The American National Standards Institute (ANSI) recently approved a key fire design standard for vegetative roofs developed by SPRI in cooperation with Green Roofs for Healthy Cities (GRHC).

ANSI/SPRI VF-1 “External Fire Design Standard for Vegetative Roofs” was approved on Jan. 29 after a final round of revising and re-balloting earlier in the year. SPRI Technical Director Mike Ennis, who also chairs SPRI’s Codes & Standards Task force, worked for several years with task force members Dave Roodvoets and Kelly Luckett on the standard. This team also continues work on ANSI/SPRI RP-14, a wind standard for vegetative roofing systems.

At the same time, SPRI’s Sid Teachey is leading the development of a root penetration standard for vegetative roof systems. The second draft of GRHC-SPRI VR-1, “Procedure for Investigating Resistance to Root Penetration on Vegetative Roofs,” is currently being prepared for ANSI canvassing.

Because of the rapid growth of the green movement, it is critical that the roofing industry develop standards like these to guide contractors and specifiers in the design and installation of vegetative roofs.

The recently released ANSI/SPRI VF-1 standard includes fire-control designs to limit the spread of flame if a vegetative roof system were to catch fire. The standard uses barriers of non-vegetative zones to contain a potential fire.

The standard’s use is limited to roof slope designs up to 2 inches in 12 inches and specifies use of fire stop walls and fire break roof areas. Fire walls must be of non-combustible construction and extend above the roof surface a minimum of 36 inches (914 mm).

The fire break roof areas must consist of a Class A (per ASTM E108 or UL790) rated roof system that creates a minimum 6 feet (1.8 m) wide continuous border around the vegetative roof. Fire break roof areas must also be included where vegetative roof systems abut vertical surfaces, such as rooftop structures, equipment and roof penetrations.

Fire stops are also specified for spread of fire protection for large roof areas. Fire walls or fire breaks are used to partition large roof areas into sections not exceeding 15,625 square feet (1,450 m2), with each section having no unbroken linear dimension greater than 125 feet (39 m). Incorporating the border zones into expansion joints or roof area dividers are recommended wherever possible.

“This was truly an industry effort including manufacturers, green roofing professionals, testing organizations, contractors, design professionals and consultants,” said Mike Ennis, technical director for SPRI.