5 February 2026
Firefighting Shaft and Lift Lobby Doors — What Approved Document B Requires
Lift shafts are one of the most common routes for vertical fire spread. Here's how Approved Document B and BS 9999 set out when EI 60 and EI 120 rated doors are required.
A lift shaft is, structurally, a vertical chimney running through every floor of a building — which makes it one of the most efficient routes for fire, smoke and hot gases to travel from a fire floor to floors above. The doors at each lift landing are the only barrier between the shaft and the occupied floor plate, which is why Approved Document B and BS 9999 treat lift landing door specification as a height-dependent, non-negotiable requirement.
Firefighting Shafts and the Fire Service Lift
Above the height thresholds set out in Approved Document B, a building requires a firefighting shaft — a protected enclosure combining a firefighting stair, lobby and often a firefighting lift — to give fire and rescue services a protected route to upper floors. The doors and enclosure forming this shaft are held to a doubled standard compared with a typical protected stairway, reflecting their role as an active rescue route during a fire rather than just a passive compartment boundary.
Hollow Metal Shaft Door Specification
BÖLDT's hollow metal shaft doors are purpose-built for this application: heavy-duty hollow metal construction with 0.8–1.6mm shutter steel, 1.2–1.8mm frame steel, honeycomb infill, and an overall finish thickness of 46mm, tested up to 120 minutes. The honeycomb infill construction is specifically suited to the repetitive, high-cycle use that lift landing doors experience over a building's lifetime — these are among the most frequently operated fire doors in any building, opening and closing hundreds of times per day across a tower's full height.
EI 60 vs EI 120 — Where the Threshold Sits
The practical specification logic under Approved Document B and BS 9999 typically runs as follows: general protected stairway and lift lobby doors are specified to EI 60 in most mid-rise configurations, while firefighting shaft enclosures, pressurised lobbies and lift lobbies serving taller buildings step up to EI 120. Confirm the applicable threshold against the current edition of Approved Document B and BS 9999 for the specific building, as the precise trigger height and configuration depend on the building's use class and overall fire strategy.
Coordination with Lift Consultants
Because lift landing door dimensions, sightlines and operating clearances are tightly constrained by the lift car and shaft design, fire door specification for lift shafts cannot be finalised in isolation from the lift consultant's drawings. Frame depth, landing sill detail, and the interface between the fire-rated door frame and the lift shaft wall all need to be coordinated early — particularly on retrofit projects where shaft dimensions are fixed and any deviation in frame depth has knock-on effects for the lift car envelope.