Vegetated (green) roofs continue to be incorporated into an ever-increasing array of buildings across North America. The architecture and landscape architecture communities continually push the envelope on the design of vegetated roof assemblies on these buildings.
Wind is a natural force that affects every part of a building. Architects and engineers use wind data to design building facades and window assemblies to be sure that those elements are properly fastened to the building structure. Fortunately there has not been a documented incident of a vegetated roof assembly being damaged by wind to the point where it comes off the building. One reason for this is the vegetated roof industry is fortunate to have certain guidelines to aid the designers in good vegetated roof practices. ANSI/SPRI RP-14 “Wind Design Standard for Vegetative Roofing Systems” was created in a partnership between GRHC and Single Ply Roofing Industry (SPRI) to be one of those guidelines.
Up until 2015, however, there was never an actual test protocol for testing vegetated roofing assemblies. In early 2015, the Canadian Standards Association (CSA) adopted a new standard (CSA 123.24-15) entitled “Standard Test Method For Wind Resistance Of Modular Vegetated Roof Assembly”. This protocol was developed at the National Research Council of Canada (NRCC) facility with a group of pre-vegetated tray and mat manufacturers and addresses the wind uplift resistance of modular roof assemblies (trays) and mats only.
In 2016, the NRCC and the Canadian Roofing Contractors’ Association (CRCA) pulled together a group of commercial companies to fund and begin work on refinement of this standard so that it would also to include built-up (loose laid) vegetated roofing assemblies. This group includes: Bioroof Systems, Inc.; Hydrotech Membrane Corporation; Sedum Master, Inc.; Soprema, Inc. and ZinCo Canada, Inc.
These individual companies have agreed to fund the research and testing, provide materials, and work together to develop a set of wind uplift design standards that are appropriate for built-up (loose laid) vegetated roofing assemblies. These new standards could reside in one of two places: within the existing CSA 123.24 standards or within a new, stand-alone standard. That decision will be determined as the testing protocols are developed this year.