Camden Extension Guide 2025: Planning, Costs & Rules
Everything you need to know about extending your home in Camden. Planning permission requirements, Article 4 directions, conservation area rules, and typical costs.
Camden Extensions: Quick Facts
- Cost: £2,000-2,800/m² typical (add 10-15% in conservation areas)
- Planning: 8-13 weeks for standard applications, longer for conservation areas
- Article 4: Extensive coverage removes permitted development in many areas
- Basements: Strict controls - structural assessments and SuDS required
- Get your Camden extension estimate (Free)
Planning Permission in Camden
Camden has stricter planning controls than many London boroughs. Large parts of the borough are covered by conservation areas and Article 4 directions, meaning many extensions that would qualify as permitted development elsewhere require full planning permission here.
Before planning any extension, check if your property is in a conservation area or subject to an Article 4 direction. Use our free checker tool to see what planning constraints apply to your property.
Permitted Development Rights in Camden
Under permitted development rights, you may be able to extend without planning permission, but Camden has extensive restrictions:
| Extension Type | Max Without Permission | Camden Notes |
|---|---|---|
| Single-storey rear (detached) | 6m deep, 4m high | Often restricted by Article 4 |
| Single-storey rear (semi/terrace) | 3m deep, 4m high | Very limited in conservation areas |
| Side extension | Half width of house | Planning required in most areas |
| Two-storey rear | 3m deep max | Almost always needs permission |
| Basement | N/A | Always requires planning permission |
Key Restrictions in Camden
- All 36 conservation areas have some Article 4 restrictions
- Hampstead, Highgate, and Primrose Hill have extensive Article 4 coverage
- Listed buildings always require listed building consent regardless of size
Check your Camden property constraints
Instantly see conservation areas, Article 4 directions, and tree preservation orders.
Check Planning Constraints →Camden Basement Policy
Camden has one of the strictest basement policies in London. The Camden Planning Guidance on Basements (2021) requires extensive documentation and assessments.
Key Requirements
- Structural Impact Assessment (BIA): Independent verification required, costs £3,000-8,000
- Sustainable Drainage (SuDS): Mandatory to reduce flood risk, adds £5,000-12,000
- Construction Management Plan: Details on noise, vibration, access, working hours
- Monitoring protocols: Pre and post-construction surveys of neighboring properties
Basement projects in Camden typically cost £100,000-300,000+ and take 12-18 months from planning to completion. See our complete basement guide for detailed costs and requirements.
Extension Costs in Camden
| Extension Type | Cost per m² | Typical Total |
|---|---|---|
| Single-storey rear (20m²) | £2,000-2,500 | £40,000-50,000 |
| Side return (12m²) | £2,500-3,500 | £30,000-42,000 |
| Two-storey rear (40m²) | £2,200-2,800 | £88,000-112,000 |
| Loft conversion (30m²) | £1,800-2,400 | £54,000-72,000 |
| Basement (40m²) | £3,000-4,000 | £120,000-160,000 |
Conservation area premium: Add 10-15% for matching materials, sash windows, and heritage detailing
Additional Costs to Budget For
- Architect fees: £4,000-12,000 (10-15% of build cost)
- Structural engineer: £1,500-3,500
- Planning application: £206 (householder) or £462 (full planning)
- Party wall: £1,500-3,000 per neighbor (for surveyors)
- Building Control: £800-2,000 depending on project size
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Frequently Asked Questions
Do I need planning permission for an extension in Camden?
It depends on your location and extension type. Many areas in Camden have Article 4 directions that remove permitted development rights, especially in conservation areas. Single-storey rear extensions up to 6m (detached) or 3m (terraced/semi) may be allowed under permitted development if no restrictions apply. Always check with Camden Planning before starting.
How much does an extension cost in Camden?
Extension costs in Camden: £2,000-2,500/m² for single-storey rear extensions, £2,200-2,800/m² for two-storey extensions, £2,500-3,500/m² for side returns, and £3,000-4,000/m² for basements. Add 10-15% for conservation area requirements (matching materials, sash windows). Total project costs range from £40k for small single-storey to £200k+ for basements.
What are Article 4 directions in Camden?
Article 4 directions remove permitted development rights in specific areas. Camden has extensive Article 4 coverage in conservation areas and parts of Hampstead, Highgate, Primrose Hill, and Kentish Town. This means you need planning permission for extensions that would normally be allowed under permitted development. Check Camden's Article 4 direction map before planning.
Does Camden allow basement extensions?
Yes, but with strict controls. Camden requires planning permission for all basement excavations. The Camden Planning Guidance on Basements (2021) requires structural impact assessments, sustainable drainage systems (SuDS), construction management plans, and monitoring protocols. Expect £100k-300k+ costs and 12-18 month timelines including approvals.
How long does planning permission take in Camden?
Standard planning applications take 8-13 weeks in Camden. Conservation area applications often take longer (10-16 weeks) due to additional scrutiny. Pre-application advice is recommended and costs £150-500 depending on project complexity. Complex applications (basements, listed buildings) can take 4-6 months. Check planning application timelines for more details.