In fire safety, some of the most critical protections are the least visible. Compartmentation (the use of fire-resistant barriers within a building) is a great example.
In many cases, it’s compartmentation that determines whether a fire remains a contained incident or escalates into a building-wide emergency. For property managers and duty holders, understanding compartmentation is a legal requirement that plays a vital role in protecting lives.
What Compartmentation is and Why it Matters
Compartmentation refers to the division of a building into separate fire-resisting sections using suitable materials in walls, floors, ceilings, doors, and protected shafts. These fire-protected elements are designed to contain the spread of smoke and fire for a defined period (typically 30 to 120 minutes).
This system slows the spread of fire, helps protect escape routes, and limits structural damage – allowing the fire service to respond effectively and, if required, giving residents time to evacuate safely.
The minimum performance standards for fire-resisting structures are set out in Approved Document B of the Building Regulations, which supports safe design and construction in both new and existing buildings.
Legal Responsibilities
Under the Regulatory Reform (Fire Safety) Order 2005, the “responsible person” for a building must ensure that appropriate fire precautions are in place and are effectively maintained – this includes maintaining compartmentation.
The Fire Safety Act 2021 reinforces this by clarifying that flat entrance doors and the external walls of a residential building fall under the scope of a fire risk assessment. These elements are key parts of the building’s fire containment strategy and must be kept in good condition.
For buildings considered “higher-risk” (generally those over 18 metres or 7 storeys, with two or more residential units), the Building Safety Act 2022 introduced the requirement for a Building Safety Case. This includes providing clear evidence that key fire safety measures such as compartmentation are functioning as intended.
In short, compartmentation is central to your legal responsibilities under multiple UK regulations and must be considered as part of any compliant fire safety strategy.
Risks of Inadequate Compartmentation
The problem with compartmentation is that breaches are often hidden from view. Issues may include:
- Damaged or missing intumescent seals around fire doors
- Unsealed cable penetrations and service openings
- Poor workmanship during refurbishments or retrofits
These weaknesses can allow smoke and fire to bypass barriers, undermining evacuation plans and placing residents and emergency responders at increased risk.
Government investigations (including those following major fire incidents) have repeatedly shown how small defects in fire-stopping measures can contribute to large-scale failures in fire safety strategy.
Inspections and Evidence
Fire risk assessments carried out under the Fire Safety Order must be “suitable and sufficient,” and as part of this, should consider if the compartmentation is suitable for the recommended fire policy.
If concerns are raised, such as through visual checks or resident reports, intrusive inspections may be required to verify the integrity of walls, voids, and service risers.
Regular inspections of installed fire stopping should be carried out to ensure compliance, particularly after any works like the installing of services like broadband.
Where risks are identified, property managers must:
- Record the issue clearly
- Take appropriate remedial action
- Maintain documentation of inspections, works, and re-checks
While the law does not dictate a specific inspection frequency, it does require risks to be reviewed and acted upon. Regulators expect evidence of a proactive, documented approach – particularly in higher-risk or complex buildings.
Conclusion
Compartmentation may be hidden, but its role in fire safety is critical. Regular assessment, accurate documentation, and prompt action where issues are found are key to compliance and resident safety.
At 4site, we support duty holders with risk assessments, fire compartmentation surveys, and practical guidance to help you meet your responsibilities with confidence.
If you’re unsure about the condition of your building’s compartmentation, now is the time to review and take action.
