The width of a mezzanine staircase in the United Kingdom is usually planned within a range of 800mm to 1,200mm and then checked against building regulations standards. For general access stairs in buildings other than dwellings, Approved Document K sets a minimum width of 1,200mm between enclosing walls or strings, with at least 1000mm clear between handrails and flights wider than 2m divided into sections no more than 2m wide [1]. It also defines requirements for rise, going, headroom, landings, guarding, and handrails to maintain safe movement between levels.
A correctly specified staircase supports safe daily operation, reduces accident risk, and maintains an effective evacuation route. If that was not enough, the Health and Safety Executive (HSE) provides further guidance on preventing slips and trips on stairways [2].
This article summarises the typical width range, how UK regulations apply, and the key considerations that guide safe mezzanine staircase design.
How Wide Should a Mezzanine Staircase Be in the UK?
Mezzanine staircase width varies according to use, access frequency, and whether the staircase forms part of an escape route. There is no single fixed legal width for mezzanine staircases. Instead, mezzanine designers work within typical width ranges that reflect the building’s use, its occupancy, and the relevant parts of the UK building regulations.
Different operational environments require different widths. Office and light commercial settings may support narrower staircases where footfall is controlled. Warehouses, production areas, and high-traffic spaces often require wider designs to:
- Support carrying tasks
- Handling equipment
- Maintain safe evacuation
Good design practice also considers how staff will usually carry tools, cartons, or paperwork up and down stairs. It might sound trivial, but this influences the space needed to pass safely and maintain a steady pace.
Where a staircase forms part of a fire escape route, additional width may be required to support safe evacuation. Wider landings, clear headroom, and predictable step geometry help reduce collision risk and maintain visibility. For tasks involving equipment handling or stock transfer, secure guarding and uninterrupted handrail placement support consistent health and safety.
How to Specify Safe, Compliant Mezzanine Staircase Widths
The width of the mezzanine staircase should follow the same principles as those for escape stairs in non-domestic buildings. Approved Document B Volume 2 links minimum stair width to the number of people using the stair and to the overall escape strategy for the building [3].
It also sets clear baseline dimensions for different types of use, for example:
- Minimum 800mm width for escape stairs serving up to 50 people in many non-domestic buildings
- Minimum 1,000mm width for specific institutional uses where additional protection is required
- Minimum 1,100mm width for stairs serving assembly areas, with greater widths needed as occupant numbers increase
- Escape stairs at least as wide as any storey exit that discharges onto them
- Stair widths calculated from the occupant load that do not fall below 1,000mm
In practice, mezzanine staircase width should be based on expected occupancy, the number and location of escape routes, and whether evacuation will be simultaneous or phased. Designers should review the occupancy calculations and escape route widths set out in Sections 2 and 3 of Approved Document B Volume 2, then apply those figures to the mezzanine layout. This way, the staircase width, landings, and exits operate together as a compliant means of escape.
Choosing the Right Mezzanine Staircase Type for Your Space
Different staircase types support different sites and usage patterns, and each option influences how much floor space is used, how quickly people can move, and how easily loads can be handled on the stairs.
Standard mezzanine staircase configurations include:
- Straight staircases provide a direct route with clear sightlines and consistent treads. They are well-suited to regular traffic and equipment handling, and their simple geometry makes it easier for users to judge each step and maintain a stable walking pattern.
- Dog-leg or half-turn staircases include an intermediate landing that allows a change in direction. These designs can reduce overall run length in restricted spaces while maintaining compliant gradients and safe resting points.
- Spiral staircases reduce floor footprint where space is limited. They can be appropriate for infrequent access or controlled areas, but are less suitable for bulky loads due to the reduced tread depth on the inner curve.
- Custom staircases are designed to work around columns, racking, loading areas, and other building constraints. These can integrate with mezzanine components such as pallet gates or guarding systems to support specific workflows.
Avoiding Common Mezzanine Staircase Design Mistakes
Several issues arise when mezzanine staircases are specified without a complete understanding of regulatory and operational requirements. Experienced designers help avoid these problems and ensure that staircase width, geometry, and layout are suitable for the building.
Common mistakes include:
- Constrained widths can reduce carrying capacity, force staff to wait at the top or bottom of the stairs, and increase congestion during busy periods.
- Irregular step dimensions and reduced headroom make stairs harder to use and can fall outside the tolerances set out in the building regulations.
- Limited landing space or missing guarding can lead to unsafe turning movements and increase the risk of falls from height.
A structured design process also allows drawings and calculations to be checked against the relevant parts of the building regulations before installation. This helps ensure that staircase dimensions, guarding details, and landing positions are clear to building control officers and installation teams.
Get Expert Support with Mezzanine Staircase Design
Once the key requirements for width, use, and layout are understood, the next step is to develop a staircase design that can be costed, approved, and installed with confidence. Early attention to specifications reduces the likelihood of on-site changes and helps keep projects on programme and within budget.
First Floors works with businesses that are planning new mezzanine floors or adapting existing layouts. The team can review proposed designs, identify any areas that may fall short of UK building regulations, and recommend practical adjustments to support safe access and efficient operation. Examples of completed mezzanine projects are available on our case studies page.
Call 01789 764172 or schedule a consultation to discuss your mezzanine staircase requirements and review suitable design options.
External Sources
[1] GOV.UK, Building Regulations, “Approved Document K”: https://assets.publishing.service.gov.uk/media/60d5bdcde90e07716f516cfd/Approved_Document_K.pdf
[2] Health and Safety Executive (HSE), “preventing slips and trips on stairways”: https://www.hse.gov.uk/printing/slips/stairs.htm
[3] GOV.UK, Building Regulations, “Sections 2 and 3 of Approved Document B Volume 2”: https://assets.publishing.service.gov.uk/media/67d17064a005e6f9841a1d50/Approved_Document_B_volume_2_Buildings_other_than_Dwellings_2019_edition_incorporating_2020_2022_and_2025_amendments_collated_with_2026_and_2029_amendments.pdf