Author: admin

To principal accountable persons and buildings owners,

The Building Safety Regulator (BSR) is making you aware of a potential structural safety issue affecting reinforced concrete buildings constructed with ‘transfer slabs’.

We are working with industry experts and the Ministry of Housing, Communities and Local Government (MHCLG) to better understand the extent of the risk, and how the risk can be identified and managed proportionately in existing buildings.

We are issuing this information to enable building owners to take proportionate steps to manage the safety of their buildings.

What transfer slabs are

A transfer slab is a floor arrangement where a column sits on top of a slab, but does not have a supporting column directly beneath it. The slab acts to support the load from the column and spreads it to the supporting columns below.

This design feature has been used in the UK for over 25 years, particularly in mixed-use developments where the column grid changes between floors. Not all construction of this nature will have issues. See more in the ‘important information’ section.

The potential issue with transfer slabs

In November 2024, guidance on the design of transfer slabs was published by the Institution of Structural Engineers. While this provides a robust basis for new construction, it raises some questions on the adequacy of historic engineering design methods in existing buildings.

Specifically, there is a concern regarding “punching shear in transfer slabs,” a failure mechanism where a high concentration of load causes a column to punch through a reinforced concrete transfer slab. This may result in a collapse in part of a building. Although, we are not aware of any building collapse caused by this in the UK.

Transfer slabs in residential buildings

The presence of a transfer slab alone should not require a building to be decanted. It is likely that further assessment considering other risk factors will be needed to determine if there is a risk to building residents.

Where there are visible signs of distress (for example, cracking) or specific concerns regarding the building’s condition and/or design, building owners should seek professional advice.

Decanting a residential building has a substantial impact on residents and should be weighed against the level of risk in the building. Building owners should work to ensure residents can remain in their homes where it is safe to do so.

We will be providing further advice in due course on this issue, and we ask that building owners stay informed.

What BSR is doing about transfer slabs

Fulfilling our legal duty to keep the safety of buildings under review, BSR commissioned independent research in late 2024 to establish the level of structural risk associated with transfer slabs and consulted our Building Advisory Committee (BAC). This work is ongoing and has been done in close cooperation with MHCLG.

We are currently working with industry partners and our BAC to better understand how the risk can be identified and proportionately managed in existing buildings.

Both BSR and MHCLG are committed to a proportionate response and will provide further updates via regular BSR bulletins and the BSR campaign website.