New exempted development regulations came into force on 27 July 2026. A lot of common home projects that used to need planning permission no longer do. Here is what changed.

Extensions up to 45 square metres

The limit for a rear extension rose from 40 to 45 square metres, counting everything added to the house since 1 October 1964. The limits for upstairs extensions are unchanged: 12 square metres for a terraced or semi-detached house, 20 for a detached one.

Upstairs windows now need to be 8 metres from the boundary they face, down from 11. You still have to keep 25 square metres of private open space, and the extension roof can't be used as a balcony.

Garden rooms and sheds up to 30 square metres

The limit for structures in the garden rose from 25 to 30 square metres, counting all of them together. Heights stay at 4 metres with a tiled or slated pitched roof and 3 metres otherwise. Nobody can live or sleep in one.

A small home in the back garden

The biggest change: a detached dwelling of 32 to 45 square metres can go in the rear garden without planning permission, sharing the main house's services, with at least 25 square metres of open space left.

You must tell the council in writing 14 days before you start. It can never be sold separately or let short term, and the work must be finished by 31 December 2030. Mobile homes and caravans don't count.

Dormers and roof lights

A dormer to the side or rear is now exempt if it adds no more than 30 cubic metres, stays below the ridge and is set back at least 20cm from the eaves. Up to two roof lights on the front, each up to 100cm by 90cm, no longer need permission either, so many attic conversions are now fully exempt.

Before you build

None of this applies to protected structures, Architectural Conservation Areas can restrict it, and you can't use an exemption to break a condition of an existing permission. Building Regulations apply in full whatever you build.

Every change, with the regulation numbers: https://www.permission.ie/guides/new-planning-regulations-2026

Check your own project for free: https://www.permission.ie/tools/exemption-checker