PERMITTED HOMEOWNER GUIDES

Planning a home project?
Start with a £15 guide.

Our illustrated, practical guides help you understand the rules, explore design options and budget with confidence — before you commit to building work.

Porch Guide
Rules, design options, costs and next steps.
View guide
Garage Guide
Rules, design options, costs and next steps.
View guide
Garden Room Guide
Rules, design options, costs and next steps.
View guide
Rear Extension Guide
Rules, design options, costs and next steps.
View guide
Side Extension Guide
Rules, design options, costs and next steps.
View guide
Conservatory Guide
Rules, design options, costs and next steps.
View guide
Two Storey Rear Guide
Rules, design options, costs and next steps.
View guide
Loft Conversion Guide
Rules, design options, costs and next steps.
View guide

8 project-specific guidesClear, jargon-free explanations£15 off matching drawing packages

Single-storey rear extensions

More space
at the back.

A single-storey rear extension can add valuable living space without a normal planning application if it meets the Permitted Development (PD) rules.

Check your property

See what you could build at your home and choose the right drawing package.

The key PD rules.

Single-storey rear extensions fall under Class A of the Permitted Development Order. The main limits are set by how far the extension projects from the original house, its height and overall size.

See all the rules

The important bit:

Your extension must comply with all of the relevant PD rules. If any single limit is exceeded, a normal planning application may be required.

How far can it extend?

Measured from the rear wall of the original house, a single-storey rear extension can project up to 3 metres for a semi-detached or terraced house, or 4 metres for a detached house. In both cases the total height must not exceed 4 metres.

The depth is measured from the base of the original rear wall to the outer face of the extension wall, not including guttering or barge boards.

3 metresMaximum projection for a semi-detached, terraced or any other non-detached house.

4 metresMaximum projection for a detached house.

4 metresMaximum height in both cases.

Going deeper: the Larger Home Extension route

Deeper single-storey rear extensions — up to 6 metres for a non-detached house, or 8 metres for a detached house, again with a 4 metre height limit — are possible, but not under ordinary Permitted Development. They fall under the separate Larger Home Extension provisions and are subject to a neighbour consultation scheme.

You must notify the local planning authority first. The authority notifies adjoining neighbours, who have the opportunity to object, and work cannot start until the authority confirms that prior approval is not required. This route is not available on article 2(3) land (including conservation areas, National Parks, the Broads, areas of outstanding natural beauty and World Heritage Sites) or on a site of special scientific interest.

Ask YPDS about a larger extension

The important bit:

6 metres and 8 metres are Larger Home Extension figures requiring prior approval. They are not the ordinary Permitted Development limits, and they are not what the standard drawing package is designed to.

How high can it be?

The maximum height of a single-storey rear extension is 4 metres.

Single storey rear extension: maximum 3 metres deep, or 4 metres for a detached house, and maximum 4 metres high

How wide can it be?

The extension must not be wider than the original house.

Single storey rear extension drawing package

Materials and appearance.

The materials used should be of a similar appearance to the existing house.

Materials and appearance

Other important limits.

Must be to the rear of the original house.
Maximum projection of 3 metres (non-detached) or 4 metres (detached).
Maximum height of 4 metres.
Eaves must not exceed 3 metres within 2 metres of a boundary.
Must not include a veranda, balcony or raised platform.
Must comply with any restrictions that apply to your property or area.

Real example.

A single-storey rear extension adding an open-plan kitchen and family space — built within PD limits.

The drawing package for this work

A complete, builder-ready set of drawings supplied exactly as sold.

Single Storey RearView the drawing package

More Permitted Development guidance

All Permitted Development guidance

See what you could build
at your property.

We will check your property, apply the relevant Permitted Development rules and help you configure the right design and drawing package for your home.

Check your property

How it works

01Enter your
postcode

02See what you
can build

03Configure
your design

04Get your
drawings

Permitted Development rights described on this page apply to houses in England under the Town and Country Planning (General Permitted Development) (England) Order 2015. Different planning rules apply in Scotland, Wales and Northern Ireland. This page is general guidance, not a formal planning determination — always check your own property and, where you need certainty, apply to your local planning authority for a Lawful Development Certificate.