House extensions by county across Ireland
Building on one level costs €1,500 to €2,200 per m² across Ireland, and building two storeys €2,000 to €2,500 per m² with both floors counted, VAT at 13.5% included. Dublin and the commuter counties sit higher. With design and engineer's fees, a 20 m² ground-floor room comes to €42,000 to €54,000 and a 40 m² two-storey extension with an en-suite to €105,000 to €128,000.
Pick your county for local per m² building rates, Census 2022 house sizes, what moving costs there, and the local planning authority.
Free and no obligation. Your plan goes to one builder, not a list.
- 26counties covered across Ireland
- €1,500–€2,200per m², one storey national rate
- €1,800–€2,500per m², one storey Dublin & GDA
- 45 m²exempt rear extension limit
Plan your house extension
Four quick taps, and your plan fills in as you answer: what it costs, whether it needs planning permission and how long it takes. Contact details come last, and only if you want a builder to price it.
25 m² single-storey rear, mid-range finish: €52,000 to €65,000, including VAT and fees.
How the estimate is worked out
Every kind of extension has a build rate per m² for each region of Ireland, VAT at 13.5% included. A standard finish uses the lower half of that range and mid-range the upper half; high spec or a wall of glass moves the build to the glazed rate. Design, engineer and BER fees go on top, with anything you tick (an en-suite, a kitchen, a steel beam into the house) priced at your finish. A garage conversion gets one price for the whole job, since the walls and roof are already standing. Totals are rounded to the nearest €1,000. Use it to plan with. It isn't a quote: a builder prices your house after seeing it.
All 26 counties compared: building rates, house sizes and moving costs
Regional per m² building rates (incl. 13.5% VAT), share of houses with three bedrooms or fewer (Census 2022), 2025 median mover price (CSO), and the cost of moving vs building a 20 m² room.
| County | 1-storey per m² | ≤3 bed houses | Median mover price | Moving dead costs | 20 m² extension |
|---|---|---|---|---|---|
| Carlow | €1,600–€2,200 | 60% | €265,000 | €8,000 to €16,000 | €43,000 to €54,000 |
| Cavan | €1,400–€2,000 | 49% | €260,000 | €8,000 to €15,500 | €39,000 to €50,000 |
| Clare | €1,500–€2,100 | 53% | €312,000 | €9,000 to €17,500 | €41,000 to €52,000 |
| Cork | €1,500–€2,100 | 60% | €370,000 | €10,500 to €20,000 | €41,000 to €52,000 |
| Donegal | €1,400–€2,000 | 52% | €199,000 | €6,500 to €13,000 | €39,000 to €50,000 |
| Dublin | €1,800–€2,500 | 67% | €546,000 | €14,000 to €27,500 | €48,000 to €60,000 |
| Galway | €1,400–€2,000 | 45% | €375,000 | €10,500 to €20,500 | €39,000 to €50,000 |
| Kerry | €1,500–€2,100 | 56% | €303,000 | €8,500 to €17,500 | €41,000 to €52,000 |
| Kildare | €1,800–€2,500 | 55% | €435,000 | €12,000 to €23,000 | €48,000 to €60,000 |
| Kilkenny | €1,600–€2,200 | 56% | €315,000 | €9,000 to €18,000 | €43,000 to €54,000 |
| Laois | €1,600–€2,200 | 58% | €265,000 | €8,000 to €16,000 | €43,000 to €54,000 |
| Leitrim | €1,400–€2,000 | 53% | €203,500 | €6,500 to €13,500 | €39,000 to €50,000 |
| Limerick | €1,500–€2,100 | 58% | €330,000 | €9,500 to €18,500 | €41,000 to €52,000 |
| Longford | €1,600–€2,200 | 55% | €235,000 | €7,500 to €14,500 | €43,000 to €54,000 |
| Louth | €1,600–€2,200 | 64% | €306,000 | €9,000 to €17,500 | €43,000 to €54,000 |
| Mayo | €1,400–€2,000 | 50% | €235,000 | €7,500 to €14,500 | €39,000 to €50,000 |
| Meath | €1,800–€2,500 | 50% | €385,000 | €10,500 to €20,500 | €48,000 to €60,000 |
| Monaghan | €1,400–€2,000 | 51% | €270,000 | €8,000 to €16,000 | €39,000 to €50,000 |
| Offaly | €1,600–€2,200 | 58% | €270,000 | €8,000 to €16,000 | €43,000 to €54,000 |
| Roscommon | €1,400–€2,000 | 50% | €220,000 | €7,000 to €14,000 | €39,000 to €50,000 |
| Sligo | €1,400–€2,000 | 53% | €245,000 | €7,500 to €15,000 | €39,000 to €50,000 |
| Tipperary | €1,500–€2,100 | 58% | €260,000 | €8,000 to €15,500 | €41,000 to €52,000 |
| Waterford | €1,500–€2,100 | 64% | €287,000 | €8,500 to €16,500 | €41,000 to €52,000 |
| Westmeath | €1,600–€2,200 | 53% | €315,000 | €9,000 to €18,000 | €43,000 to €54,000 |
| Wexford | €1,600–€2,200 | 59% | €292,000 | €8,500 to €17,000 | €43,000 to €54,000 |
| Wicklow | €1,800–€2,500 | 60% | €481,000 | €12,500 to €24,500 | €48,000 to €60,000 |
County extension questions
Which counties do you cover?
All 26 counties in the Republic of Ireland. Your plan goes to one vetted builder who covers your county.
Why do extension building rates vary by county?
Dublin, Kildare, Meath and Wicklow carry the highest labour and trade rates in Ireland, followed by the rest of Leinster, Munster, and Connacht and Ulster.
Are the 45 m² planning rules the same in every county?
Since 27 July 2026 you can build up to 45 m² behind the house without applying for planning permission. That 45 m² includes every extension added since 1964 and any attached garage you convert. The extension can't rise above the house, the house has to keep 25 m² of private open space, ground-floor windows need 1 m or more to the boundary they look onto, and no more than 12 m² of it can be upstairs on a semi or terrace (20 m² on a detached house). Before that date the limit was 40 m².
Is it cheaper to extend or move?
Moving costs money that buys no extra room. On a €380,000 house, the median people moving home paid in 2025, stamp duty on the next house is €3,800, the agent's fee on the sale is €4,700 to €11,700 with VAT and the solicitor €2,000 to €5,000: €10,500 to €20,500 before removals, and before the higher price of a bigger house. Extending keeps all of it in the house you already own.
Every guide, calculator and county page
Jump straight to any specification guide, our interactive calculator, the technical glossary or your county page.
Price & Specification Guides
Calculator, FAQ & Glossary
Room to grow, without moving
Pick the type, the size and the finish to see the cost in your county. When you want a firm price, your plan goes to a single vetted builder for your area.