Permitted Development Checklist for Extensions in England

A single-storey rear extension in England can go ahead without a planning application if it stays within the limits of permitted development and your property still has those rights. This checklist takes you through the questions in the order that saves most time: does your house qualify, have rights been removed, do the size and height limits work, does the larger-extension route apply, and what else you still need besides planning.

TL;DR

• Permitted development lets you extend without a planning application, but only if your house type, your address and your design all meet the rules.
• A standard single-storey rear extension is limited to 4 metres deep on a detached house and 3 metres on any other, with a maximum height of 4 metres.
• Conservation areas, National Parks, Areas of Outstanding Natural Beauty, World Heritage Sites and Article 4 Directions change or remove the rights.
• Larger rear extensions (8 or 6 metres) need the prior approval and neighbour consultation process.
• Permitted development never replaces building regulations approval or the Party Wall etc. Act 1996.

Table of Contents

• What permitted development actually is
• The checklist at a glance
• Step 1: Check your property type
• Step 2: Find out whether rights have been removed
• Step 3: Identify designated land
• Step 4: Measure the depth limit
• Step 5: Check the height limits
• Step 6: Count the total coverage
• Step 7: Decide whether the larger-extension route is worth it
• Step 8: Cover the consents permitted development does not
• Perspective: how we read the checklist
• Practical points beyond the planning rules
• Get your extension priced and checked
• A short worked example
• Common mistakes to avoid
• FAQ
• Sources

What permitted development actually is

Permitted development rights let householders improve and extend their homes without applying for planning permission, where the impact of the works is small enough that a full application would be out of proportion. The government’s technical guidance for householders sets out the detail.

The rights are not a council favour. They are granted by Parliament and set out in the General Permitted Development Order, which means that if your project fits within them, the council cannot ask you for a planning application. It also means that if your project steps outside them by even a little, you are back in the ordinary planning system.

That is why a checklist works better than a rule of thumb. Every item below is a gate. Pass all of them and you are in permitted development territory. Fail one and you need either a redesign or a planning application.

The checklist at a glance

The sections below take each gate in turn.

Step 1: Check your property type

The householder rights are written for houses. They do not apply to flats, or to houses created through specified change-of-use permitted development rights. If you own a maisonette or a flat, you will need planning permission for an extension, whatever its size.

The second point catches people out. If your home started life as an office, shop or barn that was converted to a house under a permitted development route rather than by a full planning application, the householder rights may not be available to you. Look at your property’s planning history on your council’s website, or ask the council directly.

Step 2: Find out whether rights have been removed

This is the step most people skip, and it is the one that most often ends a project. The government’s guidance tells homeowners to check with the local planning authority whether rights have been removed and to make sure the proposal meets every limitation and condition.

Rights can be taken away in two main ways:

• Article 4 Directions. A council can use an Article 4 Direction to remove permitted development rights in a specific area. It may cover a whole street, an estate or a single property.
• Planning conditions. An earlier planning permission for your house or estate may have removed rights as a condition. Newer estates often have this. The decision notice for your property will say so.

To check an address properly, use your council’s planning map and then confirm by email or phone. We have set out four checks to confirm your address-level Article 4 status if you want a walk-through.

Step 3: Identify designated land

Designated land (called Article 2(3) land in the legislation) includes National Parks, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites, where stricter permitted development rules apply. Your property may also sit next to a Site of Special Scientific Interest, which matters for the larger-extension route covered below.

Being on designated land does not automatically mean you need planning permission for everything. It means the limits are tighter and the larger rear extension route is off the table. Ask the council to confirm in writing whether your address is inside such an area, because maps can be hard to read at street level.

Step 4: Measure the depth limit

For a single-storey rear extension, the standard limits are 4 metres for detached houses and 3 metres for all other houses, measured from the original rear wall of the house. “Original” means the house as it stood on 1 July 1948 or as first built, if that was later. An extension built by a previous owner counts towards your allowance.

Two practical tips:

1. Check whether earlier extensions already use up part of your depth. A conservatory or a previous kitchen extension may mean you have little left.
2. Measure from the original rear wall, not the line of the current back of the house.

For a closer look, read our guide to 3m/4m and 6m/8m extension depth rules, or our explainer on how big a rear extension can be under permitted development.

Step 5: Check the height limits

The overall maximum height for a single-storey rear extension is 4 metres. There is a second, tighter test near the boundary: if any part of the extension is within 2 metres of a boundary, the eaves height cannot exceed 3 metres.

This matters for design. A tall, pitched roof that looks lovely in a sketch can tip you over the line on a narrow plot. Flat or low-pitched roofs, and a design that steps the eaves down near the boundary, are common ways to stay inside the limit. Our guide to permitted development heights for extensions covers where heights are measured from and how sloping ground complicates it.

Step 6: Count the total coverage

The third size test is about the whole plot, not just the extension. All extensions, together with existing extensions and outbuildings, must not exceed 50% of the total land area around the original house.

In practice, add up:

• the footprint of the new extension
• any earlier extensions
• sheds, garden rooms, garages and other outbuildings

Then compare that total with the garden and land around the original house. On a small suburban plot with a large garden room already built, this test can be the one that fails.

Step 7: Decide whether the larger-extension route is worth it

Outside designated land and Sites of Special Scientific Interest, larger single-storey rear extensions can go up to 8 metres on detached houses and 6 metres on other houses, subject to the neighbour consultation scheme.

This is a prior approval process, not a free pass. The council assesses the impact on neighbour amenity, but it cannot judge the principle of the development itself. If neighbours raise objections, the council has to weigh them, so the outcome depends partly on how your design affects the people next door.

Before choosing this route, ask yourself:

• Do you need the extra 2 to 4 metres of depth, or does the standard limit give you a good room?
• How close are the neighbours’ windows to your boundary?
• Are you comfortable with a wait for a decision before building starts?

Our page on whether the neighbour consultation scheme applies to your extension explains the process step by step.

Step 8: Cover the consents permitted development does not

Permitted development is a planning route only. It does not exempt you from building regulations approval, the Party Wall etc. Act 1996, or other necessary consents.

That means:

• Building regulations. The structure, insulation, drainage, fire safety and ventilation of the extension all have to comply, and the work needs to be inspected and signed off.
• Party wall matters. If you build on or near a shared boundary, the Party Wall etc. Act 1996 may require you to notify the neighbour.
• Other consents. Check for restrictive covenants in your title deeds, and for listed building status, which needs its own consent.

The cost of ignoring this is real. Building without planning permission when it is required can result in an enforcement notice, which can legally require you to undo the changes.

Perspective: how we read the checklist

We design, get planning for and build single-storey rear extensions, so we see how these rules play out on real houses. Our view is simple: the limits themselves are easy to learn, but the address-level checks are where projects go wrong.

Most people start with the depth figure because it is the number everyone quotes. We would start earlier. Is the house a house in planning terms? Has a direction or condition removed rights? Are you on designated land? Those three answers decide which rulebook you are playing by, and they take an hour with the council’s website, not weeks.

We also think “it is allowed” is a lower bar than “it is a good idea”. RICS suggests that before any improvement, homeowners weigh whether the project adds value, suits the property and affects the neighbours, even when it is technically permitted development. We agree. A design that fits the house and respects the neighbours’ light is less likely to attract objections on a prior approval, and tends to be nicer to live in.

That is why our process puts live 3D modelling, fixed pricing and planning handling in the same place. You see the extension at its real size against your house before you commit, and the planning route is chosen by the same team that will build it.

— Esskay

Practical points beyond the planning rules

Passing the checklist tells you the planning route. It does not tell you the best way to build. Once you know you are within permitted development, think about:

• Build method. Traditional masonry is the usual choice for rear extensions. If you are weighing alternatives, modular home extensions built from insulated panels are one approach to look at, though you will still need building regulations sign-off.
• Layout. A deeper extension is not always a better one. Think about how light reaches the middle of the house and how the garden will feel afterwards.
• Garden. Remember the 50% coverage rule if you plan a garden room later. Build the extension first and you reduce what is left for outbuildings.
• Future plans. If you might extend again, or add a loft room, count the allowance you will use today.

Our practical guide to rear extension design and UK rear extension planning rules go further on these.

Get your extension priced and checked

If your checklist comes out green, the next question is cost and who handles the paperwork. We handle design, planning (including permitted development and prior approval routes), architectural plans, structural calculations, project management and construction of single-storey rear extensions, all in-house, with a fixed VAT-inclusive price and a 12-month workmanship warranty.

You can design and price your extension online with our instant extension quote tool, with no sales visit needed. When you are ready to go ahead, the booking fee is £499, paid once. You can read more about our single-storey rear extension service on the main site.

A short worked example

Imagine a semi-detached house on an ordinary suburban street, not in a conservation area, with no Article 4 Direction. The owner wants a kitchen extension.

1. Property type: a house, built as a house. Pass.
2. Rights removed: the council confirms no Article 4 Direction and no condition on the original permission. Pass.
3. Designated land: not in a National Park, AONB, conservation area or World Heritage Site. Pass.
4. Depth: a semi-detached house is not detached, so the standard limit is 3 metres. The design is 3 metres. Pass.
5. Height: a flat roof at 3.4 metres overall. Under 4 metres. Pass. Eaves height near the boundary is under 3 metres. Pass.
6. Coverage: extension plus an old shed is well under half of the land around the original house. Pass.
7. Other consents: building regulations needed; the extension sits on the party wall line, so a party wall notice is likely to be needed.

The owner wants 5 metres instead. That is beyond the standard 3 metres for this house, but within the larger limit of 6 metres for non-detached homes. It now needs the prior approval route with neighbour consultation, and the neighbour’s side window becomes the key issue.

The example is invented to show the sequence, not a prediction for your house. The council’s view of your address always decides.

Common mistakes to avoid

• Assuming the neighbour’s extension sets a precedent. They may have had planning permission, or their house may have been on different land.
• Forgetting earlier extensions. Previous owners’ work counts against your allowance.
• Measuring from the wrong wall. The measurement starts at the original rear wall.
• Treating prior approval as automatic. The council can refuse on neighbour amenity grounds.
• Skipping building regulations. Permitted development covers planning only.
• Not confirming in writing. If you want certainty, you can apply to your council for a lawful development certificate. Planning permission is required if a project exceeds the limits or rights have been removed, and the council can confirm which applies.

FAQ

Do I need planning permission for a single-storey rear extension in England?

Not if the extension stays within permitted development limits and your house still has those rights. That means a house rather than a flat, no Article 4 Direction or condition removing rights, and a design within the depth, height and coverage limits. If any one of these fails, you need planning permission.

How far can I extend under permitted development?

The standard limit is 4 metres for a detached house and 3 metres for other houses. Outside designated land, a larger extension of up to 8 metres (detached) or 6 metres (other houses) can be allowed through the prior approval process with neighbour consultation.

Does permitted development mean I can skip building regulations?

No. Permitted development deals with planning only. Your extension still has to meet building regulations and be signed off, and you may need to follow the Party Wall etc. Act 1996 if you build near a shared boundary.

How do I find out whether my permitted development rights have been removed?

Ask your local planning authority, and check your property’s planning history for conditions that remove rights. Look at whether an Article 4 Direction covers your street. The council can also confirm in writing through a lawful development certificate application.

What happens if I build something that needed planning permission?

The council can issue an enforcement notice. That can legally require you to undo the changes, so it is far cheaper to check first.

Sources

• Permitted development rights for householders: technical guidance, GOV.UK
• When is planning permission not needed? Permitted development, House of Commons Library
• Single-storey extension mini guide, Planning Portal
• Planning permission: when you need it, GOV.UK
• Home extensions and improvements, RICS

Recommended

• 4m & 3m Limits: Permitted Development Heights for Extensions in England
• Get Completion Certificate: Building Regs for Extensions in England
• How big can a rear extension be under permitted development?
• Planning fees for an extension: what England homeowners need to know