Which two areas in a data centre should have VESDA detection coverage?

Very Early Smoke Detection Apparatus (VESDA) coverage is essential in concealed areas that contain high concentrations of cabling and are part of the primary airflow path. The space under raised floors (subfloor plenum) and the area above suspended ceilings (ceiling plenum) are the most critical locations. These plenums are used for cooling air distribution and contain dense power and data cabling, which are primary fire risks. Placing detection sampling points here ensures that any microscopic particles from an overheating cable are immediately drawn into the detector by the airflow, enabling the earliest possible warning.

B. The lobby and cafeteria are ancillary spaces that do not house critical IT infrastructure and are protected by standard fire codes.
C. Parking lots and utility yards are external or support areas where this highly sensitive and specialized detection is not required.
D. Roofs and stairwells are structural and egress elements protected by general building fire codes, not specialized IT protection systems.

1. TIA-942-B, Telecommunications Infrastructure Standard for Data Centers, Section 8.4.3.2, explicitly states that for early warning detection, detectors "shall be installed in the data center rooms, in the ceiling plenums above the data center rooms, and in the access floor plenums below the data center rooms."

2. BICSI 002-2019, Data Center Design and Implementation Best Practices, Section 11.3.2.1.1, recommends the placement of very early warning fire detection (VEWFD) systems in the return air stream, which includes ceiling plenums and underfloor plenums.