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.
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
Online guides give you a benchmark — accurate pricing requires a builder who has seen your garage. BestBuilders matches you with up to 3 vetted local garage conversion specialists for free.
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
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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.