Single-storey rear extensions, lofts and side extensions you can build in Merton without full planning — and the exceptions.
Sceptically. Merton refused 246 larger home extension notifications and granted 58, a 19.1% grant rate against 34.6% across London, though it told 431 households no prior approval was needed at all. It issued only 156 lawful development certificates over the same window.
| Larger home extension route | Merton | London |
|---|---|---|
| Prior approval not required | 431 | 9,067 |
| Granted | 58 | 1,930 |
| Refused | 246 | 3,646 |
| Grant rate | 19.1% | 34.6% |
| Lawful development certificates | 156 | 36,657 |
| Decisions delegated to officers | 99.3% | 97.0% |
Sources: MHCLG District Planning Application Statistics (PS1 and PS2), twelve quarters to March 2026. A zero in this return means the measure was not recorded for that borough, never that no such decisions exist. Open Government Licence v3.0.
In detailSingle-storey rear extension up to 3m deep (attached house) or 4m (detached); side extension up to half the original width; loft conversion up to 40m³ (terraced) or 50m³ (semi-detached); single-storey outbuilding within the curtilage; replacement windows and doors. All subject to material match, eaves setback (20cm), and not facing a highway.
No. Permitted Development rights apply only to houses (Class C3 dwellings). Flats and maisonettes require full planning for almost every external alteration.
Yes — significantly reduced. In a conservation area: side extensions and two-storey rear extensions are not PD; cladding is not PD; chimney removal needs planning; roof additions are restricted.
An LDC is a formal confirmation from the council that your proposal is lawful PD — recommended before building, useful when selling. Costs around £103 for council fees + drawings.
Yes. Building regulations are entirely separate from planning. Permitted Development removes the planning requirement only — you still need building control sign-off for structure, insulation, fire safety, drainage, and ventilation. We deliver both planning and building regs drawings.



Pick a slot that suits you. No obligation and no sales pressure, just straight answers on your planning route.
Every Merton postcode district we draw in, the stock that dominates it and the authority that validates a permitted development scheme there. Merton fees below are the statutory England rates for 2026, not permitted development scheme estimates.
| Postcode | Area | Dominant stock | What it means for a permitted development scheme |
|---|---|---|---|
| SW19 | Wimbledon / Colliers Wood | Victorian villas, Edwardian terraces | A permitted development scheme in Wimbledon / Colliers Wood may land with Merton Council or Wandsworth Council — SW19 crosses the boundary, and the SW19 policies map decides it street by street. |
| SW20 | Raynes Park | Victorian villas, Edwardian terraces | SW20 covers Raynes Park only; Merton Council handles the permitted development scheme. |
| SM4 | Morden | 1930s semi-detached, post-war flats | SM4 covers Morden only; Merton Council handles the permitted development scheme. |
| CR4 | Mitcham | 1930s semi-detached, post-war estates | CR4 covers Mitcham only; Merton Council handles the permitted development scheme. |
| SW16 | Streatham / Norbury | Edwardian terraces, post-war flats | SW16 straddles a boundary: Streatham / Norbury addresses fall to Lambeth Council or Wandsworth Council or Merton Council or Croydon Council, so confirm which authority validates the permitted development scheme before submitting SW16 drawings. |
| SW17 | Tooting / Earlsfield | Edwardian terraces | SW17 straddles a boundary: Tooting / Earlsfield addresses fall to Wandsworth Council or Merton Council, so confirm which authority validates the permitted development scheme before submitting SW17 drawings. |
Roof pitch, wall build-up and plot depth change every few Merton streets, and each one changes what a permitted development scheme can achieve at that address.
Merton conservation designations: there are 28 across Merton Council, Wimbledon Common, Wimbledon Village, John Innes among them. Designation costs a Merton owner the permitted-development route: a permitted development scheme then needs a £548 householder application over 8 weeks, in place of the £249 prior approval route that takes 6 weeks. John Innes is the Merton designation that most often changes a permitted development scheme design.
No blanket Article 4 over Merton: Merton Council has not withdrawn permitted development across Merton, so a permitted development scheme outside a Merton conservation area usually keeps it. The £274 Lawful Development Certificate is still the document a SW19 owner wants on file.
What Merton is built from: 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. That mix decides the permitted development scheme route in Merton more than the postcode does.
Sources for this Merton permitted development scheme 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.

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