Permitted Development Rights for House Extensions in London: What You Can Build Without Planning Permission
Updated: Nov 2
Permitted development rights allow homeowners in London to build certain house extensions without applying for planning permission, saving time and money. However, the rules are specific and depend on the type of property, size of extension, and whether you are in a conservation area. At LCCL Construction, we advise on permitted development rights for every project and handle all planning applications when they are required.
Not sure whether your project needs planning permission? Enter your postcode and tick what you want to build — we look up the conservation areas, Article 4 directions and listed buildings for you, and you see which parts are permitted development and the from-price for each. Lawful Development Certificate included on every permitted development job.
What Are Permitted Development Rights?
Permitted development rights are automatic planning permissions granted by Parliament that allow certain types of building work without a formal planning application. They are set out in the Town and Country Planning (General Permitted Development) Order. For house extensions, the most relevant class is Class A, which covers single storey rear extensions. These rights apply to houses but not to flats or maisonettes. Properties in conservation areas, Areas of Outstanding Natural Beauty, or listed buildings have more restricted permitted development rights.
Size Limits for Permitted Development Extensions
For single storey rear extensions, the size limits are 6 metres from the original rear wall on semi-detached and terraced houses, or 8 metres on detached houses, with a maximum eaves height of 3 metres and overall height of 4 metres. Side extensions are limited to half the width of the original house, single storey only, with a maximum height of 4 metres. Additions must not exceed 50% of the total area of land around the original house. Materials should be similar in appearance to the existing house. The extension must not be forward of the principal elevation fronting a highway.
When Do You Need Planning Permission?
You need planning permission when your extension exceeds the permitted development size limits, your property is in a conservation area and the extension is visible from the road, your property is a listed building, you live in a flat or maisonette, previous extensions have already used up the permitted development allowance, or the extension would be forward of the principal elevation. Multi-storey extensions, mansard loft conversions, and some larger projects also require planning permission.
Certificate of Lawfulness
Even when your project falls within permitted development rights, LCCL Construction recommends obtaining a Certificate of Lawfulness from your local council. This is a formal confirmation that your proposed work is lawful and does not require planning permission. It costs approximately £103 for a householder application and provides legal certainty. It is also valuable documentation when you come to sell your property, as buyers and their solicitors will want evidence that the extension was built lawfully.
Get Expert Planning Advice
Not sure whether your project needs planning permission? Enter your postcode and tick what you want to build — we look up the conservation areas, Article 4 directions and listed buildings for you, and you see which parts are permitted development and the from-price for each. Lawful Development Certificate included on every permitted development job.
LCCL Construction provides expert advice on permitted development rights and planning permission for all house extension projects across London and Hertfordshire. We handle all planning applications, certificates of lawfulness and building regulations as part of our design and build service. Call 020 8037 7332, email info@lcclconstruction.co.uk, or book a free consultation at lcclconstruction.co.uk/booking-calendar/free-consultation-call.
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