Planning in Merton looks straightforward until it isn't. Plenty of homeowners assume their project is fine — a loft conversion, a rear extension, a new fence — and only discover the complications after work has started or a planning application gets refused. The rules that apply to your property depend on factors most people have never heard of, let alone checked. WhatCanIBuild is built to cut through that complexity before it costs you.
The short version
- Permitted development rights don't apply equally to every property in Merton — your street matters
- Conservation areas, Article 4 directions, and Green Belt land all change what you can do without permission
- What got approved next door may have nothing to do with what you can do
Permitted development isn't a universal pass
Most homeowners know the phrase "permitted development" — the idea that certain work doesn't need a full planning application. What most homeowners don't realise is how many exceptions quietly undermine it.
Merton has multiple conservation areas, concentrated around Wimbledon Village and Merton Park. In those areas, work that would be completely fine elsewhere in the borough may require permission. But it doesn't stop there — Article 4 directions can strip permitted development rights from specific streets or even individual properties, meaning the rules that apply to your neighbour may not apply to you.
Do you know whether your property sits within one of these areas? Do you know whether an Article 4 direction has been applied to your street? Most people don't — and that's where projects go wrong.
The south of the borough adds another layer
If your property is in the southern part of Merton — parts of SM4, CR4, or KT3 — there's a further complication: Green Belt land. Development in the Green Belt is subject to different and generally stricter considerations than elsewhere. What looks like a simple garden project or outbuilding can take on a different character entirely depending on where your boundary sits.
And then there's listed buildings. If your property is listed, or if it sits next to one, the rules shift again in ways that aren't obvious from a quick search.
The best way to understand what's actually in play for your specific address — not just your postcode, not just your borough — is to use WhatCanIBuild, which maps your property's constraints against what's actually been approved and refused nearby.
What your neighbour's extension tells you (and doesn't)
A common mistake: seeing a similar project on your street and assuming you can do the same. Planning decisions are property-specific. What got approved next door may have depended on that property's exact position, its history, its relationship to a conservation boundary, or a planning officer's judgement on a particular day.
Merton Council typically takes around 8 weeks to determine a householder application, and the fee for a householder application is £258. But that's only relevant if your application stands a reasonable chance — and that's the part most homeowners are guessing at.
Approval odds for the same project type vary across the borough. They vary by street. They're shaped by what's happened on your road before — applications that sailed through, applications that were refused, reasons that set precedent.
Don't assume
A project that looks straightforward from the outside may face constraints you can't see. Guessing — or relying on what a neighbour did — is genuinely risky in a borough as varied as Merton.
That's the information WhatCanIBuild surfaces: not just the constraints on your property, but what those constraints have actually meant for projects like yours, on streets like yours. It's the difference between knowing you're in a conservation area and knowing what that means for your loft conversion specifically.
These rules vary by property
Conservation areas, Article 4 directions, and other constraints can change everything. Check what actually applies to your address.
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