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Post updated: February 5th, 2025
If you’ve had solid wall insulation fitted under the Energy Company Obligation 4 and Great British Insultation Schemes (GBIS) since 2022, it may be ‘substandard’, homeowners have been warned.
Routine checks carried out by Trustmark have uncovered examples of solid wall insulation problems including:
As a result of the findings, 39 businesses have been suspended from installing solid wall insulation in government schemes and installers responsible for the substandard work will be required to fix the work at no cost to households, Minister for Energy Consumers Miatta Fahnbulleh told the House of Commons on Thursday 23 January. Find a list of the suspended businesses here.
Installers responsible for substandard work will remain banned from installing new solid wall insulation on any government scheme if they don’t fulfil their obligation to put any issues right.
Just over 65,000 households have had external wall insulation and internal wall insulation measures fitted using the Energy Company Obligation 4 (ECO4) scheme and Great British Insulation Scheme, according to official government figures.
However, it’s unclear how many of these homes have been fitted with substandard solid wall insulation.
If you’ve had external wall insulation or internal wall insulation fitted through one of these government schemes, you may be very concerned about what to do next. Here’s the government’s advice to households:
The letter will be sent to the address of the property where the work has been done. So tenants are being asked to tell their landlord about the letter.
You’ll find more information on the GOV.UK guidance page.
Paula Higgins, Chief Executive of the HomeOwners Alliance, says, ‘We’re extremely frustrated that people who thought they were doing the right thing for their homes, their energy bills and the environment by investing in improving their home’s energy efficiency via a government scheme have been badly let down.
‘It’s not the first time it has happened: many people who had spray foam insulation fitted under government schemes are still facing difficulties today when trying to remortgage or sell their homes due to having had it installed.
‘However, with the case of solid wall insulation problems we’re pleased to see the government has taken swift action.
‘But we still have the following concerns:
KEY INFORMATION
There are two types of solid wall insulation: internal wall insulation and external wall insulation. It’s used by people who have solid walls– and therefore you can’t install cavity wall insulation – to make their home more energy efficient.
With both types, if you have solid walls you’ll need to ensure they can breathe, otherwise you’re at risk of damp issues.
Internal wall insulation involves fitting insulation boards to the walls inside your home. Or by fitting a stud wall filled with insulation material.
The cost of internal wall insulation depends on how many rooms you are renovating, the size of the walls and the type of material being used. But Energy Saving Trust estimates installing internal wall insulation in a typical three-bedroom semi-detached home would be £7,500.
External wall insulation involves fixing a layer of insulation material on your home’s exterior walls, then covering it with a special type of plasterwork or cladding.
According to Checkatrade, the cost of external wall insulation is usually around £100 per sq/m. And the average cost ranges from £8,000 for a small flat, rising to £22,000 for a large detached house.
Find more information on these and other types of insulation in our guide How to make your home more energy efficient.
If you meet certain criteria, you may be eligible to have multiple energy-efficiency improvements to your home under the Energy Company Obligation (ECO). It requires energy suppliers to help households cut their heating costs by fitting energy-saving measures ranging from loft and wall insulation to air source heat pumps.
The current scheme ECO4, which runs until 31 March 2026, focusses on improving the least energy efficient homes (properties with an EPC rating rating of D-G) and households in fuel poverty. The scheme also aims to deliver a more complete upgrade of those homes, shifting to a multi-measure ‘whole-house retrofit approach’.
Under the ECO4 scheme you may also be able to get your boiler repaired, upgraded or even replaced, and if you own your own home, you might qualify for free heating controls, such as thermostatic radiator valves, as well as other measures such as improved window glazing. These measures are not available under the Great British Insulation Scheme.
This extends the support offered by the ECO4 scheme to those who don’t receive government benefits. The scheme is open to homeowners, landlords or tenants. But if you’re renting, you’ll need your landlord’s permission before any insulation can be installed.
You may get support if your home:
The types of insulation you may be able to get support to install include cavity wall insulation, solid wall insulation (internal or external), loft insulation, flat or pitched roof insulation, underfloor insulation, solid floor insulation and room-in-roof insulation
You can check your eligibility. However, you’ll only be able to get one type of insulation installed and you may need to pay a proportion of the costs.
Find out in a matter of minutes whether you qualify for the Great British Insulation Scheme by using this online eligibility checker. If you’re eligible, your energy supplier will contact you within 10 working days asking for extra information and to arrange an assessment of your property. Alternatively phone 0800 098 7950 or contact your supplier directly.
Find more on these and other help available in our guide on Energy grants and how to get them.
March 25, 2025 
