Means of escape design is the foundation of life safety. From travel distances to exit widths, staircase capacity to dead-end corridors — this guide covers the critical design parameters.. The Fundamental Principle Means of escape design is governed by a simple principle: every person in a building must be able to reach a place of safety within a reasonable time, regardless of where fire occurs. The challenge lies in translating this principle into specific design parameters that account for the infinite variety of building types, uses, and occupant profiles. Travel Distance — The Primary Metric Travel distance is the most fundamental means of escape parameter. It represents the maximum distance any person should need to travel from their position in the building to the nearest exit or protected escape route. Key Travel Distances (Approved Document B) Use One Direction Only Alternative Directions Residential (flat to front door) 9m 9m Office 18m 45m Shop/commercial 18m 45m Assembly (bars, clubs) 15m 32m Industrial (normal hazard) 25m 45m Storage (normal hazard) 25m 45m Hotel bedroom to staircase 9m 18m These distances can be modified through fire engineering analysis — but only with proper justification and compensating features such as sprinklers or enhanced detection. Exit Width Calculations Exit widths must accommodate the number of people who need to use them. The calculation methodology depends on the evacuation strategy: Simultaneous Evacuation Door widths: Minimum 850mm per leaf; 2.5mm per person for calculations Staircase widths: Minimum 1000mm (1100mm for over 220 people) Calculation basis: Total occupancy divided by available exits (discounting the largest) Phased Evacuation Staircase capacity based on simultaneous evacuation of the fire floor plus the floor above Remaining floors evacuate in sequence Wider staircases typically required Stay Put (Residential) Single staircase acceptable in many residential buildings (subject to height limits) Staircase width: minimum 1000mm New buildings over 18m: minimum two staircases (from 2026) Dead End Conditions Dead end corridors — where escape is only possible in one direction — represent the highest risk escape condition: Maximum dead end distances are significantly shorter than alternative direction distances Dead end corridors should be avoided wherever possible in new designs Where unavoidable, dead end corridors must be protected (fire resistant construction) Enhanced detection and alarm coverage in dead end areas The dead end condition must be clearly identified in the fire risk assessment Common Design Pitfalls 1. Inner Room Conditions An inner room (one accessed only through another room) creates a dependency on the outer room for escape. Requirements: Vision panels or borrowed lights to allow early fire detection Limited travel distances Automatic detection in the outer room 2. Staircase Discharge Final exit from staircases must discharge directly to outside or via a protected route: Staircases must not discharge through ground floor accommodation The route from staircase foot to final exit must be protected Exit doors must open in the direction of escape 3. Security vs Escape Security measures must not compromise means of escape: Electrically locked doors must release on fire alarm activation Break glass units or similar override must be provided Revolving doors must be flanked by conventional escape doors Electronic access control must fail safe (unlock) on power failure Fire Engineering Alternatives Where prescriptive compliance is not possible or appropriate, fire engineering can justify alternative approaches: Extended travel distances — with sprinklers, enhanced detection, and smoke control Reduced exit widths — with phased evacuation and management procedures Open staircases — in specific circumstances with compensating features Single escape routes — with enhanced protection and management All fire engineering solutions must be documented in a fire safety strategy and accepted by the approving authority. For means of escape design and fire engineering consultancy, contact Magnus Opifex.