Most disputes with a builder are decided not by a point of law but by what can be proved: what was agreed, what was paid, what was built, and what it costs to put right. This guide explains the evidence that carries weight in a claim against a builder or tradesperson in England and Wales, and the court rules on expert evidence. It is written mainly for homeowners.
The contract documents
The first question is what the builder agreed to do. Many domestic jobs have no single signed contract. The agreement is pieced together from the quote or estimate, any specification or drawings, and the emails and text messages.
For consumers, section 50 of the Consumer Rights Act 2015 treats anything said or written to the consumer by or on behalf of the trader, about the trader or the service, as a term of the contract if the consumer took it into account when deciding to enter the contract, or when making a later decision about the service. That is subject to anything the trader said at the same time to qualify it, and to any change expressly agreed. A message promising a particular material or finish can therefore matter as much as the quote.
Changes agreed part-way through are a common source of argument: see quotes, estimates and extras.
Practice Direction 27A, which supplements the small claims rules, sets out in Appendix A the information and documents the court usually needs in a building dispute, where they are available:
- any written contract, photographs and plans;
- a list of works complained of, and a list of any outstanding works;
- relevant estimates, invoices and receipts, including any for repairs to each defect;
- estimates for work to be completed, and a valuation of work done to date.
A dated record
Photographs and notes made at the time are usually more persuasive than recollection months later. A useful record shows the state of the work on a known date. Timing matters most when the builder leaves the job and before any replacement contractor starts. After that the original work may no longer exist to be looked at.
Proof of payment
A claim for money back, or for the extra cost of finishing, depends on showing what has been paid. Bank and card records speak for themselves. Cash payments are much harder to establish without a receipt or a message acknowledging them. Invoices from the replacement contractor show what repair actually cost: see what can be claimed for putting bad work right.
The independent expert
A trader supplying a service to a consumer must perform it with reasonable care and skill (section 49 of the Consumer Rights Act 2015). Whether work meets that standard is often a technical question. An independent expert, commonly a chartered building surveyor or a structural engineer, can give an opinion on what is wrong, what caused it and what is needed to correct it.
A replacement builder's quote is evidence of what the work will cost. It is not the same as an independent opinion on whether the original work fell below a reasonable standard.
How the court controls expert evidence
Expert evidence in civil claims is governed by Part 35 of the Civil Procedure Rules (CPR). The main points are:
- It is restricted. Expert evidence is limited to what is reasonably required to resolve the proceedings (rule 35.1).
- The expert's duty is to the court. An expert's duty is to help the court on matters within their expertise, and that duty overrides any obligation to the person who instructs or pays them (rule 35.3).
- Permission is needed. No party may call an expert or put in an expert's report without the court's permission (rule 35.4).
- A single joint expert may be ordered. Where both sides want expert evidence on the same issue, the court may direct that it is given by one expert instructed on behalf of both (rule 35.7). Unless the court directs otherwise, those parties are jointly and severally liable for that expert's fees, meaning each can be pursued for the whole amount (rule 35.8).
A report commissioned before a claim starts is not automatically evidence the court will accept. The Practice Direction on Pre-Action Conduct says that many disputes can be resolved without expert evidence, and that where it is needed, particularly in low value claims, the parties should consider a single expert, jointly instructed, with the costs shared equally.
Expert evidence in a small claim
The small claims track is the normal track for a claim worth not more than £10,000 (CPR rule 26.9, at the time of writing, October 2026). Most of Part 35 does not apply on that track, but the duty to restrict expert evidence, the expert's overriding duty and the single joint expert rules still do (rule 27.2). Under rule 27.5, no expert may give evidence, written or oral, at a small claims hearing without the court's permission.
Under rule 27.14 and paragraph 7.3 of Practice Direction 27A, the general rule is that the most a court may order one party to pay towards the other's expert fees is £750 for each expert, at the time of writing (October 2026). A report costing more is not normally recoverable in full on this track, even by a party who wins. See court tracks and recoverable costs.
Letting the builder inspect
Inspection by the builder matters for two reasons.
The first is proof. If defective work is covered over or redone before anyone independent has seen it, the only evidence of its condition is the record made beforehand. A court can also direct one party to allow the other to inspect: the special directions in Appendix C to Practice Direction 27A include one in those terms.
The second concerns remedies and the size of the claim. A consumer has a statutory right to require the trader to perform the service again so that it conforms to the contract, within a reasonable time, without significant inconvenience and at the trader's cost (section 55 of the Consumer Rights Act 2015). More generally, a claimant is expected to act reasonably to keep the loss down. A builder who was never told of a defect, or never allowed to look at it, may argue that the cost of the remedial work was not reasonably incurred. Where work has to be redone urgently, the record made beforehand carries the weight.
Exchanging documents before a claim
The Practice Direction on Pre-Action Conduct expects the parties, before proceedings start, to have exchanged enough information to understand each other's position and to try to settle. The usual steps include disclosing key documents relevant to the issues in dispute, and a court can take non-compliance into account when it decides costs. See what to do before suing.
Does the construction pre-action protocol apply?
Paragraph 1.1 of the Pre-Action Protocol for Construction and Engineering Disputes says it applies to all construction and engineering disputes. The exceptions in paragraph 2 cover matters such as enforcing an adjudicator's decision, claims for an interim injunction, summary judgment claims, and cases where all parties agree in writing not to follow it. They do not mention homeowners or small claims.
The protocol does address modest cases. Paragraph 5.1 says that in many cases, including those of modest value, the letter of claim and the response can be simple and the costs of both sides should be kept to a modest level. Paragraph 4.1 says the court is likely to impose costs consequences for non-compliance only in exceptional circumstances, such as a flagrant or very significant disregard of the protocol.
What a solicitor will want from you
- The quote or estimate, any specification, drawings, and every message about what was to be done and for how much.
- A list of the works complained of and the works left unfinished.
- Dated photographs and video.
- Proof of every payment, including any made in cash.
- Any report already obtained, and who wrote it.
- Quotes and invoices from any replacement contractor.
- Whether the builder has been told of the problems and offered a chance to inspect.
This guide is general information about the law of England and Wales. It is not legal advice. What evidence a court will allow, and what it makes of it, depends on the facts of each case and the directions the court gives, and time limits apply to any claim.
Frequently asked
Do I need an expert report to bring a claim against a builder?
Not always. The Practice Direction on Pre-Action Conduct says many disputes can be resolved without expert advice or evidence. Where the argument is about whether work was done to a reasonable standard, an independent opinion is often what a court relies on, but the court's permission is needed before any expert evidence can be used.
Can the cost of a surveyor's report be recovered from the builder?
It depends on the court track and the order the court makes. On the small claims track, at the time of writing (October 2026), the general rule is that the most the court can order the other side to pay towards an expert's fees is £750 for each expert. On other tracks the court may limit the amount of expert fees that can be recovered.
Does the builder have to be given a chance to inspect the work?
The pre-action rules expect both sides to exchange enough information to understand each other's position, and a court can direct one party to allow the other to inspect. Once defective work has been covered up or redone, nobody can examine it, so the dispute is then decided on whatever record was kept.
Does the construction pre-action protocol apply to a homeowner's claim?
The Pre-Action Protocol for Construction and Engineering Disputes says it applies to all construction and engineering disputes, and its listed exceptions do not mention homeowners or low-value claims. It also says that in cases of modest value the letter of claim and the response can be simple, and that costs should be kept to a modest level.