Dormer loft conversion in Lewisham
A dormer loft conversion in Lewisham can be built under permitted development if the added roof space stays within 50 cubic metres for a detached or semi-detached house, or the lower limit for a terrace, the other Class B conditions are met and no restriction applies to your street. DrawingsDirect draws dormer conversions across the borough from £695.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
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The allowance and where it stops
Class B of the General Permitted Development Order sets the volume allowance. Any house other than a terrace may add up to 50 cubic metres of roof space, as the order itself states.
That volume is a ceiling, not a design brief. A dormer that fills the whole allowance can look heavy against the neighbouring roofs, and it is easy to underestimate what earlier roof extensions have already used up.
Article 4 directions in Lewisham
Our analysis of the MHCLG Planning Data Platform conservation-area and article-4-direction datasets counts 89 Article 4 direction entries for Lewisham on the national register. A direction can remove permitted development rights for a street, and the national register may not be complete, so an empty result for your address is not proof that none applies.
Before you pay for a design, check the council's own planning map for your address. If a direction applies, the dormer needs a full application and the drawings need to make the case.
Our analysis of the MHCLG Planning Data Platform conservation-area and article-4-direction datasets counts 89 Article 4 direction entries for Lewisham on the national register.
When the council says no
Our analysis of the MHCLG planning application statistics shows that Lewisham refused 61 householder applications in the latest four quarters of published data. Our analysis of the Planning Inspectorate casework database shows that 30% of the 162 householder appeals decided in the borough were allowed.
Redrawing a refused dormer, for example with a set-back and matching materials, is usually quicker than an appeal.
Fees and the lawful development route
Our dormer loft conversion drawings start at £695. If you want a certificate of lawful development to prove the work is permitted, the statutory fee for a proposed-use certificate is £274, which is half the householder application fee.
Other Lewisham routes sit on the Lewisham floor plans page and the Lewisham loft conversion page.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 89 | 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 |
| 50 cubic metres | GPDO 2015 Sch 2 Pt 1 Class B para B.1(d): roof space addition limit, any other case (source wording: 50 cubic metres) | www.legislation.gov.uk |
| £695 | DrawingsDirect starting fixed fee for a rear extension, dormer or loft | drawingsdirect.co.uk |
| 61 | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 30% | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 162 | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| £274 | Statutory fee, proposed lawful development certificate (half of householder fee), from 1 April 2026 | assets.publishing.service.gov.uk |
Questions people ask
How big can a dormer be in Lewisham without planning permission?
Does Lewisham have Article 4 directions?
What does a certificate of lawful development cost?
Photographs: Chris Whippet (CC BY-SA 2.0); GRALISTAIR (CC BY-SA 4.0).
