Wimbledon Planning: Article 4, CIL & Merton's Portal

Wimbledon, Merton Park, Raynes Park and Colliers Wood are full of houses that suit a loft or a rear extension. They also sit in a borough with a few rules worth knowing before you start: two conservation areas with long-standing Article 4 Directions, a Community Infrastructure Levy (CIL) that can catch out larger extensions, and a planning search system that's still being improved.

Before anything else, check which council you're in. SW19 straddles two boroughs. Most of Wimbledon is in Merton, but parts of Wimbledon Park and Southfields are in Wandsworth, which has different rules. This guide covers Merton.

Permitted development basics for Merton houses

Merton's permitted development and prior approval page points homeowners to the national rules on the Planning Portal. It also highlights three things:

• Flats and listed buildings don't have householder PD rights. The council says "permitted development rights do not apply to flats or listed buildings".
• Conservation areas have extra restrictions. Nationally, roof extensions such as dormers aren't PD in a conservation area (GOV.UK technical guidance).
• Larger single-storey rear extensions go through prior approval. That's over 3 m and up to 6 m for most houses, or over 4 m and up to 8 m for detached houses. Merton notifies neighbours. You mustn't start until the council has said prior approval isn't required, has granted it, or 42 days have passed without a decision.

For lofts outside a conservation area, the Class B rules apply: 40 m³ of extra roof space for a terrace, 50 m³ for other houses, nothing higher than the existing ridge, and no dormers on a front slope facing the road (Planning Portal). Many Merton homeowners confirm this with a Lawful Development Certificate, which costs £274 from April 2026. A householder application costs £548 (government fee schedule).

John Innes Merton Park and Wilton Crescent: the Article 4 areas

What's in force

Merton's conservation areas page says that in the John Innes Merton Park and Wilton Crescent conservation areas you need planning permission for the changes set out in four directions:

• Article 4 Direction (No 1) – 1986
• Article 4 Direction (No 2) – endorsed by the Secretary of State, February 1990
• Article 4(2) Direction (No 1) – July 2007
• Article 4(2) Direction (No 2) – July 2007

The council provides a map, the "Conservation Areas Article 4s" web app, linked from the same page, so you can check whether your property is covered.

What the John Innes design guide says

The council's John Innes Merton Park and Wilton Crescent design guide explains the older directions. It's an older document that describes the 1987/1990 approvals and predates the 2007 directions, so use the web app to confirm your address. Its key points for homeowners are:

• Direction No 1 withdrew PD rights for "the enlargement, improvement or other alteration of a dwelling house", porches, and gates, fences and walls, for named properties on roads including Melrose Road, Church Lane and Watery Lane. The guide says that within this area "all extensions require planning permission".
• Direction No 2 covers gates, fences, walls and other enclosures across a wider list of roads. In practice that protects the area's distinctive holly hedges.
• Lofts: where a loft conversion changes the roof form, permission is needed. The guide says "any dormer should be located on the rear roof slope, set back from the eaves and should not project above the ridge line". It suggests lead or tile/slate hanging as suitable materials.
• Extensions should be "subordinate to the main house; generally single storey with a pitched roof" and shouldn't rise above eaves level. The guide says flat-roofed extensions "should be avoided".

Merton has other conservation areas too. The council's conservation areas list links to the guidance for each one.

CIL: the form to send before your builder starts

This is the step most likely to cost you money if you miss it.

When CIL applies

Merton's CIL page says a permission for any new dwelling, or for at least 100 square metres of new gross internal area (GIA), will usually be liable for CIL under both the Merton and Mayor of London charging schedules. Many single-storey rear extensions come in under 100 m². But a large wraparound plus a loft, or a whole-house remodel that adds a lot of floor space, can get close. Merton's page notes that lofts come up often in disputes about what counts as GIA.

Merton's planning search page carries a blunt warning: "CIL liabilities for a single house are usually in the tens or hundreds of thousands of pounds". It goes on to say that householder exemptions "must be successfully applied for by the householders themselves before the commencement date".

The exemption: Form 9

GOV.UK's CIL guidance says people extending their own home can be exempt if it's their principal residence and the extension doesn't create a new dwelling. The claim must be made before development commences, on the Residential Extension Claim (Form 9). Extensions under 100 m² that don't create a new dwelling are already exempt as minor development. GOV.UK also notes that a commencement notice isn't required for a residential extension exemption, though it is for annexes.

In Merton, claims go to the CIL team by email. The address is on the council's CIL page. Our practical advice: if your scheme is anywhere near 100 m² of new floor space, get the exemption granted before any work starts on site, demolition included.

Searching Merton planning applications

Merton's Find a planning application page links to the Regulatory Services Hub. Points to know:

• Only applications validated after 1 July 2008 are on the Hub. For older records, contact Development Control.
• The council says the portal "is under development with our system supplier to make improvements to search functionality". It expects this to be completed by November 2026. If you have problems, the council asks you to email its planning team.
• Searching your street for recent lofts and extensions is one of the best ways to see what officers have accepted nearby.

What's happening locally: Merton in numbers

Based on the Planning London Datahub, 2 October 2026 pull (applications validated 2 October 2025 to 1 October 2026):

Merton application type	Total	Approved / granted	Refused	Refused as % of decided
Householder	896	581	43	7%
Lawful development (proposed)	291	215	10	4%

Caveat: "decided" means approved plus refused. Many applications were still pending (269 householder, 65 LDC). Councils code decisions differently and the Datahub updates continually, so treat these as indicative. An earlier Datahub pull (28 September 2026) found that SW19 had more Merton householder and LDC applications than any other Merton postcode district.

FAQ

Do I need planning permission for a loft conversion in Wimbledon?

Not always. Outside conservation areas, a loft that meets the Class B PD limits doesn't need planning permission. Many people still get a Lawful Development Certificate. In a conservation area such as John Innes Merton Park or Wilton Crescent, dormers need a householder application.

Which parts of Merton have Article 4 Directions for houses?

Merton's conservation areas page names the John Innes Merton Park and Wilton Crescent conservation areas, with directions from 1986, 1990 and 2007. Use the council's Article 4 web app to check your address.

Do I have to pay CIL on a house extension in Merton?

Only if the development is liable, usually at 100 m² or more of new floor space or a new dwelling. Even then, you can claim the residential extension exemption on Form 9, but it must be granted before you start work.

How long does prior approval for a larger rear extension take in Merton?

The council has 42 days. You can't start until it says prior approval isn't required, grants approval, or 42 days pass without a decision.

Why can't I find an old planning application on Merton's portal?

The Regulatory Services Hub only holds applications validated after 1 July 2008. For older ones, contact Merton's Development Control team.

Planning a project in SW19?

If you're weighing up a loft or extension in Wimbledon, we're glad to talk through the likely planning route and timeline before you commit. See our loft conversions in Wimbledon and house extensions in Wimbledon pages, then call 07564 041115 or email admin@bluebirdspaces.co.uk.

General guidance, not planning or tax advice. Confirm CIL with Merton's CIL team before starting. Sources checked 2 October 2026.