A calculated system for a building or a calculated addition to a system in an existing building, shall supersede the rule in NFPA 13 governing pipe schedules, except that all systems shall continue to ________

• A. Area
• B. Height
• C. Volume
• D. Length

Answer: (A)

When you use a hydraulically calculated sprinkler system, you don’t rely on fixed pipe sizes from the pipe schedule method. You size and design based on the actual hydraulic demand. But even with that flexibility, NFPA 13 keeps a constant constraint: the system must still be designed by area. This means the design must account for the floor area (design area) each portion of the system serves to ensure proper coverage and zoneing. Height, volume, or length aren’t the universal constraint carried over in this context.