Thousands of homes hit by failed insulation

A new spending watchdog investigation has revealed that tens of thousands of UK homes insulated under government energy-efficiency schemes now need urgent repairs.
According to the National Audit Office (NAO), almost all properties with external wall insulation (EWI) installed under the ECO4 and Great British Insulation Scheme have serious defects that could lead to damp, mould and structural decay if not fixed.

Key findings include:

• 98 % of homes with external wall insulation have moisture problems
• Around 29 % of internal wall insulation installations need repair
• Over 1,000 homes are classed as immediate health-and-safety risks

These issues stem from poor installation, trapped moisture, and weak quality control — leaving many families living with condensation, peeling paint and unhealthy indoor air.

Why failed insulation leads to damp and mould

External wall insulation is designed to keep heat inside by attaching insulation boards to exterior walls and sealing them with render. When installed incorrectly, rainwater can become trapped behind the insulation, preventing the wall from drying naturally.

This trapped moisture can cause:

• Persistent damp patches and paint blistering
• Black mould growth on internal walls and ceilings
• Rotting timbers and damaged plaster
• Unpleasant musty odours and poor air quality

If the problem is not treated properly, moisture can spread deep into brickwork, cavities and floor structures — leading to more costly repairs later.

Structural building drying – the essential repair stage

Before any new insulation or decoration can be applied, affected buildings must undergo professional structural drying. This process removes deep moisture from walls, floors and cavities using industrial dehumidifiers, high-powered fans and, where necessary, heaters to accelerate evaporation.

A typical drying programme includes:

1. Survey and assessment – Moisture mapping and thermal imaging to locate damp areas.
2. Removal of wet materials – Damaged insulation and render are taken out to allow airflow over affected materials.
3. Dehumidification and air movement – Powerful drying equipment pulls moisture out of affected building materials.
4. Ongoing monitoring – Moisture readings are recorded until the building reaches safe levels, then reinstatement can take place.

Professional drying ensures that hidden moisture is completely eliminated, thereby preventing future damp, mould or insulation failure.

Restoring and protecting your home

Once your property is fully dried, contractors can safely begin repairs, such as:

• Re-rendering external walls with breathable materials
• Replacing insulation to modern moisture-resistant standards
• Improving ventilation in lofts, cavities and void spaces
• Sealing cracks and maintaining gutters to prevent water ingress

Skipping the drying stage risks trapping dampness behind new insulation layers, undoing all the remedial work.

Hire industrial dehumidifiers for safe, efficient drying

If your property has been affected by failed insulation, damp or mould, hiring professional building drying equipment is the fastest way to restore it safely. Our range of powerful dehumidifiers and air movers removes moisture quickly, helping homeowners, landlords and contractors prepare buildings for insulation repair or decoration.

At Dehumidifier Rental, we can hire you our energy-efficient models that deliver maximum drying power with minimal electricity use. Our newest models are increasingly economical and are perfect for short-term moisture problems.

We operate in London and the South East of England and are happy to advise what equipment may be suitable. Call us on 020 7760 7660, or email at help@dehumidifier-rental.co.uk Just let us know how many rooms are affected, and their approximate size, and we will give you a quote for suitable equipment.

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