Garden room prices by size: 9 m² to 30 m²
The short answer
A 12 m² garden room costs roughly €8,500 to €18,000 as a catalogue room, or €21,500 to €38,500 builder-built. A 20 m² room costs roughly €14,000 to €30,000 or €36,000 to €64,000. The plans below are drawn to scale on a 1 m grid.
Prices are estimates based on published Irish per m² rates, before foundations, electrics and other extras. Each plan shows typical furniture to scale, so you can picture the space.
9 m² (3 × 3 m)
What fits: One desk, a chair and shelving. Enough for a solo home office or a small studio. The smallest size most people use all year. Below this, it feels like a shed.
| Catalogue, supplied and installed | €6,500 to €13,500 |
| Bespoke, builder-built | €16,000 to €29,000 |
12 m² (4 × 3 m)
What fits: A desk plus a reading chair or small sofa, or a compact gym with a bench and rack. A popular garden office size with room to move.
| Catalogue, supplied and installed | €8,500 to €18,000 |
| Bespoke, builder-built | €21,500 to €38,500 |
16 m² (4 × 4 m)
What fits: Two desks, or an office corner plus a small gym area. A good size for a family room. The point where a room starts to feel like a real room.
| Catalogue, supplied and installed | €11,000 to €24,000 |
| Bespoke, builder-built | €29,000 to €51,000 |
20 m² (5 × 4 m)
What fits: A home gym with free-weight space, a music studio, or an office with a sofa area. Comfortable for two uses at once.
| Catalogue, supplied and installed | €14,000 to €30,000 |
| Bespoke, builder-built | €36,000 to €64,000 |
25 m² (5 × 5 m)
What fits: A family room or playroom, or a split room with an office at one end and a gym at the other. The old exemption limit, so many standard designs come in this size.
| Catalogue, supplied and installed | €17,500 to €37,500 |
| Bespoke, builder-built | €45,000 to €80,000 |
30 m² (6 × 5 m)
What fits: Two separate rooms, such as an office and a gym, or a large open studio. The largest exempt size since July 2026, if your garden can spare it.
| Catalogue, supplied and installed | €21,000 to €45,000 |
| Bespoke, builder-built | €54,000 to €96,000 |
Check your garden can fit it
Size is often limited by your garden, not your budget. To stay exempt from planning, at least 25 m² of garden must remain behind or beside the house after the room goes in. Measure that space, take away 25, and the answer is the largest room you can build without planning permission, up to 30 m². Our garden size planner does the sum for you and draws it to scale.
See what fits your garden
Enter your garden's width and depth to see the largest exempt garden room, drawn to scale.
Common questions
What is the most popular garden room size in Ireland?
Sizes between about 12 m² and 25 m² are the most common in supplier ranges. 25 m² was the exemption limit until July 2026, so many standard designs were built to it.
What is the biggest garden room I can build without planning permission?
30 m², including any other sheds or garages on the property, as long as at least 25 m² of garden remains. See our planning guide.
Are bigger garden rooms cheaper per m²?
Usually, yes. Doors, windows and electrics cost about the same whatever the size, so the cost per m² falls as the room gets bigger.
Sources
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