water rushes over the hard (and hopefully impermeable) surface and heat radiates off of the dark material.  Aside from housing HVAC units and an occasional satellite dish or telecommunications tower, rooftops do not serve much of a function other than keeping out the elements.  Green roofs are different. 

Although they have been utilized for centuries, green roofs are popping up more and more as the green building movement has accelerated the trend and properties are attempting to obtain LEED certification.  Green roofs are typically covered by a waterproof base layer, followed by a layer of soil or vegetated matting, and finally native plants.  Green roofs serve a number of beneficial purposes, including keeping the building cool in the summer and warm in the winter, absorbing rainwater, combating the heat island effect, creating wildlife habitat, and creating an aesthetically pleasing green space. 

According to the 2009 Green Roof Market Industry Survey  (“GRMIS”), more than 3.1 million square feet of green roofs were installed in the U.S. in 2008.  Michigan, like other states, has seen a significant increase in the number of green roofs.  In fact, according to the GRMIS, Grand Rapids was 8th in the number of newly installed green roof square footage in metro areas in North America in 2008 with 74,787 (Chicago was 1st with 534,507). 

There is no doubt that green roofs offer many benefits; however, green roofs can also result in increased liability if one is not careful.  Errors in design, installation or maintenance can trigger problems, and repairing a leaking green roof can be difficult and expensive.  Most green roofs are heavy and require extra structural support.  Further, there are a number of different types of green roof systems out there and a building owner should get comfortable with the anticipated watering, fertilizing and weeding requirements.  Finally, severe weather can damage green roofs and not all insurance companies are willing to cover them.  

As with any construction project, engage experienced professionals when constructing a green roof.  Second, have an attorney review the contracts in an attempt to limit unnecessary liability. Finally, check with your insurance company to make sure you are covered in the event the roof needs to be repaired if a casualty should occur.  I have no doubt that green roofs will continue to explode in numbers and I’m as big of a proponent as any.  That said, the legal risks and liabilities must be carefully evaluated before making the leap.

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