Fire safety design and codes
Domain 2 tests your ability to apply the Code of Practice for Fire Safety in Buildings 2011 and the Building (Planning) and (Construction) Regulations to a real layout, and to know exactly where the Code sits in law.
Legal status and structure
The FS Code 2011 is a code of practice, not subsidiary legislation. The legal duty lies in the Buildings Ordinance (Cap 123) and its regulations. The Code sets out deemed-to-satisfy provisions; departing from it requires an alternative approach accepted by the Building Authority, with FSD comment where fire service installations or firefighting access are affected. It covers means of escape, fire resisting construction, means of access, and firefighting and rescue provisions.
Means of escape
Design runs from occupant capacity (usable floor area ÷ occupancy factor) to the number and width of exits, travel distance and route protection. Exit capacity uses a unit width of 550 mm with an assigned discharge value per unit; round the number of units up, and remember the narrowest point on the route governs. Dead-end travel, inner rooms and routes passing through kitchens or storage are the usual failure points.
Fire resisting construction
Fire resisting periods come from tables driven by purpose group, building height and compartment volume. Compartmentation limits the potential fire size; protected lobbies and staircase enclosures protect the escape and firefighting route; fire shutters and dampers need tested closing mechanisms and clear indication of their role in the cause-and-effect strategy.
Worked example
An office floor has 900 m² of usable area. With an occupancy factor of 9 m²/person, occupant capacity is 100. If the discharge value is 40 persons per 550 mm unit, units required = 100 ÷ 40 = 2.5, rounded up to 3, giving 1.65 m of total exit width. Two protected exits are then needed because the travel distance from the far corner exceeds the single-direction limit and the floor sits above the relevant height threshold. Check both the width and each travel distance separately.
Traps
Assuming the Code is law; using gross floor area instead of usable; forgetting that a Fire Safety Direction under Cap 572 for an existing composite building can require works the 2011 Code would not; treating an FRR table value as negotiable without a fire engineering submission.