Last edited 13 Feb 2019

Lift shaft

1 Introduction
2 Construction
3 Fire considerations
4 Ventilation
5 Related articles on Designing Buildings Wiki
6 External references

[edit] Introduction

Lifts (or elevators) in buildings are normally totally enclosed by a shaft (typically square or rectangular) that will rise vertically through the building and often terminate above roof level. Lift shafts will also extend below ground if it must serve one or more basement levels, or to house operating equipment. They are commonly found in commercial, public and other types of multi-storey building.

Lift shafts have several important functions:

They provide lift cars with clear, unimpeded travel between floors.
Their fire-resisting construction is designed to ensure that lift operation is not impaired by a fire breaking out on any of the floors of a building. As such they become protected shafts. If they were not fire-resisting construction, they could form flue-like apertures that might allow the spread of fire through convection currents and firebrands.
They can provide a zone for locating the lift mechanism, although sometimes lift machinery is located in rooms located outside the shaft.
Their construction usually affords users of areas immediately around the shaft with a degree of noise separation from the lift operating machinery.
Their outside face may be used on each floor as a wayfinding marker.
They can form part of the structural core that stabilises buildings.

[edit] Construction

Generally, on large commercial and public buildings, the reinforced concrete lift shaft will form part of, and be located in the building’s core along with escape stairways, toilets and other ancillary accommodation. More often than not, the construction will be of in-situ-poured, reinforced concrete with openings left at each floor for elevator and other orifices. The core can form part of the building’s structure as it may be connected to the floors and hence provide lateral stability. This is increasingly the favoured construction in many tall buildings.

The arrangement of lift mechanics in a shaft will be very much dependant on the type of lift mechanism that is installed. A conventional traction lift will usually require a system of steel ropes, pullies and counterweight. A hydraulic lift will require installation of a piston to provide the necessary push and pull, typically located at the bottom of a shaft.

Off-site manufactured lift shaft components are also becoming more popular: precast concrete lift shafts (usually up to six storeys) can be quick to install and the offsite construction minimises on-site disruption. Typically, they have minimum dimensions of 1500mm x 1500mm, and maximum dimensions of 2000mm x 3000mm; standard wall thicknesses can range between 125mm to 140mm. Such shafts are not only pre-assembled, but can be fitted out with all required equipment. On site, they are craned into position, one on top of the other.

Shaft walls may also be constructed from brickwork, blockwork or incombustible fibre-board panels on a steel framework to give the necessary fire resistance.

[edit] Fire considerations

In the event of a fire, the potential chimney performance of a shaft that is totally enclosed may require a smoke outlet, usually an opening of a specific size with metal louvres to the open air at or near the shaft head.

The lift motor chamber, if present, must be fully enclosed by non-combustible materials and separated from the lift shaft, although there may be openings for wires and cables that are needed for the lift’s operation.

[edit] Ventilation

Ventilation of the shaft may be required to dissipate heat from lift equipment and components. EN81-20 and EN80-50 are the relevant European standards for lifts and cover requirements for lift shaft ventilation. Local codes and regulations should also be consulted.

In the UK, general guidelines on the provision of lifts within buildings are outlined in Approved Document M: Access to and Use of Buildings. Section 3 within covers horizontal and vertical circulation in buildings other than dwellings.

Additional provisions in relation to evacuation and firefighting are set out in Approved Document B: Fire safety.