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The Building Safety Regulator (BSR) has raised concerns about potential structural weaknesses in buildings constructed with reinforced concrete transfer slabs.
The regulator issued guidance on 19 December after identifying a possible failure mechanism known as “punching shear” in such slabs.
This occurs when concentrated loads cause a column to punch through the slab, potentially leading to a partial collapse.
The BSR emphasised that no such failures have yet occurred in the UK, but recent guidance issued by the Institution of Structural Engineers in November 2024 has prompted a re-evaluation of historic design approaches.
The regulator said it is working with its Building Advisory Committee (BAC) and industry partners “to better understand how the risk can be identified and proportionately managed in existing buildings”.
Transfer slabs, used in UK buildings for more than 25 years, are typically found in mixed-use developments where column layouts change between floors.
They carry loads from upper columns without corresponding support below, redistributing weight to the structure beneath.
In its alert, the BSR said the presence of a transfer slab alone does not warrant evacuation.
But it added that building owners should commission further assessments if signs of distress—such as cracking—are present, or if there are design concerns.
The regulator said it is working with the Ministry of Housing, Communities and Local Government and industry experts to review the scale of risk and identify appropriate mitigation measures.
The alert comes as part of the BSR’s statutory duty to monitor building safety and follows consultation with the BAC.