Two years after the second staircase requirement was confirmed, we examine the design solutions developers are using and the impact on residential delivery.. The Design Challenge The second staircase requirement for residential buildings 18m was a significant design constraint. 24 months into implementation, developers and architects have refined their approaches. Common Design Solutions 1. Scissor Stairs (40% of projects) Two separate flights interleaved within a single core. Most efficient floor plate impact ( 3 4%). 2. Enlarged Single Core (30%) Wider core accommodating two staircases plus lifts and services. Floor plate impact 5 7%. 3. Separated Cores (20%) Two entirely separate cores at opposite ends of the floor plate. Floor plate impact 7 10% but provides best evacuation diversity. 4. Performance Based Engineered Solutions (10%) Single staircase retained with engineered fire protection (sprinkler enhancement, smoke control, evacuation alert systems). Cost and Programme Impact CBRE Research analysis of 200+ residential projects since 2024: Average construction cost impact: +2.8% Average GIA loss: 4.6% Programme impact: Negligible if designed in from RIBA Stage 2; significant if retrofitted Sales value impact: Neutral β buyers value the safety improvement Lessons Learned 1. Engage fire engineer at RIBA Stage 1 2. Test multiple core layouts at concept stage 3. Consider structural impact of larger cores 4. Don't underestimate MEP impact (lift overruns, service zones) Need Expert Fire Safety Advice? Magnus Opifex Seven LTD provides leading fire engineering, BSR Gateway 2 support, PAS 9980 appraisals, BESS fire safety, and healthcare fire strategy services across the UK. π Call: +44 7486 691724 βοΈ office@magnus opifex.co.uk Request a Free Consultation β