What Are Means of Escape Requirements?

Means of escape is the provision made within a building to enable occupants to travel safely from any point within the building to a place of safety outside, in the event of a fire. It is the most fundamental fire safety requirement in building design and the primary focus of most fire strategy reports.

The Core Principles

• Travel distance: The maximum distance an occupant must travel to reach an exit or place of comparative safety. Approved Document B and BS 9999 specify maximum travel distances for different occupancy types and evacuation strategies
• Alternative escape routes: For most buildings, occupants must have at least two independent escape routes available so that if one is blocked by fire or smoke, another is available
• Protected routes: Escape routes — particularly stairwells and corridors — must be protected from fire and smoke so that occupants can travel to safety even when a fire is burning
• Width of escape routes: Doors, corridors and stairwells must be wide enough to allow the expected number of occupants to pass without dangerous congestion
• Emergency lighting and signage: Escape routes must be illuminated and signed so that occupants can find their way to safety even in smoke or darkness

Travel Distance Limits

Approved Document B specifies maximum travel distances for different occupancy types. For offices using simultaneous evacuation, the maximum travel distance to a final exit or protected stairwell is typically 45 metres in any direction, or 18 metres where there is only one escape route. For residential buildings under BS 9991, distances are different and depend on the evacuation strategy.

When Can Travel Distances Be Extended?

Travel distances can be extended beyond the ADB limits where compensating measures are provided — typically automatic sprinkler systems, additional detection, or enhanced means of escape. This requires a performance-based fire engineering justification in the fire strategy. Fire Safety Services regularly produces fire engineering reports justifying extended travel distances for complex commercial and mixed-use schemes.

Common Means of Escape Problems

• Travel distances that exceed Approved Document B limits without compensating measures
• Dead-end corridors where occupants have only one escape direction
• Unprotected stairwells that become smoke-logged in fire conditions
• Inadequate widths for corridor doors or exit doors
• External escape routes that are inadequately protected from fire from the building