What is the difference between a Defect, a Symptom, and a Cause – and why does that distinction matter when writing a survey report?
posted 29th June 2026
A Cause is the underlying reason that the symptom exists – the root of the problem. The damp patch may be caused by a failed roof covering, a blocked gutter, or a plumbing leak. The crack may be caused by thermal movement, differential settlement, or lintel failure.
A Defect is the condition itself – the element or component that has failed, deteriorated, or been constructed incorrectly. It sits between symptom and cause. The defective element might be the roof covering, the lintel, or the drainage channel.
The distinction matters enormously in practice for several reasons:
• If you report only the symptom, you have described what you saw but not diagnosed the problem. That is not a competent survey.
• If you misidentify the cause, the client may carry out remedial works that address the wrong thing entirely, wasting money and leaving the underlying problem unresolved.
• In an expert witness or dispute context, conflating symptom, defect, and cause will undermine your credibility and potentially expose you to a negligence claim.
• A well-structured report should move logically from symptom, to defect, to probable cause, and then to recommendation – keeping each stage clearly separate so the client and any other professionals reading the report can follow your reasoning.
