A major audit has uncovered systemic failings in government-backed home-insulation programmes, with almost every recent installation of external wall insulation found to be non-compliant and thousands of households now facing damp, mould and potential health risks. A statistical audit commissioned by the government and carried out this year reports that 92% of audited external wall insulation (EWI) jobs under ECO4 and the Great British Insulation Scheme (GBIS) had at least one major technical non-compliance—problems serious enough to compromise the effectiveness of the insulation—while 27–30% of internal wall insulation (IWI) jobs were similarly flawed.
The scale of the issue is stark. A companion report published this week says around 22,000–23,000 homes fitted with EWI since 2022 now require remediation, with roughly 3,000+ of those cases posing urgent safety risks; officials and auditors describe the failures as “systemic” and “unacceptable”. The same evidence points to widespread consumer harm—cold, damp homes that cannot easily be sold or refinanced—and a serious breach of public trust in retrofit programmes.
How did this happen? The audit trail shows a cascade of oversight failures. TrustMark—the quality-mark body overseeing installations—first alerted the energy department in October 2024 that failure rates looked abnormally high. In April 2025, Ofgem commissioned a randomised audit programme to quantify the problem across ECO4 and GBIS. The results, published on the government’s website, confirm that major non-compliance is the norm rather than the exception for recent EWI work, and is worryingly common in IWI too.
The public cost could be significant. The spending watchdog reports that installers may have made fraudulent claims for up to 16,500 homes, implying as much as £165 million wrongly paid out. Ministers are now under pressure to set deadlines for inspections and repairs—and to ensure households are not left to foot the bill.
Government and regulators have begun to act. The energy minister confirmed that dozens of installers have been suspended pending investigation, with further reforms promised to raise competence standards, toughen on-site checks and strengthen accountability. Officials stress that most major non-compliances relate to performance and durability (for example, poor fixings, missing cavity barriers or inadequate weatherproofing) rather than immediate fire danger—though a subset of cases has been categorised as urgent on health and safety grounds.
Beyond the headline failure rates lie the human and financial consequences. Botched EWI and IWI can drive moisture into building fabric, generating black mould, damaged plaster and respiratory problems—especially in older, solid-walled homes. Lenders may down-value properties with defective retrofit, trapping owners; local authorities face higher workloads as complaints rise; and reputable contractors risk reputational fallout from a market flooded with poor workmanship. Industry groups warn this could chill uptake just as the UK seeks to scale home energy upgrades to cut bills and emissions.
Context matters. Britain has a long post-Grenfell focus on façade safety and product compliance, and separate government data on cladding remediation and insulation testing shows how complex compliance has become—particularly for solid-wall buildings and high-rise blocks. The latest retrofit scandal sits uncomfortably alongside that agenda: while the current findings chiefly relate to performance and moisture risks rather than combustible façades, both episodes underline the need for rigorous product testing, competent installers and strong enforcement.
What happens next? The government has published the statistical audit and a written ministerial statement setting out immediate steps: priority remediation for the most serious cases; stronger auditing (including more on-site inspections); tighter controls on subcontracting; and reforms to the consumer-protection framework so households can secure redress quickly. Ministers also face a policy test: how to repair thousands of homes without derailing the wider insulation drive, and how to ensure the forthcoming funding rounds don’t repeat the same mistakes.
There are reasons for cautious optimism if lessons are learned. Experts point to practical fixes: mandatory upskilling for EWI/IWI crews, clearer installation standards for tricky details (sills, reveals, junctions), better moisture-risk assessment before works start, and digital “golden-thread” records so every retrofit is traceable from product to installer. Reforms that move quality assurance from paperwork to genuine site supervision will be critical to restoring public confidence.
The bottom line: Britain needs insulation to cut bills and carbon, but it needs it done properly. The latest audits show how far reality fell short—and why the fix must be swift, fair to affected households, and backed by robust regulation that rewards competence rather than volume. That is the only route back to a retrofit market the public can trust.
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