Here’s what you need to know:
You don’t need planning permission for a new house in your back garden (or live-in granny flat, cabin, seomra/shomera) if you can meet all of these conditions:
The house must be in the rear garden.
The house must be a minimum of 32sqm.
You keep the total area of the new house and cabins / sheds / garages on the site to a maximum of 45 square metres.
You don't reduce your back garden or yard below 25 square metres.
You keep the height to 4m for a slated/tiled pitched roof, or 3m for any other roof type.
You keep the house 0.6m from any walls or boundaries.
You keep windows more than 0.6m from the boundary.
The house can’t be something temporary like a caravan or a mobile home.
You don’t sell or subdivide this new house separately to your main house.
You use the same vehicular / pedestrian access from the main road, but have independent pedestrian and / or wheelchair access to the house within your plot.
Utilities (electricity, water, gas) must use the same connections as the main house, including any septic tank.
You don’t add this new house as well as subdividing your main house under the other new exemptions.
You don’t rent out the house as a short-term let (Airbnb etc.).
The main house must be your main residence (not a second home or holiday home).
You notify your local council that you intend to avail of this exemption.
Key areas to watch out for:
Building Regulations apply to any new house or cabin you build if it is to be lived in - these govern everything from fire escapes and alarms, energy performance, and ventilation.
Requirements are different for protected structures and in Conservation Areas - this exemption can’t be used for those.
If you have a septic tank, any new house or cabin shouldn’t encroach upon percolation areas for that.
The exemption is only for development commenced and completed between 27th July 2026 and 31st December 2030.
Some other important things to consider when planning a build:
If you receive planning permission to build a separate unit or subdivide your house for rental, the Residential Tenancies Board provides information on how you can comply with tenancy laws.
Depending on the size and duration of your project, you may need to appoint project supervisors to ensure your build goes safely.
Consider using the services of a registered Architect, Engineer or Surveyor who will be familiar with the planning system.
Still unsure what this means for your project? Get expert, 1-to-1 advice tailored to your build — online and at a time that suits you.
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