Where should the space come from?
Most people start by thinking about the house. The rest of the property is worth asking about too.
There are four ways to answer that, and most houses can do more than one of them. This Discovery is about choosing between them, before you start looking at anything.
What each one gives you.
The same seven questions, asked of all four.
Extend the house
A room that is part of the house, on the same heating and the same floor.
- Disruption
- The highest. A wall comes out and the room behind it is a building site.
- Speed
- The slowest of the four.
- Cost
- Roughly €2,000 to €3,500 per square metre.
- Planning
- Rarely an obstacle at ordinary sizes. More likely if you go up rather than out.
- Adds to the house
- Yes. It becomes part of the floor area.
- Later on
- Hard to undo, and rarely worth undoing.
- Costs you
- Garden, permanently.
Convert the attic
A room in space the house already has, with nothing added to the site.
- Disruption
- Contained. The stairs are the disruptive part.
- Speed
- Quicker than extending.
- Cost
- Roughly €18,000 to €55,000.
- Planning
- Rarely an obstacle inside. A dormer at the front is the exception.
- Adds to the house
- Usually, where the head height and the stairs work.
- Later on
- Permanent, and the storage does not come back.
- Costs you
- The attic.
Convert the garage
A room on the ground floor, already built, already roofed, already dry.
- Disruption
- Low. Most of it happens behind a door you can close.
- Speed
- Often the quickest of the four.
- Cost
- Roughly €10,000 to €30,000.
- Planning
- Rarely an obstacle for family use. Business use is the exception.
- Adds to the house
- Usually, though the garage does not come back.
- Later on
- Reversible in principle. Rarely reversed in practice.
- Costs you
- The garage, and wherever its contents were going to go.
Build in the garden
A separate room at the end of the garden, a short walk from the back door.
- Disruption
- The lowest. Most of the work happens outside the house.
- Speed
- Weeks rather than months.
- Cost
- Roughly €8,000 to €18,000 for an insulated room you can use all year.
- Planning
- Rarely an obstacle at ordinary sizes.
- Adds to the house
- It is a separate building, so it usually sits outside the floor area.
- Later on
- The easiest of the four to change your mind about.
- Costs you
- Garden.
Costs are broad guides for planning purposes, not quotes. The garden figures come from buildings PlotNua has already researched and compared.
The extension and conversion figures are what this kind of work generally costs in Ireland. PlotNua is building out that side of the research now. Reviewed August 2026.
Which direction suits you?
Most people already know which of these matters most to them.
The house has to stay liveable while the work happens.
Garden, or the garageThe new room needs to be part of the house, not a walk away.
Extend, or the atticYou want it finished this year.
Garden, or the garageThe budget is the tightest thing about the project.
The garage, or the gardenThe garden is small and already used.
Extend, or convertYou are not certain how long you will need the space.
GardenWhat decides it on your property?
- What the house already has. A garage, or an attic with the height to stand up in, removes a whole route from the list or puts one on it.
- How you get to the back. Side access makes building in the garden simpler. Everything has to come through the house without it.
- How much garden you are willing to give up. Two of the four take some, and two of them take none.
- Whether you can live in the house during the work. This decides more projects than cost does.
