Protecting Escape Routes and Stairwells with Detection

When a building has to be evacuated, everything depends on the escape routes staying usable. That is why fire detection strategy treats escape routes and stairwells as a priority: catching smoke in these paths early is what gives people the warning and the clear route they need to get out. This guide explains why escape routes come first, how their coverage is decided, and what engineers should check.

The organising principle is that a smoke-logged or unmonitored escape route can defeat an otherwise good evacuation plan.

Who this is for

This is for competent fire alarm engineers designing or maintaining detection on escape routes and stairwells. The experience level assumed is competent engineer. Use it for the principles; the specific category and coverage come from the fire risk assessment, the fire strategy and BS 5839-1.

Why escape routes come first

Escape routes and stairwells are the paths people rely on to leave the building, so keeping them usable is central to life safety. Early detection of smoke in these routes gives warning while escape is still possible and supports the evacuation strategy. This is precisely why even life-safety categories that do not protect every room still protect escape routes: the route out matters most. The extent of coverage follows the fire risk assessment and BS 5839-1, focused on preserving safe egress.

Categories and escape

The life-safety categories in BS 5839-1 are organised around protecting escape. A category such as L5 addresses a defined objective; L2 and L3 protect escape routes and the rooms opening onto them; L1 covers the whole building. The common thread is that escape routes are generally protected even where individual rooms are not, because a compromised escape route undermines the whole plan. Which category applies is a decision from the fire risk assessment, but the priority on escape routes runs through all of them.

Stairwell detection

Stairwells deserve particular thought. They are key vertical escape routes and often key smoke paths between floors, so their detection is considered alongside any smoke control or stair pressurisation, and alongside the risk that a single stairwell detector could cause building-wide false alarms if not handled well. From field experience, stairwell detection that ignores the interaction with smoke control, or that becomes a false-alarm source, causes real trouble. Detection here follows the fire risk assessment, the fire strategy and BS 5839-1, coordinated with the smoke-control design rather than decided in isolation.

Servicing escape-route detection

Because escape routes are life-critical, servicing them carefully matters more than anywhere else. Confirm escape routes and stairwells still carry the detection the category requires, that alterations have not removed or obstructed detectors on these routes, and that any interaction with smoke control behaves per the cause and effect. From field experience, detectors on escape routes removed or blocked during other building works are a serious and recurring finding. Record results and flag any reduction in escape-route protection immediately.

Common points to check

Recurring issues include detectors removed or obstructed on escape routes and stairs, coverage that no longer matches the category after changes, and stairwell detection not coordinated with smoke control. Confirming the escape routes remain fully protected is the essential, highest-priority check.

When not to rely on this alone

When not to use this article: do not use it to set the category or escape-route detection for a specific building. Those come from the fire risk assessment, the fire strategy and BS 5839-1, applied by competent professionals, coordinated with the smoke-control and escape design.

Relevant standards

Escape-route detection and category selection follow BS 5839-1, a code of practice, within the fire strategy and coordinated with smoke control. The legal duty to protect means of escape in most non-domestic premises sits under the Regulatory Reform (Fire Safety) Order 2005, with Building Regulations statutory guidance in Approved Document B applying to building work. Separate the legal duty from the recommended methods, and always work to current editions.

Professional disclaimer

This is an educational and workflow resource for competent engineers and does not replace the current British Standards, the fire risk assessment, the fire strategy, or competent judgement. Verify escape-route and stairwell detection against current documentation.

Related documentation

Use this with the current BS 5839-1, the fire risk assessment and fire strategy, and the smoke-control and escape design. Record escape-route and stairwell detection and any smoke-control interaction, and re-check after any building change.