Garden Dwelling (Class 3A)
A new exempted-development class from 27 July 2026: a detached habitable dwelling of 32 to 45 m² in the rear garden of a house, built without planning permission under strict conditions.
Class 3A, created by the July 2026 exemption package (S.I. 340 of 2026, in force 27 July 2026), exempts a detached habitable dwelling in the garden of a house for the first time in the history of the State's planning code. The floor area must be at least 32 m², and at most 45 m² combined with any other garden structures. The conditions are strict: the owner must live in the principal house, the dwelling can be occupied only in conjunction with it and cannot be sold or let separately (short-term letting is barred), it must sit behind the house at least 0.6 m from any boundary, and it cannot be temporary in nature - a caravan or mobile home does not qualify. A 14-day prior notification to the planning authority, including the property's Eircode, is required before works start, and the scheme runs to 31 December 2030.
This is a brand-new category of small residential build: full dwellings with foundations, structure, plumbing, electrics and fire safety, at 32 to 45 m², with no planning application to wait for. For builders, M&E trades and suppliers it is extension-scale work with new-build scope - and because these jobs skip the planning register, nobody will find them there.
Class 3A dwellings never appear as planning applications, and because they are planning-exempt houses needing no fire safety certificate, they need no BCMS commencement notice either. The only statutory trace is the 14-day prior notification, which councils keep as an internal record and report to the Minister as an annual count. The building regulations still fully apply to the construction itself.
Common questions
Not separately. It must be occupied in conjunction with the main house - no separate sale, no separate letting, and short-term letting is expressly barred. Open-market renting means a planning application instead.
Yes. A prior notification, including the property's Eircode, must reach the planning authority at least 14 days before works commence. Skip it and the works are not exempt.
Fully, including fire safety - it is a dwelling in law. Planning exemption never removes building-control obligations.
Built for planning consultants & architects: Benchmark every authority, track every appeal, never miss a decision date.
This is a plain-English summary, not legal advice. Planning rules carry conditions and exceptions - always verify a specific case against the official source or a planning professional before acting.