Evacuation lifts and what they do to a core layout

An evacuation lift is not a larger passenger lift with a sticker on it. It needs a protected shaft, a protected lobby at every storey it serves, a secondary power supply, protection from water, a communication system and a management regime that someone has agreed to operate. Add all of that to a residential core and the floor area you lose per storey is measured in square metres, which on a small footprint means one fewer flat per floor. Architects working on buildings above 18 metres should test the core with an evacuation lift in it before the planning drawings are issued.

In London the requirement has been in policy for several years. Nationally, the position has moved, and it is worth stating clearly what is settled and what is not.

Why evacuation lifts are being asked for

Three drivers are pushing them into schemes.

London Plan Policy D5 requires development proposals for buildings above 18 metres to provide at least one lift per core suitable for evacuation, which has made the provision routine on London residential towers. Boroughs apply it through their own design and fire safety policies.

BS 9991, in its current edition, recommends evacuation lift provision in residential buildings above a stated height, and building control bodies and fire engineers increasingly treat that recommendation as the design baseline rather than an option.

And government policy has moved following the Grenfell Tower Inquiry. Ministers have accepted the case for evacuation lifts in new residential buildings above 18 metres and have consulted on how to require them through the Building Regulations. As at the date of this article, check the current version of Approved Document B and any commencement date before assuming the national requirement is in force. Do not design on the assumption that it is optional either.

Shaft, lobby and power supply requirements

The engineering requirements drive the plan, so take them from the fire engineer rather than from a lift supplier's brochure.

• The lift sits in a protected shaft, with the fire resistance of the shaft continuous through every floor it passes.
• A protected lobby is needed at each storey served, separating the lift from the accommodation and giving a place for someone to wait.
• The lobby has to be large enough for a wheelchair to turn and wait clear of the door swing, alongside anyone using the stair.
• A secondary power supply, independent of the primary supply and separately routed, is needed so the lift operates when the main supply fails.
• Protection against water ingress matters, because water from firefighting or a burst riser disables a lift car and pit.
• A two way communication system between the lobbies, the car and a management position is required, and it needs a power supply of its own.
• Lift machinery, controls and cabling all need fire protection consistent with the shaft.

Firefighting lifts and evacuation lifts are different things with overlapping requirements, and on taller buildings you may need both. The interaction with firefighting shafts and core planning is the first thing to resolve, because the firefighting shaft usually sets the core geometry and the evacuation lift has to fit around it.

Effect on net to gross efficiency

The lost area is not the lift shaft. It is the lobby.

A protected lobby at every storey, sized for wheelchair waiting and for stair discharge, adds circulation that generates no rent and no sale value. On a core serving six flats per floor, that loss is absorbed reasonably comfortably. On a core serving three or four flats, it can remove one of them or push the remaining units below the nationally described space standard.

The secondary consequences are worth listing because they surprise people at the second design review. Riser space increases, since an independent supply and the communication system need routes. Plant space at roof or basement level grows. The core footprint often pushes the building envelope outwards, which affects daylight to neighbours and the massing agreed in pre-application discussions. And a deeper core reduces the number of dual aspect flats, which is a policy issue in its own right in London.

Test three core options early: single core with evacuation lift, single core with two lifts where one is the evacuation lift, and twin core. The efficiency answer varies with footprint and storey count in ways that are not obvious in advance.

Interaction with accessible dwelling standards

Evacuation provision and accessible housing provision are separate requirements that point at the same residents.

Where a proportion of dwellings is built to the wheelchair user standard under the Building Regulations optional requirement, and London schemes carry a policy requirement for such dwellings, the building will be occupied by people who cannot use a stair in an evacuation. That is the point of the lift, and it also means the lobby and the route from the flat entrance to the lift need to work for a wheelchair without a manoeuvre against a door closer.

Check the approach route as carefully as the lift. A compliant lobby reached through a 900mm door with a strong closer, around a 90 degree turn, is not usable by the resident it was designed for.

Management arrangements the lift assumes

An evacuation lift only functions inside a management regime, and the planning application should acknowledge that rather than leave it to the building's future operator.

The regime involves someone with authority to operate the lift or supervise its use, information gathered from residents who would need assistance, an evacuation strategy that matches the building's design, and signage that tells residents what the lift is for. A building designed for stay put evacuation with an evacuation lift for assisted escape needs different procedures from one designed for phased or simultaneous evacuation.

Say in the application who will hold that responsibility, usually the managing agent or the registered provider. A design that assumes a concierge on a scheme with no concierge in the service charge model is a design that will not work.

Securing provision through the application

For a relevant building, an Article 9A fire statement accompanies the application and goes to the Building Safety Regulator as a Gateway One consultee.

Put the evacuation strategy, the lift provision and the lobby arrangement in that statement, and make sure the submitted floor plans show the same thing. Inconsistency between the Fire Statement and the plans is the single most common reason for a Gateway One query, and it costs weeks. On who may author it, see who is competent to author a fire statement.

Where the detailed strategy is still developing, a condition requiring approval of the evacuation lift details and the management plan before occupation is preferable to silence. A fuller Fire Safety Strategy to BS 9991 or BS 9999 follows at Gateway Two, and the planning stage material should be consistent with where that strategy is heading.

Checking the design early with the fire engineer

1. Establish the height of the topmost storey above ground level and record how it was measured.
2. Confirm with the fire engineer whether an evacuation lift, a firefighting lift, or both are needed.
3. Draw the lobby at full size with a wheelchair turning circle, the stair door and the lift door, before fixing the core.
4. Agree the secondary supply route and the plant space with the electrical engineer.
5. Test the core against the flats per floor the appraisal assumes.
6. Record the management assumption and check it against the intended tenure and service charge.

An illustrative example: a 20 storey block with four flats per floor on a constrained urban plot. The first core layout achieves the required lift and stair but leaves a lobby too small for a wheelchair to wait clear of the stair door. Moving to a marginally wider core removes one flat on each of the top four storeys and adds a dual aspect corner unit on the rest, so the net loss is smaller than the appraisal feared. The fire statement and the plans are reissued together, and Gateway One raises no query on evacuation.

PlanScope drafts a Fire Statement and the other supporting documents from your project details, structured to UK planning policy and flagging where facts are missing. A fire statement for a relevant building must be prepared by someone with the necessary fire engineering competence under the Building Safety Act 2022 framework and Article 9A of the Development Management Procedure Order 2015, so treat the draft as a starting point for that professional.

This is general guidance, not legal advice; check the current Approved Document B, the applicable British Standard and your local plan policies before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.