Planning Permission

Not every garden building in Ireland needs a planning application. A garden room or home office is one thing; a building you plan to live in is another. Size and location matter too.

The rules changed in July 2026. The exemption for qualifying non-residential structures now covers buildings up to 30 m². At the same time, a separate exemption was introduced for certain detached residential buildings, with a minimum size of 32 m² and a combined cap of 45 m².

Neither limit is automatic. An existing shed or garage may use up part of the available area, and the amount of private open space left on the property also counts.

Garden buildings that may not need planning permission

Non-residential garden buildings up to 30 m²

The non-residential exemption is the main one to check for a garden room, home office, shed, garage or similar structure used in connection with the main house. It cannot be used as a separate home or as sleeping accommodation.

The main conditions are:
•  The building cannot be placed forward of the front wall of the house.
•  The combined area of relevant structures covered by this exemption on the property cannot exceed 30 m².
•  At least 25 m² of private open space must remain to the rear or side of the house.
•  The maximum height is 4 m with a tiled or slated pitched roof, or 3 m with another roof type.
•  A garage or similar structure built to the side of the house may also need to match the external finishes and, where relevant, the roof covering of the main house.
•  The building cannot be used for human habitation.

The 30 m² limit is cumulative. If a shed, garage or another qualifying structure covered by this exemption is already on the property, it can reduce the area available for a new building.

Certain detached residential buildings from 32 to 45 m²

The residential exemption is for a different kind of project: a permanent detached dwelling in the rear garden of a principal house. The rules are tighter here, and the full 45 m² is not always available.

•  The new dwelling itself has to be at least 32 m².
•  Together with relevant structures covered by the non-residential exemption, the total floor area cannot exceed 45 m².
•  The principal house must be the property owner's sole or main residence when the development begins, and the exemption cannot be used if that house has already been subdivided.
•  At least 25 m² of private open space must remain.
•  The same height limits apply: up to 4 m with a tiled or slated pitched roof, or 3 m with another roof type. The structure and proposed windows must also meet the relevant 0.6 m boundary separation rules.
•  No new vehicular or pedestrian access onto a road can be created under this exemption. Access must be provided within the existing property, and separate utility connections are not allowed.
•  The dwelling cannot be sold or subdivided separately from the principal house, and it cannot be used for short-term letting.
•  Give your local Planning Authority at least 14 days' notice before work starts. This exemption is also time-limited. A project using it has to start and finish within the exemption period, currently ending on 31 December 2030.

Building Regulations and Building Control requirements still apply. An exemption from planning permission does not remove those obligations.

What does the 45 m² limit actually mean?

For the residential exemption, the 45 m² cap includes relevant structures covered by the non-residential exemption that are already on the property. So if there is an existing 10 m² shed covered by that exemption, the largest new detached dwelling that could fit within the area limit would be 35 m². All of the other conditions would still need to be met.

An existing shed or garage can therefore change which residential log cabin sizes fit within the 45 m² area limit.

What if your project does not meet these conditions?

These exemptions are not the only route. A project that falls outside them may need a standard planning application before construction begins.

Still unsure? Do not be shy – ask us about it by calling +35316994541 today!