If you think an extension or loft conversion is permitted development, you do not have to ask anyone before you build. But the council can still disagree afterwards. A lawful development certificate (often shortened to LDC) is a formal decision from the council, in writing, that the work is lawful. It turns “we believe it is permitted” into something you can show.
When one is worth having
- The rules are borderline, for example because of an earlier extension, a conservation area or an Article 4 direction.
- You want certainty before spending money, or a lender, insurer or buyer is likely to ask.
- You are selling later and want proof that the work needed no planning permission.
What it is and is not
- It is a legal confirmation that proposed (or already completed) work was lawful at the time of the application.
- It is not planning permission: it confirms that none is needed.
- It does not replace Building Regulations approval, and it does not remove the need for a party wall notice where one applies.
- It is based on the drawings and facts you submit, so they must be accurate.
How it fits with the rest of the process
The application is made to your local planning authority, with drawings and a fee, and the council decides within a set period. To see what the permitted limits actually are, read our guides to permitted development rights and rear extension limits, or whether a loft conversion needs planning permission.
This guide is general information for homes in England and is not legal or planning advice. Rules can change and differ between properties and local authorities, so always confirm the position with your council or a qualified professional.
Ask us about your own project and we will explain which approvals are likely to apply.