Did you know that green roofs cannot exceed 15,625 sf for any single area, per local fire code?

The 2012 International Fire Code (IFC) adopted by both the State of Washington and the City of Seattle introduces new standards for green roofs including:

  • New size restrictions

  • Walkway requirements

  • Irrigation conditions

Concerning size and walkways, Section 317.2 states:

Rooftop garden or landscaped roof areas shall not exceed 15,625 square feet (1,450m2) in size for any single area with a maximum dimension of 123 feet (39 m) in length or width. A minimum 6-foot-wide (1.8 m) clearance consisting of a Class A-rated roof system complying with ASTM E 108 or UL 790 shall be provided between adjacent rooftop gardens or landscaped roof areas.

Section 317.4.1 pertains to irrigation objectives and states, “Supplemental irrigation shall be provided to maintain levels of hydration necessary to keep green roof plants alive and to keep dry foliage to a minimum.”

Increased prevalence of intensive green roofs – those with a depth of 6” or greater – has contributed to the development of these regulations. While these new rules promote fire safety, green roofs also inherently contribute to fire suppression by mitigating urban heat island effect and retaining moisture in biomass.