UK government sets out criteria for second staircases

In March 2024, the UK government published long-awaited technical guidance introducing requirements for second staircases in new tall residential buildings in England.

The guidance, in the form of amendments to both volumes of Fire Safety: Approved Document B, was published after a 12-week consultation with the aim of enhancing building safety standards in the wake of the Grenfell Tower fire.

The threshold of 18m has been introduced to align with that for high-risk buildings under the Building Safety Act 2022, the Fire Safety Act 2021, and other fire safety measures, the government noted in its response to the consultation.

In an initial consultation in 2022, the government had proposed to mandate two staircases in all new residential buildings in England of 30m or taller. However, with the reduction of the threshold, more projects will be affected by the changes – most likely any building of six or more storeys.

The amendments to Fire Safety: Approved Document B also require a second staircase for buildings in which flats are not separated from the common stair by a protected lobby, or where occupants would have to travel more than 7.5m in one direction – that is, where there is a single exit – or 30m in multiple directions – that is, where there is more than one exit – from flat entrance door to the nearest storey exit. The 30m requirement would therefore apply for dwellings with more than one staircase.

However, the updated guidance does not require new buildings to have evacuation lifts, even though respondents to the consultation called for wider provision of these. What the guidance does state, though, is that where such lifts are provided they should be located in an evacuation shaft that also contains a protected stairway and lift lobby.

It also clarifies that a lobby of this kind should provide a refuge area for those waiting for the lift, with direct access to the protected stairway but not to any flat, maisonette, storage room or electrical equipment room.

The rules apply only to new buildings, meaning that there is no need to upgrade existing buildings that have just a single staircase. However, the changes are part of a gradual evolution towards enhancing safety standards.

As such, some developers may choose to comply with the guidance now; and some asset owners may even look to voluntarily upgrade their single staircase structures to bring them in line with the new guidance and provide a higher level of safety, although that would likely be exceptional due to other fire safety concerns.

The government says in the guidance that it wants to mitigate any reduction in housing supply, and acknowledges the impact that the amendments could have in terms of time and cost for existing projects. As a result, it has included a transition period of more than two years.

Projects that receive Building Regulations approval before 30 September 2026 will not require a second staircase. Properties approved under the existing requirements will, however, need to have begun construction 'in earnest' by 30 March 2028; that is, 18 months later.

If construction is not under way after this time, a new application for Building Regulations approval that does meet the new requirements will have to be submitted.

Surveyors may therefore wish to flag the following points to their clients:

• Current projects that wish to remain subject to the existing rules will need to progress promptly, and surveyors and their clients should keep in mind the applicable cut-off dates – particularly where short delays could theoretically have a significant impact.
• The meaning of 'commencement of works' in relation to the cut-off date for the transitional period is less than clear. For example, is it when the works commence on site, is it when the foundations are complete, or is it when the whole substructure and lowest floor level is complete?  Fire Safety: Approved Document B matches the definition set out in The Building (Higher-Risk Buildings Procedures) (England) Regulations 2023, in an attempt to minimise ambiguity but different rules for complex buildings and horizontal structures still means that the position remains fairly opaque unless you have a detailed understanding of the provisions and different definitions.
• Compliance may have a significant impact on the useable floor area of a building, and therefore impact return on investment. For example, the guidance is clear that interlocked or so-called scissor staircases are not a viable solution, as the two staircases must be separate from each other.

It is clear that careful thought needs to be given to current and future tall building projects. Surveyors will need to work with their clients and the design team to determine the best strategy for complying on a project-by-project basis, raising these issues as early as possible.