Fewer than one in three expert witnesses who appear in English civil courts are ever recalled for a second instruction by the same legal team. The primary reason is not lack of technical knowledge — it is a failure to meet the procedural and impartiality standards set out in CPR Part 35. For building surveyors, understanding Civil Procedure Rules Part 35 for Building Surveyors: Enhancing Expert Witness Credibility in 2026 is no longer optional; it is the foundation of a sustainable and respected expert practice. This article breaks down the core requirements, explains how to structure compliant reports in property disputes, and offers practical preparation strategies for cross-examination.
Key Takeaways
- CPR Part 35 places the expert's overriding duty to the court above any obligation to the instructing party.
- Expert reports must follow a specific structure under Practice Direction 35, including qualifications, relied-upon materials, and a mandatory statement of truth.
- The RICS 5th edition of "Surveyors Acting as Expert Witnesses" (2025) provides updated compliance guidance aligned with CPR Part 35.
- Written questions from opposing parties under CPR 35.6 must be answered within 28 days, and those answers become part of the formal report.
- Cross-examination preparation is as important as report writing — credibility is won or lost in the witness box.
What Is CPR Part 35 and Why It Matters to Building Surveyors
Part 35 of the Civil Procedure Rules governs the use of expert evidence in civil proceedings in England and Wales [1]. It applies whenever a court grants permission for expert evidence to be admitted — which in property disputes is extremely common. Cases involving structural defects, boundary disagreements, dilapidations claims, and party wall damage all routinely require expert surveying evidence.
The rule establishes a clear hierarchy: the expert's duty runs to the court first, not to the solicitor or client who instructed them [1]. This is not a technicality. Judges take it seriously, and so do opposing counsel. A surveyor who appears to be advocating for their client rather than advising the court risks having their evidence dismissed or, worse, attracting a formal judicial criticism that damages their professional reputation.
For those involved in party wall disputes or boundary disputes, the stakes are particularly high. These cases often hinge entirely on the expert's opinion, meaning the quality and compliance of the expert report can determine the outcome of the litigation.
"The expert's overriding duty is to the court. That duty overrides any obligation to the person from whom the expert has received instructions or by whom the expert is paid." — CPR Part 35.3 [1]
The Structure of a Compliant Expert Report Under Practice Direction 35
Practice Direction 35 sets out precisely what an expert report must contain [3]. Building surveyors who skip or abbreviate any of these elements risk having their report challenged or excluded at a preliminary hearing.
Mandatory Content Requirements
A compliant expert report must include the following:
- Expert's qualifications: Full details of relevant professional qualifications, memberships, and experience in the specific area of dispute.
- Statement of the facts and instructions: A clear description of the instructions received and the factual basis upon which the opinion is formed.
- Literature and materials relied upon: Every source, standard, or document that informed the expert's conclusions must be identified.
- Range of opinion: Where there is a range of professional opinion on a matter, the report must acknowledge it and explain where the expert's view sits within that range.
- Summary of conclusions: A concise, plain-language summary that a non-specialist judge can follow.
- Statement of truth: A declaration that the expert understands their duty to the court and that the report is accurate to the best of their knowledge [3].
The statement of truth is not a formality. Signing it carries the same legal weight as giving sworn evidence. A surveyor who signs a statement of truth on a report they know to be incomplete or one-sided could face professional disciplinary action from the RICS as well as potential contempt of court proceedings.
The RICS 5th Edition: Updated Guidance for 2026 Compliance
The Royal Institution of Chartered Surveyors published the 5th edition of its professional standard "Surveyors Acting as Expert Witnesses" in 2025 [2]. This edition reflects the evolving expectations of the courts and provides structured guidance on how surveyors should apply CPR Part 35 requirements in practice.
Key updates in the 5th edition include reinforced emphasis on impartiality, clearer guidance on the scope of supplementary information that may accompany a report, and updated best practices for joint statements produced after experts meet [2]. Surveyors undertaking expert witness work in 2026 should treat this document as essential reading alongside the rules themselves.
Those conducting structural surveys in London or preparing specific defect reports will find the RICS guidance particularly useful when translating technical findings into court-ready language.
Civil Procedure Rules Part 35 for Building Surveyors: Writing Impartial Reports in Property Disputes
The most common reason expert reports fail in court is not technical inaccuracy — it is the appearance of bias. Judges are experienced at identifying reports that have been written to win rather than to advise. The following principles help building surveyors maintain the impartiality that CPR Part 35 demands [1].
Separating Facts from Opinion
A compliant report draws a clear distinction between observed facts and professional opinion. When a surveyor inspects a property and notes cracking in a party wall, the crack itself is a fact. The cause — whether settlement, thermal movement, or inadequate construction — is an opinion. Conflating the two is one of the most common drafting errors and one of the easiest for opposing counsel to exploit during cross-examination.
Practical tip: Use consistent signposting language. Phrases such as "the inspection revealed…" for facts and "in my professional opinion…" for conclusions make the distinction transparent to the court.
Acknowledging Contrary Views
Practice Direction 35 explicitly requires experts to acknowledge where a range of professional opinion exists [3]. A report that presents the expert's view as the only possible conclusion is immediately suspect. Courts expect experts to engage honestly with alternative interpretations, even where those alternatives support the opposing party's case.
This does not mean undermining one's own conclusions. It means demonstrating intellectual honesty — a quality that significantly enhances credibility in the witness box [4].
Avoiding Selective Use of Evidence
Cherry-picking evidence to support a predetermined conclusion is the hallmark of advocacy, not expert opinion. If a schedule of condition shows pre-existing damage that weakens the instructing party's claim, the expert is required to disclose it. Omitting inconvenient evidence is a breach of the duty to the court and will almost certainly be exposed during cross-examination.
| Common Report Errors | Impact on Credibility | CPR Part 35 Requirement |
|---|---|---|
| Conflating facts and opinion | High — undermines entire report | Separate factual basis from conclusions |
| Ignoring contrary evidence | High — suggests advocacy | Acknowledge range of opinion |
| Missing statement of truth | Procedural — report may be excluded | Mandatory under PD 35 |
| Vague qualifications section | Medium — weakens authority | Full qualifications required |
| Failure to cite relied-upon materials | Medium — conclusions appear unsupported | All sources must be listed |
Handling Written Questions Under CPR 35.6
Once an expert report is served, the opposing party has 28 days to submit written questions for clarification [1]. These questions must be directed at clarifying the report — not at obtaining a second opinion or introducing new issues. The expert's answers become a formal part of the report and are treated as evidence.
Building surveyors should approach these questions with the same care as the original report. Answers must be precise, honest, and consistent with the conclusions already expressed. Inconsistency between the original report and the answers to written questions is a significant vulnerability during cross-examination.
The Civil Justice Council's guidance reinforces that experts must be responsive and transparent throughout this process [5]. Delays or evasive answers attract judicial criticism.
Civil Procedure Rules Part 35 for Building Surveyors: Preparing for Cross-Examination
Cross-examination is where credibility is truly tested. A technically excellent report can be undermined by poor performance in the witness box, and a modest report can be rescued by a composed and authoritative expert. Preparation is the key differentiator.
Understanding the Opposing Expert's Report
Before giving evidence, the building surveyor should have read the opposing expert's report thoroughly and identified every point of disagreement. In most cases, the court will have directed the experts to meet and produce a joint statement under CPR 35.12, identifying agreed matters and areas of genuine dispute. This document becomes the framework for cross-examination.
Surveyors involved in complex commercial dilapidation surveys or party wall award proceedings should pay particular attention to the joint statement process. Courts expect experts to have genuinely engaged with each other's positions, not simply restated their original views.
Techniques for Maintaining Composure Under Pressure
Cross-examination by a skilled barrister is designed to test the limits of an expert's opinion. Common tactics include:
- Hypothetical questions: Asking the expert to agree with propositions that subtly shift the factual basis of their opinion.
- Selective quotation: Reading a passage from a relied-upon source out of context to suggest the expert's conclusion is unsupported.
- Incremental concessions: Securing small agreements that cumulatively undermine the expert's main conclusion.
The most effective defence against all three is a thorough understanding of the report and the materials that underpin it. An expert who knows their report inside out can confidently explain why a hypothetical does not apply to the facts, correct a misquotation, and resist incremental concessions without appearing evasive.
Key preparation steps before giving evidence:
- Re-read the full report and all relied-upon materials at least 48 hours before the hearing.
- Review the joint statement and identify the precise areas of dispute.
- Prepare clear, concise explanations for every conclusion — in plain language a non-specialist judge can follow.
- Anticipate the strongest points in the opposing expert's report and prepare honest, reasoned responses.
- Practice delivering answers at a measured pace — courts value clarity over speed.
The Demeanour of a Credible Expert
Courts observe how an expert behaves as much as what they say. An expert who becomes defensive, dismissive, or visibly partisan loses credibility rapidly. The qualities that courts consistently associate with reliable expert evidence are:
- Measured confidence: Expressing opinions firmly but without arrogance.
- Intellectual honesty: Conceding points that should be conceded without being prompted.
- Clarity: Avoiding jargon and explaining technical concepts in accessible terms.
- Consistency: Giving answers that align with the written report.
These qualities are not innate — they can be developed through preparation, mock cross-examination sessions, and a disciplined approach to report writing [4].
Joint Statements and the Duty to Narrow Issues
Under CPR 35.12, the court may direct experts to meet and produce a joint statement setting out agreed matters and the reasons for any remaining disagreement [1]. This process is one of the most valuable — and most misunderstood — aspects of expert evidence.
The joint statement is not a negotiation. Experts must not change their opinions simply to reach agreement. However, they are expected to engage genuinely with the opposing expert's reasoning and to concede points where, on reflection, the other expert's view is correct.
For building surveyors, joint statements in property disputes often cover:
- The cause and extent of structural damage
- The standard of workmanship against which a contractor's performance is measured
- The cost of remedial works
- The condition of a property at a specific date
A well-drafted joint statement narrows the issues the court must decide, saves hearing time, and demonstrates that both experts have approached the case with genuine professionalism. Courts notice — and reward — this.
Conclusion
Civil Procedure Rules Part 35 for Building Surveyors: Enhancing Expert Witness Credibility in 2026 is not simply a compliance exercise. It is the framework within which building surveyors can build a reputation as trusted, authoritative voices in civil litigation. The rules are clear, the RICS guidance is comprehensive, and the expectations of the courts are well-established.
Actionable next steps for building surveyors in 2026:
- Obtain and study the RICS 5th edition of "Surveyors Acting as Expert Witnesses" alongside the current CPR Part 35 and Practice Direction 35.
- Audit any existing report templates against the mandatory content requirements of Practice Direction 35 — particularly the statement of truth and the range-of-opinion section.
- Develop a disciplined approach to distinguishing facts from opinion in every report.
- Engage seriously with the joint statement process — treat it as an opportunity to demonstrate professional integrity, not a threat to your conclusions.
- Invest in cross-examination preparation, including mock sessions with legal colleagues, before any significant hearing.
Surveyors who master these requirements do not just survive cross-examination — they become the experts that solicitors and courts rely upon, time and again.
For expert surveying advice across a wide range of property matters, explore the resources available from expert surveyors with experience in litigation support and party wall legislation.
References
[1] Part 35 – https://www.justice.gov.uk/courts/procedure-rules/civil/rules/part35
[2] Viewcompounddoc – https://consultations.rics.org/surveyorsasexpertwitness/viewCompoundDoc?clientUID=&docid=16251220&partid=16251540&sessionid=&voteid=
[3] Pd Part35 – https://www.justice.gov.uk/courts/procedure-rules/civil/rules/part35/pd_part35
[4] Expert Witness Impartiality Under CPR Part 35 Building Surveyors Guide To Courtroom Credibility In 2026 – https://kingstonsurveyors.com/expert-witness-impartiality-under-cpr-part-35-building-surveyors-guide-to-courtroom-credibility-in-2026/
[5] Expert Evidence Part 35 Of The Civil Procedure Rules – https://www.quantik.co.uk/insights/articles/expert-evidence-part-35-of-the-civil-procedure-rules/
