New planning exemptions took effect in Ireland on 27 July 2026. Exempted development is work you can do to a house without planning permission, and the list just got longer: bigger rear extensions, dormers at the side or back, larger garden rooms, and a small second home in the back garden. For a buyer this cuts both ways. More of what you see at a viewing is legal without a file. And the date the work was done now matters.
What is exempt since 27 July 2026
A rear extension or conservatory, as long as it does not add more than 45 square metres to the original floor area. That total counts every earlier extension too, including ones that had permission. The limit was 40 square metres before. The extension cannot be higher than the house, and it must leave at least 25 square metres of private open space at the back. Upstairs extensions have tighter rules: at least 2 metres from any boundary, and no more than 12 square metres for a terraced or semi-detached house, 20 for a detached one.
A dormer roof extension and dormer window to the side or back, up to 30 cubic metres including any existing dormers, no higher than the ridge and at least 20 cm from the edge of the roof. Before 27 July 2026 a dormer needed permission. A dormer at the front still does.
A shed, garage, greenhouse or garden office at the back or side, up to 30 square metres on its own or with similar structures (it was 25). It must stay behind the front building line, be no taller than 4 metres with a pitched tiled or slated roof or 3 metres otherwise, and it cannot be lived in or used for business.
Smaller items on the same list: external wall insulation up to 15 cm thick, removing a chimney that is not shared with a neighbour, up to two roof lights at the front, bike or bin storage up to 3.5 square metres, and a ground heat pump.
The garden home and the split house
Two exemptions are new in kind. A detached home in the back garden of 32 to 45 square metres, built between 27 July 2026 and 31 December 2030. It cannot be sold or subdivided separately from the main house, cannot have its own utility connections, cannot be used for short-term letting, and must leave the main house at least 25 square metres of private open space. The owner must own the original house and live in it as their main and only home, and must notify the council at least 14 days before work starts.
The second: dividing a house into two self-contained units of at least 32 square metres each, built in the same window and also notified 14 days ahead. You cannot use both exemptions on one property. If a house you like has either, ask for the council notification and ask your solicitor how the owner-occupier condition applies once you buy.
Planning permission loopholes: there are none
People search for loopholes. The exemptions are the legal route, and each comes with conditions. Break one (the extension is 47 square metres with the old kitchen extension counted, the dormer faces the road, the garden room has a bedroom) and the work needs permission it does not have. Citizens Information warns that building without permission you needed can mean a large fine. Protected structures and houses in an architectural conservation area have extra restrictions, so check with the council first.
What a buyer should check
First, when was the work done. Anything finished before 27 July 2026 was judged under the old rules: 40 square metres for extensions, 25 for sheds, and no exemption for a dormer. A 2019 attic dormer with no planning file is a question for the seller’s solicitor, not a feature.
Second, add up the floor area. Measure the extension and add any older ones. Third, ask for the paperwork: the architect’s certificate of exemption for anything built without permission, and the council notification for a garden home or a split house. Your solicitor will want the same documents before contracts.
Then check what the record shows. The Planning on this property check in our report lists every application on the national planning register for the address and the building-control commencement notices for it, including works filed as not needing planning permission. It also says plainly that exempt work never appears on the register, so an extension at the viewing with no file needs that certificate. Run the free snapshot for the Eircode, and the full report (€24.99) writes out the file line by line. More on reading the register: planning search before buying.