What is the new 45m² planning exemption in Ireland?

From 27 July 2026, a new exemption called Class 3A (S.I. No. 340 of 2026) allows a detached, self-contained habitable unit of 32m² to 45m² in the rear garden of a house, without planning permission, provided it is occupied only by the homeowner's family and meets a set list of conditions. Separately, the exempted floor area for a standard rear house extension also rose to 45m² (Class 1), and the exemption for a non-habitable garden room, shed or garage rose to 30m² (Class 3). These are three different changes, not one 45m² rule that applies to everything.

Can I build a granny flat without planning permission now?

In many cases, yes, under the new Class 3A exemption — but only if it meets every condition: family occupation only, no sale or separate letting, no short-term letting, linked to the main house's water and wastewater services rather than its own connection, a maximum height of 4m, at least 0.6m from any boundary, and the main house keeps at least 25m² of private open space. You also need to notify your local council at least 14 days before work starts, and the exemption only covers work completed by 31 December 2030.

Does the 45m² exemption apply to garden rooms, home offices and gyms?

No. A garden room, home office, studio or gym that isn't used as living accommodation falls under the separate Class 3 exemption, which rose from 25m² to 30m², not 45m². The 45m² figure applies to house extensions (Class 1) and to the new self-contained rear-garden unit (Class 3A), not to a standard garden room.

How long does the new Class 3A exemption last?

It's time-limited. Under the regulations, Class 3A only covers development commenced and completed between 16 July 2026 and 31 December 2030. It isn't a permanent change to the planning rules in the way the Class 1 and Class 3 increases are.

What happens if my project doesn't meet the Class 3A conditions?

Then it needs a full planning application, the same as before this exemption existed. Common reasons a project falls outside Class 3A include wanting to let the unit separately, needing it larger than 45m² combined with any existing garden structures, or the principal house not being the owner's main residence. We'll confirm exactly where your project stands at a free site visit.

2026 Planning Update

The new 45m² planning exemption in Ireland, explained

What changed on 27 July 2026, who it actually applies to, and the conditions that come with it.

Last updated: 28 October 2026

A new 45m² exemption for a self-contained garden home

Since 27 July 2026, Ireland has a planning exemption that didn't exist before: a detached, self-contained home of up to 45m² in your rear garden, built without planning permission. It's officially Class 3A, introduced under S.I. No. 340 of 2026, and it's the first time a genuinely self-contained unit — its own kitchen, its own bathroom, built for someone to actually live in — has been exempt from planning at this scale. Most people search for this as a "granny flat," and that's exactly the kind of project it's aimed at: a family member living independently, but close by.

The floor area runs from 32m² up to 45m² (combined with any existing garden structures already on the site), the structure has to stay within the existing curtilage of your home rather than needing its own separate site, and it comes with a real list of conditions attached — this isn't a free-for-all. It's a genuinely usable amount of space, though: enough for a proper one- or two-room home, not just a shed with a shower.

The conditions that come with it

Before 27 July 2026, a self-contained garden annexe like this almost always needed full planning permission, regardless of size. Class 3A changes that — but only if every one of these conditions is met:

Family occupation only. It can only be occupied in conjunction with the main house, and cannot be sold or subdivided separately from it.
No short-term letting. The unit cannot be used for short-term letting of any kind.
Not temporary. It must be a permanent structure — a caravan or mobile home doesn't qualify.
Height limit. A maximum of 4m for a tiled or slated pitched roof, or 3m for any other roof type.
Boundary distance. At least 0.6m from any wall or boundary, and any windows at least 0.6m from the boundary they face.
Shared services. No separate utility connection — water and wastewater link back through the main house, with specific rules for on-site treatment systems where there's no mains connection.
Private open space preserved. The main house must retain at least 25m² of private open space after the unit is built.
Access. No new vehicular or pedestrian access onto a road, but independent pedestrian or wheelchair access must be provided within the existing curtilage.
Council notification. Written notice to your local planning authority at least 14 days before work starts, including the Eircode and the reason for using this exemption.
Owner-occupied principal house. The main house must be the owner's sole or main residence when the work begins, and the exemption doesn't apply if the principal house has previously been subdivided.
Time-limited. Only development commenced and completed between 16 July 2026 and 31 December 2030 qualifies — this is not a permanent rule.

Building Regulations — including fire safety and building control requirements for a habitable structure — still apply in full. This exemption removes the need for planning permission; it doesn't remove the need to build to a proper habitable standard.

Is a 45m² garden home right for your family?

This is a genuinely new option with a genuinely long list of conditions, and getting any one of them wrong can mean the exemption doesn't apply. We'll talk through what you're trying to achieve — a home office that doesn't need any of this, or a self-contained space for a family member that might — and confirm honestly which route fits your garden and your plans at a free site visit, before any price is discussed.

The other 2026 changes: extensions and garden rooms

The new 45m² Class 3A exemption was part of a wider package of changes that all took effect the same day. Two more are worth knowing, even though neither is the 45m² story above: the exempted floor area for a standard rear house extension (Class 1) also rose, from 40m² to 45m² — so if you're extending the house itself rather than building in the garden, that's the figure that applies to you. And separately, the exemption for a non-habitable garden room, shed, office or gym (Class 3) — the kind of structure we build most often — rose from 25m² to 30m², not 45m². If you're planning a home office, studio or gym rather than a self-contained living space, 30m² is the number that matters, with none of the Class 3A conditions around family occupation, shared services or council notification. See our garden room planning permission guide for that exemption in full, and our cost guide for what a build like that typically costs.

Common questions

45m² exemption FAQs

The questions we hear most about the new 2026 rules.

From 27 July 2026, a new exemption called Class 3A (S.I. No. 340 of 2026) allows a detached, self-contained habitable unit of 32m² to 45m² in the rear garden of a house, without planning permission, provided it is occupied only by the homeowner's family and meets a set list of conditions. Separately, the exempted floor area for a standard rear house extension also rose to 45m² (Class 1), and the exemption for a non-habitable garden room, shed or garage rose to 30m² (Class 3). These are three different changes, not one 45m² rule that applies to everything.
In many cases, yes, under the new Class 3A exemption — but only if it meets every condition: family occupation only, no sale or separate letting, no short-term letting, linked to the main house's water and wastewater services rather than its own connection, a maximum height of 4m, at least 0.6m from any boundary, and the main house keeps at least 25m² of private open space. You also need to notify your local council at least 14 days before work starts, and the exemption only covers work completed by 31 December 2030.
No. A garden room, home office, studio or gym that isn't used as living accommodation falls under the separate Class 3 exemption, which rose from 25m² to 30m², not 45m². The 45m² figure applies to house extensions (Class 1) and to the new self-contained rear-garden unit (Class 3A), not to a standard garden room.
It's time-limited. Under the regulations, Class 3A only covers development commenced and completed between 16 July 2026 and 31 December 2030. It isn't a permanent change to the planning rules in the way the Class 1 and Class 3 increases are.
Then it needs a full planning application, the same as before this exemption existed. Common reasons a project falls outside Class 3A include wanting to let the unit separately, needing it larger than 45m² combined with any existing garden structures, or the principal house not being the owner's main residence. We'll confirm exactly where your project stands at a free site visit.

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