We assess external walls for a living. We open up facades, inspect cavity barriers, test insulation, and report on whether a building’s external wall system is safe. And there is a pattern we see over and over again, even on buildings that are sometimes only a few years old.
Missing cavity barriers. Compressed fire stopping. Insulation that does not match the specification. Junctions left incomplete because the next trade needed access, and nobody stopped them.
These are not old buildings. They are new-build developments: handed over, occupied and sold, where no one watched the work closely enough during construction. The person who should have been watching is the Clerk of Works. And for too long, this role has been treated as an optional extra, a nice-to-have on a cost plan, easily cut when budgets tighten.
That era is over.
Clerk of Works: The role the industry quietly deleted
Through the 1990s and 2000s, the Clerk of Works was steadily removed from project teams. Value engineering, a phrase that too often means cutting quality oversight to protect margins, stripped out independent site inspection on thousands of projects.
The consequences are now measured in billions. Grenfell Tower was the catalyst, but the problem extends far beyond a single building or a single era of construction. Assessors have found combustible materials, missing cavity barriers, or defective fire stopping in the external wall systems of hundreds of residential buildings. This includes developments completed in the 2010s and beyond.
These are not exclusively legacy problems. New-build developments are failing external wall assessments within years of practical completion. These were not design failures. They were construction failures. Failures of oversight. Failures that a competent, independent Clerk of Works would have identified and escalated before the cladding was sealed shut.
What a Clerk of Works actually does
For those unfamiliar with the role, a Clerk of Works is an independent construction inspector, typically appointed by the client or contract administrator, whose job is to verify that the works on site match the drawings, the specification, and the required standards.
They do not manage the programme or direct the contractor. They observe, inspect, record, and report. Their independence is the point.
On a new-build residential development, this means checking:
- That specified materials arrive on site, and contractors store them correctly
- That contractors install cavity barriers at every required location, to the correct product data sheet
- That fire stopping at floor and wall junctions is continuous and properly recorded
- That insulation is the correct type, thickness, and classification – not a substitution
- That weather-tightness detailing is completed before the next phase proceeds
- That the as-built records reflect what was actually installed, not what was drawn
In short, they verify the things that matter most and are hardest to check once contractors close up the facade.
The Building Safety Act changed the stakes
The Building Safety Act 2022 introduced a regulatory framework that makes independent quality oversight not just sensible, but effectively essential.
For Higher-Risk Buildings (residential buildings at least 18 metres in height) the Act requires:
- A Golden Thread of building information, maintained from design through construction and into occupation, recording what was specified and what was actually built
- Mandatory Occurrence Reporting, requiring duty holders to report any safety occurrence that could pose a risk to building residents
- Gateway 2 and Gateway 3 approval stages, where the Building Safety Regulator must be satisfied that the building work meets the functional requirements of the Building Regulations before construction proceeds and before occupation begins
None of this works without someone verifying the physical reality on site against the documented intent. The Golden Thread is only as strong as the accuracy of the information fed into it. If no one checks whether the cavity barrier was actually installed at Level 6, the Golden Thread records a fiction.
A Clerk of Works does not just support compliance with the Building Safety Act. They make compliance possible.
What we find when we assess new buildings
DALA Surveys carries out Fire Risk Appraisals of External Walls (FRAEW) and EWS1 assessments on residential buildings across the UK. The EWS1 (External Wall System) form was introduced in 2019 as a mechanism for mortgage lenders to assess the fire risk of external wall systems on residential buildings. A building that cannot obtain a satisfactory EWS1 assessment faces restricted mortgage lending, reduced property values, and significant distress for leaseholders.
The assumption is that this is a problem confined to older buildings. It is not.
We regularly assess buildings completed within the last five to ten years, new-build developments delivered under the current Building Regulations, and find defects in their external wall systems that should never have left the construction phase. Common findings include:
- Cavity barriers omitted entirely at floor levels, party wall junctions, or around window and door openings – creating uninterrupted vertical cavities through the facade
- Cavity barriers installed but compressed, displaced, or incorrectly oriented, rendering them ineffective against fire and smoke spread
- Insulation substituted on site – the correct product specified but a cheaper or different classification installed, sometimes without anyone recording the change
- Fire stopping at floor slab/external wall junctions incomplete or missing, particularly where services penetrate the facade
- Cladding support systems installed without regard to fire performance, including combustible brackets or inadequate thermal breaks
These are not obscure technical points. They are fundamental fire safety provisions. And in every case, they are defects that a Clerk of Works conducting systematic hold-point inspections during construction would have identified before the facade was closed up.
The cost of rectifying these defects after completion is staggering. Remediating an external wall system on an occupied high-rise residential building typically costs between £3m and £15m, takes 18 to 36 months, and causes significant disruption to residents. Appointing a Clerk of Works during original construction costs a fraction of a single percentage point of the contract value.
The return on investment is not marginal. It is orders of magnitude.
The EWS1 problem that should not exist
Here is the uncomfortable truth: a new-build residential development, constructed under current Building Regulations, should not fail an EWS1 assessment. If it does, something went wrong during construction.
Every time we open up a recently completed facade and find a missing cavity barrier, we’re looking at evidence that no one with the right knowledge checked this element before someone concealed it. The design was correct. The specification was compliant. The product was available. But between the drawing and the installed reality, something was lost, and no one independent person was there to catch it.
For developers, housing associations, and freeholders commissioning new-build residential schemes, this is a direct financial and reputational risk. A building that fails an EWS1 assessment within years of completion triggers remediation costs, leaseholder distress, potential litigation, and reputational damage – all of which are avoidable.
The Fire Safety Act and the Responsible Person’s obligations
The Fire Safety Act 2021 clarified that the external wall system falls within the scope of the fire risk assessment under the Regulatory Reform (Fire Safety) Order 2005.
This means the Responsible Person for a residential building must assess the fire risk posed by the external walls and take reasonable steps to mitigate that risk. For buildings under construction or undergoing remediation, this obligation does not wait until handover. It applies during the works.
For developers and contractors delivering new-build residential schemes, this creates a direct interface between construction quality and statutory fire safety obligations. The quality of cavity barrier installation, the continuity of fire stopping, the classification of insulation materials – these are not just contractual specification items. They are fire safety measures that the Responsible Person must be able to rely upon from the day the building’s occupied.
A Clerk of Works provides the independent verification that connects construction delivery to fire safety assurance. Their inspection records become evidence the Responsible Person can use to demonstrate that they took reasonable steps.
What good planning looks like
Effective planning for new-build external wall construction should embed quality oversight from the outset – not bolt it on as an afterthought. This means:
- Appointing a Clerk of Works at pre-construction stage. This means they understand the design intent, the specification, and the fire strategy before work begins.
- Define hold points and witness points in the inspection and test plan, requiring the Clerk of Works to inspect fire safety critical elements before contractors conceal them.
- Aligning inspection records with the Golden Thread, so that as-built information is captured contemporaneously and feeds directly into the building’s permanent record.
- Requiring photographic evidence of cavity barrier and fire stopping installation at every floor level before the next phase proceeds.
- Building the EWS1 evidence pack during construction, not after – so that at practical completion, the building already holds the documented evidence needed for a clean external wall assessment.
- Commissioning an independent FRAEW or EWS1 assessment shortly after practical completion, while the construction team is still available and any defects can be addressed under the defects liability period.
This last point is transformative. A building that completes construction with a fully documented record of its external wall system. This includes materials, installation, inspection, and test evidence, should sail through an EWS1 assessment. Avoiding the intrusive surveys and uncertainty that plague buildings where no one kept records.
The Clerk of Works is central to making this happen. And when the external wall assessor arrives, the quality of the Clerk of Works’ records is the difference between a clean assessment and a costly problem.
A message to Clerks of Works
If you are a Clerk of Works reading this, know that your role has never been more important.
The regulatory landscape: the Building Safety Act, the Fire Safety Act, the competence requirements of PAS 8671 and PAS 8672, is catching up with what you’ve always known. That buildings are only as safe as the quality of their construction. And that quality requires independent verification by someone who knows what they are looking at.
You are not a cost to manage. You are the mechanism that makes everything else credible.
Ant Attree FCCA is Managing Director of DALA Group, a specialist fire safety and building consultancy. DALA Surveys carries out Fire Risk Appraisals of External Walls (FRAEW). As well as PAS 9980 assessments, and EWS1 assessments on residential buildings across the UK. We see firsthand the consequences when construction quality oversight falls short.
