Can I claim against an architect or engineer? What a negligence claim involves

This guide is for homeowners, landlords and small businesses in England and Wales who think an architect or engineer got something wrong and it cost them money: a design that does not work, a building that was never properly checked, a report that missed a structural problem, or advice that a scheme could be built for a budget it could not. It explains who counts as an architect or engineer, where their duty comes from, the standard they are judged by, and how insurance and complaints fit in. If the problem is the builder's work rather than the design, the builder disputes series covers it.

Who you engaged matters

Under section 20 of the Architects Act 1997, a person "shall not practise or carry on business under any name, style or title containing the word 'architect'" unless registered with the Architects Registration Board (ARB). The Act protects the title, not the work. The Engineering Council puts it this way: "there is no restriction on the use by individuals of terms such as architectural designer, and anyone may offer architectural services."

Engineering is different again. The Engineering Council says "anyone in the UK may describe themselves as an engineer". What is protected are its professional titles, such as Chartered Engineer (CEng) and Incorporated Engineer (IEng), which it says are "fully protected under law".

The legal standard is the same whoever you engaged, but the regulator, the professional body and the insurance position can all differ. The engagement letter, the firm's letterhead and the registers are where that is checked.

Where the duty comes from

The appointment

The contract with an architect or engineer is usually called the appointment. The law adds a term that the work will be done with reasonable care and skill:

• Consumers: section 49 of the Consumer Rights Act 2015 says every contract to supply a service includes a term "that the trader must perform the service with reasonable care and skill", and section 57 stops a term excluding that liability from binding the consumer.
• Businesses: section 13 of the Supply of Goods and Services Act 1982 implies a term that a supplier acting in the course of a business "will carry out the service with reasonable care and skill".

That is a duty to take care, not a promise of a result. A stricter obligation, such as a promise that a design will be fit for a stated purpose, has to be found in the contract itself.

Tort

A professional can also owe a duty of care in negligence alongside the contract. In Robinson v P E Jones (Contractors) Ltd [2011] EWCA Civ 9, Jackson LJ said the "conceptual basis upon which the concurrent liability of professional persons in tort to their clients now rests is assumption of responsibility", adding that professionals typically "give advice, prepare reports, draw up accounts, produce plans and so forth" and expect their clients to rely on them. The distinction matters mainly for time limits: see time limits for claims against architects and engineers.

The Defective Premises Act 1972

Where the work is for or in connection with the provision of a dwelling, section 1 of the Defective Premises Act 1972 imposes a duty "to see that the work which he takes on is done in a workmanlike or, as the case may be, professional manner, with proper materials" so that the dwelling is fit for habitation when completed. The duty is owed to the person who ordered the dwelling and to everyone who later acquires an interest in it, so it can matter to a later buyer with no contract with the designer.

The standard: the reasonably competent professional

The test comes from a medical case, Bolam v Friern Hospital Management Committee [1957] 1 WLR 582, which the Supreme Court summarised in Montgomery v Lanarkshire Health Board [2015] UKSC 11 at [40]: a professional is not negligent if they acted "in accordance with a practice accepted as proper by a responsible body" of practitioners skilled in that field.

In construction cases the question is what a reasonably competent architect or engineer would have done. Following the type of design that others use is not automatically a defence. In Martlet Homes Ltd v Mulalley & Co Ltd [2022] EWHC 1813 (TCC) at [271], the judge quoted 199 Knightsbridge Development Ltd v WSP UK Ltd for the point that there must be "evidence of a responsible body of opinion that has identified and considered the relevant risks", and that "A defendant is not exonerated simply by proving that others … [were] … just as negligent".

In Vainker v Marbank Construction Ltd [2024] EWHC 667 (TCC), a claim by homeowners, the judge held that an architect's specification of a damp-proof course set back from the face of the brickwork "was in my view a negligent error", because it let rainwater soak into the wall. In the same case he did not accept that designing the parapets without copings was, on its own, a failure of reasonable care: it was a recognised detail, even though guidance recommended copings.

What were they engaged to do?

The scope of the appointment sets the limits of the duty. A designer engaged only to produce drawings for a planning application has not taken on the job of inspecting the build. An engineer asked to look at one crack has not carried out a structural survey of the whole house. Whether the professional also had to inspect the works, administer the building contract or advise on cost is often the first question in these claims: see inspection and certificates and budgets and cost estimates.

Causation and loss

The claimant also has to show that the failure caused a financial loss, by comparing what happened with what would have happened if the professional had acted competently. How that loss is measured, and the limits on claims in tort, are covered in how loss is measured.

Insurance, and practices that have closed

ARB's Architects Code, Standard 4, expects architects to have adequate and appropriate professional indemnity insurance. ARB's guidance (published June 2025) says that, at the time of writing (October 2026), there "should be in place a minimum level of indemnity to be £250,000", on an each and every claim basis, and that architects should maintain at least six years of run-off cover after they stop practising. These are expectations in professional guidance, not a guarantee that cover exists or is enough. Engineers have no equivalent statutory regulator, so insurance depends on the firm and any professional body rules.

Professional indemnity cover is usually written on a "claims made" basis, which ARB's guidance explains means insurance "must be held when a claim is made, rather than when an incident occurred". If the insured business becomes insolvent, the Third Parties (Rights against Insurers) Act 2010 can transfer its rights under the policy to the person it owes, who may then proceed against the insurer, but must still establish the liability (s.1).

A complaint is not a claim for compensation

ARB investigates complaints of "unacceptable professional conduct and serious professional incompetence". Its Professional Conduct Committee can make a reprimand, a penalty order, a suspension order or an erasure order (Architects Act 1997, s.15). ARB lists what it cannot do, including "Order your architect to put right something which has gone wrong, or award compensation for poor service" and "Become involved in disputes about a contract or fee levels". At the time of writing (October 2026), it will not usually investigate complaints more than six years old unless there are special circumstances.

The RIBA handles complaints about the professional conduct of its members and Chartered Practices under its codes. For engineers, the Institution of Civil Engineers deals with "improper conduct" by members, and the Institution of Structural Engineers states that it "has no power to award compensation" and that it is not within its remit "to decide whether a member has been negligent".

A claim for financial loss follows the construction pre-action protocol and, if needed, the Technology and Construction Court. A complaint does not stop the court time limit running.

What a solicitor will want from you

• The appointment or engagement letter, fee proposal and any terms limiting liability.
• The drawings, specifications, calculations or reports the professional produced, with dates.
• The building contract, if there was one, and who administered it.
• A dated chronology: when they were engaged, when the work was done and completed, when the problem appeared, and when you connected it to their work.
• Photographs and any report from another architect, engineer or surveyor.
• Repair quotes, costs already incurred and other evidence of loss.
• Any complaint you made, the reply, and any insurer details you were given.

Run the free case check

This guide is general information about the law of England and Wales. It is not legal advice. Whether an architect or engineer was negligent depends on the appointment, the facts and expert evidence, and strict time limits apply to court claims.