Garden homes and granny flats in Ireland: the 2026 exemption explained
Since 27 July 2026, you can build a detached garden home of between 32 and 45 square metres in your back garden without planning permission. You must notify your council at least 14 days before work starts, meet a list of conditions, and finish the build by 31 December 2030.
For families who want an elderly parent close by, or a grown-up child to have their own space, this is a big change. Here’s what the rules say in plain English, and what they mean for the garden around it.
What is a “detached auxiliary dwelling”?
That’s the official name for a small, self-contained home in the back garden of your house. It’s often called a garden home or granny flat. It is linked to the services of the main house and can only be used together with it, never sold off separately.
It’s a different exemption from a garden room. A garden room (up to 30 m²) can’t be lived in; a garden home is designed to be. I’ve covered garden rooms in Garden rooms without planning permission: the 2026 rules.
The key rules
Size: between 32 m² and 45 m². The 45 m² limit includes any garden rooms or sheds you already have in the back garden.
Position: in the rear garden, at least 0.6 m from every wall or boundary. Windows must also be at least 0.6 m from the boundary they face.
Height: no more than 4 m with a tiled or slated pitched roof, or 3 m for any other roof.
Garden left over: at least 25 m² of private open space must remain for the main house.
Access: its own path within your property. No new gate or entrance onto the road.
Services: connected through the main house, with no separate water, wastewater or utility connections.
Permanent building: not a caravan, mobile home or other temporary structure.
Use: only with the main house. It can’t be sold or split off separately, or used for short-term letting.
Your home: the main house must be your sole or main residence when work begins.
Notice: notify your council at least 14 days before work starts, with your Eircode.
Deadline: the exemption ends on 31 December 2030. The build must be finished by then.
You also can’t use this exemption if you’ve already divided your main house into two units under the separate 2026 subdivision exemption. It’s one or the other.
Building Regulations still apply
No planning permission doesn’t mean no rules. A garden home is somewhere people will live and sleep, so Building Regulations, fire safety and building control requirements all apply. You’ll need an architect or engineer for the building itself, and they’ll advise on the paperwork.
Designing the garden around a garden home
This is where a garden designer earns their keep. You’re no longer designing one garden for one household. You’re designing a shared outdoor space for two, on what is often a modest Dublin plot.
Make the 25 m² genuinely useful
The rules say 25 m² must stay open for the main house. A well-designed 25 m² can hold a dining terrace, planting and a small lawn. A badly shaped one is just leftover space. I plan the garden at the same time as the building’s footprint, so neither is squeezed.
Give each household some privacy
Both homes will look out onto the same garden. Careful placement of windows, hedging, pleached trees or a screen of tall grasses gives each side a sense of its own space without walls.
Plan a safe, step-free path
The garden home needs its own route in, within your property. If it’s for an older relative, design that path to be wide, level, well lit and non-slip from day one.
Respect the 0.6 metre gap
The strip between the building and the boundary is easily forgotten. Planned properly, it’s a useful space for bins, a narrow bed of climbers, or simply good access for maintenance.
Work with the architect early
Trenches for services, drainage and levels all affect the garden. The earlier the garden designer and architect talk, the less gets dug up twice.
[Add your view: one or two sentences in your own words. What you’d tell a family considering a garden home, or a project where you’ve coordinated with an architect.]
Quick questions
Can I rent out a garden home?
It can’t be used for short-term letting such as holiday rentals, and it can’t be sold separately. For any other kind of letting, get professional advice before you build.
Do I need to tell the council?
Yes. You must notify your local council at least 14 days before work starts. Most councils have a notification form on their website.
Can I have a garden room as well?
Possibly, but the 45 m² cap includes any existing garden structures. A 15 m² shed leaves 30 m², which is below the 32 m² minimum for a garden home.
Is this legal advice?
No. This is a general guide to the 2026 regulations. Always confirm your plans with your local council and a qualified professional.
Planning a garden home?
I design the garden around the building and coordinate with your architect, so both homes get an outdoor space that works. A site visit to talk it through is €120.
Official sources: Department of Housing announcement · South Dublin County Council: new exemptions and notification form
Written by Ingrid Smyth, garden designer, Dublin. Last updated November 2026.
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