Where in Merton does a house extension actually get determined?
Every Merton postcode district on our books, what its streets are mostly built of, and the authority that validates a house extension at that address. Fee figures further down are statutory England rates for 2026 — the council's charge, not our quote.
| Postcode | Area | Dominant stock | What it means for a house extension |
|---|
| SW19 | Wimbledon / Colliers Wood | Victorian villas, Edwardian terraces | SW19 covers Wimbledon and Colliers Wood and is shared between Merton Council and Wandsworth Council. An SW19 address is checked against both policies maps before extension drawings are started. |
| SW20 | Raynes Park | Victorian villas, Edwardian terraces | Raynes Park sits entirely within SW20 and entirely within the borough, so Merton Council validates every house extension submitted from an SW20 address with no boundary question to settle. |
| SM4 | Morden | 1930s semi-detached, post-war flats | Morden sits wholly inside SM4, so Merton Council validates every house extension submitted from an SM4 address. |
| CR4 | Mitcham | 1930s semi-detached, post-war estates | Mitcham lies wholly inside CR4 and wholly inside the borough, so Merton Council validates every house extension coming from a CR4 address. |
| SW16 | Streatham / Norbury | Edwardian terraces, post-war flats | SW16 is divided four ways. A Streatham or Norbury address can fall to Lambeth, Wandsworth, Merton or Croydon, and the policies map settles it street by street, which is why it gets checked before anything is drawn. |
| SW17 | Tooting / Earlsfield | Edwardian terraces | SW17 runs across Tooting and Earlsfield, where either Wandsworth Council or Merton Council may turn out to be the validating authority. Establish which one before an SW17 extension set is issued. |
Which Merton neighbourhoods suit a house extension best?
Ridge height, wall construction and plot depth can all change within a couple of streets in Merton, and between them they decide what a rear extension can actually reach at a given address.
- Wimbledon (SW19, SW20) — a house extension in Wimbledon starts from victorian villas, edwardian terraces, and Wimbledon reads as Victorian villas, Edwardian terraces. The side-return infill is the classic move on these Victorian terraces — 3 m of permitted development depth plus the width of the original side passage in SW19. Merton Council assesses Wimbledon house extensions against its own Wimbledon character guidance, and the location plan we draw for Wimbledon references All England Club.
- Wimbledon Village (SW19) — a house extension in Wimbledon Village starts from georgian and victorian villas, and Wimbledon Village reads as Georgian and Victorian village conservation. Georgian rear elevations here are usually the listed or locally listed face of the building in SW19. Merton Council assesses Wimbledon Village house extensions against its own Wimbledon Village character guidance, and the location plan we draw for Wimbledon Village references Wimbledon Village High Street.
- Raynes Park (SW20) — house extension work in Raynes Park means 1930s semi-detached, edwardian terraces. Raynes Park is 1930s semi-detached, Edwardian terraces. Edwardian plots here are wider throughout SW20. Merton Council decides the Raynes Park application, and Raynes Park station anchors the Raynes Park location plan.
- Morden (SM4) — a house extension in Morden starts from 1930s semi-detached, post-war flats, and Morden reads as 1930s semi-detached, post-war flats. 1930s semis here have the deepest rear gardens in the area in SM4. Merton Council assesses Morden house extensions against its own Morden character guidance, and the location plan we draw for Morden references Morden Tube.
- Mitcham (CR4) — house extension work in Mitcham means 1930s semi-detached, post-war estates. Mitcham is 1930s semi-detached, post-war estates. 1930s semis here have the deepest rear gardens in the area throughout CR4. Merton Council decides the Mitcham application, and Mitcham Cricket Green anchors the Mitcham location plan.
- Colliers Wood (SW19) — Edwardian terraces, post-war flats defines Colliers Wood, where edwardian terraces, post-war flats set what a house extension can do. Edwardian plots here are wider across SW19. Any Colliers Wood house extension is validated by Merton Council, with Colliers Wood Tube the usual Colliers Wood reference point on the site plan.
- South Wimbledon (SW19) — Edwardian terraces defines South Wimbledon, where edwardian terraces set what a house extension can do. Edwardian plots here are wider across SW19. Any South Wimbledon house extension is validated by Merton Council, with South Wimbledon Tube the usual South Wimbledon reference point on the site plan.
How do conservation areas and Article 4 affect a house extension in Merton?
Merton conservation designations: 28 sit across the borough, with Wimbledon Common, Wimbledon Village and John Innes the names most owners recognise. Inside one, permitted development no longer applies. The fee goes from £249 to £548 and the clock from six weeks to eight, because what would have been a prior approval has to be submitted as a full householder application. Wimbledon Village alters more extension designs here than any other designation.
Article 4 and your Merton house extension: Merton Council has made no borough-wide direction, so permitted development for a house extension in Merton generally survives outside Merton conservation areas and listed curtilages. A Lawful Development Certificate at £274 is how a SW19 owner records that a house extension was lawful.
Merton housing stock: Victorian villas in Wimbledon; Edwardian terraces in Tooting and Colliers Wood; 1930s semi-detached in Morden and Raynes Park; post-war flats in Mitcham. Wimbledon is heavily conservation-controlled; outer Merton (Morden, Mitcham) is permissive. Read that before choosing a house extension route in Merton — construction, not postcode, sets what is achievable. Merton Council charges £548 for a householder application and has 8 weeks to determine it.
What happens if a Merton property sits on a boundary?
- Wandsworth — cross the Merton boundary and Wandsworth Council takes the house extension instead, applying 45 conservation areas of its own around SW8. We re-price house extensions at the Merton edge because Wandsworth policy and Merton policy rarely align on house extension depth.
- Lambeth — cross the Merton boundary and Lambeth Council takes the house extension instead, applying 64 conservation areas of its own around SE1. We re-price house extensions at the Merton edge because Lambeth policy and Merton policy rarely align on house extension depth.
- Croydon — the Croydon boundary runs against Merton, so a house extension a street from Merton is decided by Croydon Council instead. Croydon runs 24 conservation areas across CR0 and its neighbours, which is why house extensions priced for Merton are re-checked against Croydon policy whenever the Merton address sits on that edge.
- Sutton — cross the Merton boundary and Sutton Council takes the house extension instead, applying 17 conservation areas of its own around SM1. We re-price house extensions at the Merton edge because Sutton policy and Merton policy rarely align on house extension depth.
Sources for this Merton house extension page: borough policies maps and
conservation-area registers (2025–26), Royal Mail postcode district boundaries,
the Town and Country Planning (Fees for Applications) (England) Regulations, the Town
and Country Planning (General Permitted Development) (England) Order 2015 as amended,
and the Party Wall etc. Act 1996.
