What is the minimum depth required for draft stops according to NFPA 13?

The minimum depth required for draft stops according to NFPA 13 is indeed 18 inches. Draft stops are important components in fire sprinkler systems because they help limit the movement of smoke and heat during a fire, which can be critical for both fire control and occupant safety.

The 18-inch minimum depth is specified to ensure that draft stops are effective in trapping smoke and heat, preventing them from traveling unimpeded through large open spaces, and directing them towards the fire protection system. This depth is typically applied in concealed spaces, such as attics and ceiling voids, where smoke and heat can accumulate if not properly managed.

By adhering to this standard, fire protection systems can remain more effective, ensuring prompt activation of sprinklers in affected areas and aiding in the overall firefighting strategy. The established depth is based on extensive research and testing, ensuring it meets the safety and performance requirements outlined in NFPA 13, which governs the installation of sprinkler systems.