A new possibility.
Know the conditions.

In the rear garden of the principal house, which must be the owner’s sole or main residence when development starts.

At least 32 m², with a 45 m² combined cap including existing Class 3 structures such as sheds and garages. A 45 m² design is not automatically eligible.

Keep at least 25 m² of qualifying private open space. The structure and windows facing a boundary must meet the 0.6 m separation conditions.

Up to 4 m with a tiled or slated pitched roof; otherwise 3 m. Temporary structures such as caravans are excluded.

No new road access or separate utility connections. Independent pedestrian and/or wheelchair access is required within the plot. Wastewater capacity and percolation safeguards apply.

No separate sale or subdivision of the garden dwelling. The exemption cannot be combined with subdivision of the principal house.

Yes: notify the planning authority at least 14 days before starting, with the location, Eircode, intended use and confirmation of compliance.

The regulations took effect on 27 July 2026. Works must commence and finish within the specified relevant period, which ends on 31 December 2030.

Yes. Planning exemption does not remove Building Regulations, fire-safety or Building Control obligations. Other planning restrictions can also prevent exemption.

Get site-specific advice from the planning authority. Ask about heritage restrictions and whether a Section 5 declaration is appropriate; this checklist is not an exemption decision.

RTB guidance distinguishes qualifying exempt units added from 27 July 2026, which are outside its remit, from older or non-qualifying units that must be registered. Confirm the correct category with your local authority.

No. Short-term letting is excluded under Class 3A.

No. Revenue’s published manual excludes a self-contained unit beside, but not attached to, the main residence from Rent-a-Room Relief. Check current tax advice for your circumstances.