Loft conversion in Wandsworth
Outside Wandsworth's conservation areas, most rear-dormer loft conversions on houses can proceed under permitted development, within the 40m³ (terraced) or 50m³ (semi-detached) volume limits, and a Lawful Development Certificate is worth getting even then. Inside one of the borough's conservation areas, permitted development rights for roof enlargement are removed, so you need a full application judged on roof form — a traditional rear mansard or dormer in matching materials, set back from the ridge and eaves, has a strong track record, while anything altering the street-facing roof slope is the classic refusal.
Strong loft stock; conservation-area dormers and rooflines get the closest scrutiny.
Wandsworth's Victorian and Edwardian terraces are some of London's most loft-friendly stock, and loft conversions sit alongside side returns and rear extensions as one of the borough's most common projects. The practical split runs along conservation-area lines: outside them, permitted development carries the standard rear-dormer conversion with little friction; inside them, the roofline itself — pitch, materials, how far the dormer sits back from the ridge — becomes the whole application, weighed against what's already been consented on comparable roofs nearby.
What actually applies in Wandsworth
Conservation areas in Wandsworth
Real · planning.data.gov.ukEvery designated conservation area in Wandsworth from the official dataset — inside one, permitted development narrows and design scrutiny rises.
- Alton
- Bathgate Road
- Battersea Park
- Battersea Square
- Charlwood Road and Lifford Street
- Clapham Common
- Clapham Junction
- Coalecroft Road
- Culverden Road
- Deodar Road
- Dinsmore Road
- Dover House Estate
- East Putney
- Garrad's Road
- Heaver Estate
- Landford Road
- Latchmere Estate
- Magdalen Park
- Mellison Road
- Nightingale Lane
- Old Devonshire Road
- Oxford Road
- Park Town
- Parkfields
- Putney Embankment
- Putney Heath
- Putney Lower Common
- Roehampton Village
- Rusholme Road
- Shaftesbury Park Estate
- St John's Hill Grove
- Streatham Park
- Sutherland Grove
- Three Sisters
- Totterdown Fields
- Town Hall Road
- Victoria Drive
- Wandsworth Common
- Wandsworth Town
- West Hill Road
- West Putney
- Westbridge Road
- Westmead
- Wimbledon North
- Wimbledon Park Road
Source: planning.data.gov.uk · Open Government Licence. Boundaries are checked at address level by the area report.
Article 4 directions in Wandsworth
Real · planning.data.gov.ukNo Article 4 geometry for Wandsworth appears in the national planning.data.gov.uk dataset. The borough's most significant householder control is its basement regime — Local Plan Policy LP6 (Basements and Subterranean Developments) and the council's basement guidance: multi-level basements are not supported, roughly half of front and back gardens should be retained, and at least a metre of soil above the basement is expected. Check the council's planning pages for any Article 4 directions in force.
Source: planning.data.gov.uk · Open Government Licence. Checked at address level by the area report.
Prices: HM Land Registry UK House Price Index, November 2025 · Open Government Licence.
The planning route — PD or permission?
Permitted development (GPDO Class B) allows roof enlargements up to 40m³ on terraced houses and 50m³ on semis and detached — enough for a substantial rear dormer — provided nothing projects beyond the roof plane of the principal elevation, materials are similar, and dormers sit back from the eaves. Class B is excluded in conservation areas.
In conservation areas the route is a full application, and roof form decides it: rear mansards with traditional slate and proportioned dormers have a strong record on Victorian terraces; box dormers and front-facing alterations are the classic refusals. Article 4 directions (Muswell Hill is the local example) pull roof works into planning control even where conservation policy alone might not.
Whatever the route, building regulations approval is always required — fire escape, stair geometry and floor structure — and a Lawful Development Certificate is cheap insurance on PD schemes.
What it really costs
| Cost per m² (low — rooflight conversion) | £3,000 |
| Cost per m² (expected — rear dormer) | £3,700 |
| Cost per m² (high — mansard, conservation spec) | £4,500+ |
| Typical project (20–28m² with bathroom) | £86,000 – £180,000 |
| Professional fees, surveys, party wall (add) | 8–15% of build |
Mansards in conservation areas sit at the top of the range — natural slate, lead detailing and officer negotiation all cost. Ranges calibrated from real project data; VAT excluded.
Realistic timeline
| Design and drawings | 4–6 weeks |
| PD route (Lawful Development Certificate) | 4–8 weeks |
| Full application (conservation areas) | 8–12 weeks (8-week statutory target) |
| Party wall award | 4–8 weeks (parallel) |
| Build | 10–14 weeks |
What catches people out in Wandsworth
In a conservation area, box dormers and anything visible from the street are the reliable refusals, so the design has to earn consent on traditional form and materials rather than on volume alone. Away from the planning question, low headroom — under roughly 2.2m from the existing ceiling joists to the ridge — quietly kills more Wandsworth loft schemes at feasibility than any refusal does, and steels bearing on the party wall put neighbour agreements on the critical path regardless of route.
Loft conversion in Wandsworth, district by district
First check: Whether the dormer needs planning permission
Service guide →First check: Whether the dormer needs planning permission
Service guide →First check: Whether the dormer needs planning permission
Service guide →First check: Whether the dormer needs planning permission
Service guide →First check: Whether the dormer needs planning permission
Service guide →Loft conversion in Wandsworth, asked straight
Can I convert my loft without planning permission in Wandsworth?
What loft design gets approved in a Wandsworth conservation area?
How much does a loft conversion cost in Wandsworth?
How do I know if my loft has enough headroom to convert?
Do I need building regulations approval as well as planning permission?
What applies at your address?
Borough-level rules only narrow it down. Enter a Wandsworth postcode for the live constraint check — conservation area, Article 4 and sold-price comparables, cited to source.
Planning Permission Checker provides planning and cost intelligence for early feasibility only. It is not legal, planning, valuation, architectural, structural, or surveying advice. All estimates are indicative and must be verified by qualified professionals before purchase, design, planning submission, or construction.
Cost estimates are indicative only — not a quotation. Final price depends on survey, specification, structure, access, party wall matters, VAT, professional fees, and contractor availability.
Planning outcomes are not guaranteed. Local planning authorities make final decisions.