Chapter 7
Mechanical Ventilation & Smoke Control Systems
Chapter 7 governs the design, installation and maintenance of air-conditioning, mechanical ventilation, pressurisation and smoke control systems in buildings to limit fire and smoke spread and to maintain tenable conditions for evacuation and firefighting. It sets out ductwork construction rules, fire damper requirements, special ventilation requirements for exits and protected spaces, pressurisation performance criteria, smoke extraction and purging system designs, and mandatory redundancy provisions for all critical life-safety ventilation systems.
Scope: All buildings (except PG I where explicitly exempted) that incorporate air-conditioning or mechanical ventilation systems, pressurised exit staircases or corridors, or engineered smoke control systems. Specific clauses apply to hotels, car parks, kitchens, battery rooms, and buildings with large or basement compartments.
Source: SCDF Code of Practice for Fire Precautions in Buildings 2023. This is a guidance summary — always verify against the full Fire Code clause text.
Critical points
Pressurisation is mandatory for any internal exit staircase without adequate natural ventilation in a building whose habitable height exceeds 24 m.
CriticalClause 7.2.1aPressurisation is mandatory for exit staircases connected to fire lift lobbies in buildings with more than four basement storeys.
CriticalClause 7.2.1bThe pressurisation system must maintain a minimum pressure differential of 50 Pa between the pressurised exit staircase and the occupied area when all doors are closed.
CriticalClause 7.2.2aThe force required to open any door against the combined resistance of pressurising air and the automatic door closer must not exceed 110 N at the door handle.
CriticalClause 7.2.2cThe air flow velocity averaged over the full area of each door opening shall not be less than 1.0 m/s when two consecutive storey doors plus the main discharge door are fully open simultaneously.
CriticalClauses 7.2.3b–cSupply air intake must be from external space with intake point ≥5 m from any exhaust discharge. System must be automatically activated by the building fire alarm system, with remote manual override at FCC or fire alarm panel.
ImportantClause 7.2.6b–c
Compliance thresholds
| Parameter | Value | Condition | Clause |
|---|---|---|---|
| Habitable height triggering pressurisation | Exceeds 24 m | Internal exit staircase without adequate natural ventilation | Clause 7.2.1a |
| Basement depth triggering pressurisation | More than 4 basement storeys | Exit staircases connected to fire lift lobby in basements | Clause 7.2.1b |
| Minimum pressure differential (all doors closed) | 50 Pa | Between pressurised staircase and occupied area | Clause 7.2.2a |
| Maximum door opening force | 110 N at door handle | Combined resistance of pressurising air and door closer | Clause 7.2.2c |
| Minimum air velocity through open door | 1.0 m/s (averaged over full door area) | When 2 successive storey doors + main discharge door are fully open | Clause 7.2.3c |
| Supply air intake separation from exhaust discharge | Not less than 5 m | Pressurisation system supply air intake | Clause 7.2.6b |
Interactive decision tree
Determine if staircase pressurisation is required.