A new requirement mandating second staircases in new residential buildings over 18 metres is now in force in England, moving from ministerial intent to enforceable standard. The change captures high‑rise schemes moving through planning and into building control and is aimed at strengthening evacuation resilience and access for firefighting. Developers, design teams and contractors are recalculating core arrangements, escape strategies and net‑to‑gross ratios as drawings are updated. Market talk suggests transitional routes exist for schemes already well advanced, but treatment will depend on each project’s approvals status and the stance of the relevant authority. Lenders and insurers are also expected to query compliance positions on live deals given the heightened focus on life‑safety measures. Supply chains for stair structures, fire doors, smoke control and associated MEP are bracing for specification shifts and potential pinch points.
TL;DR
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– New residential buildings over 18m in England are now expected to include a second staircase, affecting live and upcoming designs.
– Expect redesign of cores, potential loss or reconfiguration of units, and programme rework to pass building control.
– Transitional handling will be case by case; teams should document decisions and engage early with regulators and planners.
– Costs, tender risk and procurement will move as supply chains adjust to higher demand for compliant stair, lobby and fire‑safety components.
Implications for design, cost and programme
/> The step‑change for buildings above 18 metres will push many schemes to revisit their cores. Two stairs alter the geometry of escape routes, firefighting access, lift and riser positioning, and lobby arrangements, with knock‑ons for structural grids and service distribution. In tight urban plots, an additional stair can pull out the core, reduce sellable or lettable area, or require unit typology changes to maintain daylight and ventilation. Designers will be reassessing corridor widths, smoke control strategies and refuge spaces to ensure the overall package meets guidance as interpreted by building control.
Commercially, the rule lands mid‑cycle for many projects, shifting tender risk and allowances. Contractors may seek longer pre‑construction periods to lock down re‑designs, while subcontractors reprice for extra steel, precast or in‑situ concrete, additional doorsets, balustrades and finishes. Programme impacts hinge on how quickly planning amendments can be agreed where massing or elevations change, and whether sequencing must flex to accommodate revised cores. Employers’ Requirements and design responsibility matrices will need tightening to clarify who carries the redesign and approval burden through to sign‑off.
# UK site scenario: how it plays out
/> A residential tower at RIBA Stage 3 pivots to a two‑stair core after initial planning consent. The design team models alternative core rotations to recover floorplate efficiency while retaining façade rhythm approved by the local authority. A non‑material amendment is sought to address minor changes to elevations and access, with the planning officer requesting updated fire statements. The main contractor revises logistics so the second stair core can climb in parallel with the first, adjusting temporary works and crane time allocation. Building control asks for fresh escape calculations and coordination drawings before accepting the compliance position at technical gateways. The client’s funder requests written confirmation of the regulatory route to mitigate perceived delivery risk.
Transition, compliance and what to watch
/> Now that the requirement has taken effect, the immediate task is to establish each project’s regulatory footing and agree the validation path with the approving body. For schemes early in design, the direction is clear: plan for two stairs and align layouts with the latest fire‑safety guidance. For those part‑way through planning or procurement, the treatment is more nuanced and will likely depend on whether key approvals have been secured and how material any design changes might be. Teams should keep meticulous audit trails of decisions, peer reviews and correspondence with authorities to demonstrate a reasoned approach.
# What to watch next
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– How building control bodies interpret transitional positions on projects already in the approvals pipeline.
– Whether planning authorities accept minor‑amendment routes for core changes that have limited façade impacts.
– Supply chain lead times for stair structures, fire doors and smoke control systems as demand rises.
– Any further clarifications to guidance documents and how they dovetail with the Building Safety regime.
# Caveats
/> This is a fast‑moving regulatory area and practical application can vary by project stage and authority. Some schemes may be able to proceed under transitional arrangements, while others will be expected to redesign immediately. Detailed compliance remains a matter for the responsible dutyholders and their advisers, and project‑specific decisions should be documented against the latest published guidance.
The industry appears to be moving towards a more conservative baseline for egress and firefighting access in tall residential buildings. The open question is how quickly teams can redesign without undermining viability, and whether the supply chain can keep pace with the new baseline.
FAQ
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Does the second staircase requirement apply across the whole UK?
Approaches differ by nation and building type, and the latest change relates to England. Scotland, Wales and Northern Ireland set their own standards, so project teams working outside England should check local regulations and guidance. Cross‑border portfolios may need divergent design solutions to remain compliant.
# What counts as 18 metres for the purpose of the rule?
/> Height is typically measured as the vertical distance from ground level to the top occupied storey, but definitions in guidance can be specific. Teams should confirm the measurement basis with their fire engineer and building control to avoid marginal compliance risks. Where a scheme sits close to the threshold, conservative assumptions are likely to be favoured.
# Do existing planning permissions avoid the need to add a second staircase?
/> Not necessarily. The treatment of consented schemes depends on how far they are through approvals and the nature of any design changes required. Authorities may accept amendments in some cases, but others may need fuller revisions to demonstrate compliance under the current standard.
# Does this affect non‑residential buildings over 18 metres?
/> The present change is focused on residential high‑rise projects, reflecting evacuation and occupation characteristics. Mixed‑use schemes with residential elements above the threshold will need careful zoning and core planning to meet the intent. Purely commercial buildings should be checked against the relevant sections of fire‑safety guidance applicable to their use class.
# Can enhanced fire‑safety systems substitute for a second staircase?
/> The policy direction favours a physical second means of escape for tall residential buildings rather than compensatory measures. While additional systems like sprinklers, smoke control and firefighting lifts remain critical, they are not generally framed as substitutes for a second stair under the new baseline. Project‑specific strategies should be agreed with the fire engineer and the approving authority early in design.
