Fire Detection in Risers and Service Cupboards
The smallest spaces in a building can carry an outsized fire risk. A service riser packed with cables and pipework, running unbroken through every floor, is exactly the kind of concealed, vertical space where a fire can start unseen and climb between levels. Service cupboards are similar in miniature. Deciding whether such spaces need detection — and, where they do, keeping it testable — is a quiet but real part of good coverage. This guide covers how detection in risers and service cupboards is approached and what to check.
The central point is that risers and cupboards can be a genuine, vertically-connected fire risk despite their size, so whether they need detection is a considered decision.
Who this is for
This is for competent fire alarm engineers assessing detection in service risers and cupboards. The experience level assumed is competent engineer. Use it for the principles; what is required comes from the fire risk assessment and BS 5839-1 applied to the specific space, coordinated with the compartmentation, which is a building-design matter. The engineer covers detection; the containment of the riser is designed elsewhere.
Why small spaces can matter
Service risers and cupboards often contain electrical, data and other services in a concealed space that can allow fire and smoke to spread — so they can be a real fire risk despite being small. It is a mistake to dismiss them as insignificant simply because they are not occupied or are easy to overlook. Whether they need detection depends on their contents, fire load and role in the building. What is required comes from the fire risk assessment and BS 5839-1 applied to the specific riser or cupboard, coordinated with the compartmentation. The starting recognition is that fire load and concealment, not floor area, determine how much a space matters.
Whether detection is needed
As with any concealed space, the answer is not automatic in either direction. Whether a riser or cupboard needs detection depends on its fire load, contents and role — a riser full of services with vertical spread potential is very different from a small, empty cupboard. Some warrant detection; others may be legitimately omitted within the category, as a justified decision rather than an oversight. The decision comes from the fire risk assessment and BS 5839-1 applied to the specific space, not a blanket rule. Engaging with what is actually in the space, and how it connects to the rest of the building, is what makes the decision sound.
Vertical spread and compartmentation
Risers deserve particular thought because of their geometry. A riser is often a continuous vertical shaft passing through floors, so a fire there can spread between levels if not contained — which is why compartmentation of risers matters and why detection may be considered. The containment itself is a building-design and compartmentation matter beyond the fire alarm; the fire alarm's part is any detection provided within the space. How the two work together comes from the fire strategy, with detection following BS 5839-1 and the fire risk assessment. For the engineer, the practical point is to provide and maintain sound detection where it is required, and to flag compartmentation concerns rather than judge them.
Servicing riser detection
On service, risers and cupboards are easy to skip and easy to get wrong, so they reward attention. Confirm any detection in risers and cupboards is present, accessible for testing and functional, that spaces needing detection have it, and that changes — new services, increased fire load — have been considered. From field experience, detection that is inaccessible or quietly forgotten, and risers steadily filled with services but never reviewed, are the recurring findings. Record what you find, and flag any riser or cupboard whose detection, or lack of it, no longer suits its contents, referring compartmentation concerns to the appropriate specialists.
Common points to check
Recurring issues include inaccessible or forgotten riser detection, risers filled with services but never reviewed, and cupboards whose fire load has grown. Confirming detection suits the contents and remains testable is the essential check.
When not to rely on this alone
When not to use this article: do not use it to decide detection or assess compartmentation for a specific riser. Detection comes from the fire risk assessment and BS 5839-1; compartmentation is a building-design matter for specialists, applied by competent professionals.
Relevant standards
Detection sits within BS 5839-1, a code of practice, and the fire risk assessment; riser compartmentation follows the building design and statutory guidance in Approved Document B for building work. The legal duty for fire precautions in most non-domestic premises sits under the Regulatory Reform (Fire Safety) Order 2005. 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 building design, or competent judgement. Verify riser and cupboard detection against current documentation, and refer compartmentation to specialists.
Related documentation
Use this with the current BS 5839-1 and the fire risk assessment. Record detection in risers and cupboards and its access for testing, and review whenever their contents or fire load change.