Loft conversion in Lewisham: which route fits your house
A loft conversion in Lewisham goes one of two ways: a certificate of lawful development when the work fits permitted development, or a householder application when it does not. Lewisham granted 89% of its householder decisions in the latest four quarters. Our drawings for a rear dormer start at £695 and serve both routes.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
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Two routes, one set of drawings
The certificate route asks the council to confirm that your loft is lawful without a planning application. The application route asks for permission. The drawings are close to identical, because both need existing and proposed plans, a roof section and elevations.
What differs is the test. For a certificate the council checks the work against fixed rules. For an application it weighs the design against local policy, neighbours and the street, so the drawings carry more of the argument.
The rules a certificate rests on
A rear dormer qualifies when it adds up to 40 cubic metres to the roof space of a terrace house, or up to 50 cubic metres to any other house, and the face is set back not less than 0.2 metres from the eaves. Class B, which holds these rules, is in Schedule 2, Part 1 of the General Permitted Development Order.
The right is lost for flats and maisonettes, for houses in conservation areas and where an Article 4 direction applies. Our analysis of the MHCLG Planning Data Platform datasets (bulk snapshot retrieved 14 Aug 2026) counts 30 live conservation-area entries on the national register for Lewisham, so look up your street on the council's map.
In our analysis of the Planning Inspectorate casework database (release 2609), 162 householder appeals in Lewisham were decided between 2021 and 2026, and 30% were allowed.
How busy each route is in Lewisham
In our analysis of MHCLG planning application statistics, table PS1, Lewisham decided 722 certificates of lawful development of all kinds across the eight quarters from 2024 Q3 to 2026 Q2. Table PS2 shows 578 householder decisions in the four quarters from 2025 Q3 to 2026 Q2, with 89% granted and 95% of the non-prior-approval cases decided within 8 weeks.
The two counts cover different periods and different kinds of work, so they are not a ratio of lofts to anything. They do show that both routes are in steady use in the borough. Our Lewisham lawful development certificate drawings page covers the first route in detail.
If the application is refused
A householder refusal can be appealed. In our analysis of the Planning Inspectorate casework database (release 2609), 162 householder appeals in Lewisham were decided between 2021 and 2026, and 30% were allowed. That is a history of all householder appeals, and it argues for a careful first submission over counting on an appeal.
We offer free redraws until the council or building control is satisfied, with the rear dormer set starting from £695 and delivered in 7 days. Larger or more complex roofs are on the pricing page. If you live in SE23, the Forest Hill loft conversion page looks at timing in that part of the borough.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| £695 | DrawingsDirect starting fixed fee for rear dormer loft conversion permitted development drawings, from the published price list | drawingsdirect.co.uk |
| 40 cubic metres | GPDO 2015 Sch 2 Pt 1 Class B.1(d)(i): roof additions may add up to 40 cubic metres to the roof space of a terrace house (source wording: "40 cubic metres in the case of a terrace house") | www.legislation.gov.uk |
| 50 cubic metres | GPDO 2015 Sch 2 Pt 1 Class B.1(d)(ii): roof additions may add up to 50 cubic metres to the roof space of any other house (source wording: "50 cubic metres in any other case") | www.legislation.gov.uk |
| 578 | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 89% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 95% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 162 | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 30% | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 30 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 14 Aug 2026) | www.planning.data.gov.uk |
| 722 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
Questions people ask
Do I need planning permission for a loft extension in Lewisham?
Is a dormer loft conversion in Lewisham easier to get approved than a hip-to-gable?
What does a gable loft conversion in Lewisham need drawn?
Photographs: Chris Whippet (CC BY-SA 2.0); GRALISTAIR (CC BY-SA 4.0).
