OSCAR Onsite | Consumer Guidance
If you are experiencing damp, mould, staining, cold areas, damaged plaster or other problems at a property containing cavity wall insulation, you may be considering contacting your insurer, installer or guarantee provider. Before describing the insulation as "failed", it is important to establish what has actually happened. A failed cavity insulation insurance claim usually begins with the evidence — not with an assumption.
A household insurance policy, a cavity wall insulation guarantee and an installer's responsibilities are separate matters. Whether any of them apply will depend upon the facts, the cause of the problem, the installation history, the available evidence and the wording of the relevant policy or guarantee.
Evidence → Cause → Responsibility → Appropriate Route
📖 In This Guide
Section 01
Damp or damage in a property containing cavity wall insulation does not, by itself, establish that the insulation has failed or caused the problem.
Potential contributing causes may include:
CWI may be relevant. But the presence of insulation and the presence of damp do not, by themselves, prove causation.
A SYMPTOM IS NOT A DIAGNOSIS.
Section 02
A household insurance policy, a CWI guarantee and an installer's responsibilities are three different things.
A household insurance policy is a contract between the policyholder and insurer. Whether a particular loss is covered depends upon the policy wording and the cause of the damage. Policies may distinguish between defective workmanship, defective materials, wear and tear, gradual deterioration, maintenance, an insured event, resultant damage, pre-existing defects and exclusions.
Some policies may provide cover for certain resulting damage where the relevant cause is insured, but this cannot be assumed without reviewing the individual policy.
A cavity wall insulation guarantee is separate from home insurance. A guarantee may provide rights concerning particular defects or remedial matters subject to its own terms, exclusions, conditions, homeowner obligations, installation date and guarantee period. The actual guarantee applicable to the property must be identified.
The installer may also have contractual, consumer-law or scheme responsibilities depending upon who commissioned the work, when it was undertaken, how it was funded, installer status, applicable certification, applicable guarantee and the facts of the complaint.
DO NOT TREAT INSURANCE, GUARANTEE AND INSTALLER RESPONSIBILITY AS THE SAME THING.
Section 03
There is no single universal claim route for every cavity wall insulation complaint.
The correct route depends upon installation date, funding scheme, installer status, guarantee, nature of the problem, insurance policy and available evidence. For historic or ECO-funded CWI complaints, official guidance may direct consumers towards identifying the installer and installation paperwork before considering the relevant guarantee or scheme route.
Do not assume a fixed sequence of installer → CIGA → insurer → Ombudsman. The appropriate order depends on the facts of your case. See Ofgem's CWI complaints guidance for ECO-funded measures.
Section 04
OSCAR recommends assembling an evidence file before approaching an insurer, guarantee provider or installer.
Cavity wall insulation in an existing building is within Building Regulations / Competent Person Scheme arrangements. GOV.UK guidance.
BUILD THE EVIDENCE BEFORE CHANGING THE EVIDENCE.
Section 05
A damp patch on an internal wall cannot reliably establish the condition of an existing CWI installation. Where appropriate, the cavity itself may need inspection.
PHOTOGRAPHED → LOCATED → RECORDED → RETAINED
A small number of convenient inspection points should not automatically be treated as representative of the entire property. An independent CWI inspection establishes that evidence properly.
Section 06
Diagnostic tools are valuable, but each has limits and requires proper interpretation.
Thermal imaging can identify surface temperature differences and thermal patterns that may justify further investigation. It does not, by itself, prove missing insulation, slumped insulation, moisture within the cavity or the cause of damp.
Moisture readings may assist an investigation but require interpretation alongside material, location, weather, ventilation, construction, temperature and other evidence. They cannot, alone, distinguish CWI-related penetrating damp from condensation.
A borescope provides direct visual evidence at the location inspected. However, sufficient representative inspection locations are required before broader conclusions are drawn.
USE DIAGNOSTIC TOOLS TO BUILD EVIDENCE — NOT TO FORCE A PREDETERMINED CONCLUSION.
Section 07
There is no universal answer. Whether a household insurer will cover a particular loss depends upon the individual policy wording, the cause of the damage, applicable exclusions and the facts of the loss.
A policy may distinguish between:
EVIDENCE CAN ESTABLISH WHAT HAPPENED. IT CANNOT CREATE POLICY COVER WHERE NONE EXISTS.
Before approaching an insurer, locate:
Section 08
Consider an example: a homeowner may have damp plaster on a wall that contains cavity wall insulation. That alone does not establish the cause.
THE PRESENCE OF CWI AND THE PRESENCE OF DAMP DO NOT, BY THEMSELVES, PROVE A CAUSAL CONNECTION.
Section 09
Where CWI was installed through ECO or another funded energy-efficiency scheme, additional organisations or complaint routes may be relevant.
Try to establish:
Ofgem provides specific guidance for ECO installation complaints. See Ofgem's CWI complaints guidance and GOV.UK guidance on poor-quality wall insulation.
Section 10
If a guarantee exists, identify and read the actual guarantee applicable to the installation.
For detailed guidance on CIGA guarantees — including Building Regulations, aftercare, property history and Subject Access Requests — see our dedicated page: CIGA Guarantee Claims: What Homeowners Should Check Before Making a Claim.
Section 11
If a property has or may have a CIGA guarantee but the documentation is missing, the homeowner can contact CIGA regarding guarantee records.
A Subject Access Request may separately be used to request personal data an organisation holds about an individual. However, a Subject Access Request is not automatically a way to obtain a free duplicate guarantee certificate.
See our OSCAR CIGA Guarantee Claims & Subject Access Request guide, and the ICO guidance on your right of access.
Section 12
Where an insurance, guarantee or contractual dispute may exist, document the condition of the cavity before substantial extraction wherever reasonably possible.
Once CWI is removed:
Before extraction:
PRESERVE THE EVIDENCE BEFORE CHANGING THE EVIDENCE.
Section 13
OSCAR Onsite does not approach a CWI investigation on the assumption that insulation needs to be removed.
These qualifications were developed to establish structured occupational competency for the specialist people responsible for assessing existing CWI installations and undertaking extraction and clearance. OSCAR's experience includes:
INSPECTION → EVIDENCE → DIAGNOSIS → APPROPRIATE ACTION
Read more about OSCAR's industry recognition and qualification authorship and the OSCAR Academy training and qualifications.
Section 14
An OSCAR Cavity Wall Insulation Condition Inspection Survey is intended to establish the current condition of an existing CWI installation and relevant factors affecting the property.
It can provide technical evidence before decisions concerning:
The CIS process:
The purpose of the OSCAR CWI Condition Inspection Survey is not to manufacture an insurance or guarantee claim. It is to establish the evidence.
Establish the evidence first with an independent OSCAR CWI Condition Inspection Survey.
Section 15
A professional condition report should be structured and honest about what it can and cannot establish.
What was actually seen, recorded or measured.
Photographs, inspection locations and relevant records.
What the findings may indicate.
What cannot reliably be concluded from the evidence available.
What should happen next.
A PROFESSIONAL REPORT SHOULD NOT PRESENT ASSUMPTION AS FACT.
An OSCAR report does not guarantee a successful insurance or guarantee claim.
Section 16
Not every CWI investigation needs to end in extraction. Depending on the evidence, an appropriate outcome might be:
Current evidence does not justify CWI intervention.
A building-envelope or other defect requires attention.
More evidence is required.
A specific area may require intervention.
Evidence warrants referral under relevant arrangements.
Evidence establishes that controlled removal is technically appropriate.
THE REMEDY SHOULD FOLLOW THE DIAGNOSIS.
Section 17
Before contacting the insurer, try to establish the facts.
Be factual. Do not state technical causation as fact where it has not yet been established.
Avoid: "My cavity wall insulation has failed and caused damp."
Prefer: "I have identified damp/damage at a property containing cavity wall insulation and am investigating the cause. I would like the matter considered under my policy based upon the available evidence."
Section 18
If your insurer declines the claim, take it step by step.
Additional evidence may assist where disputed facts or causation are central to the decision. However:
EVIDENCE CANNOT CREATE POLICY COVER WHERE THE RELEVANT LOSS IS EXCLUDED.
Individual Financial Ombudsman decisions relate to their own circumstances. See the Financial Ombudsman Service.
Section 19
This distinction is one of the most important messages on this page.
EVIDENCE CAN PROVE FACTS. IT CANNOT REWRITE AN INSURANCE POLICY.
A technically strong report may help establish condition, damage, cause, cavity characteristics, installation distribution and relevant building defects. But whether the resulting loss is insured is determined by the contract between the policyholder and insurer.
Likewise, a CWI guarantee is governed by its own terms. Installer responsibility is a separate issue again.
Section 20
There is no universal answer. Cover depends on the individual policy, the cause of the loss and the applicable exclusions. A policy may distinguish between defective work itself and damage resulting from an insured event. The relevant policy wording must be reviewed before any assumption is made.
No. Damp has several potential causes including condensation, inadequate ventilation, plumbing leaks, roof defects, failed gutters, deteriorated pointing, defective render and other building defects. The cavity insulation may be relevant, but the property and cavity should be properly investigated before causation is assumed.
There is no single universal sequence for every property. The correct route depends on the installation history, guarantee, scheme arrangements, insurance policy and the nature of the problem identified. Establish the evidence first, then approach the most appropriate party.
No. OSCAR can independently inspect and document the property and cavity. Insurance cover is determined under the policy by the insurer and, where disputed, through the relevant complaint and redress process.
No. A CWI Condition Inspection Survey establishes technical evidence. It cannot guarantee insurance or guarantee-provider liability, which depend on the applicable policy or guarantee terms and the facts of the case.
Where practical, preserve and document the original cavity condition before substantial disturbance — particularly where causation or installation condition may later be disputed. Once insulation is removed, evidence of its previous condition can be lost.
Not on its own. Thermal imaging shows surface-temperature patterns that may justify further investigation. It does not, by itself, prove missing insulation, slumped insulation, moisture within the cavity or the cause of damp.
Not on its own. Moisture readings form one part of a wider investigation and require interpretation alongside material, location, weather, ventilation, construction and other evidence.
Find the installer, guarantee and scheme information and follow the relevant complaint arrangements. Ofgem provides specific guidance for ECO installation complaints, although it does not itself regulate the insulation industry or determine every contractual dispute.
Ask for the written reasons and the policy clauses relied upon, follow the insurer's formal complaint process, and consider the Financial Ombudsman Service where eligible. Additional independent technical evidence may assist where disputed facts or causation are central to the decision.
OSCAR Onsite authored the specialist NVQ qualifications for Cavity Wall Insulation Surveying & Inspection and Cavity Wall Insulation Extraction & Clearance.
INSPECT. EVIDENCE. UNDERSTAND. THEN ACT.
Important Information
This page provides general technical consumer guidance concerning cavity wall insulation. OSCAR Onsite is not an insurer, insurance broker, loss adjuster, solicitor or guarantee provider. An OSCAR inspection can provide independent technical evidence concerning the property, cavity and insulation but does not determine insurance cover, legal liability or whether a guarantee claim must be accepted.
Insurance decisions depend upon individual policy wording and circumstances. Guarantee decisions depend upon the applicable guarantee terms. Consumers should obtain appropriate insurance, legal or other professional advice where required.
OSCAR ONSITE AUTHORED THE TWO SPECIALIST NVQ QUALIFICATIONS FOR CAVITY WALL INSULATION SURVEYING & INSPECTION AND CAVITY WALL INSULATION EXTRACTION & CLEARANCE.