Garden Roofs Are Cool, But Who’s Using Them?
It is estimated that there are about 360 rooftop gardens, partially or fully covered with vegetation in the City of Chicago alone. In a 2010 report, the City of Chicago estimated that, 5,469,463 SF of Rooftop Gardens have been installed in Chicago. Although that seems like a large number, the approx. 5,000,000 SF is a very small percentage of the total roofing market in Chicago. Plus, the average size of the rooftop garden is about 5,234 SF, relatively. It is report that about one third of the Chicago roofing contractors have been involved in this rooftop garden market since 2000, but the number of annual projects is on the decline. However, the rooftop garden concept is a costly proposition, and the roof must be installed right the first time. A conventional low slope roof costs anywhere from $4 – $10/ SF depending on insulation, roof membrane type and access for the workforce and materials to work. A rooftop garden is between 2-5 times the cost of a conventional roof.
That being the case, it often ends up that these types of projects are too costly of a venture for ownership. While there are some added environmental benefits in addition to the possible added usable space, it often just takes make sense to construct or retrofit these systems. In many cases, a cool roofing system is more economical and still provides a great deal of environmental benefits. Or better yet, restoring and maintaining your current system may be the most economical and practical solution. To determine the right fit for your roofing needs, contact a roofing professional who can help provide you with your options and help choose the right roofing solution for you and your building.
Another interesting fact to add about these garden roofs is that rooftop gardens, when placed on roofs, are regulated by the International Fire Code (IFC). The IFC points the designer to the roofing related code requirements in the International Building Code, (IBC) Chapter 15, Roofing section, which references Chapter 16, the wind uplift section.
This focus of rooftop equipment on the roof, keeps all things on the roof, regulated with the roof. Why? Rooftops are subject to wind, water, snow, fire and hail exposure. Plus, they are on top of a roof. Makes sense, doesn’t it?