Compartmentation; When It Looks Right but Isn’t
Compartmentation is often presented as one of the most fundamental elements of fire safety. Walls, floors, and doors are designed to resist fire and smoke, limiting spread and protecting escape routes. On drawings, this is usually clear, with lines defined, boundaries marked, and periods of fire resistance specified.
In buildings, it is less straightforward.
Compartmentation depends on continuity. It relies not only on the presence of fire-resisting elements, but on how they connect, how they interface, and how they are maintained through the complexity of a real building. It is rarely a single element that fails; more often, it is a junction, a penetration, or an assumption that proves to be incorrect.
The result is what might be described as compartmentation theatre: a building that appears to be subdivided correctly, but where the reality is more uncertain.
Ceilings may be assumed to provide protection without confirmation, service routes may pass through multiple compartments with inconsistent sealing, and interfaces between different wall types may remain unresolved. Small gaps, voids, or discontinuities are often overlooked because they are not immediately visible or easily categorised. While each of these issues may appear minor in isolation, their combined effect can significantly alter the way in which fire and smoke behave within a building.
The difficulty is that compartmentation is frequently considered in terms of components rather than systems. A wall may be specified to provide a defined period of fire resistance, but if it does not properly connect to the floor above, or if services pass through it without effective sealing, its performance in practice is compromised. Fire safety depends on how systems behave, not how individual elements are specified.
There is also a difference in how compartmentation is approached between design and occupation. Within a fire strategy, it is typically considered in a structured and rigorous way, with boundaries defined, periods of fire resistance assigned, and the intent clearly articulated. Within a fire risk assessment, the approach is necessarily more observational, relying on what can be seen, accessed, and reasonably inferred, often without intrusive inspection. These two perspectives are not equivalent, and the limitations of each are not always fully recognised.
This is not simply a construction issue, but one of design and management.
Compartmentation strategies are often defined in principle but not fully resolved in detail, leaving interfaces to be interpreted on site and responsibilities fragmented across the project team. By the time the building is complete, the original intent may have been diluted, not through a single failure, but through a series of small, uncoordinated decisions. In use, further changes may be introduced without a clear understanding of their impact on the overall strategy.
Once built, these conditions are difficult to detect and even harder to rectify.
The consequence is a building that appears compliant but does not perform as expected, allowing smoke to travel further and faster than anticipated, enabling fire to spread beyond assumed boundaries, and compromising escape routes that were intended to remain protected.
Compartmentation is not achieved by drawing lines on a plan. It is achieved through continuity, coordination, and verification.
The question is not whether compartmentation exists, but whether it has been made to work.