Many homes have been extended, knocked through, converted or re-windowed by previous owners. Most of that work needs building regulations approval, and some of it needs planning permission. When the paperwork is missing and nobody tells the buyer, the problem usually surfaces at the worst moment: when you come to sell, remortgage or build again, and a buyer's conveyancer asks for the certificates you do not have.
This guide goes deeper on unauthorised works. For the wider picture of conveyancing negligence, start with what conveyancers commonly get wrong.
What the conveyancer had to do
The seller completes the Law Society's TA6 Property Information Form, which asks about alterations, extensions, planning permission and building regulations approvals. The edition used depends on when you bought; the 2024 (5th) edition moved some key information into an upfront Part 1. The answers are the seller's; the conveyancer's job is to test them.
A reasonably competent conveyancer is expected to:
- Compare the form with what is known about the property — the local authority search (which lists planning decisions and building control records), the estate agent's particulars, the survey and the title. A conservatory, loft room or rear extension that appears nowhere in the council's records should prompt a question.
- Raise further enquiries where answers are missing, vague or inconsistent, and ask for copies of planning permissions, building regulations completion certificates, and certificates from competent-person schemes for windows, electrics and boilers.
- Report and advise — explain in the report on title what is missing, what the risk is, and the options: ask the seller to obtain retrospective approval, negotiate on price, take indemnity insurance, or withdraw.
Many extensions do not need planning permission because they fall within permitted development, but almost all structural work still needs building regulations approval. The two are separate, and a conveyancer who checks one and not the other has done half the job.
Planning enforcement: how long the council has
Section 171B of the Town and Country Planning Act 1990 sets the time limits for planning enforcement. Section 115 of the Levelling-up and Regeneration Act 2023 changed them in England from 25 April 2024:
- Building and other operations (an extension, for example): in England, ten years from substantial completion; in Wales, four years.
- Change of use to a single dwelling (such as converting a barn or garage into a separate home): in England, ten years from the breach; in Wales, four years.
- Any other breach, including breach of a planning condition: ten years in both countries.
The transitional rule matters for buyers. In England, the ten-year limit does not apply where operations were substantially completed, or the change of use to a dwelling happened, before 25 April 2024; the old four-year limit still governs those cases.
In England, a council that believes a breach was deliberately concealed can apply to the magistrates' court for a planning enforcement order under s.171BA, which allows action even after the normal limit has passed. Once the time for enforcement has run, the owner can apply for a certificate of lawfulness of existing use or development under s.191, which confirms that the works are immune.
Building regulations enforcement
Under s.36 of the Building Act 1984, the council can serve a notice requiring non-compliant work to be removed or altered. The Building Safety Act 2022 extended the time limit for that notice from 12 months to ten years from completion of the work: from 1 October 2023 in England, and fully from 1 July 2026 in Wales. How the longer period applies to work finished before those dates depends on the facts. Separately, s.36(6) preserves the council's right to apply for an injunction, which is not subject to the same limit.
For work carried out without approval since 11 November 1985, the owner can apply for a regularisation certificate under regulation 18 of the Building Regulations 2010. The council may require work to be opened up so it can be inspected.
Indemnity insurance and when it fails
Indemnity insurance is the conveyancer's usual answer to missing paperwork. A policy for lack of planning permission or building regulations approval typically covers financial loss if the council takes enforcement action, such as the cost of complying with a notice or the drop in value. It does not normally cover the cost of fixing defective work, and it does nothing for safety.
These policies usually carry conditions. An article published by the Law Society lists typical ones: the works were completed at least 12 months before the policy started, the local authority has not been alerted to the works, no enforcement has been taken or threatened, and the survey shows no problem with the works. Contacting the council about the works can therefore void the cover.
The conveyancer must check the conditions are met before relying on a policy, and must explain to you what it covers and the restrictions it places on you. A policy taken out without that explanation, or one that was void from the start, does not answer a negligence claim.
Causation and loss
Breach alone is not enough. You need to show what would have happened if you had been properly advised — that you would not have bought, would have paid less, or would have insisted on approvals before exchange — and what that cost you.
Loss is usually the difference between what you paid and what the property was worth with the problem at the date of purchase. Where the problem can be cured, the reasonable cost of the cure — a regularisation application and any remedial work, a lawful development certificate, or a valid policy — may be the better measure. Where the issue only emerged on a later sale, you may also be able to recover wasted costs of that sale. A missing certificate for sound work may have little effect on value; unapproved structural alterations or a converted outbuilding with no permission may have a large one.
The Professional Negligence Pre-Action Protocol applies before any court claim — see how the pre-action protocol works. Time usually runs six years from the negligent advice, or three years from when you knew or could have known the relevant facts, subject to a 15-year longstop (ss.2, 5, 14A and 14B Limitation Act 1980) — see professional negligence time limits.
What a solicitor will want from you
- The completed TA6 form, the replies to any further enquiries, and the report on title.
- The local authority search, the survey and the estate agent's particulars.
- Any indemnity policy, with its schedule and conditions, and anything showing whether the council has been contacted.
- When the work was done and finished, as best you know, and any evidence of that date.
- Correspondence from the council, a buyer's conveyancer or a lender that revealed the problem, with dates.
- Quotes or reports on regularisation or remedial work, and any valuation evidence.
This guide is general information about the law of England and Wales. It is not legal advice. Planning and building regulations time limits differ between England and Wales and depend on dates that need checking in each case.
Frequently asked
The extension was built years ago. Can the council still do anything about it?
It depends on when the work was finished, what kind of breach it is, and whether the property is in England or Wales. In England, building work substantially completed on or after 25 April 2024 can be the subject of planning enforcement for ten years; work completed before that date keeps the old four-year limit. In Wales the limit for building work is still four years. Building regulations enforcement notices now have a ten-year limit in both countries, and the council's power to seek an injunction is not time-limited in the same way.
My conveyancer arranged indemnity insurance. Doesn't that solve the problem?
Only partly. These policies typically cover financial loss if the council takes enforcement action, not the cost of putting defective work right. They usually carry conditions, commonly that the council has not already been alerted to the works, and they can be invalidated if those conditions are broken. A conveyancer who arranges a policy should explain what it covers and what it does not.
The seller ticked the boxes on the property information form. Isn't the seller to blame?
If the seller's answers were untrue, you may have a separate claim against the seller for misrepresentation. That does not excuse the conveyancer: their job includes checking the answers against the searches and the title, raising enquiries where something does not add up, and advising you on what is missing.
Do I have a claim if the council is never likely to take action?
You may still have a claim, but the loss may be modest. The question is what the problem did to the value of the property, or what it costs to put right, at the time you bought. A missing certificate for sound work that a buyer's surveyor would accept may have little effect on value; unsafe or unapproved structural work may have a large one.