A Lawful Development Certificate (LDC) is a legal document from your council confirming that a building project is lawful, most often because it is permitted development and does not need planning permission. It is optional, but it removes doubt before you build and gives your buyer’s solicitor proof when you sell. There are two types: one for proposed work (before you build) and one for existing work (already built). It is not the same as building regulations approval.
Key takeaways
- An LDC confirms planning lawfulness. It does not confirm the work complies with building regulations.
- Apply for a proposed-use LDC before work starts if your project is close to permitted development limits.
- It is the standard proof solicitors ask for when a permitted development extension or loft is sold.
- The council looks only at the facts and the law, not at whether it likes the design.
- Applications need accurate drawings and measurements.
01What does a Lawful Development Certificate do?
It answers one question: is this use or building work lawful in planning terms? For homeowners, that usually means confirming an extension, loft conversion or outbuilding is within permitted development. Unlike a planning application, the council does not judge design or neighbour impact. It checks whether the project meets the legal limits.
02The two types
| Type | When used | Example |
|---|---|---|
| Certificate of lawfulness of proposed use or development | Before work starts | A rear dormer loft conversion you plan to build under permitted development |
| Certificate of lawfulness of existing use or development | After work is complete | An extension built years ago without an application, where you need proof for a sale |
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03When is an LDC worth getting?
- Your project is close to the limits, for example a loft near the 40 or 50 cubic metre allowance, or an extension near 3 or 4 metres.
- The house has been extended before, so previous additions may have used part of the allowance.
- You are unsure of the “original house” as it stood on 1 July 1948.
- You plan to sell in the next few years and want a clean paper trail.
- Your lender or buyer requires it.
It is less important for a small, clearly permitted project, but many homeowners still apply for peace of mind.
04What do you need to apply?
- Existing and proposed plans and elevations, drawn to scale
- A site location plan
- Dimensions showing compliance with the relevant limits (depth, height, eaves, volume)
- A description of the work and of any previous extensions
- The application fee
Accurate drawings matter. If the drawings show a project outside the limits, the certificate is refused. Prohaus works with professional architects and designers who prepare these drawings through our planning and design service.
05LDC vs planning permission vs prior approval
| Route | When to use |
|---|---|
| Lawful Development Certificate | Project is within permitted development; you want proof |
| Prior approval | Single-storey rear extension between 3 and 6 m (or 4 and 8 m detached), outside conservation areas |
| Householder planning application | Project is outside permitted development, or rights have been removed |
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Read our planning permission guide to see which applies to your area.
06Does an LDC cover building regulations?
No. You still need building regulations approval and a completion certificate. See planning permission vs building regulations.
07Projects where homeowners often apply
- Rear dormer and hip-to-gable loft conversions under permitted development
- Single-storey rear house extensions within 3 or 4 metres
- Garden offices close to the height limits
- Outbuildings in larger gardens
08Frequently asked questions
Is a Lawful Development Certificate a legal requirement?
No. Permitted development does not need any certificate. An LDC is optional proof.
Can I start building before the LDC is issued?
You can, but if the certificate is refused you may have built something that needs planning permission. Waiting is safer.
Can neighbours object to an LDC?
The decision is based on facts and law, not opinion. Neighbours may provide factual information, but the council does not weigh objections as it would for a planning application.
Does an LDC work in a conservation area?
Yes, but fewer types of work are permitted development there. See our conservation area guide.
How long does an LDC take?
Councils generally aim to decide within about eight weeks. Check with your council.
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About Prohaus
Prohaus Ltd is a building company based in Kingston upon Thames, registered in 2015 and built on more than 20 years of residential building experience. We carry out extensions, loft conversions, renovations, new builds, kitchens and bathrooms, glazing, bespoke joinery and garden offices across Kingston, Surbiton, Richmond, Barnes, Putney, Fulham, Chelsea, Clapham and Wimbledon. Every project runs under a written contract with a 1-year guarantee.
Talk to us about your project
Send your address and what you want to build. We will look at whether it is likely to be permitted development and provide a written, itemised quotation.
