Southwark looks straightforward on a map. But its planning rules are anything but. Between its conservation areas, Thames-side flood zones, and a patchwork of restrictions that can vary street by street, what's allowed for your neighbour might not be allowed for you. WhatCanIBuild exists precisely because the answer almost always depends on your specific address — not the borough in general.
The short version
- Permitted development rights don't apply equally across Southwark — your street matters
- Conservation areas and Article 4 directions can remove rights you thought you had
- Flood zones and strategic view corridors add layers most homeowners never consider
"Permitted development" isn't a guarantee in Southwark
Most homeowners assume that if something counts as permitted development nationally, they're free to go ahead. In Southwark, that assumption gets people into trouble.
The borough has extensive conservation areas — and in those areas, work that would be completely unrestricted elsewhere can require a full planning application. We're not just talking about listed buildings. We're talking about entire streets where the normal rules simply don't apply in the way you'd expect.
On top of that, Southwark Council can issue Article 4 directions that strip permitted development rights from specific areas. Most homeowners don't realise these exist until after they've started work. Whether your property is affected isn't something you can tell from a postcode — it comes down to your exact address.
The Thames boundary creates complications you wouldn't guess
Southwark's northern edge runs along the Thames, and that brings flood zone considerations into play for a surprising number of properties. Flood zones don't just affect whether you can build — they can affect what kind of application you need to make, what assessments are required, and how likely approval is.
There are also strategic view corridors in parts of the borough — protections designed to preserve sightlines to landmarks. These aren't things most homeowners think to check. But they can determine whether a project that looks perfectly reasonable on paper is actually viable for your property.
Don't assume your project is low-risk
Even small extensions or outbuildings can trigger requirements in Southwark that wouldn't apply in neighbouring boroughs. The combination of constraints on any one property can be surprisingly complex.
What's been approved nearby matters more than the rules themselves
Here's the part most people miss entirely. Even if you know you're in a conservation area, knowing the label doesn't tell you what it means for your specific project. The same type of extension can be approved on one side of a street and refused on the other. Similar loft conversions can have completely different outcomes depending on the precedents already set in your immediate area.
This is where WhatCanIBuild does something that general guidance simply can't. Rather than telling you the rules in the abstract, it shows you what's actually been approved and refused for properties like yours, nearby — and what that means for your chances. That gap between knowing a rule exists and knowing what it means for your project is exactly where homeowners get caught out.
The best way to know where you stand
Southwark's planning landscape is layered in ways that make confident DIY research genuinely difficult. Conservation area status, Article 4 directions, flood zones, view corridors — your property might sit inside one of these, several, or none. The combination matters enormously, and it's not something you can read off a general guide.
Enter your address into WhatCanIBuild and see what constraints actually apply to your property, what similar projects nearby have had approved or refused, and what your realistic chances look like before you spend a penny on architects or applications.
These rules vary by property
Conservation areas, Article 4 directions, and other constraints can change everything. Check what actually applies to your address.
Check my address