What a Class 3A garden home costs
The short answer
A 32 to 45 m² garden home built to Building Regulations costs roughly €50,000 to €75,000 for a modular unit, €80,000 to €120,000 for a turnkey timber-frame build, or €100,000 to €140,000 builder-built. Groundworks, connections to the main house and professional fees come on top, often adding 15% to 25%.
On this page
Three price levels
| Type | Typical cost |
|---|---|
| Modular unit, 32 to 45 m² One supplier's estimate for the structure, scaled from its garden room prices | €48,000 to €74,000 |
| Turnkey timber-frame home, 45 m² Supply and installation, as reported by the Irish Examiner from advertised prices | €80,000 to €120,000 |
| Builder-built annexe, 40 m² At €2,500 to €3,500 per m², before fees and VAT | €100,000 to €140,000 |
These are estimates from different sources and measure slightly different things, so treat them as a guide. Always ask exactly what a price includes.
What else to budget for
- Groundworks and base. More than a garden office needs. Difficult ground can add €10,000 to €25,000 on its own.
- Connections to the main house. Water, waste and power must come from the main house. Long runs, pumps or upgrading the house's electricity supply add cost.
- Kitchen and bathroom fit-out. "Bathroom space" in a brochure doesn't always mean a finished bathroom.
- Design and certification. Drawings, an engineer and Building Regulations sign-off. Builders put total professional fees at 10% to 20% of the project.
- VAT. Check whether each price includes it.
A worked example
A 40 m² modular garden home in a straightforward Dublin back garden might break down like this. It's an illustration, not a quote: the unit and connection figures come from published prices, and the groundworks and fees are our assumptions.
| Modular unit, 40 m² | €60,000 to €70,000 |
| Base and groundworks | €5,000 to €10,000 |
| Water, waste and power from the house | €5,000 to €8,000 |
| Design, engineer and certification | €6,000 to €10,000 |
| Total | €76,000 to €98,000 |
Estimate your garden home
Choose a size from 32 to 45 m² and a build type to see a total with groundworks, connections and fees.
Offsetting the cost
If someone pays to live in the garden home, rent a room relief may let you earn up to €14,000 a year tax-free in 2026, rising to €16,000 from 1 January 2027, according to Citizens Information. Conditions apply, including that the main house is your home and the relief doesn't cover renting to your own child. See renting out a garden home.
Common questions
How much does a granny flat cost in Ireland?
A 32 to 45 m² garden home built to Building Regulations typically costs from around €50,000 for a modular unit to €100,000 or more for a builder-built one, before groundworks, connections and fees. Cheap log cabin kits cost less but are not homes until they meet the Building Regulations.
Is a garden home cheaper than an extension?
Often, per square metre, if you choose a modular unit. A builder-built garden home costs about the same per m² as an extension, because both must meet the same Building Regulations.
Can I use a log cabin as a Class 3A garden home?
Only if it meets the Building Regulations for a home, including insulation, fire safety, ventilation and drainage. Most basic log cabin kits would need significant upgrades.
Sources
Garden room companies serving Dublin
See all Dublin companiesFeatured
Paid placements. Featured companies pay to appear here.
Reach people planning a garden room in Ireland. Featured spots appear at the end of every guide on this site.
Get featuredCompanies serving Dublin
Listed alphabetically, not ranked. How we list companies