Compared
Garden room or extension?
Since 27 July 2026, a rear extension can be up to 45 m² without planning and garden structures up to 30 m² in total. An extension adds to the house; a garden room is a separate building with garden between it and the house.
Free, no obligation. One local company prices it, not five.
Side by side
The two compared
| Garden room (Class 3) | Rear extension (Class 1) | |
|---|---|---|
| Exempt size | 30 m² for all garden structures | 45 m² in total |
| Height | 3 m flat roof, 4 m pitched | Unchanged rules |
| Garden left | 25 m² | 25 m² |
| Can it be lived in? | No | Yes, it's part of the house |
| Work on the house | None | Knocking through, a new roof joint |
Pick the room
When a garden room suits
- You want the work away from the house: an office, a studio, a gym.
- You don't want builders inside or a wall knocked.
- The garden is long enough to keep 25 m² open after it.
Pick the extension
When an extension suits
- The space is a kitchen, a bedroom or a bathroom: rooms that are lived in.
- You want it to add to the house's floor area.
- The garden is short, and a room at the end would leave too little.
Price guide
What a garden room costs in Cork
Room-only prices are the building delivered and put up. Fitted prices are ready to use.
| Job | Typical cost | What moves the price |
|---|---|---|
| Small timber cabin, 3 × 2 m to 3.4 × 2.5 m, room only | €6,700 to €9,000 | Wall thickness and glazing. Base and power extra |
| Garden office kit, flat pack | €5,600 to €16,798 | Model and size. Fitting, base and power extra |
| Timber cabin, 4 × 4 m to 5 × 5 m, room only | €13,500 to €17,500 | Size, doors and windows |
| High-spec eco room, 3 × 3 m to 4.2 × 4.4 m | €13,420 to €21,330 | Better glazing, doors and insulation |
| Insulated, fitted garden room, 12 to 25 m² | €25,250 to €41,000 | Size. VAT included, ready to use |
| Large garden room, over 5 × 5 m | €17,000 to €51,000 | Spec and size. Over 30 m² in total needs planning |
Towns
We cover all of Cork
Free quote
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Tap what you want and leave your number. It goes to one vetted garden room company that covers your part of Cork, and they ring you back to arrange a look and a written price.
Questions
Questions people ask
Is a garden room cheaper than an extension?
Usually, for the same size: no work on the house and no foundations tied to it. A fitted 20 m² room is €32,000 VAT included.
Can I have both?
Yes. The extension counts under Class 1 and the garden room under Class 3, each with its own limits, and 25 m² of open space has to remain.
Does a garden room add value?
It can, if it's built properly and within the rules. Keep the paperwork: the spec, the guarantee, the electrical certificate and any section 5 declaration.
Get a free quote for your garden room in Cork
One vetted company that covers your part of Cork rings you. Nothing is agreed until you accept a written price.