Grenfell tragedy sheds light on inherent defects

The Building Safety Act 2022 (BSA) and the Defective Premises Act 1972 (DPA) have together created a robust regime for addressing inherent defects in residential buildings, with the BSA broadening existing duties, extending limitation periods and introducing new remedies.

A growing number of inherent defects are coming to light through safety surveys commissioned as a result of the BSA's introduction – creating far-reaching ramifications for property professionals.

The BSA has expanded duties by inserting section 2A into the DPA, which relates to work done to any part of a building containing dwellings, addressing gaps where previous duties did not apply, such as communal areas and major refurbishments.

The BSA has also created liability for manufacturers and suppliers of inherently defective construction and cladding products under sections 148 and 149.

The resulting surveys, mandated for relevant buildings – meaning a building that is at least 11m in height or has at least five storeys, consisting of or containing two or more dwellings and which is not a leaseholder-owned building – are uncovering a troubling volume of inherent defects, i.e. flaws in design, workmanship or materials that compromise the integrity and safety of buildings.

Examples of inherent defects include:

• inadequate steel reinforcement in undercroft parking structures
• poor damp proofing
• defective roofing membranes leading to water ingress 
• large panel system building defects
• inadequate or missing fire stopping.

While many of these defects may not directly relate to fire safety or structural collapse, they are increasingly being flagged under the BSA's broader remit to address building safety risks. The result is a growing number of legal disputes and remediation demands, often involving parties that previously bore little liability.

By way of example in URS Corp Ltd v BDW Trading Ltd, [2025] UKSC 21, the Supreme Court confirmed that developers have a wide scope of recourse against other parties involved in the construction of defective buildings.

In this case, a developer recovered damages from a structural engineer arising from design defects in the development of two residential tower blocks uncovered in post-Grenfell surveys.

The case reinforces the objectives of the BSA and demonstrates that those responsible for historic defects can be held to account, even if many years have passed since completion.

But what does fit for habitation mean in practice? Courts have interpreted this broadly. Defective foundations, inadequate structural support and poor waterproofing have all led to successful claims.

Importantly, defects outside the dwelling – such as collapsed drains or compromised communal areas – can still render a property unfit for habitation if they affect safety, access or essential services.

This expanded interpretation of fit for habitation means that even issues in shared or external parts of a residential building can trigger liability, shifting the legal landscape for developers, contractors and advisers.

This typically involves proving:

• breach of duty under the original construction contract
• failure to meet professional standards by advisers, e.g. architects, engineers and surveyors
• the use of substandard materials or flawed design.

The DPA now provides a statutory route for such claims, with a 15-year limitation prospective period for work completed after 28 June 2022 and a 30-year retrospective period for work completed before that date.

Additionally, sections 147–149 of the BSA allow claims against manufacturers and sellers of construction products if those products contribute to a dwelling being unfit for habitation.

This includes misleading marketing, non-compliance with product standards or inherent defects in the products themselves.

While not physically in the living space, a collapsed drain can lead to flooding, sanitation issues and structural damage – conditions that clearly impact habitability.

Section 1 of the DPA imposes a statutory duty on builders, developers and construction professionals to ensure that dwellings are constructed in a workmanlike or professional manner, using proper materials, and are fit for habitation when completed.

This duty is owed to both the original client and subsequent purchasers of the dwelling. Breach of this standard, specifically regarding fitness for habitation, is central to establishing liability for inherent defects.

The duty extends to work 'in connection with' the provision of a dwelling, a phrase given a broad interpretation in Rendlesham Estates plc & Others v Barr Ltd [2014] EWHC 3968 (TCC), where the court included structural and common parts, as well as utilities and shared facilities – and URS confirmed this approach.

However, courts are likely to interpret such cases contextually, considering the impact on residents rather than strict physical boundaries. This opens the door to broader claims and reinforces the importance of comprehensive surveys and expert legal advice.

The shift in liability away from landlords and toward construction professionals marks a fundamental change in the sector's risk profile.

These reports should:

• identify clear causes of action
• allocate liability for each defect
• quantify losses using a Scott Schedule – a tabular document used in legal proceedings to identify issues.

This approach enables a pragmatic resolution, avoiding the costs, delays and reputational risks of court proceedings. It also supports better outcomes for residents, who may otherwise endure prolonged uncertainty and disruption.

The Supreme Court decision in URS and the Upper Tribunal decision in Monier Road Limited v Nicholas Alexander Blomfield and other leaseholders [2025] UKUT 157 (LC) have clarified that while courts and tribunals will endeavour to find the best and most practical and outcomes-focused solutions to myriad circumstances, the onus remains on claimants and applicants to provide credible technical evidence from a suitably qualified expert witness when filing proceedings.

By understanding the legal tests, anticipating grey areas and embracing collaborative solutions, the surveying sector can navigate these challenges while safeguarding occupants and buildings.