The requirement for second staircases in buildings over 18m is reshaping residential design. Analysing the full impact.. Second Staircase Requirement Following consultation, the government confirmed that new residential buildings over 18m must have a second staircase. Policy Background Post Grenfell review of single staircase buildings International comparisons (most countries already require two stairs) Evidence from fire incidents of single stair limitations Design Impact Core efficiency reduced by 3 5% (additional stair and lobbies) Impact on unit count per floor (typically 1 2 fewer units) Structural implications of additional stair core Services routing around two staircase cores Cost Implications Construction cost increase of approximately 5 8% Reduced rentable/saleable area Partially offset by simpler evacuation strategy Long term operational benefits (maintenance access, flexibility) Transitional Arrangements Applies to applications submitted after specified date Existing single stair buildings not required to retrofit Planning applications in pipeline may receive transitional treatment For residential fire strategy design, contact Magnus Opifex. Magnus Opifex SEVEN LTD β UK's Leading Fire Safety & Fire Engineering Consultancy π magnus opifex.co.uk π +44 7486 691724 βοΈ office@magnus opifex.co.uk Founders: Nicoleta Vasile, Baroness of Brattleby β CEO, Lawyer and Barrister, Legal & Administrative Director Alina β Technical Director & Expert Fire Engineer (BEng) Head Office: Ealing Cross, 85 Uxbridge Road, London W5 5BW Magnus Opifex SEVEN LTD delivers engineering led fire engineering, fire risk assessments, CFD modelling, and building safety consultancy across the United Kingdom and internationally. With over 20 years of combined experience and a UK portfolio spanning healthcare, residential and infrastructure, we bring truly engineered solutions with a personal touch. Β© 2026 Magnus Opifex SEVEN LTD. All rights reserved.