The Planning Authority is responsible for deciding whether a proposed development should be allowed to go ahead. Most new buildings, major alterations to existing buildings and significant changes to the use of a building need this permission. However, certain works – known as Permitted Development– do not require Planning Permission. Under the Permitted Development rules, single-storey rear extensions and conservatories can be constructed without Planning Permission as long as they do not extend beyond the rear wall of the original house by a set distance. Further - in a temporary measure - it is possible to build more under the remit of Permitted Development. For a semi-detached property, the previous limit of three metres from the face of a building for single storey extensions and for detached homes four metres are doubled, meaning that many more extensions can now be built under Permitted Development. Rights apply only to a ‘private dwelling house’ as originally constructed, or as the dwelling stood at a certain point in time. Flats are excluded, as are listed buildings, whilst properties in designated areas such as conservation areas, Green Belt, National Parks etc have restrictions. For peace of mind you may choose to apply for a Lawful Development Certificate, which is proof that your household building work is lawful.This option is recommended even if you are sure your project falls within the constraints of Permitted Development. If you should later want to sell your property a Lawful Development Certificate may be helpful to answer queries raised by potential buyers or their legal representatives.