Modular buildings & garden dwellings in Ireland

Check whether your build qualifies under the 30 m² Class 3 or 32–45 m² Class 3A planning exemptions, see real 13.5% VAT turnkey prices, and get a written quote from one vetted modular building supplier that covers your county.

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32 to 45 m²Class 3A exempt habitable garden dwelling band (since 27 July 2026)
Up to 30 m²Class 3 exempt garden office, gym or room limit
€2,400 to €3,200/m²turnkey habitable build guide, incl. 13.5% VAT
13.5%construction VAT rate when supplied and installed

What modular buildings cost in Ireland

Our price guide by size and specification, including 13.5% VAT on supply and installation.

Job	Typical cost	What moves the price
Insulated garden office or studio, 12 to 16 m² (Class 3)	€18,000 to €32,000	Cladding, glazing, base and cable run from the house
Large garden room or gym, 20 to 30 m² (Class 3 max)	€28,000 to €55,000	Up to the 30 m² non-habitable exemption limit; no plumbing or kitchen
Class 3A habitable garden dwelling, 32 to 37 m² (1-bed)	€65,000 to €105,000	Kitchen, shower room, Building Regs insulation, base and service hook-ups
Class 3A maximum garden dwelling, 40 to 45 m² (1 to 2 bed)	€80,000 to €135,000	Largest exempt rear-garden unit (45 m² total garden structures cap)
Standalone 2 to 3 bed modular home, 75 to 85 m²	€175,000 to €255,000	Full planning permission, BCAR, foundations and site services
Factory shell only (weathertight exterior), per m²	€1,200 to €1,800 a m²	Excludes groundworks, internal plumbing/kitchen and service connections
Insulated & fitted garden room rate, per m²	€1,600 to €2,400 a m²	Includes 13.5% VAT when supplied and installed by the builder
Turnkey habitable modular home rate, per m²	€2,400 to €3,200 a m²	All-in with kitchen, bathroom, foundations and 13.5% VAT

What's included

Factory-engineered structural frame (light-gauge steel, SIPs or structural timber frame) insulated to Building Regulation U-values.
External cladding (cedar, composite, larch or architectural metal), triple or A-rated double glazing, and single-ply EPDM or metal roof.
On turnkey dwellings: full internal plastering or lining, fitted kitchen, tiled shower room, water heater, space heating and consumer fuse board.
VAT at 13.5% when the supplier both supplies and installs the building on site (supply-only DIY flat-pack kits carry 23% VAT).

What pushes it up or down

Non-habitable room vs habitable dwelling. A wired garden office needs no plumbing, kitchen or foul drain connection; a 32 to 45 m² Class 3A dwelling is a complete small house with kitchen, bathroom and Building Regulation compliance.
Foundations. Ground screws (€90 to €120 a m²) go in within a day with no concrete pour; an insulated concrete slab (€140 to €220 a m²) costs more and takes longer.
Connecting to the house's services. Running water, foul waste (or a pumped foul line) and an armoured ESB cable from the main house typically adds €3,500 to €9,500 depending on trench length.
Site access. Crane lift over the house for a pre-assembled volumetric pod vs panelised modular cassettes carried through a side passage.
Planning & BCAR over 45 m². Standalone homes and units over 45 m² need full planning permission, architectural drawings and Building Control (BCAR) sign-off.

From your garden to a finished building

Configure your size and useCheck whether you want an up-to-30 m² Class 3 office/room, a 32 to 45 m² Class 3A habitable garden dwelling, or a larger modular home.
One vetted supplier rings youWe pass your project to one vetted modular building supplier that covers your county. Not a directory list, and not five builders calling you.
Site check and written turnkey quoteThey check side access or crane reach, ground screws vs slab, and service trenches from the house, then price the whole job in writing.

Garden dwellings, offices and turnkey modular homes

Every 2026 planning rule, per-m² price band and foundation option explained.

45 m² Class 3A garden dwellingsSince 27 July 2026 (S.I. No. 340 of 2026), a 32 to 45 m² habitable dwelling in your rear garden is planning-exempt with 14-day council notice.Class 3A rules in full →Modular home pricesShell €1,200 to €1,800 a m², fitted garden rooms €1,600 to €2,400 a m², and turnkey habitable units €2,400 to €3,200 a m² incl. 13.5% VAT.Full price guide →Garden offices & rooms (Class 3)Non-habitable offices, gyms and studios up to the 30 m² Class 3 limit: €18,000 to €32,000 for 12 to 16 m², up to €55,000 for 30 m².Garden offices & rooms →Turnkey modular homesStandalone 1, 2 and 3 bed modular houses (€175,000 to €255,000 for 75 to 85 m²): planning, BCAR and 60-year structural warranties.Turnkey modular homes →Foundations & service hook-upsGround screws (€90 to €120 a m²) vs concrete slab (€140 to €220 a m²), plus water, foul waste and ESB cable trenches (€3,500 to €9,500).Foundations & services →Classrooms & commercial unitsModular classrooms, sports clubhouses, clinics and site offices built to commercial Building Regulations, DAC and fire safety standards.Commercial modular →

Modular building suppliers in all 26 counties

Each county page has CSO Census 2022 house-type figures, climate data, towns and council notification details.

Before you build

Can I build a 45 m² modular home or granny flat in my back garden without planning permission?

Yes, since 27 July 2026, if you meet the Class 3A conditions in S.I. No. 340 of 2026. A detached habitable garden dwelling between 32 m² and 45 m² in the rear garden of a house is exempt from planning permission provided total garden structures do not exceed 45 m², the owner lives in the main house, it connects to the main house's services, it is not sold separately or used for short-term letting, you give the local council 14 days prior written notification with your Eircode, it meets Building Regulations, and work finishes by 31 December 2030.

What is the difference between Class 3 (30 m²) and Class 3A (32 to 45 m²)?

Class 3 (updated by S.I. No. 338 of 2026) covers non-habitable garden rooms, home offices, gyms and sheds up to 30 m² — you cannot sleep or live in a Class 3 room. Class 3A (S.I. No. 340 of 2026) covers a detached habitable garden dwelling (granny flat) of 32 m² to 45 m² with a kitchen, bathroom and bedroom.

How much does a modular building or garden dwelling cost in Ireland?

An insulated, fitted garden office or room (12 to 30 m²) costs €18,000 to €55,000 including 13.5% VAT. A turnkey habitable 32 to 45 m² Class 3A modular dwelling with kitchen, shower room, foundations and service connections costs €65,000 to €135,000 (€2,400 to €3,200 a m²).

Is VAT on a modular building 13.5% or 23%?

When a modular builder supplies and installs the building on your site (under Revenue's two-thirds rule for construction services), the reduced 13.5% VAT rate applies. If you buy a supply-only flat-pack kit with no installation, it is taxed as goods at 23% VAT.

How long does a modular building take from order to completion?

Factory fabrication usually takes 4 to 8 weeks while your ground screws or concrete base and service trenches are prepared. On-site installation takes 1 to 3 days for a pre-assembled volumetric pod lifted in by crane, or 1 to 3 weeks for a panelised system assembled in the garden.

Who gets my enquiry when I fill in the form?

One vetted modular building supplier that covers your county, and only one. They review your garden access, foundation options and service runs, and give you a written turnkey price.

Get a written turnkey price for your modular building

One vetted supplier covering your county checks access, foundations and service connections, and gives you a written price.

Get a free quote Check Class 3A rules