One Staircase, Five Office Floors
A developer in Karachi submits a six-storey building for approval: ground-floor retail plus five office floors, each 1,800 square metres gross. Your firm is engaged to review life safety before the drawings go to the provincial building control authority. The design has one 1.20 m wide enclosed staircase serving all floors, discharging directly into the main entrance lobby. The longest travel distance from the furthest desk to the stair door measures 42 m on the fifth floor. A 16 m dead-end corridor serves the rear offices on each floor. The stair has no pressurisation and no natural ventilation at the landings. The lobby also contains the building's only transformer room and two retail units. The architect argues that the building is fully sprinklered, so travel-distance limits do not apply, and that a second stair would remove 6 percent of the rentable area.
1. Set out the egress non-compliances you would raise and the reasoning that makes each one a non-compliance.
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Start from the occupant load, because every other number depends on it.
- Occupant load. Office floors at about 9.3 square metres gross per person give roughly 190 per floor, so about 950 across five floors; retail at about 3 square metres per person adds several hundred more at ground level. The total is well over 1,200 persons.
- Number of exits. The requirement for the number of exits scales with occupant load and building height. At this height and occupancy a single exit is not permitted; two exits remote from each other are needed. This is the fundamental failure, and no sprinkler trade-off removes it.
- Egress width. A 1.20 m stair at the usual 7.6 mm per person allowance carries about 155 to 160 persons. Against an occupant load of over 1,200, it is short by an order of magnitude, not by a margin.
- Travel distance. The 42 m to the only stair on the fifth floor exceeds the limit in the code of record, typically 30 to 45 m depending on sprinkler protection and occupancy classification.
- Dead end. A 16 m dead-end corridor exceeds the usual 6 to 15 m limits and leaves occupants with no alternative if the single route is smoke-logged.
- Discharge. An exit must lead to a safe place. Discharging the only stair into a lobby containing a transformer room and retail units is not a safe discharge; the transformer room also needs its own fire separation and ventilation.
- Stair protection. An enclosed stair without pressurisation or natural ventilation at the landings cannot be assumed to remain tenable.
2. Evaluate the architect's sprinkler argument.
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Sprinklers buy concessions, not exemptions.
- What sprinklers legitimately permit. They allow extended travel distances, reduced separation between exits, and in some codes a relaxation of the single-exit threshold for small, low-occupancy floors. Those concessions are defined and bounded.
- What they do not permit. They do not allow an exit system whose capacity is a fraction of the occupant load, and they do not allow the number of exits to fall below the code minimum for the height and occupancy. The width calculation is independent of sprinklers.
- Reliability condition. Every sprinkler concession assumes a maintained, water-supplied, annually tested system. If the water supply and maintenance regime are not secured by contract and by the building's operating budget, the concession should not be taken at design stage.
- Rentable area is not a compliance argument. A 6 percent area loss is a commercial consequence of the design, not a technical justification. It should have been priced at feasibility stage.
Conclusion: the sprinkler installation is welcome and should be retained, but the second stair and the safe discharge remain mandatory. Presenting the sprinkler as an exemption would place a false statement before the authority.
3. Advise on your professional position if the client insists on submitting for approval without these changes.
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Your signature is the product; protect it.
- Report in writing, and separate fact from opinion. Set out the measured travel distances, occupant loads and stair widths, and state plainly which code clauses are not met and which cannot be traded against sprinklers. Give the client the corrected design options with area and cost implications so the refusal is not seen as obstruction.
- Do not sign the compliance statement. Certifying a life-safety design that you know does not comply is a misrepresentation, and under the PEC Code of Ethics it exposes you to disciplinary action regardless of who instructed you.
- Offer an engineered alternative honestly. If the client wants to pursue an alternative-compliance or performance-based route, say what evidence it needs: fire-engineering analysis, smoke modelling, evacuation simulation, and acceptance by the authority. Say also that approval is not guaranteed.
- Escalate internally first, then inform the client in writing that the firm cannot submit the drawings as compliant. Record the instruction and your refusal contemporaneously.
- If pressed further, withdraw from the certification scope and say why in writing, rather than let your name sit on a drawing you do not stand behind. Life-safety non-compliance is the one category where the consequences of signing are irreversible.