Written by Ireland introduced significant changes to its exempted-development planning rules in July 2026, making it easier in certain circumstances for homeowners to construct garden rooms, extensions and small detached modular-style dwellings without going through the normal planning-permission process.
The changes are particularly important for homeowners considering a garden office, garden room, granny flat or modular home. However, planning exemption does not mean that there are no rules. Size, location, use, notification requirements and building standards can still apply.
Here are four of the most important changes homeowners should understand.
- Garden Rooms Can Now Be Larger
One of the most useful changes concerns traditional garden buildings such as garden rooms, studios, home offices, sheds and garages.
The exempted-development limit for these types of structures has increased from an aggregate floor area of 25 square metres to 30 square metres, subject to the relevant conditions.
This potentially gives homeowners considerably more flexibility when creating a garden office, gym, hobby room or additional recreational space.
There is an important distinction, however: this exemption relates to non-habitable garden structures. A standard exempt garden room cannot simply be converted into an independent house or bedroom accommodation because different planning requirements apply where a building is intended for human habitation.
Homeowners must also comply with conditions concerning matters such as the position and height of the structure and the amount of private open space remaining around the house. - Detached Modular or Auxiliary Homes of Up to 45m²
Perhaps the biggest change is the introduction of an exemption allowing certain detached habitable accommodation of between 32m² and 45m² to be constructed to the rear of an existing house.
This creates new possibilities for families considering a small modular home, granny flat or independent living accommodation within the grounds of an existing property.
The Government describes these as auxiliary habitable dwellings, and they must satisfy the detailed conditions of the exemption. The detached accommodation is linked to the services of the principal house.
This is substantially different from the ordinary garden-room exemption because the new category specifically allows qualifying accommodation to be habitable.
The change could be particularly useful for multigenerational families seeking additional accommodation for adult children, elderly parents or other family circumstances without constructing a conventional house. - Planning Permission May Not Be Required – But Notification Is
Another major change is that qualifying projects can proceed as exempted development rather than requiring a conventional planning application.
For the new detached auxiliary dwelling exemption, homeowners are required to notify their local authority before construction begins. Local-authority guidance on the new regulations specifies notification 14 days before commencement of the works.
This is an important point for anyone advertising modular homes as “planning permission free.” Exempted development does not mean homeowners can simply place any modular building in their garden.
The proposed development must meet all the conditions associated with the exemption. Where the conditions cannot be satisfied, planning permission may still be necessary.
Anyone uncertain about whether a particular project qualifies should obtain confirmation from their local planning authority before construction. - House Extensions Can Now Reach 45m²
The 2026 reforms are not limited to detached garden buildings.
The existing exempted-development allowance for an extension to a principal dwelling has been increased from 40m² to 45m², provided the development complies with the other applicable conditions.
This gives homeowners an additional 5m² of potential exempted floor space, which can make a noticeable difference when designing a new kitchen extension, family room or additional living area.
The new regulations also introduce other residential exemptions, including provisions relating to subdivision of existing houses and certain roof alterations.
What Does This Mean for Irish Homeowners?
The changes represent an important expansion of what can potentially be built around an existing home without making a standard planning application.
The four headline changes are:
• Garden rooms and similar non-habitable structures can potentially reach 30m², subject to the exemption conditions.
• Certain detached habitable modular or auxiliary dwellings between 32m² and 45m² can qualify for planning exemption.
• The new auxiliary dwelling exemption requires notification to the local authority before work begins, including the specified 14-day advance notification.
• The exempted floor-area allowance for qualifying house extensions has increased from 40m² to 45m².
The new residential exemptions came into operation on 27 July 2026.
For homeowners considering a garden room or modular home in Ireland, the new rules provide significantly more options, but every project should be checked against the detailed exemption conditions before construction starts. Planning exemption should also not be confused with exemption from Building Regulations or other legal requirements.
This article provides general information rather than planning or legal advice. Requirements should be confirmed with the relevant local authority for the individual property before commencing work.