Transfer Slabs: A Rising Structural Risk That Property Owners and Managers Must Act On-Now Overview

Most buildings will not require emergency intervention. But every relevant building now requires clarity, assurance, and evidence.

What Are Transfer Slabs-and Why They Matter

A transfer slab is a reinforced concrete slab that redistributes loads from columns above to different structural elements below, typically where column layouts change (for example, above podiums or mixed-use levels).

They have been widely used in UK construction for over 25 years. Their presence alone is not a defect. The risk arises when load paths, detailing, deterioration, or historic design assumptions are not fully understood or no longer align with modern standards.

Why Transfer Slabs Are on the Agenda

The current focus is driven by concern over what’s called “punching shear”, a failure mechanism where concentrated column loads can overstress a slab locally, potentially leading to sudden and disproportionate failure.

While the BSR has confirmed there is currently no evidence of UK building collapses caused by transfer slab failure, similar failures have occurred internationally. Combined with ageing building stock and evolving engineering understanding, the potential consequences are severe enough to demand action.

At the same time, updated technical guidance from the Institution of Structural Engineers makes clear that historic design approaches may not meet today’s expectations when assessing existing buildings.

The regulatory direction of travel is unmistakable, if you have transfer slabs, you must be able to demonstrate that the risk is known and being managed.

What This Means for Owners and Managers of HRBs

Under the Building Safety Act 2022, those accountable for HRBs must maintain Safety Case Reports that clearly evidence understanding and control of structural safety risks across the building lifecycle.

Transfer slabs are now considered a “known risk contributor”. That means that silence is not neutrality, assumption is not assurance.   Historic drawings alone are not evidence of safety

Failure to address this issue creates regulatory exposure, not just technical risk.

Four Actions Ark Recommends You Take Immediately

 1.       Identify Transfer Slabs-Explicitly - review structural drawings, specifications, and historic records to confirm whether transfer slabs are present. If this is unclear, that uncertainty itself is a risk that must be resolved.

 2.       Commission a Targeted Structural Risk Assessment - where transfer slabs exist, instruct a competent structural engineer with transfer slab experience to assess:

·       Punching shear capacity

·       Original design assumptions

·       Reinforcement detailing and load paths

·       Evidence of deterioration (cracking, deflection, corrosion)

 Any visible distress should trigger immediate professional review.

 3.       Embed Findings into Your Structural Risk Framework - your structural risk assessment should test whether the original design remains valid under current standards, evaluate likelihood and consequence of punching shear failure and integrate transfer slab risk alongside other critical structural hazards (e.g. RAAC, façade systems). This is about systematic risk ownership, not one-off reports.

 4.       Update and Strengthen Your Safety Case Report - For HRBs in England, Safety Case Reports submitted through the Building Assessment Certificate (BAC) process should explicitly confirm the presence or absence of transfer slabs and summarise assessment outcomes and residual risk.  The reports must document monitoring, inspection, and remediation strategies and be updated where reassessment identifies material change.

Equivalent evidence should be maintained across devolved administrations.

Communication and Insurance: Do Not Overlook the Wider Impacts

Residents should be informed where assessments lead to increased monitoring or works that affect access or services.

Insurers should be notified where material structural risks or mitigation measures are identified, failure to do so may impact coverage or premiums.

Transparency here is not optional; it is part of good governance.

The Strategic Bottom Line

The regulator is not asking for panic, but it is expecting leadership, competence, and evidence.

Ask yourself:

Do we know whether we have transfer slabs?

Do we understand their condition and capacity?

Can we demonstrate-today-that the risk is being managed?

If the answer to any of these is unclear, now is the time to act:

• Review your structural risk assessments

• Update your Safety Case Report

• Pressure-test your evidence trails against regulatory scrutiny

Early, proportionate action now will reduce safety risk, regulatory exposure, and future cost.

Ark can help you move quickly and intelligently—from identification and assessment through to Safety Case alignment and regulator-ready documentation.

Author David J. Hills FRICS, FIIRSM, MIFireE, MSFPE, RSP
Senior Director - Regulatory, Technical & Technology Solutions

Ark Workplace Risk