Do you need planning permission for a single storey extension? | Resi (2023)

When embarking on any building project, the question of planning permission is bound to come up at some point. While the entire concept of planning permission might not be new, it can be easy to get lost when learning about permitted development rights, plus the recent updates and additions.

Fortunately, this post is dedicated to answering all the questions you could possibly have about planning permission for house extensions, such as:

  • Do you need planning permission for a single storey extension?
  • How big can I build my storey extension without planning permission?
  • Do I benefit from permitted development rights?

Let's dive right in, shall we? And don't forget, you can get FREE planning advice at anytime here.

Do I need planning permission?

Do you need planning permission for a single storey extension? Not necessarily!

(Video) House Extension (Single Storey) - Do you need Planning Permission? UK Permitted Development

According to the law, homeowners can add extensions to their homes without applying for planning permission when they use their permitted development rights, as long as the extension follows the stipulated requirements.

Regardless of these restrictions, many homeowners prefer to build within their permitted development rights as it’s a safer route. Permitted development is not subjective, saving homeowners the stress and added expense of re-doing an application in a situation where the first application is not approved. The fact that you can build an impressive extension within its regulations is, of course, a bonus.

It's worthy of mention that permitted development rights aren’t applicable in all situations.

  • Flats
  • Maisonettes
  • Listed buildings

These properties are not covered by permitted development. In the same vein, owners of houses located in conservation areas or areas of outstanding beauty have limited permitted development rights.

You should discuss your project with a Resi expert to ensure that permitted development rights apply to your project.

(Video) Planning Permission V Permitted Development Rights

Lawful development certificates

As stated earlier, building within your permitted development rights eliminates the need for full planning permission. Nevertheless, it’ll be good if you apply for a lawful development certificate. With this document, you’ll be able to prove that your project was compliant when it was built. This document will particularly come in handy if you ever sell your home.

The criteria for building within permitted development rights for different extensions are stated below. However, it’s recommended that you seek professional guidance to ensure you're building within your permitted development rights.

To find out more about the permitted development rights relating to your project, you should book an appointment with your local authority or discuss your project with the right professionals.

For single storey extensions

For a single storey extension to be permissible under permitted development rights:

  • The size of the extension must not exceed half of the land area around the initial house. This covers the time since the property was built. As a result, you must factor in if any previous owners have carried out extension works in the land before
  • The extension, after it’s built, must not be nearer to the public highway
  • No part of the extension can exceed the highest part of the roof of the original house
  • Its eaves and ridge height must not be higher than that of the existing house
  • Materials used for the extension must be similar in appearance to the current house
  • It cannot include a verandah, balcony, microwave antenna, chimney, flue, soil, and vent pipe.
  • No alterations can be made to the roof of the existing house as well

Wraparound extensions

Permitted development rights do not cover wraparound extensions. Wraparound extensions are a combination of side and rear extension, meaning your project will be assessed as a side extension and a rear extension respectively. The space a wraparound extension requires plus its structural complexity makes it an unlikely candidate for permitted development rights.

(Video) Top 10 Projects You Could do WITHOUT Planning Permission

For side extensions

For a side extension to be permissible under permitted development rights:

  • The side extension must be single storey
  • It must have a maximum height of 4m
  • It must not exceed half of the widths of the original house
  • It must not front into the road

For rear extensions

Rear extensions are very common and are a great way to use the extra space at the back of the house. For a rear extension to be permissible:

  • Single storey rear extensions must not be longer than the rear wall of the original house by more than 3m (for a semi-detached house) and 4m (for a detached house)
  • Its maximum height must be 4m.

Single storey rear extensions can use 'prior approval' to double this allowance, allowing you to extend up to either 8m (detached) or 6m (other).

How big can I build a single storey extension without planning permission?

Permitted development rights allow homeowners to install an extension of up to 6m for a semi-detached or terraced house and 8m for a detached house, but only by going through the prior approval process. If you want to avoid prior approval, your allowance will be up to 3m or 4m, depending on your property type.

Before planning your extension, you should find out if previous owners have added an extension to it in the past. This is because extensions carried out by previous owners will eat into your permitted development rights, limiting how big you can build your extension without planning permission.

(Video) How to Extend Your Home WITHOUT Planning Permission

Get a quote for our design and planning service.

Case study: a single storey rear extension that didn’t need planning permission

Here’s a look at a storey extension project we completed in the past that did not need planning permission.

Do you need planning permission for a single storey extension? | Resi (1)

Do you need planning permission for a single storey extension? | Resi (2)

We used a rear extension to expand this Coventry based home, creating a beautiful country-style kitchen in the process. These homeowners utilised their permitted development rights to bring this project to life, and had our planning team liaise with the council to get a lawful development certificate in place. Even without using a full planning application, this family was still able to completely transform this vital part of their home!

(Video) Do I Need Planning Permission For An Extension? | Planning Permission for Extensions

Other restrictions you need to check before building a single storey extension?

Here’s a breakdown of some other restrictions you should check before building a single storey extension.

  • You should ensure your project is building regulations compliant. Building regulations are laws that guide how a house should be built before it's considered habitable. These laws are geared at the safety of the building, environment, and the inhabitants and cover things like ventilation, insulation, structure, and fire safety.
  • Another restriction you might run into is party wall agreement. They’re designed to protect the interest of your neighbours when doing structural work on a shared wall. You'll need to serve them a party wall notice and obtain written consent for the works within 14 days. However, if they do not grant you written permission, you'd need to contact a surveyor to arrange party wall agreements.
  • Similar to the party wall agreement is prior approval. They’re similar in that they both protect your neighbour’s interest but differ in that you do not need to share a wall with the supposed neighbour before they raise their concerns. Prior approval comes into play when you’re adding a larger rear extension, between 3-6m or 4-8m (if your home is detached). It allows your neighbours to voice their concerns if your new extension leads to a loss of privacy, natural light or constriction of views.

For most homeowners, keeping up with these regulations can be overwhelming. For tailored advice, book a call with our experts here.

And don't forget, for financing advice or help with a remortgage, our Resi Finance brokers are always on hand. Learn more here.


What is the biggest single story extension without planning permission? ›

Single-storey extensions must not exceed 4m in height. Single storey extension width must not exceed half of the original size of the house. Extensions on the side or front of a house must be closer to the property than a public highway.

What size extension can you have without planning permission? ›

1. Under the relaxed rules, you can extend up to eight metres for detached houses and six metres for all other houses. Please note that for these larger extensions (beyond four and three metres respectively) you will need to give notification under the Neighbour Consultation Scheme.

Do I need permission for a single storey extension? ›

The short answer is that you DON'T need planning permission for an extension if you build within your permitted development rights. Most of the restrictions that don't fall under permitted development are for work to the front of a house, next to a road or near a boundary.

Do I need planning permission for a single storey extension at the side? ›

What planning permission do I need for my side extension? Single storey side extensions, like a lot of extensions, can fall under permitted development. This means you won't need to apply for a full planning application, if you meet the stipulated criteria.

How far can you extend a single storey? ›

What is a single-storey extension? A single-storey extension is added to the back or side of a domestic property. It can be a maximum of four metres in height and up to six/seven metres from the rear wall.

Can I build a single storey extension up to my boundary? ›

Normally, an extension will need full planning permission and can be built up to neighbouring boundary lines, provided you have a party wall agreement.

What happens if I build an extension without planning? ›

Whether it's an outhouse or an extension, failure to comply with the rules will mean you're committing a planning breach – which isn't good! In the worst-case scenario, you'll be given an enforcement notice to resolve the issues. This can sometimes result in taking down the whole of the building completely.

Do you have to notify Neighbours permission for extension? ›

The technical term for this is called serving notice. In short if you want to make your home bigger and are attached to (or are in close proximity to) another property, you will most likely need to notify the neighbour(s) about your extension.

Can I build an extension on my house without planning permission? ›

Rules, known as 'permitted development' rights, allow you to extend a house without needing to apply for planning permission if specific limitations and conditions are met. If you want to exceed these, then it is likely that an application for householder planning permission will be required.

What are the rules on a single story extension? ›

Single-storey rear extensions must not extend beyond the rear wall of the original house by more than three metres (if a semi-detached house) or by four metres (if a detached house). The maximum height of a single-storey rear extension should be four metres to avoid having to get planning permission for an extension.

What structures can you build without planning permission? ›

When you do not need it
  • industrial premises and warehouses.
  • some outdoor signs and advertisements - though there are special rules around adverts.
  • demolition - but before you begin you must get approval to demolish from your local planning authority ( LPA ) through your local council.

How much would a small single storey extension cost? ›

All of the guideline prices listed below are for construction only, updated as of 2022. They do not include VAT or professional fees. House extension costs: Single storey – A single storey extension in London will usually cost between £2,200 and £3,300 per sqm (£200 and £300 per square foot).

How deep are foundations for a single storey extension? ›

Minimum Depth of Foundations for a Single Storey Extension

For a single storey extension using strip foundations, 150mm would generally be sufficient for the concrete foundation base. The actual foundation trench should be at least 1 metre deep, with brickwork and blockwork making up the rest of the foundation depth.

Do I need an architect for a small extension? ›

There is no law saying you have to employ an architect. It is up to you. Some people successfully undertake quite major works – including whole house refurbishments and extensions without an architect. Others employ one for comparatively minor jobs, such as redoing a bathroom or redesigning a kitchen.

What is the 7 year boundary rule? ›

Many people believe in a mysterious 7-year boundary rule, thinking that if you possess a piece of land for 7 years, you're entitled to apply for adverse possession over it. However, this is incorrect.

Can my Neighbour stop me building extension? ›

In summary, your neighbour can have no influence on the development with regards to planning permission, as planning permission is not required. The exception to this would be if you are planning to take advantage of the Larger Home Extension Scheme under permitted development, which has its own particular process.

Can my Neighbour build right to my boundary? ›

The party wall act allows an absolute right to build up to the boundary between you and your neighbour. It also allows you to build astride the boundary line, but only with your neighbour's consent.

What is the cheapest way to build an extension? ›

1. Consider a single storey extension. Single storey extensions are often the cheapest and most viable option, and could totally transform a small home, bringing in light, extra living space and opening up the house to the garden.

Do I need insurance to build an extension? ›

Building a home extension

It's not without its challenges, however, and there's plenty to think about. Before work starts, you might want to consider having home insurance – specifically buildings insurance – in place. A buildings insurance policy isn't designed to cover large-scale changes to your home.

Can I build my own extension? ›

When it comes to planning the addition, you can take on the job yourself, but many homeowners choose to employ an architect, designer or specialist company to work with them to turn initial ideas into illustrations and formal plans – more on working with a professional in the box opposite.

Can a Neighbour reject extension? ›

If a neighbour objects and challenges your application, you have the right to appeal. However, if the objections can be addressed with an alteration to the design of the extension, you can also opt to amend the plan accordingly and re-submit the application.

On what grounds can planning permission be refused? ›

The more common reasons for refusal are: Your project would overshadow a neighbour, causing them loss of light. Your building or structure overlooks other homes, causing loss of privacy. The appearance would be out of character with the existing property.

What to do if Neighbour builds without planning permission? ›

If you suspect that your neighbour may have failed to comply with everything contained within what was agreed, you should notify your local authority's planning department at the earliest opportunity.

How long after an extension is built without planning permission? ›

The 4-year rule covers any breach of building or operations development which has not been challenged by enforcement action for the period of at least four years.

What is the 45 degree rule? ›

In normal circumstances, no development should intrude over a line drawn at an angle of 45° in the horizontal plane from the midpoint of the nearest window of a habitable room (includes kitchens but not for example bathrooms, w.c.'s, en-suites, landings, utility rooms or garages.)

What extensions are exempt from building regulations? ›

Exemptions. A detached single storey building with an internal floor, no more than 30m², without bedrooms and is: less than 1m from any boundary, or. built mostly of non-combustible material.

What is the largest structure you can build without planning permission? ›

As long as the material you are using is porous there is no need for planning permission whatever the size of the new hardstanding. However, if the material is impermeable, anything over 5 square metres requires planning permission.

What is the no planning permission 4 year rule? ›

The '4 year rule' is a term used within town planning, particularly within the planning enforcement specialism, regarding whether enforcement action can be taken against certain types of development (that require planning permission) carried out in breach of planning control.

How tall can a structure be without planning permission? ›

Maximum height of 2.5 metres in the case of a building, enclosure or container within two metres of a boundary of the curtilage of the dwellinghouse. No verandas, balconies or raised platforms (a platform must not exceed 0.3 metres in height)

What can I build on my land without planning permission? ›

When you do not need it
  • industrial premises and warehouses.
  • some outdoor signs and advertisements - though there are special rules around adverts.
  • demolition - but before you begin you must get approval to demolish from your local planning authority ( LPA ) through your local council.

What is exempt from planning permission? ›

Exempt development is development for which planning permission is not required. It generally relates to developments of a minor nature such as: Works of improvement, maintenance or other alterations that affect only the interior of a structure.

What happens if you build without planning permission? ›

It is an offence to do work that requires planning permission, without having planning permission. This offence can carry very large fines and possible imprisonment. However, if a genuine mistake has been made, it is possible to apply for planning permission to retain an unauthorised development.

What happens if you build an extension without building regs? ›

If you're planning to extend your home, you will need to comply with the building regulations. This is a legal requirement and, without formal approval and control, your local council could force you open up or re-build sometimes significant aspects of the project. It could even lead to prosecution and unlimited fines.

What are the building regulations for a single storey extension? ›

Single-Storey Extension Rules

You can only cover half the area of land that is around the original house with an extension or any other type of build. This can also include a shed or outbuilding. The extension cannot be forward of the side elevation or side elevation fronting a highway.


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