How Much Does a Garage Conversion Cost in London?
Real 2025 figures from completed London projects — not guesses. A single garage conversion typically costs £15,000–£25,000. Here's what changes the price and what to watch out for.
Quick Answer — 2025 London Garage Conversion Costs
Single garage — basic
£15,000–£22,000
Room only, no en-suite
Single garage — mid-range
£20,000–£28,000
Better spec, storage
Double garage
£25,000–£42,000
Two rooms or one large
⚠️ Ballpark figures only. Actual costs depend on size, condition of existing structure, spec level, and M&E complexity. A detailed estimate requires a site visit.
Garage Conversion Price Breakdown
Figures are London market rates for 2025, based on completed projects by RCB Design & Build. All figures exclude VAT. Second-fix materials (flooring, furniture, fixtures) are client-supplied unless otherwise agreed.
| Conversion type | Low estimate | High estimate |
|---|---|---|
| Single integral garage — basic room | £15,000 | £22,000 |
| Single integral garage — mid-range | £20,000 | £28,000 |
| Double garage conversion | £25,000 | £42,000 |
| Garage + en-suite addition | £28,000 | £45,000 |
| Garage to habitable bedroom (Building Regs) | £18,000 | £32,000 |
| Detached garage conversion | £22,000 | £40,000 |
✅ Typically Included
- ✓Strip-out of existing garage structure/fittings
- ✓Concrete slab or insulated floor system
- ✓Wall insulation and re-plastering
- ✓Ceiling insulation and plasterboard
- ✓New electrical circuits and sockets
- ✓Heating supply (radiator or underfloor)
- ✓Window and door installation
- ✓Building Regulations application and sign-off
- ✓Structural engineer report (where required)
❌ Usually Excluded
- ✗Second-fix materials (flooring, paint, light fittings, furniture)
- ✗En-suite plumbing and tiling (priced separately)
- ✗Carpet installation
- ✗External landscaping or driveway alterations
- ✗Planning permission (if required — most don't need it)
- ✗Architect drawings for complex schemes
- ✗Boiler upgrades if current system is undersized
- ✗Garage door removal and facade works beyond standard scope
What Changes the Price
Structural condition
Older garages may need new lintels, damp-proofing, or a new concrete slab. A good contractor will flag this during a site visit — not mid-project.
En-suite addition
Adding a shower room or WC adds £6,000–£12,000 depending on spec and proximity to existing waste runs. Most garage conversions that become bedrooms include this.
Detached vs integral
Detached garages cost more because they need new utility connections (electric, heating, possibly water). Integral garages connect to the main house more easily.
Finish specification
Standard = good quality materials. High-end = custom joinery, underfloor heating, premium fittings. The labour doesn't change much — it's materials that drive the gap.
Insulation type
Building Regs require minimum U-values. Achieving this in older structures may mean thicker wall builds or specialist products — both affect cost and usable floor space.
Garage door opening
The existing opening usually becomes a window + wall or full glazed section. The type of infill — brick, blockwork, or a glazed frame — affects both cost and look.
Planning Permission & Building Regulations
🏛️ Planning Permission
Most garage conversions in England do not require planning permission — they fall under Permitted Development rights.
Exceptions: conservation areas, listed buildings, Article 4 directions, or where you're extending the footprint. We always check before proceeding.
📋 Building Regulations
Building Regulations approval is always required for a habitable garage conversion, covering: structural integrity, insulation (U-values), ventilation, fire egress, and electrics.
RCB manages the full Building Regs process — from application to final sign-off.
Does a Garage Conversion Add Value?
In most of London, yes — significantly. Converting a garage to a bedroom or home office typically adds 10–15% to property value, often exceeding the build cost. Adding a bedroom (especially with en-suite) has the most impact.
⚠️ One caveat: parking
In areas where off-street parking is scarce (inner London especially), losing a garage space could reduce buyer appeal. If your road has good street parking or you have a second space, this is rarely an issue. Discuss this with your estate agent before committing.
Get a Garage Conversion Estimate
Use the estimator for a rough budget range before booking a free survey.
Ballpark figures only. A detailed fixed-price estimate follows a site visit.
Quick Estimate
Adjust the options to get a quick ballpark — not a quote, but a useful starting point.
Want more detail? Try the full cost calculator →
What Garage Conversion Clients Say About RCB
All reviews verified by Checkatrade, TrustMark, or FMB.
"Vasi and the team delivered exactly what was promised. We now have a stunning master bedroom with en-suite and a separate study in the loft. Finished on time and within budget."
James T.
Lewisham, SE13 · L-Shaped Dormer Loft Conversion
"RCB managed everything from planning drawings through to the final coat of paint. Professional throughout, always on time, site kept clean every day. Would not hesitate to recommend."
Sarah M.
Islington, N1 · Rear Extension + Kitchen
"The wraparound extension has transformed how we use the house. RCB managed every trade, coordinated the steel installation, and the bifold doors are perfect. Professional from start to finish."
David W.
Hackney, E8 · Wraparound Extension
Garage Conversion FAQs
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Get a free estimate for your garage conversion
Tell us about your garage — size, current condition, intended use. We'll respond within a few hours with a realistic budget range and arrange a free site visit when you're ready.