Dormer loft conversion in Sydenham
A dormer loft conversion in Sydenham is limited, under permitted development, to 50 cubic metres of added roof space for a house that is not a terrace. A hip-to-gable with dormer, or a front dormer, is drawn from £795 by DrawingsDirect and can need a full planning application in Lewisham.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
Prefer to talk it through?
Why hip-to-gable and dormers go together
On a semi-detached house with a hipped roof, the gain from a dormer alone can be modest. Swapping the hip for a gable end adds head height on the stairs side and makes room for a full dormer behind it, so the two are often designed together. An end-of-terrace house counts as a terrace under the order and has the lower limit.
The volume matters twice. Class B of the General Permitted Development Order caps added roof space at 50 cubic metres for a house other than a terrace (legislation.gov.uk), and a hip-to-gable uses up a large part of it before the dormer is counted.
What Lewisham decides in general
Our analysis of the MHCLG planning application statistics shows that Lewisham made 1,256 planning decisions of all kinds in the latest four quarters of published data, and granted 1,060 of them. That includes everything from new homes to householder work, so read it as a sign of how the council behaves in general.
Our hip-to-gable loft conversion drawings page covers the design questions in detail, and our general dormer loft conversion drawings service explains the standard package.
Our analysis of the MHCLG planning application statistics shows that Lewisham made 1,256 planning decisions of all kinds in the latest four quarters of published data, and granted 1,060 of them.
Doing the loft and the kitchen in one go?
Some owners want the dormer and a deeper ground-floor extension at the same time. Our analysis of the same statistics shows that Lewisham determined 85 larger home extension prior approvals in the latest eight quarters and refused 81 of them. Those 85 leave out cases where prior approval was found not to be required, which are counted separately.
If you are combining the two, we draw the loft and the extension as separate parts of one set, so a problem with the ground-floor route does not hold up the roof.
If the answer is no
If Lewisham refuses a householder application, you have 12 weeks from the date on the decision letter to appeal, as the government's guidance explains. The decision notice lists the reasons for refusal, and those reasons are the brief for any revised design.
Our fee starts at £795 for a front dormer or a hip-to-gable with a dormer. Read about the other loft options on our loft conversion drawings page.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 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 |
| £795 | DrawingsDirect starting fixed fee for a front dormer or a hip-to-gable loft with a dormer | drawingsdirect.co.uk |
| 12 weeks | Householder planning appeal deadline from date on decision letter (source wording: 12 weeks) | www.gov.uk |
| 1,256 | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 1,060 | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 85 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 81 | 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
Can I build a hip-to-gable and dormer in Sydenham without planning permission?
How much will the drawings cost?
How long do I have to appeal a refusal?
Photographs: GRALISTAIR (CC BY-SA 4.0); GRALISTAIR (CC BY-SA 4.0); David Hawgood (CC BY-SA 2.0).
