Which London Boroughs Are Hardest for Planning Permission?

Why Planning Constraints Matter for Extensions

Most homeowners assume they can extend under permitted development (PD) rights. In many boroughs, that's true. But four types of planning designation can strip those rights away:

• 1.Conservation areas remove most PD rights for rear extensions, cladding changes, and roof alterations. You'll need full planning permission for work that would be automatic elsewhere.
• 2.Article 4 directions remove specific PD rights even outside conservation areas. A borough can target individual streets or entire districts. Waltham Forest has used them extensively.
• 3.Listed buildings require separate listed building consent for any alteration, internal or external. This applies regardless of whether the work would otherwise be permitted development.
• 4.Tree Preservation Orders (TPOs) protect trees that may sit where you want to build. Extensions near TPO trees need arboricultural reports and sometimes foundation redesigns to avoid root damage.

How We Scored Planning Difficulty

We created a composite planning difficulty score by counting features across four constraint datasets from planning.data.gov.uk and weighting them by impact on extension projects:

• -Conservation areas (weight: 3x) - highest impact, removes most PD rights
• -Listed buildings (weight: 2x) - requires separate consent process
• -Article 4 directions (weight: 2x) - targeted PD removal
• -TPO zones (weight: 1x) - adds cost and complexity but rarely blocks projects entirely

Boroughs where data isn't published to the national platform are scored only on available datasets, which may understate their true constraint density. The score is relative, not absolute - it shows how boroughs compare to each other.

All 33 Boroughs Ranked by Planning Difficulty

Higher scores mean more constraints and greater likelihood of needing full planning permission. The score combines conservation areas (3x), listed buildings (2x), Article 4 areas (2x), and TPO zones (1x).

Dashes indicate the borough has no features recorded in that dataset on the national platform, or the data is maintained locally. Some boroughs publish constraint data directly rather than through planning.data.gov.uk. Scores for these boroughs will be understated.

The 5 Hardest Boroughs

1. Westminster

Westminster dominates with 3,455 listed buildings - more than any other borough by a wide margin. Add 56 conservation areas and 263 TPO zones, and the vast majority of properties fall under at least one constraint. Almost every extension project here requires full planning permission and often listed building consent. Expect heritage officers to scrutinise materials, fenestration, and even mortar colour.

2. Kensington & Chelsea

With 2,609 listed buildings and 41 conservation areas covering most of the borough, Kensington & Chelsea layers on 84 Article 4 direction areas for good measure. The borough is also known for its basement policy, which restricts subterranean extensions to a single storey following well-publicised structural incidents. High property values make the effort worthwhile, but expect a 6-12 month planning timeline.

3. Southwark

Southwark is the hidden constraint giant. Most people associate planning difficulty with prime west London, but Southwark's numbers tell a different story: 480 Article 4 areas, 724 TPO zones, 56 conservation areas, and 909 listed buildings. Areas like Dulwich Village and Camberwell are heavily protected, while the regeneration zones around Elephant and Castle present a different kind of planning complexity.

4. Camden

Camden has 1,967 listed buildings and 40 conservation areas. The Bloomsbury, Hampstead, and Belsize Park areas are particularly constrained. Camden's planning department is known for detailed design scrutiny and a preference for traditional materials in conservation areas. Extensions that might be approved elsewhere are often refused or required to be redesigned here.

5. Barnet

Barnet's headline number is TPOs: 3,217 tree preservation order zones, far more than any other borough. While TPOs don't prevent extensions outright, they add cost and complexity. Properties near protected trees need arboricultural impact assessments (£500-1,500), and foundations may need to be redesigned to avoid root zones. Add 649 listed buildings and 48 Article 4 areas, and Barnet is harder than its suburban reputation suggests.

The 5 Easiest Boroughs

1. Barking & Dagenham

Just 4 conservation areas, 3 Article 4 direction areas, and 48 listed buildings across the entire borough. The overwhelming majority of properties have full permitted development rights. A standard rear extension or loft conversion here is straightforward - submit a lawful development certificate, pay £258, and build.

2. Newham

Seven conservation areas and minimal other constraints. Newham's housing stock is largely post-war, with fewer heritage designations than inner London boroughs. The Olympic regeneration has brought new housing but hasn't added significant planning constraints for existing homeowners looking to extend.

3. Havering

Eleven conservation areas and no other constraints published to the national platform. Havering's suburban character means most homes are detached or semi-detached with good-sized gardens - ideal for extensions. The borough also has a high freehold rate (62%), avoiding the leasehold consent complications common in central London.

4. Greenwich

Just 14 conservation areas. While the historic Greenwich town centre is protected, the wider borough - Eltham, Woolwich, Thamesmead - has relatively few constraints. Most residential streets have full PD rights for standard extensions.

5. Sutton

Fifteen conservation areas and no other constraint data on the national platform. Sutton's suburban housing stock - predominantly 1930s semis and post-war builds - is well suited to extensions, and the low constraint count means most projects proceed under permitted development.

Constraint Breakdown by Type

Conservation areas: top 10

Article 4 directions: top 10

Listed buildings: top 10

Tree Preservation Orders: top 5

What This Means for Your Extension

Borough-level data gives you the big picture, but planning decisions happen at property level. A property on a constrained street in an otherwise easy borough still needs careful checking. Conversely, not every property in Westminster is listed or in a conservation area.

The practical takeaways:

• -High-constraint boroughs: Budget £5,000-10,000 extra for planning fees, heritage consultant reports, and longer timelines. Expect 8-16 weeks for a planning decision vs 8 weeks for PD.
• -Low-constraint boroughs: A lawful development certificate (£258) confirms your PD rights. Most standard extensions can proceed without a full planning application.
• -Article 4 surprises: Waltham Forest, Southwark, and Lambeth have extensive Article 4 coverage. Even if you're not in a conservation area, your PD rights may have been removed. Always check before assuming.
• -TPO areas: If you're in Barnet, Southwark, or Brent, get a tree survey early. An arboricultural report costs £500-1,500 and can influence foundation design and extension footprint.