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Service area · London Borough of Merton

Architectural Designers in Merton

Magna Studio prepares planning and Building Regulations drawings for homeowners across the London Borough of Merton. Our typical Merton projects are rear and side-return extensions to Victorian terraces in Colliers Wood and South Wimbledon, dormer lofts on Edwardian houses in Wimbledon Park and Raynes Park, side extensions on 1930s semis in Morden and Mitcham, and larger two-storey extensions on Wimbledon Hill. Every quote is a fixed fee agreed in writing before we start.

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Planning authority
Merton
Decision time
8 weeks statutory
Common work
Rear extension
Quote
Within 24 hours
01Local context

Typical homes we work on in Merton

  • Victorian terraces in Colliers Wood, South Wimbledon, Mitcham and around Haydons Road
  • Edwardian houses in Wimbledon Park, Raynes Park and West Wimbledon
  • Large detached and semi-detached houses on Wimbledon Hill, Wimbledon Village and Copse Hill
  • 1930s semis and bungalows in Morden, Lower Morden, Mitcham and Pollards Hill
  • The St Helier estate, 1930s LCC cottage housing straddling Morden and Sutton
  • Post-war estates and recent apartment schemes in Colliers Wood, Mitcham and Morden
02Planning permission

Do I need planning permission in Merton?

Answer-first guides for the projects we see most here, with the national rules and the local constraints that change them.

03Constraints

Planning constraints in Merton

What changes the planning route in this area. Always confirm on the council's constraints map before relying on permitted development.

Conservation areas

Merton has numerous conservation areas, concentrated in Wimbledon Village, Wimbledon Park, Merton Park, Mitcham Cricket Green and along the Wandle. Roof extensions and cladding in these areas need planning permission. Check the council's constraints map for your address before relying on permitted development.

Source · Checked 15 Sept 2026

Article 4 directions

Several Merton conservation areas, including Merton Park and parts of Wimbledon, are understood to carry Article 4 directions removing permitted development for front alterations, windows and boundary treatments. The exact rights removed vary by area, so we confirm with the council before recommending a route.

Checked 15 Sept 2026

River Wandle flood zones

The Wandle runs through Mitcham, Colliers Wood, Merton Abbey and Wandsworth-bound Earlsfield. Land along it falls within Flood Zones 2 and 3 and some areas also have surface water flooding history. Basements and new ground-floor habitable rooms may need a flood risk assessment.

Source · Checked 15 Sept 2026

Metropolitan Open Land and Green Belt

Wimbledon Common, Wimbledon Park, Mitcham Common, Morden Hall Park and Cannizaro Park are Metropolitan Open Land, and the borough's south-western edge includes Green Belt. Houses backing onto these areas are judged on the effect of extensions and outbuildings on openness.

Checked 15 Sept 2026

Listed buildings and Wimbledon Village character

Wimbledon Village, Merton Park and Mitcham Cricket Green contain many listed buildings and locally listed houses. Listed houses need listed building consent for almost any alteration; locally listed houses attract closer design scrutiny.

Checked 15 Sept 2026

What London Borough of Merton planning officers look for

Merton's officers follow the London-wide conventions for householder extensions, and refusals most often cite excessive depth beyond neighbouring precedent, breach of the 45-degree rule or bulky roof extensions. In Wimbledon Village and the Merton Park garden suburb expect detailed comments on materials, windows and boundary treatments, and resistance to front dormers. On 1930s streets in Morden and Mitcham side extensions are expected to be set back and lower than the main roof so the gap between semis is kept. Pre-application advice is available for a fee.

Council links

Extensions and loft conversions in Merton

Merton runs from the Victorian terraces of Colliers Wood and South Wimbledon through Edwardian Wimbledon Park and Raynes Park to the 1930s suburbs of Morden, Lower Morden and Mitcham, with the large houses of Wimbledon Hill and the Village at its centre. That mix means our Merton work is varied: side-return and rear extensions on terraces, dormer lofts on Edwardian houses, side extensions on semis, and two-storey extensions and basements on larger detached homes.

Much of the terraced and semi-detached stock outside conservation areas suits permitted development, and a good share of our Merton projects go through the Lawful Development Certificate route. Where planning permission is needed, the design conversation is about depth, daylight and the gap between houses.

Planning constraints in Merton

The designations that most often change the route for a Merton home are:

  • Conservation areas at Wimbledon Village, Wimbledon Park, Merton Park, Mitcham Cricket Green and along the Wandle, which remove PD for roof extensions and cladding.
  • Article 4 directions in several of those areas removing rights for front alterations and boundary treatments; we confirm coverage with the council.
  • Flood Zones 2 and 3 along the River Wandle through Mitcham, Colliers Wood and Merton Abbey.
  • Metropolitan Open Land at Wimbledon Common, Mitcham Common and Morden Hall Park, and Green Belt on the south-western edge.
  • Listed and locally listed buildings, particularly in Wimbledon Village and Merton Park.

Flats and maisonettes, including many converted houses around Haydons Road and Colliers Wood, have no householder PD rights, so every extension needs planning permission.

What Merton planning officers look for

Merton’s officers apply the Local Plan’s design and amenity policies conventionally. For rear extensions they want depth in step with neighbouring precedent, the 45-degree rule respected to neighbours’ habitable room windows and eaves kept low near boundaries. For lofts they support rear dormers set down from the ridge and in from the party walls; front dormers are generally refused.

Side extensions on Morden and Mitcham semis should be set back from the front wall with a roof below the main ridge. In Wimbledon Village and Merton Park expect comments on window proportions, brick and boundary walls. Pre-application advice is available for a fee and is worth using for two-storey schemes and anything in a conservation area.

Our services in Merton

Example projects nearby

Guides

Read our guides on whether you need planning permission for a rear extension in London and permitted development rights in London.

Ready to start in Merton? Get an instant estimate: your indicative fee on screen and by email in two minutes, then a written fixed-fee quote within 24 hours.

04Examples

Example projects in and around Merton

Existing first floor plan of a vacant open-plan office above two shops in South CroydonExample project
Change of useSouth Croydon, Croydon

Office to Flats in South Croydon, Croydon

Conversion of a vacant 110 m² first-floor Class E office above two shops into two one-bedroom flats using the Class MA prior approval route in South Croydon.

Typical route: Class MA prior approval, decided within 56 days

05Questions

Planning questions we hear in Merton

Do I need planning permission for a rear extension in Merton?

Often not. A single-storey rear extension up to 3 m on a terrace or semi (4 m detached) is usually permitted development, extending to 6 m or 8 m through the larger home extension prior approval route. You will need planning permission if your house is a flat, sits in a conservation area with an Article 4 direction, or if the extension exceeds these limits. We check the constraints for your address before recommending a route.

Can I convert my loft under permitted development in Merton?

Yes for most Merton houses, within 40 m³ for a terrace or 50 m³ for a semi or detached house and with no dormer facing the road. In Wimbledon Village, Merton Park and other conservation areas roof extensions are excluded from permitted development and need planning permission. We recommend a Lawful Development Certificate for any PD loft so you have proof on sale.

How long does Merton council take to decide a householder application?

The statutory period is 8 weeks from validation for a householder application or a Lawful Development Certificate, and 42 days for a larger home extension prior approval. Merton's actual speed varies with workload, so we plan for the full period. The council fee is £528 for a householder application (verify before applying).

Are there special rules for extensions in Wimbledon Village?

Wimbledon Village is a conservation area with many listed and locally listed buildings, so roof extensions, cladding and most external alterations need planning permission and are judged on their effect on the area's character. Officers expect traditional materials and detailing. We prepare a design and heritage statement with every application there.

06Coverage

Everywhere we work

One team, one process, every area. Choose yours.

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