Permitted development is the quickest and cheapest route to a London extension or loft conversion, but only if your house actually qualifies. Many do not: Article 4 directions remove rights in large parts of Camden, Islington and Richmond upon Thames, flats and maisonettes have no householder permitted development rights at all, and a previous extension can quietly use up your allowance. This service tells you where you stand and, when you qualify, secures a Lawful Development Certificate (LDC) so the position is documented.
What is permitted development and why get an LDC?
The General Permitted Development Order grants houses in England a set of rights without planning permission. The ones that matter most in London are:
- Class A, extensions. Single-storey rear extensions up to 3 m deep on a terraced or semi-detached house and 4 m on a detached house, with a maximum height of 4 m and eaves no higher than 3 m within 2 m of a boundary. Side extensions must be single storey and no wider than half the original house. Materials must be similar in appearance to the existing house.
- Class B, roofs. Up to 40 m³ of additional roof volume on a terraced house and 50 m³ on a semi-detached or detached house, no dormers on a roof slope fronting a highway, and nothing at all in a conservation area or Article 4 area.
- Class E, outbuildings. Garden rooms up to 2.5 m high within 2 m of a boundary, otherwise 4 m for a dual-pitched roof or 3 m for other roofs, covering no more than half the garden and used for purposes incidental to the house, not as a bedroom.
An LDC is the council’s binding confirmation that a specific design meets these rules. It costs half the planning fee, is decided within 8 weeks and cannot be refused on design grounds, only on whether the drawings comply.
What’s included
We start with a desktop screen of Article 4 directions, conservation areas, listed status and previous extensions for your address. If you want certainty before committing to drawings, the written PD assessment sets out the limits for your house and the envelope you can build within; the fee is credited if you proceed to an LDC. The LDC package then adds a measured survey, existing and proposed drawings annotated against each condition of the relevant class, location and block plans, Planning Portal submission and agent role until the certificate is issued.
What’s not included
The council fee is paid separately: £264 for a proposed development, £528 for an existing use or development (verify before applying). If the check shows your project cannot meet the rules, we quote for a householder planning application instead and carry the survey across. Building Regulations drawings, structural calculations and party wall notices are excluded; see our Building Regulations drawings service for the next stage.
Process and timeline
| Stage | Duration |
|---|---|
| Desktop check and written quote | Within 24 hours |
| Measured survey | Booked within 1 week |
| Written PD assessment | About 1 week |
| LDC drawings | 2–3 weeks after survey |
| Submission | Within 2 working days of sign-off |
| Council decision on the LDC | 8 weeks from validation |
If your extension needs the larger home extension route (6 m or 8 m), the council decides prior approval within 42 days rather than 8 weeks.
Fees
The written PD assessment is a small fixed fee, credited against the drawings if you proceed. LDC drawings and submission are priced per project by type and size, from an outbuilding at the bottom of the range through single-storey extensions and dormer lofts to hip-to-gable conversions, all excluding VAT and the council fee. Our planning documentation page explains what the fee covers, and the quote tool emails you an indicative figure for your property.
Related guides and example projects
Our guide to permitted development rights in London walks through each class in detail, and do I need planning permission for a rear extension in London? covers the common cases. Borough constraints differ, so see our pages for Barnet, Bromley, Ealing and Richmond upon Thames.
Want to know where you stand? Get an instant estimate and we will confirm your PD position and the right route within 24 hours.
