Using an Expert Witness Surveyor in Mediation Before Court

Most property disputes never reach a courtroom, and the ones that settle early usually do so because both sides have seen credible technical evidence. Bringing an expert witness into mediation before court gives a building defect, dilapidations, boundary or valuation dispute exactly that: an independent chartered surveyor's view of what went wrong, what it will cost to put right or what the property is worth, presented at a stage when the parties can still choose the outcome. This guide explains how expert witness mediation works, what the surveyor's role is, how it differs from giving evidence at trial and what it costs.

Why mediate a property dispute before going to court?

Mediation is a confidential, without-prejudice negotiation run by a neutral mediator who helps the parties reach their own settlement. Nothing said in the room can be used in later proceedings unless both sides agree, and the mediator imposes no decision. For property claims worth tens of thousands of pounds it is often the only proportionate route.

The courts now expect it. The Civil Procedure Rules require the court to encourage alternative dispute resolution as part of active case management (CPR 1.4), and following the Court of Appeal's decision in Churchill v Merthyr Tydfil County Borough Council [2023] EWCA Civ 1416 the rules were amended in October 2024 so that judges can order parties to engage in ADR and take a refusal into account when deciding costs. A party who unreasonably declines to mediate risks losing part of their costs even if they win. In the County Court, most defended money claims under £10,000 are also referred automatically to the free HM Courts and Tribunals Service small claims mediation service before a hearing is listed.

The pre-action protocols for construction, dilapidations, boundary and housing condition claims all expect the parties to consider settlement before issuing, and each works far better when an expert has already set out the technical position.

What does an expert witness do in mediation?

An expert witness in mediation does the same core job as at trial: gives an independent, reasoned opinion on the technical questions the parties cannot answer themselves. The difference is the audience. Instead of a judge, the evidence has to persuade the other side, and often the client, that a figure is realistic. A chartered surveyor may be asked to:

• Prepare a short, focused report before the mediation day on the defects, their cause and the reasonable cost of remedial works, or on value where the dispute is about price, premium or compensation.
• Attend the mediation to explain the findings in plain terms, answer questions from the mediator and the other party, and test any competing technical case put forward on the day.
• Act as an agreed or joint expert where both parties would rather share one independent view than pay for two, which is common in boundary and lower-value defect disputes.
• Review the other side's expert evidence privately, identifying where a schedule is overstated or a valuation method is unsound.

The disputes the panel's experts most often help settle are construction and building defect claims, end-of-lease dilapidations, boundary disagreements and valuation disputes, including lease extension premiums and matrimonial property values.

Expert advisor or CPR Part 35 expert witness?

Mediation sits outside court proceedings, so CPR Part 35 does not govern it. A surveyor can be retained as a privileged expert advisor, whose advice stays confidential to the instructing party, or instructed from the outset as a CPR Part 35 expert witness, whose overriding duty is to the court and whose report will be disclosable if the case proceeds. The distinction is explained fully in the guide to expert witness vs expert advisor.

Where settlement is likely, an advisory instruction is usually enough and keeps the advice frank. Where mediation is a step on the way to court, many solicitors instruct the surveyor on Part 35 terms from day one so the report can become the formal expert evidence without a second inspection. Either way, the RICS practice statement Surveyors acting as expert witnesses applies to any surveyor acting as an expert, and a report that reads as advocacy rarely moves the other side.

How an expert's mediation report is prepared

A mediation report is shorter and more direct than a trial report but rests on the same foundations. The surveyor inspects the property, reviews the contract, lease, title plans or earlier survey reports, and identifies the standard that should have been met, whether the Building Regulations, the lease's repairing covenants, the RICS Home Survey Standard or the Red Book. The report then sets out:

• the defects or issues actually found, with photographs and, where useful, a schedule of condition;
• the most likely cause of each item and whether it is attributable to the other party;
• a costed schedule of remedial works, or a valuation with comparables and reasoning;
• a candid note of the weaknesses in the client's own position, so the settlement range is realistic.

Because the report is prepared for the purpose of settlement, it is normally headed without prejudice and cannot be relied on at trial without the parties' agreement. Where the parties want figures both can work from, a joint inspection with a single agreed surveyor and a short joint statement of agreed and disputed items, modelled on the CPR 35.12 joint statement, is often the most efficient approach.

What happens if the mediation fails?

If no settlement is reached, expert evidence can only be relied on at trial with the court's permission under CPR 35.4, restricted to what is reasonably required; on the small claims and fast track the court will usually direct a single joint expert. Three points follow for anyone planning ahead:

• A without-prejudice mediation report cannot simply be dropped into the court bundle. If the same surveyor is to give evidence, a compliant Part 35 report with the statement of truth and expert's declaration must be produced.
• An advisor who becomes the Part 35 expert must disclose the substance of all material instructions, and earlier privileged advice may become open to scrutiny.
• Concessions made in the mediation are not evidence, but they show where the live issues will be and help shape written questions under CPR 35.6.

Instructing an expert used to both settings avoids duplicated fees, because the inspection notes, photographs and cost schedule prepared for mediation form the backbone of the later court report.

What does an expert witness cost for mediation?

Expert fees for mediation are generally lower than for litigation because the report is shorter and there is no trial. The panel's chartered surveyors typically charge £150–£300 per hour, so an advisory inspection and mediation report on a single residential property often comes to a few thousand pounds, while a full CPR Part 35 report on a straightforward matter is more usually £5,000–£15,000, rising to £20,000–£50,000 or more for complex, multi-property or high-value claims. Attendance at the mediation day is charged at an hourly or day rate, broadly in line with the £1,000–£2,000 per day charged for court attendance. Each party normally pays its own expert and the mediator's fee is usually shared equally. The wider picture is set out in the expert witness cost guide.

Arrange an expert witness surveyor for mediation through Survey Merchant

Survey Merchant provides RICS chartered surveyors, engineers and Registered Valuers from a national panel of 2,400+ professionals for mediation, pre-action negotiation and court proceedings across England and Wales. The panel's experts prepare without-prejudice mediation reports, attend mediation days, accept joint appointments and, where a case proceeds, produce CPR Part 35-compliant evidence from the same groundwork. Survey Merchant matches the discipline to the dispute and quotes fixed fees for each stage. Visit the expert witness services page, call 0204 579 8270 or contact Survey Merchant with a short outline of the dispute and the mediation date to arrange an expert.