Cost guide · 2026
GarageConversionCostinLondon2026
Full 2026 pricing for every type of London garage conversion — integral, single, double and tandem. Real costs from completed projects, broken down by configuration, finish spec and London zone.
Quick answer
A garage conversion in London costs £18,000–£70,000 in 2025–2026. A single garage to a habitable room starts from £18,000–£35,000; a single with ensuite £28,000–£50,000; a double garage full conversion £38,000–£70,000; a tandem conversion £25,000–£48,000; an integral garage with structural alteration £35,000–£65,000. Cost per m² typically runs £900–£1,800. All Builderr quotes are fixed-price with no provisional sums.
What moves the price
The seven cost factors that matter most.
Single £18–35k; tandem £25–48k; integral with structural opening £35–65k; double £38–70k. Type and size dominate the budget.
Rigid insulation to floor, walls and ceiling is mandatory for building regs. Upgrading to 150mm+ boards adds £1,500–£3,000 but significantly improves U-values and comfort.
Garage floors rarely have a DPM. New DPM installation and linking to wall DPC adds £1,200–£2,500 depending on floor area and condition.
Creating a through-connection to the main house requires steel lintel, padstones, and masonry work — typically £3,500–£6,500 per opening.
A compact shower room adds £8,000–£15,000 including tanking, drainage, tiling, sanitaryware and underfloor heating.
Extending the wet central heating system adds £2,500–£4,500; electric underfloor heating is cheaper to install (£1,200–£2,000) but more expensive to run.
Cost breakdown
Where the money actually goes.
Percentage breakdown of a typical mid-spec project. Add or subtract per your finish tier.
| Line item | % of total | £ on avg project |
|---|---|---|
| Insulation & damp proofing | 16% | £7,040 |
| Structural works | 14% | £6,160 |
| Windows & doors | 12% | £5,280 |
| First fix MEP | 13% | £5,720 |
| Plaster & decoration | 10% | £4,400 |
| Floor finish | 8% | £3,520 |
| Bathroom (if ensuite) | 10% | £4,400 |
| Joinery & second fix | 5% | £2,200 |
| Fees & building control | 6% | £2,640 |
| Site management | 4% | £1,760 |
| Margin & contingency | 2% | £880 |
Real projects
Worked examples from completed builds.
London zones
Where your borough sits in the price band.
| Zone | Multiplier | Notes |
|---|---|---|
| Zone 1 (W1, SW1, NW1, EC, WC) | 1.15–1.22× | Access, conservation and parking surcharges |
| Zone 2 (NW3, SW3, SW10, N1, E1, E2) | 1.08–1.14× | Premium areas, higher trade rates |
| Zone 3 (SW6, W6, NW5, N16, E5, E8) | 1.00–1.07× | Baseline London pricing |
| Zone 4 (SW17, W7, N8, E11, SE13) | 0.94–1.00× | Slightly below baseline |
| Zone 5–6 (Outer boroughs) | 0.87–0.94× | Easier access, lower trade rates |
Builderr vs other London builders.
The construction industry has a wide distribution of operators. Here's what changes between a directly-employed, fixed-scope outfit and the alternatives.
| Criterion | Builderr | Typical London builder | Cowboy outfit |
|---|---|---|---|
| Labour model | Directly employed team (PAYE) | Mixed subcontract gangs | Day-rate cash labour |
| Pricing | Fixed-scope itemised quote | Estimate + provisional sums | Verbal price + variations |
| Design & engineering | In-house architect + SE | Outsourced, separate billing | Builder draws on the back of an envelope |
| Planning + LDC handled | Yes — included in price | Often charged extra | Builder asks you to apply |
| Party wall surveyors | Instructed by us | Your responsibility | Skipped (illegal) |
| Building control | Plans + site inspections booked by us | Building Notice route | Not registered |
| Project management | Dedicated PM, weekly photo updates | Foreman doubles up | Owner-manager juggles 5 jobs |
| Payment schedule | Stage payments against signed-off milestones | Weekly invoices | Cash up front |
| Insurance | £10M PL + 10yr structural warranty | £2–5M PL only | No documented cover |
| Snags at handover | <3 typical | 20–30 typical | Walk-off mid-job common |
| Variation creep | 0% — fixed scope | +15–25% over original quote | +40%+ regularly |
Save £8,800–£19,800 on a garage conversions.
Industry data (FMB, RICS, Which? Trusted Trader 2024) shows the average London construction project overruns by 18–22% on cost and 25–35% on time. Fixed-scope contracts with a single accountable team eliminate that variance. The savings above assume a typical project at £44,000.
Related
See the full garage conversions service page.
FAQ
Garage Conversion Cost in London:
common questions.
How much does a garage conversion cost in London in 2026?
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In 2026, a single garage conversion in London costs £18,000–£35,000 for a basic habitable room; £28,000–£50,000 with an ensuite. A double garage conversion runs £38,000–£70,000. An integral garage requiring structural alteration to connect to the main house costs £35,000–£65,000. Cost per m² is typically £900–£1,800 depending on spec and location.
Do I need planning permission for a garage conversion?
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Most integral garage conversions fall under permitted development — no planning application is required. However, you must still obtain building regulations approval, which is mandatory for all garage conversions. Detached garages, properties in conservation areas, and listed buildings may require full planning permission. Always confirm with your local borough before starting.
Is a garage conversion cheaper than an extension?
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Yes — a garage conversion is typically 40–60% cheaper than a new extension of equivalent floor area because the structure already exists. You are insulating, tanking and fitting out an existing shell rather than building foundations, walls and a roof from scratch. A single garage conversion at £18,000–£35,000 compares favourably to a new 14m² side return extension at £50,000–£75,000.
Does a garage conversion add value to a London home?
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Yes, in most cases. Converting an integral garage to a habitable room typically adds 5–10% to property value in London, provided the property retains sufficient parking. Loss of a garage in areas with limited on-street parking can slightly offset the gain. Adding a bedroom (especially with ensuite) consistently adds value; adding a utility room or study adds less.
What building regulations apply to a garage conversion?
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Garage conversions must meet Part A (structure), Part B (fire safety), Part C (damp proofing), Part L (thermal performance), Part F (ventilation), and Part P (electrical safety) of the Building Regulations. In practice this means: a new DPM and insulated floor, insulated walls and ceiling to meet U-value targets, appropriate ventilation, fire-rated door between garage and living space, and a full electrical installation by a Part P-registered electrician.
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