Section 12.5, “Site Security,” of NFPA 241-19 requires:
- guard service or alternative method of security where combustible construction exceeds three stories; and
- minimum 1.8-m (6-ft) high security fence around the entire construction site (Figure 4).
The new provisions in NFPA 241 come after successful fire management on several tall timber projects around the world. For example, the 18-story Brock Commons in Vancouver, British Columbia, Canada, utilized a detailed fire management plan to mitigate the fire risk of the high-rise mass timber structure. As discussed by naturally:wood (naturally:wood provides information about environmentally sourced forest products from British Columbia, Canada) in the “Brock Commons Tallwood House Construction Overview,” a layer of protective drywall was required for the building’s construction type. However, the mass timber elements needed to be fully dry prior to installation of the drywall, causing the latter’s installation to lag behind the timber. To mitigate the amount of exposed wood during construction, the fire management plan specified a maximum of six floors of exposed wood at a time. The plan also included several additional safety measures such as:
- fire-prevention and response training for all trades;
- standpipes installed in the core prior to installation of mass timber;
- hot work completed prior to timber installation;
- exceptionally clean construction site; and
- temporary fire doors installed on two exit stairs.
Through the use of safety practices such as those employed for Brock Commons, as well as those specified in NFPA 241, construction sites with exposed wood can effectively mitigate fire hazards prior to the installation of passive and/or active fire protection systems.
Conclusion
Not all wood projects require protective membranes. As illustrated by NDS calculations and the research presented in AWC’s “Technical Report No. 10,” exposed wood can provide substantial fire resistance. As a result, provisions for exposed wood are recognized by IBC and will be expanded in upcoming editions of the code. However, where enhanced fire resistance is required, gypsum or other protective membranes can be used to afford an additional level of fire protection. Buildings relying on noncombustible membranes for added protection should develop comprehensive construction fire management plans to ensure a safe jobsite.
However, construction site safety should not only apply to wood buildings. All buildings undergoing construction have an elevated fire risk due to the hazardous activities, the accumulation of materials, and/or the lack of permanent fire protection features. Utilizing the provisions of NFPA 241 can protect all types of buildings from construction fires, resulting in a greater level of safety for both the building and construction personnel.
Mariah Seaboldt, PE, is a registered fire protection engineer in Massachusetts. She has a bachelor’s degree in civil engineering and a master’s degree in fire protection engineering from Worcester Polytechnic Institute. Seaboldt is part of the architectural code consulting team at AKF Group in Boston where she specializes in building, fire, life safety, and accessibility code consulting for both existing building renovations and new construction projects. Seaboldt can be reached at mseaboldt@akfgroup.com.
