Below is a very useful document produced by the government for those considering extending or building new properties.
Permitted development rights allow householders to improve and extend their homes without the need to apply for planning permission where that would be out of proportion with the impact of works carried out. Larger single storey rear extensions are subject to a neighbour consultation scheme (see page 17). It is important that homeowners understand how they can exercise their rights to carry out development while protecting the interests of their neighbours and the wider environment. The Ministry of Housing, Communities and Local Government has produced this technical guidance to help them. It is designed to be used by anyone who wants to understand more about the detailed rules on permitted development and the terms used in those rules. However, anyone who has no previous knowledge of permitted development issues will find it useful to look at the Planning Practice Guidance first at: https://www.gov.uk/guidance/when-is-permission- required
The guidance set out below gives an explanation of the rules on permitted development for householders, what these mean and how they should be applied in particular sets of circumstances. Diagrams have been included for illustrative purposes only and these are not drawn to scale. Given the very substantial variations in the design of individual houses, this guide cannot cover all possible situations that may arise. Where there is any doubt as to whether a development would be permitted development, advice should be sought from the local planning authority. To be certain that a proposed development is lawful and does not require an application for planning permission it is possible to apply for a ‘Lawful Development Certificate’ from the local authority. Further information on this can be found in the Planning Practice Guidance at: https://www.gov.uk/guidance/lawful- development-certificates
Permitted development rights do not remove requirements for permissions or consents under other regimes such as the building regulations1 and the Party Wall Act2.
Householder permitted development rights are set out in the Town and Country Planning (General Permitted Development) (England) Order 2015 (“the Order”) as amended3. Part 1 of Schedule 2 to the Order sets out the permitted development rules concerning what enlargements, improvements, alterations and other additions a householder may make to their house and the area around it without the need for an application for planning permission.
These rights do not apply to houses created through the permitted development rights to change use, set out in Classes M, N, P, PA, and Q of Part 3 of Schedule 2 to the Order, from shops, premises offering financial and professional services, hot food takeaways, betting shops, pay day loan shops, amusement arcades, casinos, launderettes, premises offering storage or distribution services, light industrial premises and agricultural buildings; or any houses which are flats. In these cases planning permission should be sought.
Source Document: Permitted_development_rights_for_householders