Five residential blocks evacuated in east London have put transfer slabs firmly on the building safety agenda. For fire engineers and building safety managers, the unfolding crisis raises urgent questions about structural integrity, fire strategies and the management of high-rise buildings.

The evacuation of five residential blocks in Canning Town, east London, has brought a potentially significant structural safety issue into sharp focus.

Residents of Sovereign Tower, Centurion Tower and St Vincent Court were evacuated after engineers identified serious concerns involving a concrete transfer slab. A week later, residents of neighbouring Thanet Tower and Prince Court were also advised to leave following further engineering assessments.

The five buildings, managed by Prime Property Management (PPM), are now at the centre of an escalating investigation. The original three blocks were reported to present an "imminent risk to life".

Newham Council is supporting affected residents, while the Building Safety Regulator (BSR) and the Ministry of Housing, Communities and Local Government (MHCLG) investigate the potential prevalence of transfer-slab risks nationally.

For those responsible for fire safety and building safety management, the implications extend beyond the immediate structural concerns.

What is a transfer slab?

Transfer slabs are reinforced concrete structural elements designed to redistribute building loads. They are commonly used where a building’s structural layout changes between floors.

For example, a residential tower may have columns supporting upper floors, while lower levels require a different arrangement to accommodate entrances, commercial spaces or car parks. The slab transfers the load to supporting columns below.

However, the BSR has identified potential risks associated with inappropriate transfer-slab design. In certain circumstances, a slab may be vulnerable to punching shear failure, where a concentrated load causes a column to punch through the concrete.

In a worst-case scenario, this could trigger partial building collapse. The BSR has emphasised that most transfer slabs are likely to be adequate. Their presence alone does not mean a building is unsafe, but understanding their design and condition is essential.

What does this mean for fire safety?

Structural integrity underpins a building’s wider fire safety strategy. Where concerns emerge, assumptions about evacuation, firefighting operations and building safety management may need to be revisited.

For fire engineers and building safety managers, several considerations arise:

• Means of escape: Structural concerns may affect the safety or accessibility of escape routes, requiring a review of evacuation arrangements.
• Fire strategies: Assumptions about structural performance during a fire may need reassessment by competent professionals.
• Fire and rescue services: Structural instability could affect access, firefighting operations and emergency responder safety.
• Building safety cases: Structural failure risks must be considered alongside fire spread, compartmentation and external wall systems.

The key is ensuring structural and fire safety assessments are coordinated, rather than managed as separate exercises.

What should building safety managers check?

The BSR has advised principal accountable persons (PAPs) and building owners to establish whether their buildings incorporate transfer slabs.

A review of structural drawings, building records and previous assessments should help identify their location. Where the structural arrangement is unclear, a suitably qualified structural engineer should be consulted.

Potential indicators of structural distress include:

• Cracking in transfer slabs or columns and walls immediately above or below them.
• Cracks in floor finishes fixed directly to the slab.
• Doors becoming stuck in frames on floors above the slab.
• Evidence of building movement or deterioration.

These indicators do not automatically mean a building is unsafe. However, new or worsening defects should prompt specialist investigation.

Building managers should also consider alterations that could affect structural performance, including increased loading, changes of use or drilling and cutting into concrete.

Managing risk while investigations continue

Where structural concerns are identified, interim arrangements must be informed by competent engineering advice and a review of the building’s fire safety strategy.

For occupied buildings, this may include reviewing evacuation procedures, emergency service access and fire safety management arrangements.

Any changes should be formally assessed, documented and communicated. Fire safety professionals should not be expected to make structural judgements outside their competence.

The Canning Town evacuations raise an important question: could transfer-slab defects represent a wider challenge for the UK’s existing high-rise building stock?

The answer remains unclear. The BSR and MHCLG are investigating, and further guidance is expected as the picture develops.

For now, the priority is understanding the structural arrangements of existing buildings, identifying potential defects and ensuring that concerns are investigated promptly.

Transfer slabs are not inherently dangerous. But Canning Town is a stark reminder that structural risks cannot be overlooked when assessing the safety of high-rise buildings.

For those responsible for keeping buildings safe, the time to understand the risk is before the next evacuation.

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