Renovating in a London Conservation Area: Planning Rules Explained
London has over 1,000 conservation areas — more than any other city in the UK. If your property is in a conservation area, certain works that are normally permitted development require planning permission. Understanding the specific restrictions helps you plan properly.
What Is a Conservation Area?
A conservation area is an area of special architectural or historic interest whose character or appearance it is desirable to preserve or enhance. Designation is made by the Local Planning Authority (your London borough council). Conservation area status does not mean you cannot change or extend your property — it means that changes must preserve or be sympathetic to the character of the area.
How to Check If You Are in a Conservation Area
Search your property address on your borough council's website — most have an online mapping tool showing conservation area boundaries. The planning portal (planningportal.co.uk) also shows conservation area status for your address.
What Permitted Development Rights Are Removed in Conservation Areas?
The key PD restrictions in conservation areas that affect most homeowners:
Side extensions: Side extensions visible from a highway require planning permission in a conservation area. Under standard PD rules, a side extension up to half the width of the original house is permitted development — not so in a conservation area.
Roof alterations visible from the highway: In a conservation area, any roof alteration that is visible from a public road or footway requires planning permission. This includes dormer windows, roof terraces, and skylights visible from the street.
Cladding: Cladding the exterior of a house in stone, tile, artificial stone, timber, plastic, or similar material requires planning permission in a conservation area.
UPVC windows and doors: Replacing windows or doors with UPVC in a conservation area may require planning permission (under Article 4 directions in many London conservation areas) and is likely to be refused on design grounds.
Demolition: Demolition of buildings in conservation areas requires Conservation Area Consent (now dealt with via a planning application).
What Is Still Permitted Development in Conservation Areas?
- Rear extensions (subject to standard size limits — rear extensions are NOT excluded from PD in conservation areas, only visible side extensions are)
- Roof dormers not visible from the highway
- Internal alterations (no planning permission required for internal changes regardless of conservation area)
Article 4 Directions
Many London conservation areas have Article 4 directions that remove additional PD rights beyond the standard conservation area restrictions — for example, removing PD rights for replacement windows (to prevent UPVC replacement), removal of front garden walls, or changes to chimney stacks. Check your specific conservation area's Article 4 direction.
Applying for Planning Permission in a Conservation Area
Planning applications in conservation areas are assessed against:
- The conservation area character appraisal (if one exists)
- Local design guidance supplementary planning documents
- The NPPF requirement to preserve or enhance the character of conservation areas
Good design, appropriate materials (timber, brick, natural slate, lime mortar), and respecting the scale and character of the street are the keys to approval in conservation areas.
RCB Design & Build
RCB Design & Build advises on conservation area rules and designs extensions and alterations to achieve planning approval — working with architects to ensure proposals respect the character of the conservation area while delivering the client's space needs.