Side return extensions
A side return extension fills the narrow passage beside the back return of a terraced or semi-detached house, so the kitchen gets the full width of the plot. It costs €1,800 to €2,400 per m² across Ireland and €2,000 to €2,700 in Dublin, including VAT. Most are 6 to 12 m² of new floor, but they change the whole room.
For terraces and older semis with a back return: the cost, the light, and the planning question to settle first.
Free, no obligation. One local builder prices it, not five.
- €1,800–€2,400per m² incl. VAT
- €2,000–€2,700per m² in Dublin
- 33%of Dublin homes are terraced (Census 2022)
- 20%of homes across Ireland are terraced
A side return, in one drawing
Many Irish terraces and older semis were built with a narrow back return: the kitchen or scullery sticks out behind the main house, with a thin side passage beside it. That passage is dead space. Fill it, take down the side wall of the return, and the kitchen goes the full width of the house.
Terraced homes are 33% of households in Dublin and 20% across Ireland (CSO Census 2022), which is why side returns are mostly a city job.
What a side return costs
Per m², a side return costs more than a plain rear extension: €1,800 to €2,400 against €1,500 to €2,200 nationally. The area is small, but the work isn't: a party wall or boundary wall to build against, a long steel to take out the side of the return, a glazed roof along the side for light, and everything carried down a narrow passage.
8 m² in Dublin, mid-range with a new kitchen: €34,000 to €57,000; 12 m² in Dublin, mid-range with a new kitchen: €43,000 to €68,000; 10 m² in Cork, mid-range with a new kitchen: €36,000 to €58,000.
Plan your extension and see the cost
Nine quick taps. You see your plan build up as you go: the price range, what moves it, the planning position and the build time. Your number is only asked for at the end, if you want a real price.
A 12 m² side return extension in Ireland, mid-range, with wide glass doors and a new kitchen: €40,000 to €64,000 all in, including VAT and fees.
How this is worked out
We start from what single-storey extensions cost to build per square metre in each part of Ireland, including VAT at 13.5%, and the rates for side, wraparound, two-storey and heavily glazed extensions. Standard finishes take the lower half of the range, mid-range the upper half, and high spec or a wall of glass the glazed rate. Then we add professional fees (design, engineer, BER) and, if you want one, a new kitchen at your level of finish. Totals are rounded to the nearest €1,000. It's an estimate to plan with, never a quote: the builder prices your house after seeing it.
The planning question to settle first
The exemption covers extensions to the rear of the house. A side return is behind the main house, beside the return, so many are rear extensions in planning terms. But if any part comes forward of the back wall of the main house, down the side, it isn't covered. Get a section 5 declaration from the council (€80) before you build if there's any doubt.
The other limits still apply: 45 m² in total with earlier extensions, 25 m² of yard or garden left, and walls no higher than the house. On a terrace, the open space rule is usually the tight one. Building up to a shared boundary wall also needs your neighbour's agreement before the builder touches it.
The full list: planning permission for a kitchen extension.
Getting light into a side return
A side return is lit from above. A glazed roof along the length of the infill, or a run of rooflights, is what makes it work: without it, the middle of a deep terrace kitchen stays dark. Our roof types page compares the options.
Questions people ask
How much does a side return extension cost in Ireland?
A side return extension fills the narrow passage beside the back return of a terraced or semi-detached house, so the kitchen gets the full width of the plot. It costs €1,800 to €2,400 per m² across Ireland and €2,000 to €2,700 in Dublin, including VAT. Most are 6 to 12 m² of new floor, but they change the whole room.
Do I need planning permission for a side return extension?
Often not, if it's at the back of the house and within the limits, but if any part comes forward of the back wall of the main house it needs permission. A section 5 declaration (€80) settles it.
How much space does a side return add?
Usually 6 to 12 m², depending on the length of the return and the width of the passage. The point is the shape: the kitchen becomes the full width of the house.
Can I combine a side return and a rear extension?
Yes, that's a wraparound. It counts as one extension towards the 45 m². Wraparound extensions.
Do I need my neighbour's permission?
Not for planning if it's exempt, but you do need their agreement to build on or against a shared boundary wall.
Get a free quote for your extension
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