Revised Design Standard Minimizes Fire Risks

Sourced from the Living Architecture Monitor

The steady advance of vegetative (green) roof designs within mainstream construction under the International Building Code requires regular updating of key design standards. As part of this industry wide effort, the American National Standards Institute (ANSI) re-approved the updated VF-1, “Fire Design Standard for Vegetative Roofs” as an American National Standard on May 11, 2017.

Green Roofs for Healthy Cities and Single-Ply Roofing Industry Inc. (SPRI), the trade association representing commercial roofing system manufacturers and component suppliers, initially collaborated on VF-1. The standard was developed by SPRI in 2007 and first approved as an ANSI standard in 2010. The document was created to provide a design and installation reference for roofing professionals to help eliminate the risk of fire on vegetative roofs.

“Updates to the VF-1 Standard included collaboration between all industries and segments involved with vegetative roofing” says Brian Davis, chair of SPRI’s VF-1 Review task force. “This, in turn, helped to create the best, most comprehensive document possible for the industry to reference and design with.”

Vegetative roof designs continue to evolve, with plant types, growing media, system complexity and usage, such as rooftop gardens. When updating the VF-1 Standard, SPRI needed to consider changes relating to external fire design and fire spread based on the American Society for Testing and Materials (ASTM) E108 – 17, “Standard Test Methods for Fire Tests of Roof Coverings.”

“Some of the key changes included new definitions and clarifying or removing some of the previous explanations and classifications, as well as additions to the VF-1 commentary section,” says Davis. “Some of the most important changes revolved around firebreaks, fire barriers, border zones, and area dividers, to name a few.”

The updated standard describes and provides more in-depth definitions of the three main categories of vegetative roofs—extensive, intensive, and semi-intensive. The standard also adds the spread of fire requirements that include combustible features that are part of the vegetative roof design, but not part of the building structure. Roof planters are one example.

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