Two residential blocks in Tower Hamlets were handed over in June 2013. On paper they were finished buildings. Thirteen years later their landlord is in the High Court asking a contractor for £3.4 million, because of what was found when the walls were opened up.

What happened

Poplar HARCA has issued a claim against Rydon over Anne Matthews Court and William Cotton Court, two blocks at the William Cotton Place development in east London, completed in June 2013. The housing association alleges the buildings contained aluminium composite material cladding, combustible insulation and expanded polystyrene in the spandrel panels, together with missing or inadequate cavity barriers. It pleads breach of contract, breach of statutory duty, non-compliance with the Building Regulations, and that the blocks were not fit for human habitation when they were completed, which engages the Defective Premises Act 1972.

The association says it secured £1.8 million from the Building Safety Fund and that the remediation was finished in 2023 by another contractor. It is now seeking £3.4 million in damages. The claim was reported on 13 August 2026 by Inside Housing and on 14 August by Construction News. None of it has been tested in court, and at the time of those reports Rydon had not commented publicly.

The part that should worry every building owner

Set the cladding aside for a moment. Cladding gets the headlines, and if you own a high rise you have almost certainly had your external wall looked at by now.

Look instead at the last item on the list: missing or inadequate cavity barriers. That defect has three properties that make it the most dangerous item in the whole claim, and none of them are specific to tall residential buildings.

It is invisible. A cavity barrier sits inside a wall cavity, above a ceiling, or in a riser. Nobody walking the building sees it, and nobody moving in notices it is absent. It does not leak, sag, or make a noise.

It does not show up on a drawing check. This is the point most owners miss. The specification said cavity barriers, and the drawings very likely showed cavity barriers. What matters is whether they were installed, installed in the right place, and installed to the right detail around every service penetration. A set of drawings tells you what somebody intended. It is not evidence of what was built.

And it took a fire in another building, and a national programme of intrusive investigation, before anyone looked. These blocks stood for the best part of a decade with a signed handover pack and a completion certificate. The defects were not found by an audit or a routine inspection. They were found because somebody eventually opened the wall.

Why this is not just a high rise problem

The Building Safety Act regime and the remediation funds have concentrated attention on residential buildings above 18 metres. That focus is right, but it has produced a blind spot.

The same trades, the same subcontract chains and the same site pressures that left cavity barriers out of a 2013 block of flats were also at work in offices, schools, hotels, care homes and warehouses built in the same period. Those buildings have had no equivalent programme, no fund, and in most cases no intrusive survey. Their compartmentation is unverified rather than verified sound. A building with an unopened riser and a suspended ceiling nobody has lifted is not a building with a clean bill of health. It is a building with no information.

Compartmentation is also the provision that everything else leans on. A phased evacuation strategy, a stay put policy, a protected escape route, a fire alarm cause and effect matrix that assumes the fire stays in one place: all of it assumes the compartment holds. If a service run breaches a compartment wall above a ceiling, that assumption fails quietly, and it fails at the worst moment.

What to check

  • Do you hold an as-built compartmentation record, or only design drawings? If it is the second, you do not know what you own.
  • Has anyone lifted the ceilings and opened the risers? Not the accessible ones. All of them, sampled properly.
  • Do your fire risk assessment and your fire strategy agree with each other, and does either rest on compartmentation nobody has verified?
  • Where have you had works since handover? Every cable pull, new data run and boiler replacement is a potential new breach, and refurbishment records are where breaches hide.
  • If defects are found, who is on the hook? A defect discovered now may still sit inside a claim window, and that turns on limitation periods and on the records you hold.
  • Is your evidence in a form an auditor or insurer would accept? Photographs with locations, product data and a dated report, not a verbal assurance.

How we can help

Gemini AMPM carries out compartmentation surveys on existing buildings: lifting ceiling tiles, opening riser doors and inspecting concealed voids against the building’s fire strategy, then reporting located defects with photographs and a prioritised remediation programme.

Where remediation is needed, fire barriers and fire stopping are installed by our own FIRAS approved teams, with certificates of conformity and a structured evidence pack for your golden thread record. We work across social housing and residential stock and commercial premises alike.

If you cannot answer the first question on that checklist, talk to us about a survey.