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Property Extensions & Conveyancing UK: Permissions Guide

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Part ofConveyancing

Written by Brad Askew Solicitor (non-practising)
Brad is on the roll of solicitors of England & Wales but does not hold a practising certificate and does not provide legal advice.
Updated June 2026 · England & Wales
Thinking about extending your home, or buying a property that already has an extension? The interaction between planning rules, building regulations and conveyancing catches a lot of people out. An extension built without the right paperwork can knock thousands off a sale price, cause delays on completion, or in the worst cases lead to enforcement action from the council. This guide walks through what you need to know before you pick up a hammer or exchange contracts. It covers when permission is needed, what permitted development actually allows, how local restrictions can change the picture, and why keeping proof of compliance matters when you eventually come to sell. The rules below apply to England and Wales, with some differences in Scotland and Northern Ireland.

Overview

Conveyancing is the legal process of transferring ownership of property from seller to buyer. When an extension is involved, the conveyancer's job expands. They need to check that any building work on the property was properly authorised, that the right consents were obtained, and that the paperwork matches what has actually been built on the ground.

Planning permission is the consent granted by the local planning authority confirming that a proposed change to a building or its use is acceptable. It is separate from building regulations approval, which deals with construction standards, safety, insulation and structural soundness.

Many extensions need both. For buyers, missing or incorrect paperwork on a past extension can become a serious problem. Lenders often refuse to release funds until the position is resolved, and indemnity insurance is not always available. For sellers, discovering issues late in the process can collapse a sale. Getting the documentation straight early saves time, money and stress.

Key steps

  1. Check whether you need planning permission. Before committing to a design, contact the local planning authority or check your council's website. Some projects fall under permitted development rights and need no formal application, while others require a full submission. Size, height, proximity to boundaries and the existing use of the property all feed into the decision.
  2. Look into local restrictions and designations. Article 4 Directions, conservation areas, listed building status and National Park boundaries can all remove or limit permitted development rights. A short call to the planning department, or a search of the council's online maps, will usually confirm whether any of these apply to your address.
  3. Apply for permission or a Lawful Development Certificate. If planning permission is required, submit a full application with drawings, a site plan and the correct fee. If you believe the work is permitted development, applying for a Lawful Development Certificate gives you formal written confirmation, which is gold dust when you later come to sell.
  4. Meet building regulations separately. Most structural work, new openings, drainage changes and insulation upgrades need building control sign-off. This is a different process from planning. Keep every notice, inspection record and final completion certificate in one place, because your conveyancer or buyer's solicitor will ask for them.
  5. Keep a clean paper trail for resale. When you eventually sell, the buyer's solicitor will request planning decisions, building regulations completion certificates, FENSA or similar certificates for windows, and electrical safety paperwork. Organised documentation speeds up conveyancing and protects the sale price.

Common questions

If you're dealing with this kind of situation, a call with an experienced legal adviser can help you work out the right next step — from £89.

Common questions

Q Do I always need planning permission for an extension?
No. Many single-storey rear extensions, loft conversions and small additions fall under permitted development rights, meaning no formal application is needed. However, size limits, height rules and local restrictions all apply. Even when permission is not required, it is often worth applying for a Lawful Development Certificate so you have written proof the work is lawful when you come to sell.
Q What is an Article 4 Direction?
An Article 4 Direction is a notice issued by a local planning authority that removes some or all permitted development rights in a defined area. They are often used in conservation areas or places with distinctive character. If one applies to your property, you may need full planning permission for work that would normally be permitted development elsewhere. Always check with the local council before starting.
Q Are planning permission and building regulations the same thing?
No, they are two separate approvals. Planning permission deals with whether a project is acceptable in principle, looking at appearance, size and impact on neighbours. Building regulations deal with how the work is constructed, covering structural safety, fire, insulation, drainage and ventilation. Many extensions need both, and you should not assume that having one covers the other.
Q What happens if I buy a property with an unauthorised extension?
It depends on when the work was done and what paperwork exists. In some cases, indemnity insurance can cover the risk. In others, the seller may need to apply for retrospective permission or a Lawful Development Certificate before completion. Mortgage lenders often insist on clean paperwork, so unresolved issues can delay or block a purchase.
Q How long does planning permission last?
A standard planning permission in England is usually valid for three years from the date of the decision, meaning work must begin within that window. If building has not started by then, the permission lapses and a fresh application is needed. Keep a copy of the decision notice and any conditions attached, since conditions often need to be discharged as work progresses.
Q What is a Lawful Development Certificate and should I get one?
A Lawful Development Certificate is an official document from the council confirming that a proposed or existing use or building work is lawful. It is not the same as planning permission, but it gives you written certainty. For extensions built under permitted development rights, obtaining one is a practical way to protect future resale value and avoid disputes with buyers' solicitors later.
Q Can listed building status affect extension plans?
Yes, significantly. If a property is listed, you typically need Listed Building Consent in addition to any planning permission, even for work that would otherwise be permitted development. The rules also apply to internal alterations and some routine maintenance. Carrying out work to a listed building without consent is a criminal offence, so always confirm the position with the council before proceeding.
If you're dealing with this kind of situation, a call with an experienced legal adviser can help you work out the right next step — from £89.

Sources

This guide is based on primary UK law and official guidance.

Brad Askew, Solicitor (non-practising)

Written & reviewed by

Brad Askew Solicitor (non-practising)

Brad is on the roll of solicitors of England & Wales but does not hold a practising certificate and does not provide legal advice. LegalDocuments.co.uk is not a law firm and does not provide regulated legal advice.

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Legal disclaimer
This article is for general information only. It is a tool to help you find your way — not legal advice, and not a substitute for speaking to a qualified adviser about your situation.