Quick answer: The 40 m² proposal has been replaced by final rules. Since July 2026, garden structures such as offices and gyms in the Republic of Ireland can be up to 30 m² without planning permission. Conditions and limitations apply, including keeping at least 25 m² of rear garden. A separate 32–45 m² exemption applies specifically to auxiliary habitable dwellings, not to garden rooms generally.
When this article was first published, the Irish government had proposed allowing garden buildings of up to 40 m² without planning permission. The final rules turned out differently, so we have updated this guide to reflect what now applies.
What changed in July 2026?
Garden structures such as offices and gyms can now be up to 30 m² without planning permission, subject to conditions and limitations. A separate 32–45 m² exemption covers auxiliary habitable dwellings only.
The previous limit for garden structures was 25 m². The increase to 30 m² gives homeowners more room for a practical office, gym or studio, but it is not an unconditional allowance. Size, height, position, how much rear garden remains and how the building is used all matter.
The 32–45 m² exemption is a separate rule for auxiliary habitable dwellings. It should not be read as a general exemption for larger garden rooms.
How big is 30 m²?
About 6 m × 5 m, enough for a spacious garden office, gym or studio. In practice, 30 m² comfortably fits:
- A garden office for one or two people, with storage and a meeting area
- A home gym with space for a rack, cardio equipment and floor work
- A studio, treatment room or hobby space
- A multi-use room that works as an office by day and a relaxation space in the evening
What can you build without planning permission now?
In many cases, a garden office, gym or studio of up to 30 m², as long as you meet the conditions and limitations, including height and garden-area limits. The 32–45 m² exemption is for auxiliary habitable dwellings only. Before you build, check:
- Floor area: the garden structure stays within 30 m².
- Garden remaining: at least 25 m² of rear garden is left.
- Height and position: the building stays within the height limits and sits behind the house.
- Use: the building is used for a purpose covered by the exemption. Sleeping accommodation is treated differently, so check before you plan a bedroom.
- Your property: protected structures, conservation areas and existing buildings in the garden can all affect what applies.
We check these points for your site at survey and tell you before you commit.
Do the Irish rules apply in Northern Ireland?
No. Northern Ireland has its own permitted development rules for garden rooms. There, a garden room is usually permitted development if it is single storey, behind the house, under 4 m high (2.5 m if within 2 m of a boundary) and covers no more than half the garden. Listed buildings and conservation areas need extra checks.
Things to keep in mind before you build
Whatever the size of your garden room, a few practical points always apply:
- Access: make sure materials and equipment can reach your garden.
- Ground conditions: the right base ensures long-term durability.
- Utilities: plan electricity, broadband and any plumbing early.
- Orientation: make the most of natural light and privacy.
- Future flexibility: design a room that can change use as your needs change.
Planning a garden room in Ireland?
At CG Garden Rooms, we design and build fully insulated garden rooms across the Republic of Ireland and Northern Ireland. We check the planning position for your property at survey, so you know where you stand before you commit.
📞 Contact CG Garden Rooms today to discuss your garden room and get advice on the rules that apply to your home.
Frequently Asked Questions
Did the proposed 40 m² garden room rule go ahead in Ireland?
Not exactly as proposed. Under the final rules in force since July 2026, the exemption for garden structures such as offices, gyms and sheds rose from 25 m² to 30 m². Conditions and limitations apply, including keeping at least 25 m² of rear garden. A separate 32–45 m² exemption relates specifically to auxiliary habitable dwellings and is not a general garden-room exemption.
Do the new Irish rules apply in Northern Ireland?
No. Northern Ireland has its own planning system. There, a garden room is usually permitted development if it’s single storey, behind the house, under 4 m high (2.5 m within 2 m of a boundary) and covers no more than half the garden.
How do I know if my garden room needs planning permission?
It depends on the size, height, position and use of the room and on whether your home is listed or in a conservation area. We check the rules that apply to your property at survey and advise you before you commit.
