Thirty-nine businesses have been suspended from installing new solid wall insulation in people's homes after routine checks by TrustMark, the independent body that oversees tradespeople working in homes, uncovered examples of substandard work fitted since 2022 under the Energy Company Obligation 4 (ECO4) and the Great British Insulation Scheme (GBIS)1. The Department for Energy Security and Net Zero announced the action on 23 January 20251.
The government said the problems were found under both schemes, which it describes as inherited1. Official statistics cited by the department show that to the end of November 2024, just over 65,000 external wall insulation and internal wall insulation measures had been fitted in around 65,000 households under ECO4 and GBIS1. The department said examples of substandard installation range from missing or incomplete paperwork, insufficient ventilation, or missing or exposed insulation, which if left unchecked could lead to damp and mould, adding that while this is a serious issue, it is not considered a widespread threat to safety1.
Installers responsible for the work will be required to fund repairs themselves under protections in the schemes, and the government said no household should be asked to pay any money by an installer1. Businesses that do not fulfil their obligation to put issues right will remain banned from installing new solid wall insulation on any government scheme1. Ofgem has begun writing to all affected households, explaining that qualified professionals have started a system of checking every installation under the schemes; in some cases an on-site visit will follow to determine whether a repair is needed, and if so the certification body that oversees the installer, or TrustMark, will arrange to fix the problem1.
Miatta Fahnbulleh, Minister for Energy Consumers, said:
"I know this news will be concerning for people who have had external or internal wall insulation fitted through either scheme we have inherited."
The department said the government is confident these systemic issues are particular to solid wall insulation installed under ECO4 and GBIS, because it considers there is a stronger system of checks and balances for other energy efficiency schemes delivered through local authorities and social housing providers1. It named the Home Upgrade Grant (HUG), Local Authority Delivery (LAD) and Social Housing Decarbonisation Fund (SHDF) as other government schemes1.
Why it matters for households
Solid wall insulation is one of the more disruptive and harder-to-reverse measures a home can take, and the failures described here concern work already installed rather than work still to be booked. For a household, the practical questions are whether their installation is among those affected, whether any defect is one that could lead to damp and mould, and who carries the cost of putting it right. The government's position is that the installer pays and the household does not1. The checking process is being run through Ofgem, with letters going to affected households, and repairs arranged through the installer's certification body or TrustMark1. The department has not reported how many of the roughly 65,000 installations will need repair, nor how long the checking programme will take1.
What happens next
Ofgem has started writing to affected households and a system of checking every installation under the two schemes is under way, with on-site visits where needed1. The government said ministers will press ahead with an overhaul through the Warm Homes Plan, covering how installers working in people's homes are certified and monitored and where homeowners turn for rapid action and enforcement when things go wrong1. No date has been reported for that legislation.