Unauthorised development is any works, use, or structure that required planning permission under the Planning and Development Act 2000 but was carried out without it, or that departs from the terms of a permission that was granted. It also covers a continuation of an unauthorised use, and can apply to older buildings as well as recent works.
The Planning and Development Act 2000 defines unauthorised development broadly to include the carrying out of any development, or the making of any material change of use, that requires planning permission but has not received it, as well as development that does not comply with the conditions attached to a permission that was granted. It also covers an unauthorised use that continues after it began, meaning the passage of time alone does not necessarily make it lawful.
Common examples include extensions built beyond what is exempted development, houses or structures built with no permission at all, a change of use such as converting a house into multiple flats without permission, exceeding the terms of an existing permission (for example building higher or larger than approved), or continuing a business use in a residential zone without the required permission. Works that qualify as exempted development under the Planning and Development Regulations 2001, Schedule 2, are not unauthorised, provided they genuinely meet all the conditions and limits set out for that exemption.
Determining whether something is unauthorised is not always straightforward, since it depends on the planning history of the site, whether any exemption applies, and whether a permission was correctly implemented. Where there is doubt, a person can apply to the local authority for a Section 5 declaration on whether specific works constitute development or are exempted development, which gives a formal, appealable answer.