Conservation Area Rules in London: What You Can and Cannot Do

Understand how conservation area designation affects your permitted development rights in London, what works need planning permission, and how local authorities assess proposals.

London has over 1,000 conservation areas, covering everything from Victorian terraces to Georgian squares and post-war housing estates. Living in one does not mean you cannot make changes to your home — but it does mean that some works that would normally be permitted development require planning permission, and that the design of any changes will be scrutinised more carefully.

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When it may be permitted development

These are the common features that keep a project on the simpler route.

Rear extensions can still fall within permitted development in conservation areas, provided they do not exceed the applicable size limits and are not visible from a highway.

Internal works — including loft conversions that do not alter the roofline externally — are typically not affected by conservation area designation.

Works that are genuinely minor and do not materially affect the external appearance of the building can often proceed without planning permission.

When planning permission is more likely

These are the usual triggers that push a scheme beyond straightforward PD rights.

Roof extensions, dormer windows, and rooflights on the principal or side elevations facing a highway require planning permission in conservation areas.

Cladding the exterior of a house in stone, artificial stone, pebble dash, render, timber, plastic, or tiles requires planning permission in conservation areas.

Outbuildings and structures in front of the house, or visible from a highway or public open space, generally require planning permission in conservation areas.

What CanUBuild checks

Faster answers before you speak to an architect or builder

The tool is designed to answer the first question most homeowners have: is this worth pursuing, and what is most likely to block it?

CanUBuild identifies whether your address falls within a conservation area as part of the constraint check — before you spend money on drawings.

The tool also flags other overlapping designations such as listed building status, Article 4 directions, and tree preservation orders that commonly accompany conservation area coverage.

You can see how nearby planning applications — including those in the same conservation area — have been decided, giving you a read on how your local authority applies its policies.

FAQ

Questions people ask before starting a project

Do I need planning permission for everything in a conservation area?

No. Many works — including rear extensions within size limits, internal works, and modest repairs — remain permitted development in conservation areas. The main restrictions apply to roof alterations visible from highways, cladding, front extensions, and visible outbuildings.

Can I replace my windows in a conservation area?

Window replacement is not always controlled by planning in a conservation area, unless an Article 4 direction is in place that removes that permitted development right. However, many conservation areas have Article 4 directions specifically targeting windows, so you should always check for your specific address.

What is a conservation area character appraisal?

A character appraisal is a document that describes the special architectural or historic interest of a conservation area — its layout, buildings, materials, and features. Planning officers use it to assess whether proposed works preserve or enhance that character, which is the statutory test for planning applications in conservation areas.

Is planning permission more likely to be refused in a conservation area?

Not necessarily refused, but the design is scrutinised more carefully. Applications that demonstrate understanding of local character, use appropriate materials, and avoid harm to the setting of the conservation area can succeed. It is the quality of the design response — not the designation itself — that usually determines the outcome.

Next step

Check your property before paying for drawings

Search for the address, choose your project type, and get a planning feasibility answer based on permitted development rules, constraints, and local precedent data.

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