Green Roofs - Living Architecture Monitor - Spring 2010 - (Page 30)

GRHC UPDATE DAMPENING GREEN ROOF FIRE RISK GREEN ROOFS FOR HEALTHY CITIES AND THE SINGLE PLY ROOF INDUSTRY HIT A MILESTONE WITH THE ACCEPTANCE OF THEIR CO-DEVELOPED ANSI/SPRI VF-1, FIRE DESIGN STANDARD FOR VEGETATIVE ROOFS By Kelly Lucke� he long-awaited fire and wind design guidelines for vegetative green roof systems are finally complete. In February, the American National Standards Institute (ANSI) accepted VF-1 Fire Design Standard for Vegetative Roofs, developed by Green Roofs for Healthy Cities (GRHC) and SPRI, Inc., the trade association representing the manufacturers of commercial roofing systems and component suppliers. A code change proposal has also been submitted to the International Building Code to include this fire standard in the 2012 edition of the International Building Code. On the wind side, RP-14 is currently awaiting approval by ANSI. Both VF-1 and RP-14 were the result of consensus of stakeholders from the roofing, landscaping and green roof industries, including Green Roofs for Healthy Cities. While not everyone agrees with every provision, these standards set definitive design and construction requirements for green roofs that have been absent in the building codes that govern construction in North America. Acceptance by the International Code Council will make the RP-14 wind design guide and the VF-1 fire design guide the law of the land in many jurisdictions and likely change the way we design and construct green roofs. VF-1 addresses three fundamental green roof design considerations; location on a rooftop where the green roof abuts vertical surfaces, dividers in the green roof called “fire breaks” that are intended to limit the spread of fire from one section of the rooftop to another, and the maintenance of green roof systems to minimize their flammability. Historically, non-vegetation zones at the perimeter of the roof and around roof penetrations have consisted of varying widths of gravel to limit the risk of fire spreading from the field of the green roof to the exterior walls and through openings in the roof surface to the interior of the building. However, the use of gravel aggregate on rooftops is prohibited in wind borne debris zones near coastlines, and there has been a trend within the building engineering comunity to eliminate the use of gravel on rooftops all together. Not all parapet and roof 30 LIVING ARCHITECTURE MONITOR T “While not everyone agrees with every provision, these standards set deﬁnitive design and construction requirements for green roofs that have been absent in the building codes that govern construction in North America.” penetrations are constructed of flammable materials. Rather than arbitrarily mandating barriers at all vertical surfaces, VF-1 requires attention only to vertical surfaces that are constructed of flammable materials. Additionally, the new standard requires the sixfeet of roof surfaces adjacent to the flammable vertical surfaces to be covered with a “Class A” fire-rated material. Therefore, the use of a Class A fire-rated roofing membrane at these locations eliminates the need for non-vegetation zones. Green roofs that do not employ Class A fire-rated roofing membranes will be required to utilize six foot-wide, non-vegetation zones consisting of non-flammable materials such as concrete pavers. “Fire breaks” are similar to set-backs at the perimeter and roof penetrations, only they are required in the interior of very large rooftops. VF-1 requires a six foot-wide strip of Class A fire rated material every 125 feet or 15,625-square feet. As with the perimeter and roof penetrations, the use of a “Class A” fire-rated roofing membrane also eliminates the need for non-vegetation zones at fire breaks. Finally, prudent design can only go so far to reduce the risk of flame spread across a green roof. The primary factor in reducing the flammability of green roof plants lies in the maintenance of the green roof. VF-1 stops short of mandating irrigation systems on all green roofs, instead requiring property owners to perform necessary maintenance to keep the plants healthy; including irrigation, fertilization and weeding. Additionally, owners of green roofs with plants that produce dead foliage (such as prairie grasses) must remove this flammable material no less than twice per year. An interesting sidebar story, the core action items in VF-1 were proposed and adopted into the International Fire Code last fall. The approved measure included language that entitled the local fire marshall to require a maintenance plan for vegetative green roof systems. This effectively moves green roof maintenance requirements from post-construction to preconstruction as the fire marshall’s review of the construction documents occurs prior to the issuance of building permits. This new measure also transfers the policing of the green roof maintenance requirements from the building inspector to the fire marshall. This is significant because the building inspector only enters the building at the conclusion of construction and at subsequent occupancy changes. The fire marshall, however, conducts routine inspections and will now have the authority to identify violations of the green roof maintenance requirements and issue citations to the property owner. The green roof industry has long been fighting early misconceptions spread by various media outlets espousing green roofs to be “maintenance free.” The actions taken by the International Code Council will make huge strides in correcting the resulting unrealistic expectations regarding the necessary maintenance onus that falls to the owner of a green roof. Educating prospective green roof owners about the maintenance requirements of their green roof investment is critical to the success of the green roof concept. Unpleasant as it may be to discuss the future expenses of a roofing option that is already much more expensive than traditional roofing processes, it pales in comparison to that of the conversation with an unhappy green roof owner who was allowed to enter into a green roof endeavor expecting zero maintenance. Kelly Luckett, LEED AP, GRP, is the chair of GRHC's Technical Committee and president of Saint Louis-based Green Roof Blocks and author of a new book entitled Green Roof Construction and Maintenance (The McGraw-Hill Companies, Inc., 2009). SPRING 2010

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Spring 2010

Green Roofs - Living Architecture Monitor - Spring 2010
Contents
From the Founder
Letters
Strata
Roofing Industry Research Summit
New LAM Editorial Advisory Board Kicks Off
On the Roof With Steve Windhager
Green Philly
Taking the Pulse
Greening the Green Roof System
More Bees, Please!
Dampening Green Roof Fire Risk
New Online Tools for Green Roof and Wall Professionals
New Corporate Members
New GRPS
GHRC Professional Development Calendar
Building Green Together

Green Roofs - Living Architecture Monitor - Spring 2010