Planning and building regulations: when the architect or engineer got it wrong

Many claims against architects and engineers involve the planning and building control systems: a design that needed planning permission that was never obtained, a condition that was overlooked, or work that does not meet the Building Regulations. This guide explains how the law approaches those claims, for homeowners and small businesses in England and Wales. Where the problem came to light on buying a property, conveyancing has its own guide on unauthorised works.

Is it within what they were engaged to do?

The starting point, as in every claim against a professional, is the appointment. An architect engaged to prepare and submit a planning application has taken on that task. An engineer engaged to produce structural calculations for building control has taken on that. A professional engaged to draw up a design and nothing more may not have agreed to advise on whether planning permission is needed.

Where the task was taken on, the duty is to perform it with reasonable care and skill (Consumer Rights Act 2015, s.49 for consumers; Supply of Goods and Services Act 1982, s.13 for businesses). That is not a guarantee that a council will grant permission or approve plans. It is a duty to give the advice, and prepare the design, that a reasonably competent professional would have done.

Building Regulations: the designer's duties in England

Since 1 October 2023, Part 2A of the Building Regulations 2010 has applied in England. Regulation 11K(2) says that a designer "must take all reasonable steps to ensure that the design is such that if the building work to which the design relates were built in accordance with that design the building work would be in compliance with all relevant requirements". Regulation 11F requires anyone carrying out design work to have the "skills, knowledge, experience and behaviours necessary" (or, for a business, the "organisational capability") to do it so that the work, if built, would comply, and other provisions set duties for the client, for principal designers and for contractors.

These are regulatory duties enforced through the building control system. Whether a breach of the Building Regulations gives a direct right to sue is a separate question: section 38 of the Building Act 1984, which would make such breaches actionable, has been brought into force only for limited purposes at the time of writing (October 2026). In practice, a claim for compensation against a designer is normally brought under the appointment or in negligence, with the regulations as evidence of what competent design required.

When building control has a problem

Under section 36 of the Building Act 1984, a building control authority can serve notice requiring work that contravenes the Building Regulations to be removed or altered. Following amendments made by the Building Safety Act 2022, the notice cannot be given more than ten years "from the date of the completion of the work in question" (s.36(4)), at the time of writing (October 2026).

Building control approval does not shift responsibility for a design onto the council. In Murphy v Brentwood District Council [1991] UKHL 2, the council had approved foundation plans after taking advice from independent consulting engineers, and the house later cracked. The House of Lords held that the council owed the owner no duty in tort for the economic loss. Lord Bridge said such losses "are recoverable if they flow from breach of a relevant contractual duty, but, here again, in the absence of a special relationship of proximity they are not recoverable in tort". See how loss is measured.

Planning enforcement time limits

If building work goes ahead without the planning permission it needed, the local planning authority can take enforcement action within the time limits in section 171B of the Town and Country Planning Act 1990. At the time of writing (October 2026), for "building, engineering, mining or other operations" carried out without permission, those limits are:

• England: ten years beginning with the date the operations were substantially completed;
• Wales: four years beginning with the date the operations were substantially completed.

The ten-year period in England was introduced on 25 April 2024 by the Levelling-up and Regeneration Act 2023. Under the transitional rules, it does not apply where the operations were substantially completed before that date (SI 2024/452, reg. 5), so older works remain subject to the four-year period. Other breaches of planning control, such as breaches of conditions, generally have a ten-year limit (s.171B(3)).

The timing matters to a negligence claim because it affects what the planning error has actually cost, and what steps were needed to deal with it.

What the loss can include

Depending on the facts, a claim might include the cost of a retrospective planning application or a revised design, the cost of altering or removing work to satisfy the council, delay costs, wasted fees, or a reduction in the property's value. It is measured by comparing the client's position with where they would have been with competent advice, and some of those costs might have been incurred anyway. See how loss is measured.

Defective Premises Act claims

For new dwellings, and for work on existing dwellings completed after 28 June 2022, the Defective Premises Act 1972 imposes a duty to do the work in a "workmanlike or, as the case may be, professional manner" so that the dwelling is fit for habitation (ss.1 and 2A). Work that seriously breaches the Building Regulations may also raise that question. These claims have longer time limits than ordinary claims: see time limits.

What a solicitor will want from you

• The appointment, showing whether planning and building control applications were part of the job.
• The planning application, decision notice and conditions, or the advice that permission was not needed.
• Building control plans, approvals, inspection records and any completion certificate.
• Any letter, notice or enforcement notice from the council, with dates.
• The date the work was substantially completed.
• Quotes or invoices for putting things right, and any valuation evidence.

Run the free case check

This guide is general information about the law of England and Wales. It is not legal advice. Planning and building control rules differ between England and Wales and change over time, and whether a designer was negligent depends on the appointment and expert evidence.