Mixed-Use Building Egress: Single Staircase and a Proposed Food Court
A 6-storey mixed-use building has retail on floors 1–3 and offices on floors 4–6. The building has one enclosed staircase serving all floors. The longest travel distance from the far end of the retail floor to the staircase is 45 m. A 12 m dead-end corridor serves two retail units on the third floor. The staircase discharges directly into the main retail lobby at ground level. The building is proposed to add a food court on the third floor, increasing occupant load. The fire consultant has flagged non-compliance with the National Building Code of India. The owner wants to avoid losing leasable area and is reluctant to add a second staircase. The architect must propose a compliance strategy that addresses egress, compartmentation, and smoke control while minimizing area loss.
1. Identify the egress non-compliances and explain why each is a life-safety risk, not just a code technicality.
Read the worked answer
Three issues stand out. First, a single staircase for a 6-storey mixed-use building with retail and a proposed food court is a single point of failure: if smoke enters the stair, all upper floors lose their means of escape. Second, a 45 m travel distance in retail exceeds the typical code limit unless the building is fully sprinklered and has additional egress provisions; the food court will increase occupant load and worsen queuing. Third, a 12 m dead-end corridor is dangerous because occupants can be trapped if fire starts at the corridor entrance. The staircase discharging into the retail lobby is also problematic: smoke from a ground-floor retail fire can contaminate the exit path, and the exit is not protected. These are life-safety risks, not paperwork: they reduce the number of independent escape routes and increase smoke exposure time. The architect should document each non-compliance with the relevant code clause and the occupant-load calculation for the new food court.
2. Propose alternative compliance measures that could avoid a second staircase. Under what conditions would they be acceptable, and what are their limits?
Read the worked answer
Alternative measures could include: (a) a full automatic sprinkler system throughout, including the food court; (b) smoke exhaust or pressurization for the single staircase; (c) compartmentation of the retail floors with fire-resisting construction and fire doors; (d) an additional horizontal exit or an external escape route from the third floor; (e) reducing travel distance by relocating the food court closer to the stair or adding an exit passageway. These measures can be acceptable only through a performance-based fire-engineering analysis approved by the local fire authority. Their limits are important: sprinklers reduce fire growth but do not create a second independent exit; pressurization can fail if not maintained; and a dead-end corridor may still be unacceptable without a second way out. If the occupant load of the food court is high, the authority may still require a second staircase. The architect should present the trade-offs honestly rather than promise that a single stair can always be made equivalent.
3. If a second staircase is unavoidable, recommend its location and design to minimize leasable area loss and improve egress.
Read the worked answer
Locate the second staircase at the opposite end of the floor plate from the existing stair, preferably on an external wall. An external cantilevered or projecting staircase reduces interior area loss and can be naturally ventilated, which improves smoke control. If an internal stair is required, use a scissor stair or integrate it with the service core and toilets to share circulation space. Design requirements: 2-hour fire-resisting enclosure, self-closing fire doors, direct discharge to open air at ground level or through a protected lobby, and emergency lighting. To minimize leasable-area loss, negotiate a small floor-plate adjustment or use the stair as an architectural feature on the façade. The second stair should also serve the food court directly and reduce the dead-end corridor. The owner should be shown that the lost area is smaller than the potential loss from a fire closure or refused occupancy certificate.