Class 3A explained: a 45 m² garden home without planning permission

What Class 3A allows

Class 3A is the first route in Ireland to a habitable building in your back garden without a planning application. It is aimed at family members, such as an older parent or an adult child, living alongside the main household. Unlike a Class 3 garden room, a Class 3A unit can be lived and slept in.

In exchange, the conditions are much stricter. It is a home, so it is built and regulated like one.

The conditions

Every condition must be met. These are the main ones, grouped by topic.

Size and position

• 32 m² minimum, 45 m² maximum, and the 45 m² includes any existing sheds, garages or garden rooms on the property.
• Detached and in the rear garden of the main house.
• At least 25 m² of private open space must remain for the occupants.
• Height: up to 4 m with a tiled or slated pitched roof, 3 m otherwise.
• At least 0.6 m from any boundary wall, and windows at least 0.6 m from the boundary they face.

Services and access

• Connected to the main house's services, with no separate utility connections.
• On a septic tank, it can't sit on the approved percolation area, the system must have enough capacity, and you can't add a second treatment unit under this exemption.
• No new entrance onto a road. Access must be through the existing property, with independent pedestrian or wheelchair access to the unit within the grounds.

Ownership and use

• The main house must be the owner's main residence when work starts.
• The unit can only be lived in alongside the main house. It can't be sold or split off as a separate property.
• No short-term letting.
• The main house must not have been subdivided, and the unit can't be temporary.

Building standards

• It must comply with the Building Regulations, including fire safety, and Building Control requirements.

How existing sheds count

This catches people out. The garden home and any Class 3 structures must together stay within 45 m². With the 32 m² minimum, that leaves room for only 13 m² of other garden buildings.

Notifying the council

Before work starts, you must send your council a notification form at least 14 days in advance. It includes the location and Eircode. Councils have published the form on their websites. This isn't an application, so the council doesn't approve it, but skipping it means the exemption doesn't apply.

The 2030 deadline

Class 3A is time-limited. Work relying on it must be started and completed by 31 December 2030. If you are considering it, allow time for design, Building Regulations compliance and construction, which takes longer than for a garden office.

Class 3A or a garden room?

For an office, gym or studio, a garden room is simpler and cheaper. For someone to live in, Class 3A is now the planning-free route, but budget for a proper small home, including a bathroom and kitchen. Residential garden units from Irish suppliers are advertised from around €50,000 upwards, before groundworks and connections.

Garden home guides

• Garden home checker: check your plan against every condition
• How to build a garden home: notices, certifiers and the completion certificate
• Modular homes and granny pods: what to check before you buy
• A garden home for your parents: designing for later life
• Property tax, insurance and mortgages
• What a garden home costs: modular, turnkey and builder-built
• Layouts from 32 to 45 m²: scale floor plans
• Notifying your council: the 14-day notice
• Renting it out: licences and rent a room relief
• Garden home, extension or garden room?
• Garden annexes and family flats: the other ways to build a granny flat
• Grants: what's available, and what isn't
• Mobile homes and pods: why living in a mobile home is different