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Lift shaft design is where most commercial lift projects run into problems. Not during the installation itself, but during the planning and structural assessment stage — when the shaft dimensions do not match the lift specification, the fire rating is insufficient for the building use, or the pit depth cannot be achieved without significant groundwork. Getting these parameters right before a spade goes in the ground is the difference between a project that runs to programme and one that runs over budget.
This guide covers the standards, structural requirements, construction methods, fire safety, accessibility dimensions, and electrical provisions that determine whether a commercial lift shaft is designed correctly. The key specifications are referenced throughout so building owners, developers, and project managers know what to expect from their design team.
Essential Building Codes and Standards
Commercial lift shafts in the UK must comply with EN 81-20 and EN 81-50 (the core European safety standards for lifts, implemented in September 2017), Building Regulations Approved Document M (accessibility), the Lifts Regulations 2016, and where applicable, LOLER 1998. For evacuation lifts, BS EN 81-76:2025 applies. ASME A17.1 is the US equivalent and is not required for UK installations.
Key compliance thresholds from the standards: minimum shaft wall strength of 1000N; minimum illumination of 50 lux within the shaft and 200 lux in machine rooms; fire resistance ratings of 30–120 minutes depending on building use and floor count; minimum car internal dimensions of 1100mm x 1400mm for an 8-person lift.
Structural Design Requirements
Lift shaft construction must accommodate dynamic structural loads — the forces generated not only by the static weight of the lift and counterweight, but by acceleration, braking, buffer impact, and the load from passengers. These loads are significantly higher than most building owners expect. A structural engineer must verify that the proposed shaft walls, floor slab, and any padstones and lifting beams can withstand both the installation loads (lifting equipment into position) and operational loads over the lift’s working life.
Reinforced concrete is the most common shaft wall material for new builds, offering the required strength and fire resistance in a single specification. Steel frame structures are the standard choice for retrofits into existing buildings — lighter, faster to construct, and suited to glass cladding where the shaft is externally visible. Precast concrete modular systems offer the fastest installation for standard shaft sizes, with factory quality control eliminating many of the variables that arise in in-situ construction.
Construction Method Comparison
| Construction Method | Installation Time | Cost Efficiency | Quality Control | Best Use Case |
| In-situ Concrete | 4–6 weeks | Moderate | Variable | Custom dimensions; non-standard shaft shapes |
| Precast Concrete | 1–2 weeks | High | Excellent | Standard sizes; new-build with programme pressure |
| Steel Frame | 1–3 weeks | High | Good | Retrofit into existing buildings; glass cladding |
Load calculations vary by lift type: traction and MRL systems generate higher dynamic loads than hydraulic systems due to the counterweight travel and rope tensions involved. Machine room loads — the weight of the machinery, safety gear, and installation equipment — must also be calculated for the supporting slab or beam.
Fire Safety and Protection Requirements
Shaft wall fire resistance must meet the building’s fire resistance requirement, typically 30 minutes for low-rise commercial buildings and up to 120 minutes for high-rise or high-occupancy buildings. Protected enclosures formed from concrete or laminated glass provide the required barrier. Door apertures must use fire-rated lift landing doors — the door specification is a component of the overall shaft fire rating, not a separate consideration.
Evacuation lifts, required in buildings above 18m and in some lower buildings with specific fire strategies, must comply with BS EN 81-76:2025. Class A and Class B evacuation lifts require backup power (UPS or generator), protected lobbies, and dedicated communication systems. These requirements are specified at the design stage and directly affect the shaft and lobby layout.
Accessibility and Dimensional Planning
Minimum car dimensions for an 8-person lift are 1100mm x 1400mm internally; for wheelchair access with 180° turning (the standard for full Part M compliance), the car should be 2000mm x 1400mm. Clear door opening widths must be 800–900mm minimum. Call button height is 1067mm (42 inches) above finished floor level. A wheelchair turning space of 1500mm diameter must be maintained in the lift lobby.
These dimensions are not simply accessibility requirements — they determine the shaft plan dimensions. A shaft designed to the minimum 8-person compliant car without wheelchair turning clearance is not Part M compliant and will not pass Building Control.
Pit and Overhead Requirements
Standard pit depth for a commercial passenger lift is 1080mm. Overhead clearance — the clear height from the top floor landing level to the underside of the shaft overhead — is typically 3650mm. Both dimensions are determined by the lift specification and must be confirmed with the lift manufacturer before the shaft is designed. Refuge spaces at pit level (minimum 0.4m x 0.5m plan, 2m height) are required for maintenance technician safety.
Electrical Systems and Control Integration
Primary and secondary power supplies must be provided to the lift shaft. For evacuation lifts, a dedicated backup power source — UPS or generator — is a mandatory provision. Maintenance isolators must be accessible and separated from operational controls. Emergency communication devices and destination control systems are installed in accordance with EN 81-20.
Looking for Expert Lift Shaft Design and Installation?
Future Lift Services design and install passenger lifts for commercial buildings across Essex and London, working with architects, structural engineers, and building owners from initial specification through commissioning. Our engineers understand EN 81-20, Part M, and Building Regulations, and can advise on shaft design before your structural team finalises drawings. Contact us for a free consultation.