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What size extension can I build without planning permission?

In many circumstances, rules known as ‘permitted development’ rights allow you to extend a house without needing to apply for planning permission, providing specific limitations and conditions are met. If you want to exceed these limits and conditions, then it is likely that an application for householder planning permission will be required.

You can find information about the limits and conditions, prior approval and the building regulations on the Planning Portal by using the links below.  

Read about planning permission for extensions

Read about prior approval for larger single storey extensions

Find out about building regulations for an extension

Common Questions

Can I replace my grass lawn with artificial grass?

In most cases neither planning permission nor building control approval are required for replacing grass with artificial grass. If you live in a protected areas such as a conservation area, or listed building, it is best practice to contact your local planning authority to check whether any consents are required.

 Find your local planning authority.

What are Approved Documents and where can I find them?

Approved Documents are official guides that explain how to comply with the building regulations. Published by the government, each document provides practical guidance on meeting the requirements of a specific ‘Part’ of the regulations. They cover a wide range of building work, including plumbing, electrical installations, extensions and ventilation.

The latest versions of the Approved Documents, which support the technical ‘Parts’ of the building regulations, along with Regulation 7, are available on Planning Portal.

Browse the Approved Documents.

What is permitted development?

Permitted development rights allow certain types of work to be carried out without the need to apply for planning permission. It typically covers things like small extensions, loft conversions and outbuildings, provided they meet specific size and location limits. These rights can vary or be removed in areas like conservation zones and by Article 4’s, so it’s best to check before proceeding.  

Read about permitted development and Article 4 directions on Planning Portal

Do I need planning permission to put up a fence, gate or garden wall?

You will not need to apply for planning permission if you wish to erect a new; or alter, maintain, improve or take down* an existing fence, wall or gate if certain conditions are met. If any of the conditions are not met, then you will need to apply for planning permission.

Find out about the limits and conditions for fences, gates and walls.

Fences, walls and gates do not require building regulation approval. Even though building regulations do not apply, the structures must be structurally sound and maintained.

If you share a wall with a neighbour, it may be classed as a ‘party fence wall’.

Do I need planning permission to add a garden office?

Rules governing outbuildings apply to sheds, playhouses, greenhouses and garages as well as other ancillary garden buildings such as swimming pools, ponds, sauna cabins, kennels, enclosures (including tennis courts) and many other kinds of structures for a purpose incidental to the enjoyment of the dwellinghouse.

If you are unsure if your planned building falls into the category of 'outbuildings' or if you are unsure if planning permission is required, please contact your local planning authority.

Outbuildings are considered to be permitted development, not needing planning permission, subject certain limits and conditions.

Read about the limits and conditions for outbuildings

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