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CROSS Safety Report

Compartmentation issues found in premises converted to residential flats

Report ID: 1184 Published: 20 May 2024 Region: CROSS-UK


A fire safety audit of a premises that was converted from commercial premises to residential use, identified that there were potential fire compartmentation and other safety issues.

Key Learning Outcomes

For Responsible Persons, designers and contractors:

  • Conversions of commercial premises to residential use are often complex. This is due to the differing evacuation strategies required for commercial versus residential use
  • Stakeholders should be aware that the original fire compartmentation and other life safety systems may require significant upgrades to meet residential requirements
  • Upon occupation, premises immediately become subject to the Regulatory Reform (Fire Safety) Order 2005 in England, and similar legislation in other UK jurisdictions. A completion certificate does not prove compliance with the Order
  • The appointment of a building control body does not remove the obligation of the person carrying out the work to achieve compliance with the building regulations

Full Report

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This section contains the Full Report submitted to CROSS and describes the reporter’s concerns or experiences. However, the text has been edited for clarity, and identifiable details have been removed to ensure anonymity and confidentiality. If you would like to know more about our secure reporting process, or submit a report yourself, please visit the reporting to CROSS-UK page.


The Responsible Person (RP), who was the developer, had converted an office block into a block of apartments. They claimed they did not need to carry out a compartmentation survey because they had been issued with a final certificate from their Approved Inspector.

In actuality, each flat had been issued with a final certificate, not the whole building. Residents moved in without the final certificate for the whole building being issued, despite there only being a single staircase.

A compartmentation survey was commissioned, and the company concerned informed the reporter that they had serious concerns about compartmentation in the building and they had specifically identified that the single staircase was not adequately protected.

In the event of a fire occurring in any of the flats, the fire could spread throughout the building and might seriously affect the means of escape. In the view of the reporter, a fire in these circumstances could result in death or serious injury.

There was, says the reporter, a total disregard for the safety of the residents

There were procedural failures at several points:

  • The Approved Inspector did not properly consult the fire and rescue service
  • The developer did not install adequate fire stopping and ensure that the compartmentation of the building was suitable for its intended purpose
  • The Approved Inspector did not provide proper building control oversight
  • The developer did not act on the findings of the fire risk assessment
  • The fire and rescue service had to deal with the problems using the Fire Safety Order

There was, says the reporter, a total disregard for the safety of the residents on the part of both the developer and the Approved Inspector. There needs to be a more streamlined way to deal with potential conflicts between building control and the fire and rescue service.

Expert Panel Comments

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Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

Whilst there is no reason why these types of conversion projects cannot be done well, anecdotally, they often seem to be done badly in practice. Given the need for more housing in the UK and the sustainable use of existing buildings, this is an area designers and builders must get right. 

Fundamentally the difficulties arise due to the differing fire strategies. Offices are predominantly simultaneous evacuation and require less compartmentation than a block of flats, especially when using a stay put policy in their evacuation strategy. Checking and installing compartmentation to meet the changed use and strategy is critical to the safety of the residents.

Another common issue with these conversions is that the fire and rescue service access and facilities requirements are very different. This can prove challenging in the design phase.

Given the need for more housing in the UK and the sustainable use of existing buildings, this is an area designers and builders must get right

Furthermore, the assumption that the existing compartmentation is satisfactory can be dangerous. Unless there were robust permits to work and quality assurance process for all works in the original building during its lifetime, there would very likely be breaches in compartment walls and floors. This is particularly true for the service risers. Additionally, the conversion process will likely require many new holes for domestic plumbing and electrical services, increasing the chance for the existing compartmentation to be damaged.

The correct time to carry out surveys and repair compartmentation is during the design and the building process, not after occupation. 

Unfortunately, the procedural failures involving the duties of Approved Inspectors listed as bullet points by the reporter are not uncommon. From 2011 to 2015 the Fire Industry Association's Fire Engineering Council spent a considerable amount of time and effort attempting to convince the industry to improve the building control process and the quality of construction work concerning fire safety.

The FSO is not an appropriate mechanism to address failings under the Building Regulations

Approved Inspectors should consult with fire and rescue services (FRS) before the build is complete and with sufficient time to ensure FRS comments can be addressed. The FRS in this case was consulted far too late and had to use the Regulatory Reform (Fire Safety) Order 2005 (FSO) to address these failings, which is akin to using a hammer to tighten a nut. The FSO is not an appropriate mechanism to address failings under the Building Regulations. 

The report doesn't comment on the height of the building so it is unclear if the building was a higher risk residential building. If so the BSR's gateways will be applied for all future builds in this scope, hopefully avoiding this issue in the future. Furthermore, the Expert Panel assumes that this work took place before mandatory occurrence reporting came into force. 

Since January 2024, a mandatory occurrence report must be submitted for all building safety occurrences that resulted in, or are likely to result in:

  • the death of a significant number of people
  • serious injury that needs immediate treatment in hospital for a significant number of people
  • a permanent or irreversible disabling condition to a significant number of people

Significant compartmentation issues in a single stair premises would likely constitute the risks described above. In this case, the report might need to come from both the design and construction team for failings during this stage as well as from the Accountable Person for the risks found in occupation.

Our Expert Panel asks, when will we, as an industry, see the needed cultural change? In England, the new regime under the Building Safety Act 2022, overseen by the Building Safety Regulator, will undoubtedly have a positive effect. Lessons can be learned through voluntary occurrence reporting, such as this report, that can be applied across the regulatory landscape. 

It should also be noted that, in England, those wishing to practice as building control bodies across the sector now have to register with the building safety regulator (BSR) from April 2024, and they are bound by the building control operational standards rules

With the recent government statement about brownfield sites, more of these types of developments will likely be proposed. It is clear the quality of these schemes needs significant improvement.

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