Garage Conversion in Richmond upon Thames | RCB Design & Build
Garage conversions are the most cost-effective way to add a habitable room in Richmond upon Thames — typically gaining a 15–20 m² home office, gym or guest bedroom. RCB Design & Build delivers garage conversion projects right across Richmond upon Thames (TW9) from our Dartford base — typically on site within 48 hours of enquiry, with a fixed written quotation in 5 working days. Our typical garage conversion project in Richmond upon Thames costs between £20,000 and £52,000 in 2026, with most Edwardian villas and mansion blocks landing around £36,000. We are FMB, TrustMark, Checkatrade and TrustATrader accredited and operate as a Principal Contractor under CDM 2015.
Heritage refurbs, full house renovations and limited-footprint extensions. Premium finish is the norm. Working out of London Borough of Richmond upon Thames's area, we know the planners, the local building inspectors, and the named conservation officers — that personal relationship cuts weeks off the consenting timeline. Our typical Richmond upon Thames project is on Edwardian villas within easy reach of Kew Gardens or the Thames, and we work with a small panel of trusted London-area subcontractors we have used for years.
What's included in our garage conversion price
Up-rated foundations and floor build-up to current insulation standards, masonry infill of the garage opening, new window/door, full insulation to Part L, plasterboard and skim, electrics, heating, flooring sub-base. Our written quotation covers labour, first-fix materials, project management, scaffolding, skips, Building Control fees and statutory inspections. Second-fix materials (kitchens, bathrooms, flooring, tiles, paint, sanitaryware) are supplied by the client as a deliberate cost-control measure — this typically saves homeowners £2,880–£5,400 in trade markup. We exclude planning fees, party-wall surveyor fees and structural engineer drawings, which we coordinate at cost.
Richmond upon Thames planning, party walls and Building Regs
Richmond is the most conservation-heavy outer borough; Article 4 Directions are widespread. Garage floors are usually 100–150 mm below the house floor — plan the new floor build-up early or you will lose ceiling height to the screed. Note that Richmond upon Thames has multiple conservation areas — design must match prevailing materials, roof shape and fenestration. Party Wall Awards are typically needed for any excavation within 3 metres of a shared wall — we coordinate the surveyor and serve notices. Building Control is lodged at the start, with inspections at foundation, damp-course, pre-plaster and completion stages.
Timeline and process for Richmond upon Thames projects
Garage conversions run 4–6 weeks on site. The biggest constraint is typically getting the new floor level to align with the rest of the house. We hold a weekly call with the client throughout, send a written progress report with photos every Friday, and the lead PM is always reachable on WhatsApp. From TW9 postcodes we can have someone on site within 48 hours of a phone call.
Guarantees and after-care
Every project we deliver in Richmond upon Thames is backed by a 12-month workmanship guarantee. Where we install manufacturer-warranted systems (roofing membranes, windows, MVHR), the manufacturer warranty (typically 10–25 years) runs alongside. As an FMB member we can also arrange an FMB-backed 2-year insurance warranty on qualifying Richmond upon Thames schemes — worth considering for any project above £50,000.
Garage Conversion cost in Richmond upon Thames — 2026 price guide
Project size
From
To
Integral single garage
£20,000
£26,000
Attached single garage
£22,000
£28,000
Double garage
£28,000
£36,000
Double + ensuite
£32,000
£44,000
Indicative Richmond upon Thames (TW9) ranges for 2026. A site visit firms the figure to +/-5%.
Frequently asked questions
How much does a garage conversion cost in Richmond upon Thames in 2026?
Typical Richmond upon Thames pricing ranges from £20,000 to £52,000 depending on size, finish and site complexity. Richmond upon Thames sits in the upper-tier London market so labour rates run 15–25% above outer-borough averages. A free site visit firms the number up to ±5%.
How long will a garage conversion take in Richmond upon Thames?
Allow 6–12 weeks of design, planning and procurement before work starts, then a project-dependent build phase. Garage conversions run 4–6 weeks on site. The biggest constraint is typically getting the new floor level to align with the rest of the house. We share a Gantt-style schedule with every quotation.
Does a garage conversion in Richmond upon Thames need planning permission?
Most integral garage conversions sit inside Permitted Development as long as the building footprint doesn't change. Detached garages and conservation areas typically need full planning.
Which areas of Richmond upon Thames do you cover?
We cover all of TW9 and the surrounding London postcodes from our Dartford base. Recent projects sit close to Kew Gardens and the Thames. Anywhere within 45 minutes of Dartford is comfortably inside our core delivery zone.
Is RCB insured?
Yes — we hold £5 million Public Liability, £10 million Employer's Liability, full Contract Works insurance and Professional Indemnity. Certificates are provided with every quotation.
How do I get a quote?
Use the free instant calculator at /quote for a 60-second ballpark, configure your project in detail at /configure, or call +44 7359 872594. We respond to every enquiry within 4 working hours.