Getting damp after cavity wall insulation put right

A house built after the 1920s probably has cavity walls, with two layers of masonry and a gap between them. Insulation can be blown into that gap to keep heat in.

The Welsh Government says most of this work was done in suitable homes and to good standards. Where a homeowner does find damp or mould afterwards, there is a set order of people to contact. These notes follow it.

Finding the real cause first

Damp in a home has several possible causes. Condensation is the most common. Water can also get in through defects in walls, roofs or windows, or rise from the ground. GOV.UK guidance says rising damp is often misdiagnosed.

The Welsh Government says taking the insulation out is not always the right remedy. It recommends advice from a building surveyor.

Going back to the installer

The first step is to contact the company that installed the insulation. It should investigate and put right any defects. The installer's name should be in the paperwork from the installation.

Some insulation was paid for through the Energy Company Obligation (ECO), a scheme Ofgem administers. For ECO work from April 2015, Ofgem may be able to confirm the installer's name. For work handed over from 1 January 2020 and registered with TrustMark, TrustMark may be able to help.

Using your guarantee

If the installer has closed down or has not dealt with the problem, the next step is the guarantee provider. Work under UK and Welsh Government schemes after 2013 has needed a 25-year guarantee.

The Cavity Insulation Guarantee Agency (CIGA) gives 25-year guarantees for insulation fitted by its registered installers in the UK and the Channel Islands. CIGA can check whether a guarantee was issued for your home. Since 2012 some insurance-backed guarantees have been issued by other providers too.

If you are unhappy with CIGA's findings, you can apply for independent arbitration. You have 12 months from the letter setting out CIGA's findings. An arbitrator can require the installer to put right defects in materials or workmanship. For other insurance-backed guarantees, the Financial Ombudsman Service handles complaints.

Why some installations struggle

The Energy Saving Trust says cavity wall insulation may not suit a home exposed to extreme weather or flooding. It may also not suit a home in poor condition, or one with a cavity narrower than 50mm.

It says repairs to the outside of a building should be finished before any insulation goes in. That includes damaged brickwork, pointing, roofs, gutters and downpipes. Without those repairs, the insulation can trap damp or fail.

If a claims company calls

Some homeowners are contacted by claims companies by phone or at the door. The Welsh Government advises care, because some of these cases are not genuine.

It also warns about a claims company that never pursues the claim. If nobody tells the guarantee provider, and the damage gets worse in the meantime, the guarantee may become invalid. Citizens Advice can refer problems to Trading Standards.

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