Detached garage conversions
A detached garage costs about €15,000 to €25,000 to convert into an office or gym at a standard finish, VAT included, plus the trench for power and water. It isn't part of the house, so Class 1 doesn't cover it: a use that goes with the house can need no permission, but a bedroom or somewhere to live needs planning permission.
A garage apart from the house: what it can become without permission, what needs it, and running power and water across.
Free and no obligation. Your plan goes to one builder, not a list.
- €15,000–€25,000office or gym, standard finish
- NoClass 1 exemption for a detached garage
- 12 weeksfor permission, if needed
- €80section 5 declaration
What a detached garage can become
- An office, a gym, a playroom or a hobby room that goes with living in the house: often no permission needed, if the outside barely changes. A section 5 declaration confirms it.
- A bedroom or a granny flat: a garage built under the shed and garage exemption (Class 3) can't be lived in, so this needs planning permission. Councils usually add a condition that it stays part of the main home. A newer exemption (Class 3A, from 27 July 2026 to the end of 2030) covers a detached unit up to 45 m² in the back garden, but it is written for building one: ask the council with a section 5 declaration before relying on it for a garage.
- A separate home to let: a new dwelling, judged like any other, with parking, private open space and access to consider.
Power, water and drains
A detached garage may have a single light and socket on an old cable, or nothing. A converted room needs a proper supply in armoured cable in a trench, with its own consumer unit, and a network cable alongside if it is an office. Water and a drain for a shower room or kitchenette mean more digging, and the drain needs a fall back to the house's system. Get the trench in the first price.
Plan your garage conversion
Four quick taps, and your plan fills in as you answer: the cost in your county, the planning position for your kind of garage and how many weeks it takes. Contact details come last, and only if you want a builder to price it.
A detached garage made into a home office, mid-range finish: €20,000 to €30,000, including VAT.
How the estimate is worked out
A garage conversion is priced as one job, because the walls, roof and floor slab are already standing: insulating the floor, walls and roof, building up the door opening with a window, wiring, heating, plastering and the finish. The range for your finish is adjusted to your county the same way building rates move between regions of Ireland, VAT at 13.5% included. A shower room, a small kitchen or a steel beam into the house go on top. Totals are rounded to the nearest €1,000. Use it to plan with. It isn't a quote: a builder prices your garage after seeing it.
What a garage can become
Each has its own page: what it costs, the rules that apply to that room, and what to decide first.
Garage to bedroomA downstairs bedroom, with a shower room of its own if the drains allow.
Garage to home officeA room with a door that shuts, away from the kitchen table.
Garage to playroomSomewhere for the children and their things, off the hall.
Garage to granny flatA bedroom, a shower room and a small kitchen for a parent.
Garage to gymA warm, dry room with a floor that takes weights.
Integral and front garagesBuilt into the house or facing the road: check before you start.Questions before you convert
Can I convert a detached garage without planning permission?
For a use that goes with the house, like an office or gym, often yes. For a bedroom or somewhere to live, no.
Can I turn a detached garage into a granny flat?
Yes, with planning permission. Councils usually grant it with a condition that it stays part of the main home.
How much does a detached garage conversion cost?
About €15,000 to €25,000 for an office or gym at a standard finish, plus the trench for services.
Does a detached garage office need building regulations?
If it becomes a room people use, the Building Regulations apply to it: insulation, ventilation, electrics and fire safety.
Every guide and county page
Conversions
Costs, rules and help
The room you need is already built
Pick the kind of garage, what it becomes 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.