30,000 botched insulation jobs: what homeowners need to know

The government has admitted that 30,000 homes were fitted with botched insulation under its flagship energy-efficiency schemes. That is 30,000 households – many on low incomes or in fuel poverty – who were promised lower bills and instead got damp walls, mould, and wasted money.

As reported by the BBC, ministers confirmed the figure in a written parliamentary answer. The failures span multiple programmes, including the Energy Company Obligation (ECO) and its successor ECO4, which together have insulated hundreds of thousands of homes since 2013. The catch is that while the schemes aimed to cut carbon and fuel bills, poor installation has left many households worse off.

Who qualifies – and who doesn’t

ECO and ECO4 target low-income and vulnerable households, often those on benefits or with low EPC ratings. Installations are funded by energy companies, not homeowners. But the admission covers only cases that have been formally reported and investigated. The real number is likely higher. Ofgem, which oversees the schemes, has previously flagged concerns about installer standards, but enforcement has been patchy.

Homeowners who had insulation fitted under ECO or ECO4 should check for warning signs: cold spots on walls, damp patches, mould growth, or a sudden rise in heating costs. If you suspect a problem, your first step is to contact the installer. If they are unresponsive or no longer trading, report the case to Ofgem’s ECO compliance team. The government has promised a remediation programme, but details are still thin.

What it costs a typical 3-bed semi

For a typical 3-bed semi using 12,000 kWh of gas per year, properly installed cavity wall insulation can save around £300 annually on heating bills. But botched insulation does the opposite: it can trap moisture, reduce thermal performance, and even cause structural damage. Remediation costs vary widely – from a few hundred pounds for a simple vent installation to several thousand for stripping and replacing defective material. The government has not yet set a fixed budget for the remediation scheme, so homeowners may face delays.

Energy Saving Trust recommends that any homeowner considering insulation – whether through a scheme or privately – uses a certified installer registered with a recognised body such as the National Insulation Association or Cavity Insulation Guarantee Agency. The guarantee scheme typically covers work for 25 years, but only if the installer followed correct procedures.

What this means for your EPC rating

A botched insulation job can also harm your EPC rating. The assessor may flag poor installation as a defect, reducing the score. Since April 2024, landlords in England and Wales cannot let properties with an EPC rating below E. A failed insulation job could therefore make a property unlettable. Homeowners planning to sell or rent should check their EPC certificate for any notes on insulation condition.

Ofgem told the BBC it is working with installers to fix the worst cases. But the onus is on the homeowner to report problems. If you had insulation fitted under ECO or ECO4, do not assume it is fine. Check your loft, check your walls, and check your bills. The government’s admission is a start, but without a fast, funded remediation plan, 30,000 homes – and possibly more – will continue to pay for someone else’s mistake.

Homeowners who suspect defective insulation should contact Ofgem’s ECO compliance team via gov.uk. If you are a tenant, report the issue to your landlord and your local council’s environmental health department. The sooner you act, the sooner you can get the fix you were promised.