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Fire & Life Safety FOCUS ON PREPARATION AND PREVENTION Fire and Life Safety for Green Roofs Factors to consider concerning green building design and installation. BY MIKE HALLIGAN A T FIRST GLANCE YOU MIGHT wonder why a fi re and life safety column is talking about roof vegeta- tion. In the concept of green building design there are more and more applications of this type of roof appearing on the tops of our build- ings. Your local fi re department will want to know when a building roof system contains a vegetation component. They will be interested in items such as roof loading, roof drainage, roof slope, roof access, supporting structure, and fi re exposure to help determine safety issues during fi re operations. They will also be interested in parapets as a safety issue for containing debris from falling off the edge and injuring emergency responders on the ground. Roof Access All fi re and building codes require some form of roof access for fi refi ghters. A noncombustible area should be provided around the access point to allow fi refi ghters onto the roof surface. In addition, noncombustible pathways should be provided to allow access to hazardous roof areas, rooftop equipment, skylights, and locations necessary for rooftop ventilation can take place. Consideration should also be given to "compartmentalizing" roof vegetation. This will as- sist in minimizing fi re spread from one rooftop area to the next. Roof Loading Traditional roof loading is a fairly easy calculation to make. Introducing plants and soil that are in different growth stages throughout the season or year will have an impact on what addi- tional loads are added to the roof. In addition, water capacity from fi refi ghting will need to be included. If, over time, pavers, stone, or new planting materials are added, there will be a need to recalcu- late what the roof load capacity is for the roof. Roof Slope Particular attention will need to be paid to the slope of a green roof. While most have a 3 or 4 percent slope, the percentage of slope could be reduced to prevent the materials growing on the roof from shifting during rain events. In addition, how vegeta- tion is held in place on a slope must be considered, so fi refi ghting efforts don't block drainage systems. Hose streams can dislodge vegetation and block drainage, which, if not considered in design, can lead to roof failure from excessive loading. Some engineers also suggest that on steep-slope green roof 14 COLLEGE PLANNING & MANAGEMENT / NOVEMBER 2012 systems, anti-shear anchors be installed to assist with erosion control, and that if the slope exceeds 40 percent that green roofs be avoided altogether. Fire Exposure Vegetation is a combustible material. This must be taken into account when considering green roof systems. Fire exposure can occur from below, above, and from adjacent structures. Careful consideration must be given with regard to placement. Choice of materials can aid in providing some basic levels of resistance to fi re exposure. Plants with higher moisture content will perform slightly better if they are healthy and well maintained. Additional measures, as far as use of watering systems that can be fed from fi re department connections, may also help reduce fi re exposure. Parapets While parapets are traditionally considered a roof element used to screen equipment or to provide a fall barrier, they take on another role when green roofs are installed. The parapet should be designed to be tall enough to contain all vegetation and materials that might "fl oat" when subject to additional water from fi refi ght- ing efforts. This will ensure the safety of fi refi ghters working on the exterior near the perimeter of the building. The application of vegetation systems on roofs will require careful consideration on the part of the building owner and local fi re department. Green buildings don't always mean increased fi re and life safety. In fact, owners of green buildings need to be aware that these buildings typically bring challenges many jurisdictions have not previously considered. Green buildings should have a full fi re protection and life safety analysis conducted by stakeholders from the fi re prevention offi ce and building maintenance staff. Most reviews will be considered a performance-based review. And while a performance-based review takes more time, the result should be a roof system that meets the goals of a green roof but also meets the fi re and life safety goals of the project as well. CPM Mike Halligan is the associate director of Environmental Health and Safety at the University of Utah and is responsible for Fire Prevention and Special Events Life Safety. He frequently speaks about performance-based code solutions for campus building projects, is recognized as an expert on residence hall fi re safety programs, and conducts school fi re prevention program audits/strategic planning. He can be reached at 801/585-9327 or at mike.halligan@ehs.utah.edu. WWW.PLANNING4EDUCATION.COM