UK regulators raise concerns over transfer slabs in buildings
April 2026The Building Safety Regulator (BSR) has recently issued warnings in relation to a potential structural safety issue affecting reinforced concrete buildings incorporating transfer slabs. These warnings following a growing concern within the engineering profession that certain historical design approaches may, in certain circumstances, have underestimated the risk of brittle structural failure, most notably punching shear.
Regulators and professional bodies have emphasised that transfer slabs are not inherently unsafe. However, the scale and coordination of the regulatory response represent a significant development for the construction and property sectors, particularly given the age, height and use of many buildings in which transfer slab construction is present.
What are transfer slabs?
A transfer slab is a reinforced concrete floor system designed to redistribute vertical loads where the structural load-bearing arrangement above does not align with that below. Transfer slabs have been a common feature of UK construction for over 25 years and are most frequently encountered in high-rise and mixed-use developments. Their use enables architectural flexibility, including column-free spaces at lower levels (such as car parks or retail spaces) or the stepping back of upper floors to create terraces.
Many transfer slabs are designed as flat slabs, without the use of downstand beams. While this approach can reduce the cost and complexity of temporary works, it also places greater reliance on slab thickness and reinforcement to achieve adequate structural performance. These arrangements have attracted increased professional scrutiny, as their apparent simplicity can obscure more complex structural behaviour, particularly in relation to load transfer and punching shear capacity.
Issue / reason for concern
The current concern centres on the risk of punching shear, a brittle failure mechanism in which a highly concentrated load, typically from a structural column, causes a column to effectively ‘punch’ through a reinforced concrete slab. This mode of failure is of particular significance as it can occur with limited or no warning, potentially giving rise to a sudden localised collapse. As a consequence, relatively small inaccuracies in structural modelling and the detailing of construction can have disproportionate effects on structural performance.
In November 2024, the Institution of Structural Engineers (IStructE) published new guidance on the design of transfer slabs. While the guidance provides a comprehensive framework for new construction, it also highlighted an uncertainty as to whether some historic design approaches adequately addressed punching shear, particularly in relation to:
- The complex interaction between offset columns above and below a transfer slab
- The susceptibility of thick reinforced slabs to long term shrinkage
- The influence of temporary works and construction sequencing on structural behaviour
The guidance does not conclude that existing buildings incorporating transfer slabs are unsafe and expressly states that non-compliance with the new recommendations does not, of itself, imply structural inadequacy or statutory non-compliance. Nevertheless, it establishes a revised benchmark against which the performance of existing transfer slab structures may increasingly be assessed.
These professional concerns attracted further attention following commentary from CROSS-UK in December 2024, and subsequent correspondence from Government and the BSR in December 2025, which sought to clarify how risks associated with transfer slabs can be identified and proportionately managed in existing buildings. Together, these developments have placed transfer slab design and assessment firmly within the current building safety agenda.
Current position
As mentioned, the recent alerts do not suggest all transfer slabs are inherently unsafe, highlighting that the current regulatory response is intended to be risk-based rather than a blanket safety alert.
Pending the publication of further guidance, the BSR has advised building owners to remain informed, establish whether their buildings incorporate transfer slabs, and seek appropriate professional advice where there are visible signs of distress or specific concerns regarding design or condition. This approach reflects the regulator’s emphasis on early identification, informed assessment and proportionate risk management. Adherence to the BSR’s advice is leading building owners to engage structural engineers to assess relevant buildings for punching shear risks arising from issues with transfer slabs.
Regulatory focus on transfer slab construction intensified following notable cases during 2025. These demonstrate the practical and legal consequences that may follow where uncertainty arises in relation to structural safety and reflect the increasingly active role of the tribunals and regulators in addressing potential risks under the post-Grenfell building safety framework.
- Wooton Court, London
The First-tier Tribunal granted a remediation order in relation to a 12-storey residential building at Wooton Court. The tribunal considered expert evidence identifying cracking around key support columns and the first-floor slab, which was indicative of a potential punching shear mechanism, concluding that the severity of the risk justified emergency evacuation.
- Stratford Halo Village, London
Residents of the Stratford Halo Village development were evacuated at short notice, following structural investigations that raised immediate concerns regarding building stability and transfer slab construction. Residents have since commenced legal proceedings against the building owner, alleging breaches of the Defective Premises Act 1972 (as amended).
Limitation, the Defective Premises Act and the Building Safety Act
One reason the construction sector has largely avoided widespread liability for issues relating to the use of Reinforced Autoclaved Aerated Concrete (RAAC) is the operation of limitation (see article here). RAAC was predominantly used from the 1950s to mid-1980s, with the result that many affected buildings fell outside applicable contractual and statutory limitation periods.
Transfer slabs present a materially different limitation profile. As they have been widely used in UK construction more recently, many residential buildings incorporating potentially defective transfer slabs are likely to have completed less than 30 years before 28 June 2022 (when the Building Safety Act (BSA) 2022 came into force). Complete limitation defences are unlikely to be available in relation to any claims pursued against those responsible for the design and/or construction of such defective transfer slabs.
Structural defects affecting the stability or integrity of a building may be capable of rendering a dwelling unfit for habitation, and accordingly, depending on the facts, transfer slab defects may fall within the scope of the statutory regime.
Commentary
While it remains unclear how many buildings may ultimately be affected, the increased focus on structural assessment, particularly through safety case reporting under the BSA and in light of recent First Tier Tribunal decisions, is likely to result in a greater number of structural investigations being undertaken. As that process continues, it is reasonable to anticipate that claims will arise, particularly where defects or inadequacies are identified or where warning signs may not have been appropriately addressed.
Potential exposure may arise, among others, for:
- Design and build contractors and structural engineers involved in historic design and construction of buildings incorporating transfer slabs.
- Surveyors involved in pre-acquisition due diligence, where visible signs of structural distress were present but not adequately identified.
- Managing agents who failed to commission appropriate condition surveys or investigations during a project’s lifecycle.
For the present, regulators and professional bodies continue to emphasise the importance of balance rather than alarm. Transfer slabs have performed successfully in many buildings for decades, and the issuance of new guidance does not imply systemic failure. However, the recent statements provided by the BSR, IStructE and RICS make clear that transfer slabs may, in certain circumstances, warrant renewed scrutiny as part of the UK’s evolving approach to building safety.
We advise clients across the construction sector on building safety regulation, structural defect risk and related disputes, including matters arising under the Building Safety Act 2022 and Defective Premises Act 1972. If you would like to discuss how emerging issues relating to transfer slabs may affect your assets or projects, please contact Ian Masser or Nick Kenny.
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