Granny flat planning permission in Ireland — the family-flat condition and the 2026 exemption

The seven Greater Dublin Area councils we index received 153 applications describing a granny flat, family flat or ancillary family accommodation in the 12 months to 12 September 2026. Of the 122 decided, 102 were granted and 20 refused: 84%, which is ten points below the rate for ordinary extensions. The gap is about independence. A council will grant a flat for a relative that stays part of the house. It refuses one drawn as a separate home, and it can tell the difference from the plans.

There are three ways to build one, and since 27 July 2026 one of them needs no application at all.

An attached flat is an extension with a condition

A flat built onto the back or side of the house is an extension. Under 45 m² to the rear, with the open-space and height conditions met, Class 1 of Schedule 2, Part 1 of the Planning and Development Regulations 2001 exempts it, and the fact that it has its own kitchen does not change that. Above the limits, or to the side or front, you apply for €34 like any other extension.

What makes it a "family flat" in the planner's eyes is the internal connection. Dún Laoghaire-Rathdown's development plan, like Fingal's and Dublin City's, asks for an internal door to the main house, no separate front door onto the street, and a single set of services. The grant then carries a condition, worded much the same in every council: the flat is to remain ancillary to the main dwelling, shall not be sold, let or otherwise disposed of separately, and shall revert to the use of the main house when the family member no longer needs it. That condition follows the house through every future sale.

A detached flat in the garden: Class 3A

From 27 July 2026 a detached dwelling of 32 m² to 45 m² in the rear garden of a house is exempted development under new Class 3A, on conditions: 25 m² of private open space kept for the main house, a single storey, and a notification to the council within 14 days of completion. The class expires on 31 December 2030 unless renewed. It is the first time a self-contained home in a garden has been exempt, and it was written for exactly the granny-flat case. The garden rooms guide has the conditions in full.

Build under Class 3A and there is no ancillary condition, because there is no grant. The dwelling is a separate unit, and whether it can later be sold on its own is a matter of title and services, not planning. Our reading: if the flat is for a parent and the garden allows it, Class 3A is the route; it costs no fee, takes no eight weeks and has no register entry to explain at a sale. Keep a copy of the 14-day notification with the deeds.

Refused: the ones drawn as a second house

We read the 20 refusals. Dublin City refused a detached single-storey family flat to the rear of 60 Edenmore Crescent, Dublin 5, on 17 April 2026, before Class 3A existed; the same building, at the same size, may now be exempt. Fingal refused a scheme at 19B Sycamore Lawn, Castleknock on 12 May 2026 that demolished an existing granny flat and rebuilt it. Meath refused a detached outbuilding for a granny flat at Navan on 16 July 2026. In each the planner's report says the same thing: a separate entrance, a full-size kitchen, no internal link, a plot that could be fenced off. That is a new house on a garden site, and it is assessed as one, on density, overlooking, parking and private open space for both units.

Letting it out later

The ancillary condition is enforceable. A family flat let to a tenant is a breach of condition, and a council can serve a warning letter under s.152 of the Planning and Development Act 2000. A flat that has been let separately for years is unauthorised, and s.157(4), which bars enforcement after seven years, does not apply to a condition about use. If you want a unit you can let, apply for that: a change of use to two dwellings under Class 1A, exempt from 27 July 2026 for a house subdivided into two units subject to its own conditions, or a full application for a second dwelling. The change of use guide covers the route.

Check your street

Open the Explorer on your address and search the applications tab for "family flat". Where a neighbour was granted one with the ancillary condition, the grant text is on the application page. The Fingal place page shows that council's live figures.

Figures from the register on 12 September 2026 (live callouts refresh hourly); law checked 12 September 2026. Check with the council or a planning consultant before relying on this.

Frequently asked questions

Do I need planning permission for a granny flat in Ireland?

An attached flat within the Class 1 extension limits (45 m² to the rear from 27 July 2026) is exempt. A detached one of 32–45 m² in the rear garden is exempt under Class 3A with a 14-day notification. Anything larger, or to the side or front, needs an application.

What is the family-flat condition?

A condition on the grant that the flat stays ancillary to the main house and is not sold or let separately. It binds every future owner. Letting the flat to a tenant breaches it, and the seven-year enforcement limit does not apply to conditions about use.

Can I sell a granny flat separately?

Not if it was granted as ancillary accommodation. A Class 3A dwelling has no such condition, but selling it separately depends on title, access and services, and most gardens cannot support it.

How often are granny flats refused in Dublin?

Twenty of the 122 decided in the past 12 months across the seven councils, 16%. The refusals are the ones with a separate entrance and no internal link to the house.

Does a granny flat need its own address or Eircode?

Not for an ancillary flat. A Class 3A dwelling can apply for an Eircode through An Post's address process; the council's 14-day notification is separate.