Master BS 9999:2017 — the flexible alternative to Approved Document B that enables risk-based fire safety design with greater design freedom.. What is BS 9999? BS 9999:2017 'Fire safety in the design, management and use of buildings — Code of practice' provides a comprehensive framework for fire safety design that offers greater flexibility than the prescriptive guidance in Approved Document B. It is widely used by fire engineers as the basis for performance based fire safety design. BS 9999 vs Approved Document B Key Differences Aspect ADB BS 9999 Approach Prescriptive Risk based Travel distances Fixed values Variable based on risk profile Compartment sizes Fixed limits Adjustable with compensating features Suppression credit Limited Explicit trade offs for sprinklers Management quality Assumed Categorised and credited Flexibility Rigid Significant design freedom Risk Profile System BS 9999 categorises buildings using a risk profile matrix: Occupancy Characteristics (A, B, C) A — Occupants awake and familiar with the building B — Occupants awake but unfamiliar with the building C — Occupants likely to be asleep Fire Growth Rate (1, 2, 3, 4) 1 — Slow fire growth 2 — Medium fire growth 3 — Fast fire growth 4 — Ultra fast fire growth The combination (e.g., A2, B3, C1) determines the appropriate fire safety provisions. Travel Distances BS 9999 provides travel distance tables based on risk profile: Example: Office (Profile A2) One direction only: 18m (no sprinklers) / 27m (with sprinklers) More than one direction: 45m (no sprinklers) / 60m (with sprinklers) Example: Hotel bedroom (Profile C3) One direction only: 9m (no sprinklers) / 18m (with sprinklers) More than one direction: 18m (no sprinklers) / 35m (with sprinklers) The sprinkler credits are significant, often enabling design solutions that would be impossible under ADB alone. Compartmentation Flexibility BS 9999 allows larger compartments where compensating features are provided: Sprinkler protection can increase maximum compartment sizes Enhanced detection can credit reduced response times Smoke control systems can extend travel distances Management quality categorisation affects acceptable risk levels Management Quality Levels A unique feature of BS 9999 is the explicit recognition of management quality: Level 1 — Basic fire safety management Level 2 — Standard fire safety management with trained fire wardens Level 3 — Enhanced management with dedicated fire safety personnel Level 4 — Exceptional management with 24/7 fire safety monitoring Higher management quality levels can unlock additional design flexibility. Practical Application BS 9999 is particularly valuable for: 1. Complex mixed use buildings where ADB categories overlap 2. Large open plan offices requiring extended travel distances 3. Retail and leisure with variable occupancy and fire growth characteristics 4. Building refurbishment where existing constraints prevent ADB compliance 5. Innovative architectural designs that don't fit ADB prescriptive models Integration with BS 7974 BS 9999 provides the 'halfway house' between full prescriptive compliance (ADB) and full performance based fire engineering (BS 7974). For projects requiring further flexibility beyond BS 9999's provisions, BS 7974's fire engineering framework can be used to demonstrate that functional requirements are met through detailed analysis. Our BS 9999 Design Services Magnus Opifex SEVEN LTD routinely uses BS 9999 as the basis for fire safety design, enabling our clients to achieve their architectural vision while maintaining the highest fire safety standards. Our fire engineers are experienced in navigating the risk profile system and presenting BS 9999 based solutions to building control bodies and fire authorities. Magnus Opifex SEVEN LTD — UK's Leading Fire Safety & Fire Engineering Consultancy 🌐 magnus opifex.co.uk 📞 +44 7486 691724 ✉️ office@magnus opifex.co.uk Founders: Nicoleta Vasile, Baroness of Brattleby — CEO, Lawyer and Barrister, Legal & Administrative Director Alina — 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. © 2026 Magnus Opifex SEVEN LTD. All rights reserved.