England has now confirmed that new residential buildings at 18 metres and above will need a second staircase, firming up a major change to high-rise fire safety design. The move signals the Government’s intention to embed the policy in building guidance, with updates anticipated to Approved Document B and related standards. It will affect developers, architects, building control professionals and contractors working on taller blocks, including build-to-rent, affordable housing and student accommodation. Local planning authorities are already weighing how to treat live applications, and funders and insurers are watching for clarity. While transitional arrangements are expected for schemes well advanced, many teams are now treating a two-stair core as the default. The confirmation follows years of debate over single-stair towers and is likely to reset early feasibility, massing and viability assumptions across the 18m-plus pipeline.
TL;DR
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– Two staircases are now expected for residential buildings 18m and above in England.
– Updates to Approved Document B are anticipated; engage early with building control and fire authorities.
– Live schemes may need design amendments or planning variations; transitional routes will be important.
– Expect impacts on cores, net area, cost plans and build sequencing.
Design, cost and programme: what it means for project teams
/> For designers, the key shift is that a compliant means of escape strategy for taller housing will now centre on two independent staircases rather than one. That cascades into decisions about core placement, lobby arrangements, smoke ventilation, and the relationship between stairs, lifts and MEP risers. Space taken up by the additional stair is likely to displace net sellable or lettable area, with knock‑ons for unit mix and façade setting-out. Structural layouts may need rebalancing around dual cores or a widened core, and the geometry of stairs, lobbies and doorsets will come under closer scrutiny to meet egress and fire-fighting objectives. Procurement teams should expect design iterations and coordination time, particularly where pre‑cast stair systems, shaft ventilation, and evacuation lift strategies intersect.
For contractors, the rule solidifies a buildability picture that leans on more complex vertical logistics and additional temporary works around cores. Programme pressures could emerge where re‑design triggers planning variations or new fire strategies, with steelwork or concrete sequencing needing adjustment to suit revised shafts and openings. Cost plans are likely to show pressure from additional structure, fit-out, fire doorsets, extract systems and wayfinding, although some of this may be mitigated by early standardisation and careful flat layout optimisation. Commercially, risk allowances around approvals and potential re‑submission costs may rise in the short term until guidance and transitional pathways settle.
# Site-level scenario
/> A city-centre residential project at mid-design stage reviews its single-core tower in light of the announcement. The client asks the design team to test a second stair within the existing envelope, prompting a re‑stack of flats and a revised plant and riser strategy. Planning advisers recommend engaging the local authority to agree the route to vary the consent, while the cost consultant refreshes the estimate to account for additional structure, doors, smoke control and finishes. The main contractor flags effects on craneage, lift installation sequencing and temporary fire escape provision during construction. The team collectively decides to front‑load coordination, so any re‑submission can be made with a robust fire statement and minimal risk of further iteration.
Delivery timetable, approvals and the road ahead
/> Attention now turns to how the change is implemented through guidance and how it interacts with approvals. Building control bodies and the Building Safety Regulator will look for clear strategies that demonstrate two independent escape routes, appropriate lobbying and smoke control, and coherent evacuation planning. Planners will want assurance that massing and amenity changes remain policy-compliant, while housing clients will be testing viability and lender appetite on revised layouts. Supply chains for staircases, doors, smoke extract and evacuation lifts may see tightening demand as schemes shift to the new norm.
The market impact will be uneven. Taller schemes progressing from early feasibility will likely absorb the rule with fewer shocks, while projects deep into design or procurement may need targeted redesigns and carefully managed approvals timetables. Regional authorities could take slightly different interim positions as they await finalised guidance language, so early dialogue remains important. Over time, the consistency of a two-stair expectation may provide more certainty for underwriters and residents, even if it reshapes some business cases.
# What to watch next
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– The precise wording and diagrams in the next update to Approved Document B and associated guidance notes.
– How transitional arrangements define cut-offs for new applications, re-submissions and projects already on site.
– The stance local planning authorities take on variations, design codes and any height/massing adjustments.
– How building control bodies and the fire service interpret separation, lobbying and smoke control in typical layouts.
# Caveats
/> There is still uncertainty around the detailed technical parameters, such as minimum separation, lobby configurations and how smoke control systems should be arranged alongside two stairs. Any exemptions or special cases, if they exist, will only be clear once guidance is final. Interactions with other measures like sprinklers, evacuation lifts and fire-fighting shafts will continue to be assessed scheme by scheme. This report is for general information and should not be treated as regulatory advice.
For now, the direction of travel is towards a consistently applied two‑stair design standard for taller residential buildings in England. The key question is how quickly project teams and approval pathways can adapt without stalling much‑needed housing delivery.
FAQ
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What does the second staircase confirmation mean in practice?
It means that new residential buildings meeting the height threshold in England are expected to be designed with two independent escape stairs rather than one. The aim is to improve resident egress options and fire-fighting access, and to align practice with a more conservative approach to life safety in taller blocks. Detailed expectations will be set out through building guidance.
# Which buildings are captured by the 18m threshold in England?
/> The policy is aimed at multi‑occupancy residential buildings that reach 18 metres or more, such as blocks of flats. The precise scope, including how student accommodation or mixed‑use schemes are treated, will be clarified through guidance and building control interpretation. Other building types follow different parts of the regulations and may not be affected in the same way.
# How will this affect schemes already submitted or consented?
/> Transitional arrangements are expected to outline how projects already in planning or under construction are handled. In the interim, many teams are reviewing designs to include a second stair to reduce approval risk, and discussing variation routes with planning and building control. The best approach will depend on project stage, local authority views and the evolving guidance.
# Does a second staircase change requirements for sprinklers or smoke control?
/> No. The second staircase sits alongside, not instead of, other fire safety measures such as sprinklers, compartmentation, evacuation lifts and smoke ventilation. Requirements for those systems come from separate parts of guidance and will continue to apply based on height, use and risk assessments. Designers should assume a layered strategy remains necessary.
# Will refurbishments or change-of-use projects be affected?
/> The confirmation primarily targets new-build residential towers, but substantial refurbishments or conversions may trigger regulatory expectations that align with current guidance. How this applies will depend on the extent of works, the resulting height/use, and the judgement of building control and fire authorities. Early engagement is advisable to understand proportional requirements.
