Comparative Analysis of Green Roof Guidelines and Standards In Europe and North America

The German FLL Guidelines for green roofs are designed to inform about state-of-the-art performance expectations for green roofs. North America is experiencing steady growth in the green roof market and has no single-source set of standards or guidelines; therefore there is a need to identify what type of guidance may be lacking. Seven domains of knowledge from the FLL Guidelines are compared to similar areas of content in North American documents. It was found that although there are several North American green roof guidelines in use, compared to the FLL Guidelines there are areas where knowledge is lacking: guidance for compatibility of system components, slope application, filter fabrics, root barriers, surface and subsurface drainage, growth media, and erosion control, as well as standards or postconstruction testing requirements for fabrics, bulk density of growth media, root barrier performance, drainage media, and growth media. A case study of the Chicago City Hall green roof examines its content compliance with FLL performance standards. Recommendations for further advancement of North American guidelines include the need for more collaborative research and development in efforts to advance existing and new guidelines across ecoregions.