Expert witnesses in housing disrepair cases: a guide for professionals

In housing disrepair litigation, expert witness evidence is central to how courts assess the nature, extent, and cause of defects, and to the quantum of compensation. This article sets out the key principles governing expert evidence in disrepair cases, the duties owed to the court, and practical considerations for professionals instructed in this context.

The role of expert evidence in disrepair claims

Housing disrepair claims typically involve technical questions that go beyond the knowledge of lay fact-witnesses or the court itself. The most common areas requiring expert input are:

• Building surveying: the nature and extent of disrepair, its cause, the works required to remedy it, and their cost
• Environmental health: the effect of conditions on health and habitability, including damp, mould, and ventilation assessments
• Structural engineering: where defects involve the structural fabric of the property
• Causation disputes: where landlord and tenant disagree about whether a defect was caused by a structural failure or tenant misuse

Expert evidence is admitted under the Civil Procedure Rules (CPR) Part 35 and the accompanying Practice Direction. Permission from the court is required before expert evidence can be relied upon.

The overriding duty to the court

An expert witness owes an overriding duty to the court. This duty takes precedence over any duty owed to the instructing party. The expert must:

• Provide independent, objective, and unbiased opinion
• State the substance of material facts upon which the opinion is based
• Make clear which matters lie within their expertise
• Distinguish between matters of fact and opinion
• Identify and explain any qualification or limitation on the opinion

An expert who advocates for the instructing party, rather than genuinely assisting the court, risks sanctions including adverse costs orders and having evidence struck out.

Form and content of the expert report

CPR Part 35 requires expert reports to comply with Practice Direction 35. Every report must:

• State the expert's qualifications
• Identify the instructions received and the documents relied upon
• Identify any facts or assumptions upon which the opinion is based
• State where a question falls outside the expert's expertise
• Contain a statement of truth and the Part 35 declaration that the expert understands and has complied with their duty to the court

In disrepair cases, the survey report should include: an itemised schedule of defects, photographs and measurements, assessment of cause, remedial works specification, and an estimate of costs. The report should address conditions as they existed at the material time (the period of claim), not merely at the time of inspection.

Single joint experts

Courts in disrepair cases, particularly fast-track and intermediate cases, commonly direct parties to use a single joint expert (SJE) rather than each instructing their own expert. An SJE is appointed by both parties jointly and owes their duty equally to both.

Where an SJE is directed:

• Both parties draft and agree on instructions, or the court settles disputed points
• Both parties can put questions to the SJE under CPR Part 35.6
• The SJE's report is generally determinative on technical issues unless the court permits further expert evidence

Solicitors should advise clients of the implications of SJE directions early, including that the expert's conclusions cannot simply be rejected in favour of a second opinion.

Expert discussions and joint statements

Where each party has their own expert, the court will normally direct a without prejudice discussion between experts before trial, followed by a joint statement setting out agreed and disputed points. This requirement (CPR Part 35.12) is designed to narrow the issues before the court.

Solicitors must not attend the experts' discussion. The joint statement must be signed by both experts and is binding in the sense that neither expert should resile from it at trial without permission.

Causation and the disrepair period

A critical function of expert evidence in disrepair cases is establishing when defects first arose and whether the landlord had notice. The quantum of compensation, typically a percentage of rental value, depends on the length of the disrepair period. Experts should be instructed to address:

• When, on the balance of probabilities, each defect first became apparent
• Whether earlier works would have prevented subsequent deterioration
• Whether any claimed damage is attributable to the landlord's failure or to other causes

When should professionals seek further guidance?

For complex multi-defect claims, expert evidence from more than one discipline may be needed with court permission. Where causation is strongly disputed, for example, an allegation that condensation rather than structural penetrating damp caused mould, the quality of expert evidence often determines the outcome.

Sources

• Pre-Action Protocol for Housing Conditions Claims, England (justice.gov.uk)
• Landlord and Tenant Act 1985, Section 11 (legislation.gov.uk)
• Homes (Fitness for Human Habitation) Act 2018 (legislation.gov.uk)

Related articles

• Housing disrepair, the pre-action protocol for professionals
• Disrepair witness statements, guidance for professionals