Garage Conversion Cost by Type: Single, Double & Detached (2026)
The type of garage you own sets the price more than anything else. In 2026 a single or integral garage conversion starts from £6,800 (regional starting prices £6,800–£10,800), a double garage from £12,750 (£12,750–£20,250) and a detached garage from £15,300 (£15,300–£24,300), because detached buildings need power, heat and often drainage run from the house. Below: installed prices by garage type and by room, a full cost breakdown, Building Regs rules and honest value-added figures from our 519-town dataset.
- Single, double, detached and partial conversion prices
- Cost by new room, from home office to granny annexe
- Building Regs vs planning permission, explained honestly
- Free quotes from vetted local conversion specialists
Garage Conversion Cost by Type: Quick Answer
In 2026 a single or integral garage conversion costs from £6,800 in the cheapest UK regions (from around £8,000 as a UK-typical starting price, and from £10,800 in London), a double garage conversion starts at £12,750 (£12,750–£20,250 by region) and a detached garage from £15,300 (£15,300–£24,300). The room you create moves the number too: a home office sits at the bottom of each range, a bedroom with an en-suite adds £3,500–£5,500, and a self-contained annexe in a detached double is the most expensive conversion of all. All prices include VAT at 20%; for a range tailored to your garage, spec and postcode area, try our garage conversion cost calculator or see the town-by-town figures in our full garage conversion cost guide.
Jump to: Cost by garage type · Cost by new room · Full cost breakdown · Planning vs Building Regs · Value added · Price chart · Free quotes · FAQs
Garage Conversion Cost by Garage Type
These are installed prices for a finished habitable room: infill wall and window, insulated floor, walls and ceiling, electrics, heating, plastering, decorating and Building Regs fees. The bottom of each range is a standard-spec job in the cheapest regions (Scotland, Wales, Northern Ireland, North East); the top is a high-spec conversion in London or the South East.
| Garage type | Installed cost range | Typical size | Duration | Planning permission? |
|---|---|---|---|---|
| Integral single (built into the house) | £6,800 – £16,000 | 12–16 m² | 4–6 weeks | Rare — usually permitted development |
| Attached single (shares one wall) | £7,500 – £17,500 | 13–18 m² | 4–7 weeks | Rare — occasionally for external changes |
| Double (integral or attached) | £12,750 – £30,000 | 24–36 m² | 6–9 weeks | Occasional — more external alteration |
| Detached (single or double) | £15,300 – £35,000 | 15–40 m² | 8–12 weeks | Likely — especially annexe or separate use |
| Partial (half-garage, door kept) | £4,500 – £9,500 | 6–9 m² | 2–4 weeks | Rare — garage door and frontage unchanged |
“From” prices are cheapest-region starting prices from our 519-town dataset. All figures include VAT at 20%. En-suites, kitchenettes and structural knock-throughs are priced separately below.
Integral single garage: from £6,800
An integral garage sits inside the footprint of the house, usually with a bedroom above. It is the cheapest conversion per square metre because three sides are already part of the heated building, the roof needs no work, and the electrics and heating are a short run away. In most of England expect starting prices nearer £8,000; from £6,800 applies in the cheapest regions.
Attached single garage: from around £7,500
An attached garage shares one wall with the house but has its own roof and three external walls, so there is more insulation to install and often a roof to check, felt or insulate. Budget roughly 5–10% above an equivalent integral conversion, plus a lintel if you are forming a new doorway through the shared wall.
Double garage: from £12,750
A double garage gives you 24–36 m², enough for an open-plan living space, a large bedroom with en-suite and dressing area, or two smaller rooms. Setup, design and fee costs are shared, so it is never double the price of a single; typical jobs land at £15,000–£22,000 in most of England. Many owners convert one bay and keep the other for parking, which is the partial route below.
Detached garage: from £15,300
Detached garages cost the most to convert because everything the room needs has to travel: a new power supply or sub-main, heating, and water and drainage if you want a shower room or kitchenette. Budget £1,500–£4,000 for the services run alone depending on distance and ground. Planning permission is also more likely, particularly if the building will be used as a self-contained annexe rather than an ordinary spare room.
Partial (half-garage) conversion: from £4,500
A partial conversion keeps the garage door and front bay for parking or storage, and turns the back half into a small office, utility room or gym behind an insulated stud partition. Because the frontage is untouched it almost never troubles the planners, and at £4,500–£9,500 it is the cheapest way to get a warm usable room out of a garage. Building Regulations still apply to the converted half.
Garage Conversion Cost by the Room You Want
Two identical garages can come back with very different quotes purely because of what is going inside. Anything with water (en-suite, kitchenette, utility) adds plumbing and drainage; a living room usually means opening up the wall into the house; an annexe is effectively a tiny self-contained dwelling built to full spec.
| New room | What changes in the spec | Typical cost (single garage) | Notes |
|---|---|---|---|
| Home office | Standard insulation, extra double sockets, data/Cat6, good lighting | £6,800 – £11,500 | Cheapest habitable option; no plumbing |
| Bedroom | As office plus escape window (Part B), quieter spec, wardrobe space | £7,000 – £12,000 | En-suite adds £3,500 – £5,500 |
| Living room | Often a structural knock-through into the house, larger window or French doors | £7,500 – £13,500 | Steel beam and design add £1,500 – £3,000 |
| Gym | Reinforced/rubber flooring, extra ventilation, simpler finish acceptable | £6,000 – £11,000 | Lighter spec can dip below standard prices |
| Utility room | Plumbing for washer and sink, tiled splash areas; half a garage is often enough | £5,500 – £9,500 | Pairs well with a partial conversion |
| Granny annexe | Detached, highest spec: kitchenette, shower room, independent heating, sound insulation | £28,000 – £50,000 (detached double) | Planning usually needed; possible council tax banding |
A garage to bedroom conversion is the most common single-garage project: budget £7,000–£12,000, or roughly £10,500–£17,500 with the en-suite. For a garage conversion to living room, the knock-through is the swing item; skip the steel and you stay near the bottom of the range.
Cost Breakdown: Typical Integral Single Garage Conversion
Here is how a standard integral single garage conversion breaks down in 2026. This assumes a sound slab and walls, a room like a bedroom or office (no plumbing), and heating teed off the existing system.
| Cost item | What it covers | Typical cost |
|---|---|---|
| Infill wall & window | Remove garage door, build insulated infill wall with DPC, fit uPVC window | £1,400 – £2,500 |
| Floor | Damp-proof membrane, rigid insulation, screed or boarded build-up to house level | £1,000 – £1,800 |
| Wall & ceiling insulation | Insulated stud or batten lining, plasterboard to walls and ceiling (Part L) | £1,500 – £2,500 |
| Electrics | 6–8 double sockets, lighting circuit, any consumer unit work, Part P certification | £800 – £1,500 |
| Heating | Radiator teed off the central heating, or efficient electric panel heater | £400 – £1,000 |
| Plastering & decorating | Skim to walls and ceiling, mist coat and two top coats, woodwork | £900 – £1,500 |
| Floor finish | Carpet, laminate or LVT supplied and fitted | £400 – £900 |
| Building Regs fees | Building control application and inspections, completion certificate | £400 – £900 |
| Total — typical integral single | 12–16 m², standard spec, incl. VAT | £6,800 – £12,600 |
Add £300–£800 for drawings and structural calculations if you are opening up into the house, £3,500–£5,500 for an en-suite, and a 10–15% contingency for surprises such as a damp slab or an undersized foundation under the infill wall.
Planning Permission vs Building Regulations by Conversion Type
Here it is plainly: most garage conversions do not need planning permission, because converting existing internal space is normally permitted development. But Building Regulations approval is required for every single one, because you are turning a non-habitable space into a habitable room. Structure, damp-proofing, floor, wall and roof insulation, escape windows, ventilation and electrics all have to be signed off.
| Scenario | Planning permission? | Building Regulations? |
|---|---|---|
| Integral or attached garage, internal works only | Usually not — permitted development | Always |
| Replacing the garage door with a wall and window | Usually permitted development; check with your council | Always |
| Detached garage → office, gym or hobby room (ancillary use) | Often not, provided the use stays ancillary to the house | Always |
| Detached garage → self-contained annexe | Usually yes, and possibly separate council tax banding | Always |
| Conservation area, Article 4 direction or listed building | Yes — permitted development rights restricted or removed | Always |
| New or wider dropped kerb to replace lost parking | Yes — separate application via the highways authority | n/a |
Two catches worth knowing. Some newer estates carry a planning condition requiring the garage to stay available for parking; check your deeds before you start. And even where no permission is needed, a Lawful Development Certificate costs a few hundred pounds and is worth having for resale.
For the full rules and how to apply, read our guide: do I need planning permission for a garage conversion?
How Much Value Does Each Conversion Type Add?
Estate agents typically quote a garage conversion as adding around 10–15% to a home’s value in most areas. Treat that as a commonly quoted range rather than a promise: the real figure depends on your street and what you gave up to get it.
| Conversion | Typical cost (2026) | Typically quoted value uplift | Watch-outs |
|---|---|---|---|
| Integral single → bedroom or office | £6,800 – £16,000 | Around 10–15% of property value in most areas | Lowest risk; replace lost storage with loft or shed |
| Double → large living space or bed + en-suite | £12,750 – £30,000 | Around 10–15%; strongest where reception rooms are scarce | Keep at least one off-street parking space if you can |
| Detached → annexe or studio | £15,300 – £50,000 (annexe spec) | Varies most; strongest for multi-generational buyers | Planning, possible council tax; a niche buyer pool |
The arithmetic is usually comfortable. On a £250,000 home, 10–15% is £25,000–£37,500, against a typical integral single conversion cost of £6,800–£16,000. Even if your street rewards only half the quoted range, the conversion usually still returns more than it costs.
The honest caveat is parking. On streets with a controlled parking zone or scarce kerb space, losing your only off-street spot can offset a meaningful slice of the gain, and occasionally most of it in dense urban areas. If the driveway in front of the garage survives the conversion, as it usually does, the risk largely disappears.
Weighing a conversion against building out instead? A garage conversion runs £900–£1,800/m² because the shell, slab and roof already exist, while an extension costs £1,650–£4,200/m² and a single-storey extension starts from around £22,000. See extension cost by size, the full house extension cost guide and the extension cost calculator to compare like for like.
Garage Conversion Starting Prices Compared
2026 starting prices for each garage type, from our live pricing across 519 UK towns. The integral single, highlighted in orange, is where most conversions begin; each step up reflects extra external walls, floor area and services distance.
Starting prices in the cheapest UK regions. London starting prices run roughly £10,800 (single), £20,250 (double) and £24,300 (detached).
What Affects Garage Conversion Cost
1. Garage type and position
The single biggest factor. An integral garage borrows the house’s warmth, roof and services; a detached garage needs everything brought to it. The same room built in an integral single versus a detached single can differ by £6,000 or more before you change a single finish.
2. Floor level and slab condition
Garage slabs usually sit 100–150mm below the house floor and were never built with a damp-proof membrane or insulation. Raising and insulating the floor is routine, but a cracked, sloping or damp slab that needs tanking or partial replacement can add £1,000–£3,000.
3. Wall construction
Many garages have single-skin (half-brick) walls, which need an insulated stud lining to meet Part L and eat 75–100mm of room width on each cold wall. Cavity walls are cheaper and quicker to bring up to standard.
4. What happens at the door opening
Infilling the garage door with a matching brick wall and a window is the standard approach. Matching weathered brick well costs more than a rendered or boarded finish; a partial conversion that keeps the door avoids the question entirely.
5. Plumbing distance
An en-suite adds £3,500–£5,500 when the soil stack is nearby. If the fall to the nearest drain does not work, a macerator pump adds cost, noise and maintenance; put the wet room on the drainage side where you can.
6. Spec and structural openings
A knock-through into the house means a steel beam, structural design and making good, typically £1,500–£3,000 all-in. Underfloor heating, bespoke joinery, high-end flooring and fitted storage push a job from the middle of the range to the top.
How to Save Money on a Garage Conversion
Genuine savings, not corner-cutting. Building Regs items are not the place to economise; these are.
- Convert half. A partial conversion from £4,500 keeps parking or storage in the front bay and still gets you a warm office or utility room.
- Keep water close to the drains. Put en-suites and sinks on the side nearest the existing soil stack. A metre of extra pipe is cheap; a pumped macerator system is not.
- Choose a rendered or boarded infill rather than hunting down reclaimed brick to match the frontage, where the elevation allows it.
- Use a building notice for simple jobs. A straightforward internal conversion can proceed on a building notice, saving full-plans drawing fees; use full plans for anything structural.
- Tee heating off the existing system. One radiator usually copes with a well-insulated single garage; a whole new heating circuit rarely earns its keep.
- Get three like-for-like quotes. Quotes for the same job often vary by thousands. Send each builder the same written spec, then compare. Our free garage conversion quotes service matches you with three vetted local specialists.
- Book off-peak. Conversion specialists are quieter in late autumn and winter, and the work is almost entirely internal, so the season barely matters.
How Much Region Moves the Price
London and the South East sit roughly 20–30% above the cheapest UK regions, consistent with our UK cost index. In practice that means a single garage conversion starting from £6,800 in Scotland, Wales, Northern Ireland and the North East starts from around £10,800 in London; a double moves from £12,750 to £20,250; and a detached garage from £15,300 to £24,300. The Midlands, the South West and the North of England fall in between.
Labour is the main driver, so the gap is widest on labour-heavy work and narrowest on fixed items like windows and Building Regs fees. For your local figure, see the town-by-town tables in our garage conversion cost guide, which covers all 519 towns in our dataset.
FAQs
In 2026 a single or integral garage conversion costs from £6,800, with regional starting prices of £6,800 to £10,800. A double garage conversion starts at £12,750 (£12,750 to £20,250 by region) and a detached garage conversion from £15,300 (£15,300 to £24,300). The room matters too: a home office sits near the bottom of the range, a bedroom with an en-suite adds £3,500 to £5,500, and a self-contained annexe in a detached garage costs most of all. All figures include VAT at 20%.
A single garage conversion costs from £6,800 in the cheapest UK regions, from around £8,000 in most of England, and from roughly £10,800 in London. A typical integral single of 12 to 16 square metres converted to a standard habitable room lands between £6,800 and £16,000 installed, depending on spec and region. That covers the infill wall and window, floor, wall and ceiling insulation, electrics, heating, plastering, decorating and Building Regs fees.
A double garage conversion starts at £12,750, with regional starting prices of £12,750 to £20,250 and high-spec jobs in London and the South East reaching around £30,000. At 24 to 36 square metres, a double gives you an open-plan living space or a bedroom with en-suite and dressing area. Many owners convert one bay and keep the other for parking; that partial route costs £4,500 to £9,500.
A detached garage conversion costs from £15,300, with regional starting prices of £15,300 to £24,300 and high-spec conversions reaching around £35,000. A full self-contained annexe runs £28,000 to £50,000. Detached conversions cost more than attached ones because power, heating and often water and drainage must be trenched from the house, typically £1,500 to £4,000 for the services run, and planning permission is more likely, especially for annexe or separate-dwelling use.
A garage to bedroom conversion costs £7,000 to £12,000 for a standard single garage, and roughly £10,500 to £17,500 once you add an en-suite, which adds £3,500 to £5,500. A bedroom needs an escape window under Part B of the Building Regulations, full insulation under Part L and proper ventilation. Bedroom conversions typically add more value than they cost.
Usually not. Converting the inside of an integral or attached garage is normally permitted development, and replacing the garage door with a wall and window is usually fine too. The exceptions are conservation areas, Article 4 directions, listed buildings, flats and maisonettes, estates where a planning condition requires the garage to stay as parking, and detached garages converted to self-contained annexes, which usually do need permission. Building Regulations approval is required in every case. Our garage planning permission guide covers the rules in full.
Yes, always, even when planning permission is not needed. Turning a garage into habitable space means building control must sign off the structure, damp-proofing, floor, wall and roof insulation, escape windows, ventilation and electrical work. Budget £400 to £900 for the application and inspections, and keep the completion certificate safe: buyers’ solicitors ask for it when you sell.
On site: a partial conversion takes 2 to 4 weeks, an integral single 4 to 6 weeks, an attached single 4 to 7 weeks, a double 6 to 9 weeks and a detached garage 8 to 12 weeks including the services run. Add lead time before the start date for drawings, structural design where needed and the building control application.
Estate agents typically quote around 10 to 15% of property value in most areas, though it varies by street. On a £250,000 home that is £25,000 to £37,500 against a typical single-conversion cost of £6,800 to £16,000. The honest caveat is parking: on streets with controlled parking or scarce kerb space, losing your only off-street spot can offset a chunk of the gain. Where the driveway survives, the maths usually stays comfortably positive.
Yes, and it is one of the smartest budget options. A partial conversion costs £4,500 to £9,500: the garage door and front bay stay as parking or storage, and an insulated stud partition separates the new room at the back. Because the frontage is unchanged it almost never needs planning permission, though Building Regulations still apply to the converted half.
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