NAO Report: 98% Failure Rate

The National Audit Office confirms almost all ECO4 external wall insulation installations will develop damp or mould.

ECO4 Scheme Problems: What You Need to Know

The Energy Company Obligation 4 (ECO4) scheme has been plagued by serious failures. If you've had insulation installed under ECO4 and are experiencing damp, mould, or condensation, you're not alone. Here's everything you need to know.

98%

Expected Failure Rate

23,000+

Homes Affected

£1000s

Remediation Costs

What is ECO4?

ECO4 (Energy Company Obligation 4) is a UK government scheme requiring energy suppliers to fund energy efficiency improvements for low-income and vulnerable households. Running from April 2022 to March 2026, the scheme has a budget of £1 billion per year.

The scheme focuses on installing insulation and heating upgrades, including:

External wall insulation (EWI)
Internal wall insulation (IWI)
Cavity wall insulation
Loft insulation
Room-in-roof insulation

The NAO Report Revelations

In November 2024, the National Audit Office published a damning report on government insulation schemes. The key findings include:

98% failure rate: Nearly all ECO4 external wall insulation will develop damp or mould
Serious failings: Problems identified at "every level" of oversight
Trustmark failures: The quality assurance scheme failed to prevent poor installations
23,000+ homes affected: Thousands of vulnerable households now facing expensive repairs

Common ECO4 Problems

Damp and Mould

The most common issue. External wall insulation traps moisture against the property's walls, leading to:

Black mould growth on interior walls
Damp patches and staining
Musty odors
Deteriorating plaster and decoration
Health issues (respiratory problems, allergies)

Condensation

Poorly installed insulation disrupts the property's breathability, causing:

Excessive condensation on windows
Water pooling on sills
Streaming walls during cold weather
Rotting window frames

Structural Issues

In severe cases, trapped moisture can cause:

Damage to the underlying wall structure
Crumbling brickwork
Timber rot
Reduced property value

Why Did This Happen?

The NAO report identified multiple failures in the ECO4 system:

Poor oversight: Trustmark's quality assurance was inadequate
Rushed installations: Contractors prioritized volume over quality
Wrong methods: External wall insulation applied inappropriately to solid-walled properties
No accountability: Difficult to hold installers responsible after problems emerge
Insufficient checks: Post-installation inspections were minimal

Your Rights and Options

Immediate Steps

Document everything: Take photos, note dates, keep all correspondence
Contact the installer: Report the issues in writing
Contact Trustmark: File a complaint if the installer was Trustmark registered
Get a survey: Professional assessment of the damage