Expert Evidence in Property Arbitration: How It Differs from Court

An expert witness in arbitration does the same core job as an expert in court: giving an independent, reasoned opinion on a technical question the tribunal cannot answer itself. What changes is the rulebook. The Civil Procedure Rules, including Part 35, do not apply to arbitration. Instead the arbitrator decides how expert evidence is obtained and tested, within the framework of the Arbitration Act 1996 and any institutional rules the parties have adopted. For chartered surveyors, the RICS practice statement on expert witnesses still applies in full. This guide explains where property disputes are arbitrated, how the procedure differs from litigation, and what that means for the surveyor's report.

When does a property dispute go to arbitration rather than court?

Arbitration is a private process agreed by contract. Nobody can be forced into it unless they have signed up to an arbitration clause or agree to arbitrate after the dispute arises. In property, the most common routes are:

• Rent reviews. Many commercial leases provide that, if the landlord and tenant cannot agree the reviewed rent, it is fixed by an arbitrator or an independent expert appointed through the RICS Dispute Resolution Service. Rent review is one of the most common sources of property arbitration in England and Wales. Valuation evidence from a RICS Registered Valuer is central, and the panel's rent review surveyors act on both sides of these references.
• Construction and development contracts. Standard forms such as JCT contracts can name arbitration as the final method of resolving disputes, usually after adjudication. Defects, delay and final-account disputes then go before an arbitrator rather than the Technology and Construction Court.
• Lease renewals under PACT. Professional Arbitration on Court Terms is a joint RICS and Law Society scheme that lets parties to a Landlord and Tenant Act 1954 renewal take the rent and other disputed lease terms out of the county court and have them decided by a surveyor or solicitor arbitrator.
• Agricultural tenancies and joint ventures. Agricultural Holdings Act 1986 disputes have a statutory arbitration route, and development and partnership agreements often contain arbitration clauses covering the value of land or buildings.

Party wall awards, by contrast, are not arbitration in the legal sense, and most boundary and negligence claims still go to court, usually after the mediation step that courts now expect.

How does expert witness arbitration evidence differ from CPR Part 35?

In litigation, CPR 35.4 means expert evidence is admitted only with the court's permission, the report must follow Practice Direction 35, and the expert owes an overriding duty to the court under CPR 35.3. In arbitration none of those provisions bind the tribunal. Section 34 of the Arbitration Act 1996 gives the arbitrator power to decide all procedural and evidential matters, including whether to apply strict rules of evidence and whether evidence is given orally or in writing. In practice this produces several differences:

• Permission is replaced by directions. The tribunal sets out in a procedural order how many experts each side may call, which disciplines, the sequence of exchange and whether a joint statement is required. Most arbitrators borrow heavily from Part 35, so a report that would satisfy a court will rarely fall short.
• The duty runs to the tribunal. Although CPR 35.3 does not apply, the expert's duty of independence does. The RICS practice statement Surveyors acting as expert witnesses applies to every forum, and institutional codes such as the Chartered Institute of Arbitrators' protocol on party-appointed experts restate the same principle.
• Written questions are not automatic. CPR 35.6 gives a party the right to put written questions to the other side's expert; in arbitration that right exists only if the tribunal directs it.
• The arbitrator may be a surveyor. In rent review and PACT references the tribunal is often a chartered surveyor, so reports are read by a technically literate decision-maker who will test the comparables and adjustments closely.
• The tribunal can appoint its own expert. Section 37 of the 1996 Act allows the arbitrator to appoint an expert or assessor, with the parties able to comment on the resulting advice.

What does the surveyor's arbitration report need to contain?

Because the procedural order governs, the first task for any expert is to read it and any adopted rules, such as the RICS arbitration rules or the IBA Rules on the Taking of Evidence, before drafting. A well-prepared report will then typically set out:

• the expert's qualifications and relevant experience;
• the instructions received and the questions the tribunal has asked the experts to address;
• the documents, inspections and comparable evidence relied on, with sources identified so the other side can test them;
• the analysis, with assumptions stated and alternative conclusions given where the facts are disputed;
• a statement of independence and a declaration of truth in the form the tribunal has specified.

Rent review reports have additional conventions: the hypothetical lease terms, the valuation date, the treatment of tenant's improvements and the adjustment of comparables all follow the lease wording. The panel's guide to valuation dispute expert evidence covers the Red Book standard that applies.

How is expert evidence tested at an arbitration hearing?

Arbitration is flexible about format. Many rent review references are decided on documents alone, with experts exchanging reports, replies and a joint statement before the arbitrator issues a reasoned award. Larger construction and development disputes usually involve an oral hearing in a private meeting room rather than a courtroom. Cross-examination follows the same pattern as litigation, but arbitrators make frequent use of concurrent expert evidence, questioning both experts together on an agreed agenda. Experts should also expect the tribunal to ask its own questions directly.

Timetables tend to be shorter than litigation: a documents-only rent review can conclude within three to six months of the arbitrator's appointment, while a contested construction arbitration with a hearing commonly takes nine to eighteen months. Arbitration is also confidential, so the award and the expert's evidence are not published, which matters to landlords and developers with portfolios to protect.

Costs, appeals and what they mean for the expert

Unlike a judge, the arbitrator is paid by the parties, and the Arbitration Act 1996 lets the tribunal allocate the costs of the arbitration, including expert fees, on the general principle that costs follow the event. Experts' fees must be reasonable and proportionate to be recovered. The fee picture is the same as for litigation: a straightforward expert report costs £5,000–£15,000, complex matters £20,000–£50,000 or more, hourly rates run at £150–£300, and hearing attendance is charged at £1,000–£2,000 a day.

Rights of appeal are narrow. An award can be challenged in the High Court only for lack of jurisdiction, serious irregularity or, unless the parties have excluded it, a point of law. The Arbitration Act 2025 amended the 1996 Act in several respects, including a summary disposal power for tribunals, but it did not change the position on expert evidence. There is rarely a second chance to put a technical point right, so the expert's report must be complete and defensible first time. Where a dispute has already been through construction adjudication, the arbitration is a full rehearing and the expert's evidence should be prepared afresh rather than recycled from the adjudication submissions.

Instruct an expert witness for arbitration through Survey Merchant

Survey Merchant provides RICS chartered surveyors, RICS Registered Valuers and structural engineers as expert witnesses in property arbitrations across England and Wales, from documents-only rent review references to multi-week construction hearings. The panel's experts prepare reports to the tribunal's directions and the RICS practice statement, take part in joint statements and concurrent evidence sessions, and attend hearings where required. Party and tribunal appointments are accepted, and fixed fees are quoted wherever the scope is clear. Explore the expert witness service, see how the panel's valuation expert witnesses support rent review arbitrations, or contact Survey Merchant on 0204 579 8270 to discuss the reference and the discipline it needs.