A formal requirement for a second staircase in high‑rise residential buildings is reshaping live schemes and early‑stage designs across England, with ripples felt throughout the UK market. The change, framed as a safety measure to improve evacuation and resilience, is already influencing planning decisions and lender expectations, according to project teams. Developers are reassessing layouts, consultants are redrawing cores, and contractors are warning of programme and cost pressure as designs are re‑opened. The shift lands at a sensitive moment for viability, with build costs elevated and sales values uneven outside core city centres. Local authorities are signalling that single‑stair towers will be a hard sell at planning committees, even where earlier guidance allowed them. Insurers and funders are also said to be probing schemes’ egress strategies more closely, raising the bar for financial close. While transitional arrangements are being discussed, the direction of travel is towards a two‑stair default for new high‑rise homes.
TL;DR
/>
– Two staircases are becoming the baseline for new high‑rise residential proposals, influencing planning, funding and design choices.
– Floorplate efficiency, saleable area and core engineering are the pinch points most teams will need to resolve.
– Expect re‑designs, re‑programming and potential viability reviews on taller schemes, especially on tight urban sites.
– Transitional treatment varies, so teams are documenting decision points and engaging early with planning and building control.
– Supply chain capacity for lifts, stairs and fire engineering input may be tested as schemes pivot at pace.
How a two‑stair default reshapes design, viability and planning
/> For design teams, the immediate impact is on the core. A second staircase changes the structural grid, affects lift strategy and service risers, and can squeeze apartments on constrained footprints. Architects are exploring options such as re‑centring the core, pairing stairs with shared lobbies, or marginally increasing the footprint to recover area. Fire engineers are re‑running smoke control models, lobby pressurisation assumptions and evacuation timings, which can cascade into mechanical and electrical revisions. The planning case also shifts: massing and elevations may need amending, and sunlight‑daylight or wind studies may need updates where the building envelope moves to accommodate a larger core.
The viability conversation follows quickly. A larger core typically means less net saleable or lettable area unless the building grows in plan or height, both of which may trigger fresh planning risk. Contractors are flagging knock‑on costs in structure, vertical circulation, and services, alongside the prelims needed to re‑sequence procurement. Funders are asking for certainty on compliance, which can delay term sheets until revised designs are locked. Where schemes already had tight affordable housing positions, small area losses can tip the balance, prompting renegotiation with councils or value‑engineering rounds that are harder to close in the current market.
On the ground, consider a city‑centre plot with permission-minded drawings developed around a single‑stair core. The project team pauses tender action and commissions a rapid options study to insert a second stair without losing too many dual‑aspect units. The revised core pushes a corner column line, requiring fresh structural checks and a modest shift in the façade grid. Elevations are adjusted and new drawings are prepared for planning amendments, with daylight analysis refreshed to address the changed mass. Procurement timelines slip while the lift supplier prices a different arrangement, and the cost plan is re‑based to reflect the altered NIA and programme. The client re‑engages the council early to keep momentum, accepting a short delay now to avoid a bigger compliance risk later.
Delivery pressure, transitional tests and what to watch
/> Contractors are preparing for more late‑stage design change than usual, with knock‑on effects for prelims, scaffolding durations and trade package sequencing. Fire engineering, stair and lift suppliers, and smoke control specialists are likely to see concentrated demand as multiple schemes pivot to two‑stair solutions at once. Building control bodies will be central in interpreting transitional arrangements and ensuring consistent application across local authorities. In parallel, refurbishments and change‑of‑use projects may face their own scrutiny, even if the formal requirement is aimed at new‑build high‑rise.
# What to watch next
/>
– How planning authorities handle amendment applications for schemes that were designed with a single staircase.
– Whether lenders and insurers formalise two‑stair expectations in their underwriting criteria for high‑rise residential.
– The extent to which transitional provisions protect projects already on site versus those still pre‑start.
– Market responses in design: core optimisation, modular stair solutions, or marginal increases in footprint to recover area.
# Caveats
/> There is still uncertainty around cut‑offs, grace periods and how consistently different authorities will treat live applications. The two‑stair approach improves redundancy, but it is not a substitute for holistic fire strategy, materials choices and management in occupation. Costs and programme impacts will vary widely by site, height, tenure and design, so broad assumptions are risky. Teams should treat all interpretations cautiously until formal guidance and local practice settle.
The new baseline is clear: high‑rise homes will need more robust means of escape, and schemes that adapt early are less likely to stall. The open question is how the sector balances safety gains with deliverability on tight, high‑density plots without pushing marginal projects out of the pipeline.
FAQ
/>
What types of schemes are affected?
The shift applies to high‑rise residential buildings, where additional means of escape are being mandated as standard. Mixed‑use towers with significant residential elements are likely to be assessed against the same expectations for the residential floors.
# Does this apply to projects already in planning or on site?
/> Transitional arrangements are being discussed and may differ by stage, jurisdiction and local interpretation. Many planning authorities are already signalling a preference for two stairs, so even pre‑mandate designs can face pressure to change.
# How will the requirement alter building layouts?
/> A second staircase typically enlarges the core and reshapes the structural and MEP strategy, with potential effects on apartment mix and net area. Designers may adjust footprints, re‑configure lift groups, or refine lobby strategies to manage the space and cost consequences.
# Are refurbishments and conversions captured?
/> The mandate is framed around new high‑rise residential buildings, but change‑of‑use or major refurbishments may still attract closer scrutiny of egress and fire strategy. Building control will look at the specifics of each case, so early engagement is prudent where heights and risks are comparable to new‑build towers.
# What should project teams do first?
/> Most teams are revisiting design assumptions, speaking with building control, and stress‑testing viability against a two‑stair core. Early conversations with lenders, insurers and planning officers can reduce later friction, even if detailed guidance continues to evolve.
