Carpentry: Fire-Resisting Divisions, Fire Doors and Concealed Spaces (SOLAS II-2)
The Carpentry domain tests joinery work that carries a fire rating under SOLAS Chapter II-2: linings, ceilings, fire doors, draft stops and penetration seals. The examiner is not testing cabinetmaking quality; every item turns on whether a timber or composite assembly preserves the class of the division it is fixed to.
Class divisions and material limits
A-class divisions are steel or equivalent, insulated with approved non-combustible material, and rated A-60, A-30, A-15 or A-0 by fire test. Insulation limits: average temperature rise on the unexposed face not more than 140 °C, and not more than 180 °C at any single point, including joints. B-class divisions are approved non-combustible, rated B-15 or B-0 by fire test; B-15 adds insulation with a single-point limit of 225 °C. C-class has no smoke or flame requirement - non-combustible construction only. Non-combustible means the material does not burn or give off flammable vapour in sufficient quantity for self-ignition when heated to 750 °C, so solid timber never forms part of an A- or B-class division.
Doors and concealed spaces
Fire doors must be self-closing and latch positively; hold-back hooks that defeat the closer are prohibited, except for approved magnetic releases tripped by smoke detection. Draft stops are required in concealed spaces behind linings and above ceilings at intervals not exceeding 14 m.
Worked example
A joiner hangs a B-15 rated door and cuts a 25 mm undercut for return air. Is that acceptable? No. The door leaf is certified only as tested; an undercut breaks the smoke seal and invalidates the B-15 rating. Ventilation must come from a tested louvre within the door assembly, not from a site cut.
Traps
- Confusing A-0 (60 minutes' smoke and flame, no insulation) with C-class.
- Treating any mineral board as automatically A-class; only a tested system qualifies.
- Quoting 180 °C for the B-class single-point rise instead of 225 °C.
- Overlooking that combustible veneers on B-class surfaces are restricted by calorific value and thickness under the FTP Code.