Homeowner guide
Granny flats in Ireland: the first planning-free routes arrive 27 July 2026
Updated 2026-07-18 · checked against the sources below
Until now, a genuine granny flat - self-contained accommodation for a family member - has almost always needed planning permission in Ireland. That changes on 27 July 2026, when two brand-new exemptions commence: a habitable garden dwelling (S.I. 340 of 2026) and the subdivision of a house into two units (S.I. 339 of 2026). Both are conditional, both are time-limited to the end of 2030, and both introduce a procedural step Irish planning has never had before: a 14-day prior notification to the council. Here is how they work.
The position today (until 26 July 2026)
A detached habitable unit in the garden has never been exempt: the garden-structure exemption (Class 3) expressly bars human habitation, whatever a supplier's brochure suggests.
An attached extension can be built exempt within the extension rules, but the moment it becomes a separate, self-contained dwelling - its own entrance arrangement, its own household - that is a material change of use requiring permission. In short: today, a real granny flat means a planning application.
Route 1 from 27 July: the garden dwelling (Class 3A)
S.I. 340 of 2026 exempts a detached habitable dwelling in the garden of a house, subject to strict conditions:
- Floor area at least 32 m², and at most 45 m² combined with any other garden structures (sheds, garden rooms).
- Height limits 4 m (pitched, tiled or slated) / 3 m (other roofs); at least 0.6 m from any wall or boundary; at least 25 m² of private open space must remain.
- Occupied only in conjunction with the main house: it cannot be sold or subdivided separately, short-term letting is barred, and the owner must live in the principal house.
- No new road entrance, no separate utility connections, and independent step-free pedestrian access.
- Not temporary in nature: a caravan or mobile home does not qualify.
- Building regulations, including fire safety, fully apply.
- A 14-day prior notification (with Eircode) to the planning authority before starting, and the works must be commenced and completed by 31 December 2030.
Route 2 from 27 July: subdividing the house (Class 1A)
S.I. 339 of 2026 exempts dividing an existing house into a maximum of two self-contained units, each of at least 32 m², again with a 14-day prior notification to the planning authority and the same window to 31 December 2030. For a family member who needs their own front door but not a separate building, this is the simpler route - no construction in the garden, and the works are largely internal.
The two routes cannot be combined on the same property, and the extension exemption's new wording confirms it applies only to the principal house - you cannot exempt-extend the granny flat itself.
What still needs permission
Anything outside the conditions: a garden dwelling over 45 m² combined, a unit you intend to rent out on the open market or list for short-term letting, a subdivision into three or more units, or any of this on a protected structure or in an architectural conservation area, where article 9 strips exemptions case by case. And because both new classes expire at the end of 2030, works after that date revert to needing permission unless the scheme is extended.
If your situation is near any line, a Section 5 declaration (EUR 80, answered within 4 weeks) gives you the council's formal answer before you spend on construction.
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Quick answers
Can I build a granny flat without planning permission?
From 27 July 2026, yes - through either the new garden-dwelling exemption (32 to 45 m², detached, strict conditions) or the house-subdivision exemption (two units, each at least 32 m²). Both require a 14-day prior notification to your council and run to 31 December 2030. Before 27 July 2026, a self-contained granny flat needs planning permission.
Can I rent out the granny flat?
Not under the garden-dwelling exemption: it must be occupied in conjunction with the main house, cannot be sold or let separately, and short-term letting is expressly barred. If open-market renting is the goal, that is a planning application, not an exemption.
What is the 14-day notification?
A brand-new procedural step in the 2026 regulations: before commencing works under the garden-dwelling or subdivision exemptions, you must notify the planning authority (including the property's Eircode) at least 14 days in advance. It is a notification, not an application - but skipping it means the works are not exempt.
Does a prefabricated garden dwelling qualify?
Yes, if it meets every condition - the exemption covers structures constructed, erected or placed. The one method restriction is that the dwelling must not be temporary in nature, so a mobile home or caravan cannot use it. Building regulations including fire safety apply regardless of how it is built.
Sources
Related
General guidance, not legal or planning advice. The regulations and your local authority's interpretation bind; conditions and local rules (protected structures, architectural conservation areas, flood zones) can change the answer for a specific property. When in doubt, ask your council for a Section 5 declaration or talk to a planning consultant.