Testing of pressurized vestibules associated with Measure N, where Measure N is used to limit smoke movement from one building to another of connected buildings as provided in Commentary C of the User's Guide - NBC 1995 (Part 3).

This applies to high buildings, as defined in Sentence 3.2.6.1.(1) of the National Building Code of Canada:

• of Group A, D, E or F major occupancy classification that is more than:
  • 36 m high, measured between grade and the floor level of the top storey, or
  • 18 m high, measured between grade and the floor level of the top storey, and in which the cumulative or total occupant load on or above any storey above grade, other than the first storey, divided by 1.8 times the width in metres of all exit stairs at that storey, exceeds 300,
• containing a Group B major occupancy in which the floor level of the highest storey of that major occupancy is more than 18 m above grade,
• containing a floor area or part of a floor area located above the third storey designed or intended as a Group B, Division 2 occupancy, and
• containing a Group C major occupancy whose floor level is more than 18 m above grade.

To limit the probability that inadequate air movement through vestibules will go unnoticed, which could lead to the smoke control system not operating as originally intended in a fire situation, which could lead to the migration of smoke from the building to an adjacent building, which could lead to damage to adjacent buildings or facilities.