MoneySavingExpert.com homepage
Cutting your costs, fighting your corner
Founder, Martin Lewis · Editor-in-Chief, Marcus Herbert
Search bar closed.
MSE News

Solid wall insulation fitted under official Government schemes may be putting homes at risk of damp and mould – what we know so far

White insulating material being applied to external wall of building
Clare Casalis
Clare Casalis
Energy & Utilities Analyst
Created 23 January 2025 | Edited 28 January 2025

Government-backed energy-efficiency measures intended to keep your home warm and lower your bills could instead be putting your property at risk of damp, mould and other serious issues. It comes after an independent body uncovered "widespread cases of poor quality" solid wall insulation fitted since 2022.

Trustmark, the independent body which oversees tradespeople working in homes, said it had found "significant examples" of solid wall insulation installed under two major Government schemes "that did not meet the required standard". This included:

  • Exposed insulation or poor ventilation that could, if not fixed, lead to damp and mould over time.

  • A "very small number" of properties raising serious health and safety concerns, such as incorrectly fitted wiring – in these cases, the problems are expected to be resolved within 24 hours.

  • More minor issues, such as missing or incomplete paperwork.

Following the findings, 39 installers have been suspended from installing new solid wall insulation in people's homes. We asked the Government for a list but it told us it wouldn't be publishing this.

Botched solid wall insulation installed under Government-backed schemes

These issues relate to solid wall insulation installed under the 'Energy Company Obligation 4 (ECO4)' and 'Great British Insulation Scheme (GBIS)' initiatives. These were launched by the last Government in April 2022 and May 2023 respectively, and have continued under the current Government.

The schemes enable eligible households to apply for free energy-efficiency upgrades, including solid wall insulation, through their energy supplier or local council.

Solid walls (without gaps or cavities) are most common in properties built before the 1920s. Insulating them involves adding a layer of material to the inside or outside to trap heat and reduce the need to use your heating as often.

A total of 65,000 households have had solid wall insulation fitted under ECO4 and GBIS to date, according to the latest Government figures. However, it's not yet clear how many of these installations could be affected.

You'll be contacted directly if you're impacted

If you've had solid wall insulation fitted under either the ECO4 or GBIS scheme since April 2022, it's not necessarily faulty or unsafe, so don't panic.

The Government says you can expect to receive a letter from energy regulator Ofgem within the next three weeks, explaining how it will determine if your home has been affected.

Over the coming weeks, qualified professionals overseen by Ofgem will review photographic evidence and carry out on-site audits of homes they believe to be affected.

You WON'T have to pay for remediation work

Where issues are found, the installer will be required to fix the problem(s) as soon as possible, at no cost to you. Installers will then need to provide evidence to TrustMark to prove the issues have been properly fixed.

If the installer has stopped trading, you should be covered by a guarantee that will cover costs up to £20,000. The details of this should be set out in the paperwork you got at the time of the initial installation.

We asked the Government what you can do if you don't want the remediation work to be done by the same installer. It didn't answer directly, but it told us you can contact TrustMark for more information.

Other energy-efficiency measures are thought to be unaffected

The Government says it's "confident" that the systemic issues identified by TrustMark are specific to solid wall insulation installed under the ECO4 and GBIS.

This is because there is a "stronger system of checks and balances" in place for other energy efficiency schemes delivered through local authorities and social housing providers.

MSE Email icon 4 February 2025

For all the latest deals, guides and loopholes simply sign up today - it’s spam free!

Add £1,000s to your pension
Martin's 16 pension boosters
Car insurance 16% cheaper
Don't settle at renewal
New cheapest loan
Now under 6%
Delay EV road tax
With our trick
Barclays outage help
How to reclaim
FREE £150 ending
Grab bank switch cash
20 Walkers 90p
With our code
Tools and calculators

Clever ways to calculate your finances

Find your odds of getting top cards
Find your odds for getting a cheap loan
Compare broadband, phone & TV deals
Compares thousands of mortgages
Eight calcs to help you work out the cost
We ensure you’re on the cheapest tariff