Loft conversion in Forest Hill
A loft conversion in Forest Hill is decided by Lewisham council, which made 95% of its householder decisions within 8 weeks in the latest four quarters. Drawings for a rear dormer start from £695. Whether the loft needs an application depends on the volume you add and on your street's designation.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
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From drawings to a decision: what the timeline looks like
The council's clock only starts once an application is valid, so the drawings come first. We deliver drawings in 7 days, and redraws are free until the council or building control is satisfied.
Householder applications then have an 8-week determination period under the Development Management Procedure Order. In our analysis of MHCLG planning application statistics, table PS2, Lewisham decided 95% of its householder applications, excluding prior approvals, inside that period across the four quarters from 2025 Q3 to 2026 Q2.
That is a record, not a promise for your case. A missing dimension or a drawing that does not agree with the form is what stops the clock from starting.
Skipping the application with permitted development
If your loft fits permitted development there is no decision to wait for. The addition must stay within 40 cubic metres for a terrace house or 50 cubic metres for any other house, with the face set back not less than 0.2 metres from the eaves. The wording is in Schedule 2, Part 1 of the General Permitted Development Order.
Many owners still want paper confirmation. Lewisham decided 722 certificates of lawful development of all kinds across the eight quarters from 2024 Q3 to 2026 Q2, in our analysis of table PS1. See our Lewisham lawful development certificate page for how that route works.
Lewisham decided 722 certificates of lawful development of all kinds across the eight quarters from 2024 Q3 to 2026 Q2, in our analysis of table PS1.
Conservation areas and appeals in the borough
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. A house inside one loses the Class B right, so check the council's map for your road before you commission anything.
Lewisham made 578 householder decisions in the four quarters to 2026 Q2 and granted 89%. At appeal, 162 householder cases were decided between 2021 and 2026 in the Planning Inspectorate casework database (release 2609), and 30% were allowed. Most householder appeals decided there were dismissed, which is a reason to get the first submission right.
Where this page sits among our Lewisham work
This page covers Forest Hill and SE23. Our borough-wide Lewisham loft conversion drawings page compares the certificate and application routes across the borough, and the Lewisham dormer page focuses on rear dormers.
Fees start from £695 for the rear dormer set. The pricing page lists larger roofs.
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
How long does Lewisham take to decide a loft extension application?
Do loft conversions in Forest Hill need planning permission?
Are loft conversions in Lewisham usually granted?
Photographs: GRALISTAIR (CC BY-SA 4.0); David Hawgood (CC BY-SA 2.0).
