Garage Conversion Cost UK 2026 · Single, Double & Detached
Real 2026 prices for converting a garage in the UK. Single garage from £8,000, double from £15,000, detached from £18,000. £900–£1,800/m² typical — the cheapest way to add habitable space without extending. Free quotes from local specialists.
Do you need planning permission for this?
Most internal garage conversions are Permitted Development, but Article 4 zones strip those rights, conservation areas need consent, and any external changes (new windows, removed garage door) usually need full planning.
Read the garage conversion planning rules →Garage Conversion Cost at a Glance
Real cost ranges drawn from BestBuilders data across 519 UK towns. Use these as your starting benchmark — then get 3 local quotes for your exact garage.
12–18 m² habitable room. Typically a bedroom, office or playroom. 6–8 weeks on site. Most fall under permitted development.
Get quotes →25–35 m². Open-plan living space, en-suite annexe or large family room. Comfortably fits a kitchenette + bathroom.
Get quotes →Annexe, home office, gym or studio. Often needs planning permission. May require utilities trenching from main house.
Get quotes →Cost Per m² (UK 2026)
| Specification | Cost per m² | What's included |
|---|---|---|
| Basic — habitable room | £900 – £1,200 | Insulation, plasterboard, electrics, basic flooring, decoration |
| Mid — bedroom + en-suite | £1,200 – £1,500 | Above + plumbing, en-suite shower room, better finishes |
| High — annexe / studio | £1,500 – £1,800+ | Full self-contained annexe, kitchenette, premium finishes |
Cost per m² is significantly cheaper than a new-build extension (£2,000–£3,000/m²) because the shell, foundations and roof already exist.
Garage Conversion Cost by Region
| Region | Single garage | Double garage | Detached |
|---|---|---|---|
| London | £10,800 – £24,300 | £20,250 – £40,500 | £24,300 – £47,250 |
| South East | £10,000 – £22,500 | £18,750 – £37,500 | £22,500 – £43,750 |
| Midlands & SW | £7,600 – £17,100 | £14,250 – £28,500 | £17,100 – £33,250 |
| North & Yorkshire | £7,000 – £16,600 | £13,800 – £27,600 | £16,600 – £32,200 |
| Scotland, Wales & NI | £6,800 – £15,300 | £12,750 – £25,500 | £15,300 – £29,750 |
Garage Conversion Hidden Costs
Most builder quotes price the conversion only — there's a layer of project costs that catches first-time converters out.
📋 Building regulations fees
Required for all garage conversions even when planning isn't. Building control submission and inspections.
📐 Architect / drawings
Most garage conversions need at least scale drawings for building control. A technician (not full architect) is usually adequate.
🔧 Damp-proofing & insulation upgrade
Older garages often have inadequate floor slabs (no DPM) and walls below current insulation standards. Both must be upgraded for habitable use.
🛁 Plumbing & drainage
Adding an en-suite or kitchenette requires running soil pipe to nearest drain — sometimes outside the existing fall line, needing a pump.
⚡ Electrical upgrade
A garage typically has 1–2 sockets — a habitable room needs 6–8 plus lighting circuit, possibly consumer-unit upgrade.
📊 Contingency (always include)
Surprises happen — buried obstacles, hidden damp, inadequate foundations. Industry standard 10–15% of total budget.
Planning Permission vs Building Regulations for a Garage Conversion
These are two separate approvals, and the difference trips up most first-time converters. In practice a garage conversion almost always skips planning permission but always needs Building Regulations sign-off — so budget for building control on every job, even the simplest.
When you do not need planning permission
Converting the inside of an attached or integral garage is usually classed as permitted development, provided the work is internal and does not enlarge the building. Because you are reusing the existing footprint and roof, most single and double conversions in England proceed without a planning application. You can check the current position for your own address against the Government-backed guidance on the Planning Portal garage conversion page before you commit.
When planning permission IS required
Permitted development rights are removed for flats and maisonettes, listed buildings, and homes in conservation areas or Article 4 zones. You also need a full application if you are creating a self-contained annexe with its own entrance, if an existing planning condition keeps the garage as parking, or if the conversion changes the outside of the house — for example a new bay window replacing the up-and-over door. A detached garage turned into independent living space frequently needs consent too. If your case is borderline, confirm it before any trades are booked rather than after.
Building Regulations always apply
Turning a garage into a habitable room creates new living space, so Building Control must sign it off regardless of the planning position. Inspectors check the insulated, damp-proofed floor build-up over the old slab, wall and roof insulation to current Part L standards, structural infill of the door opening on a proper footing, ventilation, fire safety, and an escape window where one is required. The Government overview of Building Regulations approval sets out what the inspector will expect to see. Budget roughly £500–£1,000 in local authority fees, and note that the finished room is re-assessed for council tax banding once it is complete. Because the space is being brought up to a residential standard, the regulated trades working behind the finishes all feed into that sign-off — the certified electrical work, the fresh plastering once the walls are lined and insulated, and the Part L glazing you gain by swapping the up-and-over door for a double-glazed window — so it pays to use tradespeople who can certify their own work to the inspector.
How Long Does a Garage Conversion Take?
A straightforward single garage conversion reaches a finished habitable room in about 3 to 6 weeks on site once work starts. A double, or a detached building that needs new service connections, typically runs 6 to 10 weeks. The build itself is quick because the shell, foundations and roof already exist — most of the calendar time goes on the paperwork and the trades booked around the build.
A typical single-garage schedule
Week 1 clears the space, breaks out the old slab where needed and forms the new insulated, damp-proofed floor. Week 2 infills the door opening on its new footing, fits the window and lines the walls with insulated stud. Weeks 3 to 4 cover first-fix electrics and heating, plasterboarding and skim. The final week is second-fix, flooring, decoration and the Building Control completion inspection. If you are fitting wet underfloor heating instead of a radiator, allow extra screed drying time — our underfloor heating cost guide covers the trade-offs.
What can add weeks to the job
Allow lead time before the build for drawings and, where relevant, a planning decision (up to eight weeks for a full application). Damp or an inadequate slab found on opening up is the classic hidden delay: where the old garage floor has no damp-proof membrane, a proper damp-proofing layer has to be built into the new floor before anything else can follow. A soil-pipe run for an en-suite, or a consumer-unit upgrade can each add several days on top. Keeping the industry-standard 10–15% contingency in hand stops a slipped timeline from becoming a budget problem. If floor area matters more than reusing the garage, it is worth weighing a conversion against a loft conversion or a single-storey house extension before you decide.
Garage Conversion Cost by Use Case
What you\u2019re converting the space into matters far more than its footprint. A study is a shell and a socket. A bedroom-with-ensuite is a full waste, supply, fire and thermal build-up. Here\u2019s what each realistically costs in 2026.
Single garage → study / playroom (basic)
Replace the up-and-over door with an insulated stud wall + window, insulate and plasterboard walls and ceiling, lay a new insulated floor build-up over the existing slab, add power + lighting + a radiator off the existing heating loop. Decorated. Most common conversion we see.
Single garage → bedroom (no ensuite)
Same shell as the study, plus higher-spec insulation for Part L habitable room standards, a full fire escape window (1:40 egress), smoke alarms on a mains circuit, two double sockets per wall, and sometimes a small built-in wardrobe recess. Most popular with growing families needing a 4th bedroom without building out.
Single garage → bedroom + ensuite
Adds an internal stud-partitioned shower room — typically 1.2m × 2.0m. Needs a saniflo or pumped waste, hot & cold supply extension off the existing system, MVHR or mechanical extract, and a tiled wet-zone. This is the best-value way to add a self-contained teenager or guest suite.
Double garage → open-plan room
30m² of habitable space — serious room for a home cinema, large home office for two, or living room. Two garage doors infilled with a matching brick course, a 2m-wide window (or bifolds to the garden if it faces the right way), full insulation and Part L glazing.
Double garage → fully self-contained annexe
Full self-contained granny annexe: bedroom, small living/kitchenette, shower room. Often needs a building reg application for a \u201Cchange of use\u201D and sometimes planning permission if the annexe is used independently. Typical for multigenerational families and AirBnB-able home offices.
Worked example (illustrative): Integral Single Garage, Leeds LS16
4-bed 1970s semi in North Leeds. Integral single garage (16m²) converted into a 5th bedroom with a built-in wardrobe and full egress window. Completed March 2026.
| Building Regulations application + drawings | £1,150 |
| Door removal, lintel, brick infill + render match | £1,700 |
| New A-rated casement window (egress compliant) | £950 |
| Insulated floor build-up (DPM, PIR, screed, oak floor) | £2,200 |
| Stud wall, 100mm PIR, vapour barrier, plasterboard, skim | £2,900 |
| Ceiling insulation + plasterboard (PIR between joists) | £1,100 |
| Central heating extension + new radiator | £780 |
| Electrics (6 sockets, 2 lights, mains smoke, TV/data) | £1,380 |
| Built-in wardrobe recess (MDF carcass, sliding doors) | £1,450 |
| Decoration (prime + 2 coats, skirting, architraves) | £950 |
| VAT | £1,840 |
| Total (4 weeks on site) | £16,400 |
Valuation uplift: £420,000 pre-works → £455,000 post-works valuation (local estate agent appraisal, April 2026). Net value-add £18,600 after construction costs — plus a fifth bedroom that made the house sellable to larger families in the LS16 catchment.
Garage Conversion Costs by Town
Each town page shows local garage conversion specialists, town-specific cost ranges, recent project examples and nearby areas. Compare 3 free quotes from vetted local garage conversion specialists.
Get Accurate Quotes for Your Garage Conversion
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Garage Conversion Costs at a Glance: 2026 Visual Guide
What each garage type costs to convert
The garage you start with sets the budget. An integral single — built into the house under the main roof — is the cheapest and most common UK conversion, because two or three of its walls are already insulated house walls. An attached single needs more thermal upgrading, a double has roughly twice the area to insulate and board, and a detached building adds the cost of running services from the house.
What a conversion actually adds — the cross-section
A conversion is really a fabric upgrade: Building Regulations treat the finished room as new habitable space, so every surface must reach residential standards. That means a damp-proofed, insulated floor build-up over the old slab, insulated stud linings to single-skin walls, a proper infill wall with a window where the door was, plus extended heating, compliant electrics and Building Control sign-off. The cross-section below shows all six jobs a complete quote should cover.
Where the money goes on a typical single conversion
Spread a typical £12,000 single-garage conversion across its trades and no single item dominates. Insulation and boarding is usually the biggest slice because floor, walls and ceiling are all upgraded; the door infill and structural work run it close. Note the slice most DIY budgets miss — decorating plus professional fees, including drawings and Building Control. Whatever your quote says, keep the industry-standard 10–15% contingency on top.
Registered members: Garage Conversions
7 businesses offering garage conversions have a public profile with BestBuilders. Each listing is a business that registered with us directly; the details shown are the ones it declared at registration, and a Companies House number appears only where one was given.
All registered trades · Recent projects · Run a garage conversions business? Add your free profile
What homeowners asked us for — Garage Conversion (last 90 days)
297 homeowners started a quote request for garage conversion through the BestBuilders quote tool between 9 Jun – 7 Sep 2026, UK-wide. These are their own answers to the tool’s questions, aggregated and anonymised — not a model, not an estimate.
Where is the existing garage located?
- 61% Residential – attached to main property
- 23% Residential – next to main property
- 16% Residential – away from main property
109 answers
How big is the garage to be converted?
- 72% Garage that fits one car
- 23% Garage that fits two cars
- 2% Garage that fits three cars
- 2% Other
100 answers
What are you planning to use the converted garage for?
- 31% Living space
- 25% Home office
- 19% Self contained accommodation
- 7% Utility room
96 answers
Do you have plans drawn up?
- 74% No, I don't have plans yet
- 16% Yes, I have plans
- 9% I would like the pro to help me with plans
85 answers
How likely are you to make a hiring decision?
- 45% I'm planning and researching
- 20% I'm definitely going to hire someone
- 17% I'm ready to hire
- 9% I will possibly hire someone
64 answers
Source: BestBuilders quote-tool answers, 9 Jun – 7 Sep 2026. Percentages are of the homeowners who answered each question; figures update daily. See the UK homeowner demand index for every trade.
Integral single, attached double, detached or a partial conversion — the structure you start with drives the budget. See the full breakdown in our guide to garage conversion costs by type, including planning vs Building Regs for each.
The builder matters more than the budget. Read how to choose a garage conversion builder — the checks, questions and red flags — then compare 3 free quotes.
Garage Conversion Cost FAQs
Continue Your Garage Conversion Research
How we produced these figures
The cost ranges on this page come from BestBuilders’ 2026 regional cost model: published national cost guides adjusted by a regional labour index and averaged across 519 UK towns, then reviewed against published trade pricing. They are indicative ranges for a typical specification, not quotes — access, finish level and the builder’s workload move real prices either way.
Regulatory points (planning, Building Regulations, grants and VAT) are checked against current UK government guidance. Last reviewed: August 2026. Spotted something out of date? Tell us via the form above.
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Garage conversion — guides and detail
The detail behind the number: what changes the price, the planning position, and how to check a quote before you accept it.