When did the new planning regulations come into effect?

On 27 July 2026. The seven regulations, SI 338 to SI 344 of 2026, were signed by Minister of State John Cummins on 16 July 2026 and amend Schedule 2 of the Planning and Development Regulations 2001. They apply to houses: extensions, garden structures, garden dwellings, subdivision, dormers, roof lights, heat pumps, chimneys, wall insulation and bike or bin stores.

Do I still need planning permission for a dormer in Ireland?

Not for a dormer to the side or rear of a house, since 27 July 2026, if the internal volume of all dormers combined is no more than 30 cubic metres, it is no higher than the roof ridge and it is set back at least 20 centimetres from the eaves (Class 1B, SI 344/2026). A front dormer still needs planning permission.

Can I put a heat pump at the front of my house without planning permission?

Yes, since 27 July 2026. SI 342/2026 removed the rule that a heat pump could not go on or forward of the front wall or roof. It must not encroach onto a public road, must be no larger than 2.5 square metres in total, at least 50cm from the edge of the wall or roof, and within the 43 dB(A) noise limit measured at the nearest neighbouring home.

Do the new rules let me put a mobile home in my garden?

No. The new garden dwelling exemption (Class 3A) expressly excludes anything temporary in nature, such as a caravan or mobile home. It covers a permanent auxiliary dwelling of 32 to 45 square metres built to Building Regulations standards, with 14 days' written notice to the council.

Is there a deadline for the new exemptions?

Only for the two new housing classes: the auxiliary dwelling in the rear garden (Class 3A) and subdividing a house into two units (Class 1A). Works under those must be commenced and completed by 31 December 2030. The other changes, such as the 45 square metre extension limit and the dormer exemption, have no end date.

New Planning Regulations Ireland 2026: Every Change From 27 July

Every change in Ireland's new planning exemption regulations (SI 338-344/2026, in force 27 July 2026): 45 sqm extensions, 30 sqm sheds, garden dwellings, subdivision, dormers, front roof lights, heat pumps, chimneys, wall insulation and bike stores.

The New Planning Regulations: What Changed on 27 July 2026

On 27 July 2026, seven new regulations (SI 338 to SI 344 of 2026) changed what Irish homeowners can build without planning permission. The Department of Housing says the household exemptions had not been substantially updated in almost 25 years. Each one amends Schedule 2 of the Planning and Development Regulations 2001.

In short, you can now do these without planning permission, if every condition is met:

Change	Before 27 July 2026	Now	Regulation
Rear extension	40 sq m	45 sq m	Class 1, SI 338
Shed, garden room, home office or gym	25 sq m	30 sq m	Class 3, SI 338
Detached garden dwelling you can live in	Needed permission	32-45 sq m, rear garden, 14 days' notice	Class 3A, SI 340
Splitting a house into two homes	Needed permission	2 units, each at least 32 sq m, 14 days' notice	Class 1A, SI 339
Dormer to the side or rear	Needed permission	Up to 30 cubic metres	Class 1B, SI 344
Roof lights on the front roof	No specific exemption	Up to 2, each max 100 x 90cm	Class 1C, SI 344
Heat pump	Rear and sides only	Front allowed too	Class 2(d), SI 342
Removing a chimney	No specific exemption	Exempt unless shared with a neighbour	Class 2A, SI 343
External wall insulation	No specific exemption	Up to 150mm thick	Class 63, SI 341
Bike or bin store	No specific exemption	Up to 3.5 sq m, front or rear	Class 62, SI 341

The general limits still apply: the exemptions don't cover protected structures, Architectural Conservation Areas can restrict them, and you can't use one to break a condition of an existing planning permission. Building Regulations apply in full whatever you build.

Extensions: 45 Square Metres (Class 1)

The rear extension limit rose from 40 to 45 square metres, counting everything added since 1 October 1964. The above-ground limits are unchanged (12 square metres for a terraced or semi-detached house, 20 for a detached house). Upstairs windows now need to be 8 metres from the boundary they face, down from 11. The roof of an extension still can't be used as a balcony or terrace, and you must still keep 25 square metres of private open space. Full detail: extensions guide.

Sheds, Garden Rooms and Home Offices: 30 Square Metres (Class 3)

The limit for structures in the garden rose from 25 to 30 square metres, counting every such structure together. Heights stay at 4 metres with a tiled or slated pitched roof and 3 metres otherwise. Nobody can live or sleep in it; for that, see the next section.

Auxiliary Dwelling in the Back Garden (Class 3A)

The headline change. A detached dwelling of 32 to 45 square metres can go in the rear garden of a house without planning permission, sharing the main house's services, with at least 25 square metres of open space left. The Department calls it an auxiliary dwelling. You must notify the council in writing 14 days before starting, it can never be sold separately or let short term, and works must be finished by 31 December 2030.

Mobile homes and caravans are excluded. Building Control also requires a Commencement Notice with an assigned certifier, and a completion certificate before anyone moves in. Full rules: log cabins, mobile homes and auxiliary dwellings.

Subdividing Your House (Class 1A)

You can now split a house into two self-contained units, within the existing building, each at least 32 square metres. The same 14-day written notice to the council and 31 December 2030 deadline apply. You can't use both Class 1A and Class 3A on the same property.

Dormers to the Side or Rear (Class 1B)

Before July 2026, a dormer needed planning permission. Now a dormer roof extension to the side or rear is exempt if:

the internal volume, together with any other dormers, is no more than 30 cubic metres
it is no higher than the roof ridge
it is set back at least 20 centimetres from the eaves

A front dormer still needs permission.

Roof Lights on the Front (Class 1C)

Up to two roof lights on the front roof plane, each no more than 100cm long and 90cm wide, no longer need permission. That makes many attic conversions fully exempt without a dormer at all.

Heat Pumps at the Front (Class 2(d))

The old rule that a heat pump could not go on or in front of the front wall or roof is gone. The remaining conditions: no encroaching on a public road, 2.5 square metres in total, at least 50cm from the edge of the wall or roof, ground level changed by no more than 1 metre, and noise no more than 43 dB(A) (or 5 dB(A) above background, whichever is greater) at the nearest neighbouring home.

Removing a Chimney (Class 2A)

New exemption, with three conditions: it can't be part of a joint chimney stack with a neighbouring house, the roof must be finished to match, and you must comply with the Wildlife Act protections for nesting birds and bats. Check for bats before you start; chimneys are a common roost.

External Wall Insulation (Class 63)

External insulation up to 150mm thick on the front, rear or gable walls, in line with SEAI grant works. It must not encroach on a public road or change the appearance so much that it no longer fits the building and its neighbours.

Bike and Bin Stores (Class 62)

A store of up to 3.5 square metres and 1.4 metres high, front or back, enough for 3 to 4 bikes, 2 cargo bikes or 3 wheelie bins. At the front it must be set back 0.6 metres from the front wall and can't take more than half of the front garden's open space.

The 14-Day Notification

Only the two new housing classes, Class 1A (subdivision) and Class 3A (auxiliary dwelling), need you to tell the council. The notice goes in writing at least 14 days before works start and includes the property's Eircode. Councils publish a notification form on their exempted development pages (South Dublin's is linked in the sources below). Skip it and the works are not exempt.

What Didn't Change

Mobile homes: living in one still needs planning permission. See mobile homes.
Front and side extensions: still need permission.
Protected structures and ACAs: still restrict exemptions.
Building Regulations: apply in full, whether or not you need planning permission.
Retention: if you already built something that is now within the new limits, ask the council or apply for a Section 5 declaration to confirm its status. Anything outside them needs retention permission.

What Comes Next

The Department describes these regulations as part of implementing the Planning and Development Act 2024. Minister of State John Cummins said the household package followed agricultural exemptions earlier in 2026, and that infrastructure exemptions are next. The Department also said the tax treatment of auxiliary dwellings, including how it interacts with rent-a-room relief, would be settled through the Budget and Finance Bill.

Check Your Project

Run your project through our free exemption checker, which uses the July 2026 limits, or read the full exempted development guide.

Disclaimer

This guide summarises SI 338-344 of 2026 and is not legal or professional advice. Every condition of an exemption must be met for it to apply. Always check with your local authority or a qualified professional before starting work.