Who is liable for badly installed cavity wall insulation?

Several parties can carry liability for poor cavity insulation, sometimes together. The sections below explain each and how they connect.

The installer's responsibility

The installer is the first place liability usually rests. Under the Consumer Rights Act 2015, work must be carried out with reasonable care and skill, and a contractor who fits insulation defectively — bridging the cavity, leaving gaps, blocking air bricks — is in breach of that duty and of the contract. While the installer is trading, you can hold them responsible directly: ask them to put the defect right, and if they refuse you can pursue a contract or negligence claim. The CIGA guarantee process also expects the installer to be approached first where they still exist, because they should remedy their own work.

The installer's duty covers more than the physical act of pumping in the fill. A competent contractor is also expected to have checked that the property was suitable, that the cavity was clear and of an appropriate width, and that air bricks, weep holes and other features were protected. Failures at any of these points can amount to a breach. This is why an installer cannot usually escape responsibility by pointing only at the material — the way the job was assessed and carried out is part of what they are liable for, and a defect in that process sits squarely with them while they remain in business.

The surveyor and suitability

Cavity wall insulation is not suitable for every property, and a survey should establish that before any fill goes in. Walls that are highly exposed to driving rain, already damp, or of unusual construction may be unsuitable. If the person who surveyed the property wrongly assessed it as suitable, and damp follows, liability can extend to them for a negligent assessment — separate from the quality of the installation itself. In many cases the same company surveyed and installed, so the two overlap; but where a distinct surveyor was involved, their assessment is a possible source of liability in its own right.

Indicative liability map for guidance. Sources: CIGA; Consumer Rights Act 2015.

Where CIGA fits in

CIGA does not replace the installer's liability so much as back it up. The guarantee exists to ensure that if the installer cannot or will not put a defect right — most importantly because they have ceased trading — the homeowner is still protected. In that situation CIGA effectively takes on responsibility for investigating and remedying genuine defects for the 25-year term. This is why the guarantee follows the property and survives the original company. So when people ask who is liable after an installer has closed, the practical answer is usually CIGA, provided the work was registered and the defect falls within the guarantee.

It helps to think of the guarantee as a backstop rather than a substitute. While the installer exists and is willing to act, they remain the primary route, and CIGA generally expects them to be given the chance to remedy their own work. The scheme moves to the front only when that primary route fails — through refusal, dispute or insolvency. Understanding this layering prevents two common mistakes: assuming CIGA will step in immediately while the installer is still trading, and assuming nothing can be done once the installer has gone. Both misread how the responsibilities sit in relation to each other.

Finance providers and multiple parties

If the insulation was paid for under a regulated credit agreement, section 75 of the Consumer Credit Act can make the finance provider jointly liable with the installer for breach of contract or misrepresentation, within the qualifying limits. That matters because the lender remains in business even if the installer fails. In a single case it is common for liability to point in more than one direction at once — the installer for the workmanship, the surveyor for suitability, CIGA as guarantor, and possibly the lender. The right route then depends on which party caused the specific fault, which still exist, and which offers the most reliable remedy.

In practice, sorting out liability is less about choosing one party to blame and more about matching each element of the problem to whoever is answerable for it. A wall that was both unsuitable for filling and then filled badly involves two distinct failures, and the evidence that establishes one may differ from the evidence that establishes the other. This is why an independent survey that diagnoses the cause is so central: it does not just prove there is a defect, it points to where in the chain the fault arose. Once the fault is pinned down, the question of who is liable tends to answer itself, and the homeowner can pursue the route — installer, surveyor, guarantor or lender — that actually fits the failure rather than the one a marketing approach happens to push.

Frequently asked questions

Sources & further reading

• Consumer Rights Act 2015 — gov.uk legislation
• CIGA — guarantee and liability

Figures on this page are typical UK ranges drawn from published sources and depend on your specific property. They are guidance, not a quotation.