First Steps When Considering a Green Roof For An Existing Facility
May 2014 - Roofing
If facility managers are interested in a green roof on an existing facility, what are the first steps to take?
There are a few simple steps that can help you get started in determining if a green roof is right for your project. The primary step is to determine the structural loading on the building to see if it is capable of supporting the weight of a green roof. This should be conducted by a structural engineer.
Typically if you are removing gravel ballast or pavers from the roof surface, you have some inherent structural capacity in the design of the structure that could be used for the green roof. If you are considering the green roof for a new facility, the design can include the structural capacity to support the green roof for a reasonable increase of cost.
A second important consideration is the remaining life expectancy in your current roofing membrane. Although it can be done, it typically doesn’t make a lot of sense placing a new green roof on a roofing membrane which may only have a five-year service life left before replacement. It makes the most sense to consider a green roof when you are replacing the roofing membrane which will ensure a water tight installation or replacing the membrane when installing a green roof. Seeking out a certified “Green Roof Professional” (GRP) from Green Roofs for Healthy Cities is a good way to gain a good understanding of the benefits and constraints of installing a green roof system. GRP’s can help you identify occupancy rates, code requirements, costs and evaluate systems making the process much simpler.
Answers provided by Jeffrey L. Bruce, FASLA, LEED, ASIC, GRP. Bruce is owner of Jeffrey L. Bruce & Company (JBC), a national landscape architectural firm. Founded 1986, JBC provides highly specialized technical support to many of the nation’s leading Architectural and Landscape Architectural firms on a wide variety of project profiles including engineered soils, green roof technologies, urban agronomy, green infrastructure, performance sports turf, water harvesting, and irrigation engineering. Bruce is a Fellow of the American Society of Landscape Architects, Past President of the American Society of Irrigation Consultants (ASIC), and Chairman of Green Roofs for Healthy Cities (GRHC).
Ask An Expert: Jeffrey Bruce, Green Roofs