A garage conversion costs £8,000–£25,000 in the UK in 2026, or £500–£1,600 per square metre finished. A single garage (15m²) converts for £8,000–£18,000, averaging £13,500; a double garage (30m²) converts for £14,000–£38,000. An integral garage is the cheapest to convert (£7,500–£15,000) because three walls and the roof already belong to the house. London and the South East add 13–20%. Every figure below is cross-checked against FMB, Checkatrade and builders' 2026 price guides by Home Renovation Guides.
How much does a garage conversion cost in the UK in 2026?
A garage conversion costs £8,000–£25,000 in the UK in 2026 depending on garage type, size and finish. Garage type sets the baseline; specification moves the price within it.
| Garage type | Typical conversion cost (UK, 2026) | Why the price differs |
|---|---|---|
| Single integral (14–18m²) | £7,500 – £15,000 | Cheapest: three walls and the roof are already part of the house |
| Single attached | £9,000 – £18,000 | One shared wall; door opening needs insulated infill or window |
| Single detached | £10,000 – £25,000+ | Utilities (water, drainage, electrics) trenched in from the house |
| Double integral/attached (28–36m²) | £14,000 – £35,000 | National average £20,500–£38,400 (Checkatrade, 2026) |
| Double detached | £16,000 – £46,000+ | Utility runs plus full independent insulation; exceeds £46,000 with bathroom and structural work |
How much does a single garage conversion cost?
A single garage conversion costs £8,000–£18,000 in most of the UK, averaging £13,500 at mid-range spec (Checkatrade, 2026). Basic finishes (insulation, plaster, simple electrics, paint) run £8,000–£12,000; mid-to-high specs with new flooring, heating, a window in the door opening and full lighting run £12,000–£25,000+. Adding a bathroom or en-suite costs an extra £4,000–£8,000 for plumbing and drainage. Most single garages measure 14–18m², which prices conversion work at £625–£2,000 per m² depending on spec (Checkatrade, 2026).
How much does an integral garage conversion cost?
An integral garage conversion costs £10,000–£14,000 for a standard single space, averaging £12,000, with a full range of £7,500–£20,000+ by finish and structure (builders' 2026 guides). The per-m² rate runs £450–£1,100 for basic-to-standard work and £1,440–£1,920 for higher-end finishes. Integral conversions are the cheapest type because the garage sits inside the house's thermal envelope — the walls, floor slab and roof already exist, and utilities terminate metres away instead of across a driveway.
How much does a double garage conversion cost?
A double garage conversion costs £18,000–£45,000 in the UK in 2026, with a national average of £20,500–£38,400 (Checkatrade, 2026, based on a 36m² space). An integral or attached double converts for £12,000–£35,000; a detached double runs £16,000–£46,000+ because utilities run independently from the house. A partial double conversion — half the garage to a room, half kept for storage — costs £5,500–£8,500. Adding plumbing for an en-suite or kitchenette adds £4,000–£10,000+. Replacing double garage doors with brick infills, windows or sliding glass doors needs steel lintels (RSJs) costing £500–£2,000.
What does a garage conversion cost per m²?
A garage conversion costs £500–£1,600 per square metre finished in the UK in 2026, against £1,800–£3,300 per m² for a single storey extension — the structure already exists, so the spend is insulation, openings, services and finish. Checkatrade's standard band for conversions is £625–£1,250 per m²; the wider band below covers basic garage-to-room work up to bathroom-grade finishes.
| Specification | Cost per m² (UK, 2026) | What you get |
|---|---|---|
| Basic finish | £500 – £800 | Insulation, simple electrics, plaster and paint — a dry, warm, plain room |
| Mid-range | £800 – £1,250 | New flooring, heating connected, window in the door opening, full lighting |
| High-end | £1,250 – £1,600 | Premium finishes, sliding glazing, bathroom-grade plumbing provisions |
Detached garages add £2,500–£8,000 for utility trenching regardless of spec; attached garages add £1,000–£3,000 for the shared-wall opening and services route.
Garage Conversion Cost Calculator
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What does a garage conversion cost by intended use?
The room you build sets the price: a utility room needs services but no finish; a bedroom needs an escape window; a bathroom needs drainage.
| Room created | Typical cost (UK, 2026) | What drives the price |
|---|---|---|
| Gym / utility room | £5,000 – £10,000 | Basic finish; services already nearby |
| Home office / study | £8,000 – £12,000 | Electrics, data, heating, window in door opening |
| Living room / playroom | £10,000 – £15,000 | Full finish, flooring, glazing |
| Bedroom | £10,000 – £20,000 | Part B fire escape window, acoustic separation |
| Kitchen or bathroom | £20,000 – £35,000+ | Drainage, water supply, tiling, extraction (Part F) |
What does a garage conversion cost in London?
A garage conversion in London costs 13–20% more than the UK average (FMB and 2026 London builders' guides) — a single integral conversion runs £9,000–£18,000 in Greater London against £7,500–£15,000 nationally, and a double runs £24,000–£45,000. The premium is labour rates, not materials. London conversions carry two local factors: parking pressure makes losing the garage a real cost on the resale price, and Article 4 directions across several boroughs remove the permitted development rights that make conversions permission-free elsewhere — check your borough's Article 4 map before instructing a builder.
Do you need planning permission to convert a garage into a room?
An internal garage conversion inside the house is permitted development in most of the UK — no planning application, because the conversion does not enlarge the house. Four situations require full planning permission:
- Listed houses and conservation areas — external changes to the garage opening need consent
- Article 4 areas — boroughs and councils have withdrawn conversion rights on whole streets
- Post-1990 housing estates — most carry a planning condition requiring the garage to stay a garage; check the original decision notice on the council's planning portal before starting
- Separate dwellings — converting the garage into an independent unit with its own entrance, kitchen and bathroom is a change of use, not permitted development
Building regulations approval is required for every garage conversion, with no exceptions: the room must meet Part L (insulation of walls, floor and roof to habitable standards), Part F (ventilation), Part B (fire safety — bedrooms need an escape window) and Part P (a certified electrician signs off the electrics). Statutory building control fees run £300–£700 plus £400–£1,200 in professional fees; a Lawful Development Certificate (£129) proves a permitted development conversion was legal for resale.
What is the 4 year rule for garage conversion?
The 4 year rule is the old enforcement window: councils had 4 years to act on unauthorised building works (section 171B of the Town and Country Planning Act 1990). Since April 2024, the Levelling-up and Regeneration Act 2023 extends the window to 10 years in England, so a garage conversion built without required permission stays at enforcement risk for a decade before becoming immune — and a Lawful Development Certificate (£129) then proves it. Wales keeps the 4-year window for building works. The window cures the absence of permission; it never cures a building that fails building regulations, which apply for the life of the structure.
Is it cheaper to convert a garage or build an extension?
Converting a garage is cheaper per square metre: garage conversions cost £500–£1,600 per m² because the walls, floor and roof exist, while a single storey extension costs £1,800–£3,300 per m² from the ground up. The same 15m² costs £8,000–£18,000 converted and £27,000–£42,000 extended. The extension buys new floor area and keeps the garage; the conversion spends space the house already owns and loses the parking. For adding a whole storey instead, see the first floor extension cost guide, including building over the garage — the one project that needs both the garage's structure and a full extension budget. Full size-by-size comparison in the house extension cost guide.
What extra costs come with a garage conversion?
Garage conversion quotes exclude the statutory fees and the surprise lines — single-skin walls, damp slab and old electrics are the three that move budgets.
| Extra cost | Typical fee (2026) |
|---|---|
| Building control (building notice or full plans) | £300 – £700 statutory |
| Professional fees (drawings, calculations, handling) | £400 – £1,200 |
| Structural engineer (RSJ lintel calculations) | £500 – £1,500 |
| Steel lintels / RSJs for new openings | £500 – £2,000 |
| Electrics + consumer unit upgrade (Part P) | £2,000 – £4,000 |
| Insulated infill wall or window in door opening | £2,000 – £5,000 |
| Floor raising, insulation and damp-proofing | £1,500 – £5,000 |
| Plumbing for bathroom or utility (if added) | £4,000 – £8,000 |
| Lawful Development Certificate (optional proof) | £129 |
| VAT (20%) — excluded from most builder quotes | +20% on labour and materials |
Single-skin brick walls, damp proofing failures and out-of-level slabs add £2,000–£4,000 on older detached garages (2026 builders' guides) — budget the top of the band until a builder opens the floor.
What does a builder's garage conversion quote include?
Builder quotes for garage conversions cover the conversion only — statutory fees, VAT and fit-out land on you.
| Usually included | Usually excluded |
|---|---|
| Insulated infill wall or window in the door opening | VAT at 20% (add it yourself) |
| Floor insulation, screed and damp-proofing | Building control fees and professional fees |
| Wall and ceiling insulation to Part L, plastering | Planning permission or Lawful Development Certificate |
| First-fix and second-fix electrics (Part P certified) | Kitchen, bathroom or furniture fit-out |
| Heating connection and radiator | Consumer unit replacement on older houses |
How long does a garage conversion take?
A single garage conversion takes 2–4 weeks on site (FMB, 2026); a double takes 4–8 weeks. Add 1–3 weeks beforehand for a building notice and structural calculations. Full timeline from decision to finished room: 3–7 weeks for a single garage, 5–11 for a double.
| Stage | Typical duration |
|---|---|
| Building notice + structural calculations | 1–3 weeks |
| Single garage conversion on site | 2–4 weeks |
| Double garage conversion on site | 4–8 weeks |
| Building control sign-off | 1–2 weeks after completion |
Is a garage conversion worth it?
A garage conversion is worth it when the room answers a need the street has and the parking survives. A fourth bedroom or home office converted for £8,000–£18,000 adds roughly 8–15% to the value of a typical UK home where off-street parking remains (HomeOwners Alliance and 2026 estate agent valuations). The conversion subtracts value on streets where every household parks two cars, and where the room created is too small, too dark or too cold to use. Check the maths both ways before starting: the conversion costs a third of an extension, but the extension keeps the garage.
Frequently asked questions
What is the 4 year rule for garage conversion?
The old 4-year enforcement window is now 10 years in England (since April 2024). Wales keeps 4 years for building works. Building regulations never expire.
Is it cheaper to convert a garage or build an extension?
Converting: £500–£1,600 per m² vs £1,800–£3,300 for a single storey extension. The same 15m² costs £8,000–£18,000 converted, £27,000–£42,000 extended — but the extension keeps the garage.
Do you need council approval to convert a garage into a room in the UK?
Building regulations always (Part L insulation, Part F ventilation, Part B fire, Part P electrics). Planning permission only in conservation areas, Article 4 areas, listed houses, estates with garage conditions, or for separate dwellings.
Is a garage conversion worth it?
Yes where parking survives and the room meets the street's need — £8,000–£18,000 buys roughly 8–15% added value. No where parking is scarce or the room is unusable.
How much does it cost to convert a single garage into a room?
£8,000–£18,000, averaging £13,500 at mid-range spec. Integral garages cheapest (£7,500–£15,000); detached singles run £10,000–£25,000+.
How long does a garage conversion take?
Single: 2–4 weeks on site, 3–7 weeks total. Double: 4–8 weeks on site, 5–11 weeks total.
How we researched these prices
Every range on this page is cross-checked across three kinds of source, last compared on 28 October 2026:
- Published 2026 price guides from trade bodies and cost platforms — FMB, Checkatrade, HomeOwners Alliance and named builders' guides. Where guides disagree we quote the overlapping band, not the outlier.
- Real builder quote structures — what conversion firms actually itemise (insulated infill, floor build-up, electrics, heating, openings) and what they exclude, including the VAT line most quotes leave off.
- Live search data — Home Renovation Guides re-checks current published ranges for garage conversion terms monthly, so the figures reflect what builders quote now, not last year's averages.
The ranges assume a standard UK garage — 14–18m² single or 28–36m² double, integral, attached or detached. Single-skin walls, failed damp-proof courses and sloping slabs push towards the top of each band.
Prices last checked: 28 October 2026 · Page published: 28 October 2026
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