Loft Conversion in Kingston upon Thames | RCB Design & Build
Loft conversions are usually the highest-ROI project you can run on a Kingston upon Thames home — typical uplift in resale value is 15–20% on a three-bed property. RCB Design & Build delivers loft conversion projects right across Kingston upon Thames (KT2) from our Dartford base — typically on site within 48 hours of enquiry, with a fixed written quotation in 5 working days. Our typical loft conversion project in Kingston upon Thames costs between £66,000 and £132,000 in 2026, with most Victorian terraces and Edwardian villas landing around £99,000. We are FMB, TrustMark, Checkatrade and TrustATrader accredited and operate as a Principal Contractor under CDM 2015.
Wealthier suburb — strong volume of full house refurbishments, side-return extensions and twin-dormer lofts. Working out of Royal Borough of Kingston 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 Kingston upon Thames project is on Victorian terraces within easy reach of the Thames or Richmond Park, and we work with a small panel of trusted London-area subcontractors we have used for years.
What's included in our loft conversion price
Our written quotation for a Kingston upon Thames loft conversion includes structural steels, fire-rated stair, dormer or hip-to-gable carpentry, insulation to Part L (typically 100mm PIR between rafters and 50mm under), Velux or dormer glazing, first-fix electrics and plumbing, plasterboard and skim, and balustrade. The new staircase is typically the biggest design constraint. 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 £7,920–£14,850 in trade markup. We exclude planning fees, party-wall surveyor fees and structural engineer drawings, which we coordinate at cost.
Kingston upon Thames planning, party walls and Building Regs
Surbiton and Coombe conservation areas require like-for-like detailing on extensions. Mansard, L-shaped dormer, hip-to-gable and Velux-only conversions each have their own structural and planning profile — the right option depends on roof shape and head height. Note that Kingston 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 Kingston upon Thames projects
Loft conversions run on a tight critical path: 1 week for surveys and steel design, 4–6 weeks for planning and Building Control submission, 8–12 weeks on site. We strip the roof from inside where possible to keep the house weathertight. 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 KT2 postcodes we can have someone on site within 48 hours of a phone call.
Guarantees and after-care
Every project we deliver in Kingston 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 Kingston upon Thames schemes — worth considering for any project above £50,000.
Loft Conversion cost in Kingston upon Thames — 2026 price guide
Project size
From
To
Velux-only conversion (≤20 m²)
£66,000
£79,000
Rear dormer (20–30 m²)
£73,000
£92,000
L-shaped dormer (30–40 m²)
£86,000
£112,000
Mansard / hip-to-gable (40 m²+)
£99,000
£132,000
Indicative Kingston upon Thames (KT2) ranges for 2026. A site visit firms the figure to +/-5%.
Frequently asked questions
How much does a loft conversion cost in Kingston upon Thames in 2026?
Typical Kingston upon Thames pricing ranges from £66,000 to £132,000 depending on size, finish and site complexity. Kingston 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 loft conversion take in Kingston upon Thames?
Allow 6–12 weeks of design, planning and procurement before work starts, then a project-dependent build phase. Loft conversions run on a tight critical path: 1 week for surveys and steel design, 4–6 weeks for planning and Building Control submission, 8–12 weeks on site. We strip the roof from inside where possible to keep the house weathertight. We share a Gantt-style schedule with every quotation.
Do I need planning permission for a loft conversion in Kingston upon Thames?
Most rear-dormer and Velux loft conversions in Kingston upon Thames sit inside Permitted Development. Mansards, side dormers in conservation areas, and listed buildings need full planning consent. We always recommend a Lawful Development Certificate to lock in PD status.
Which areas of Kingston upon Thames do you cover?
We cover all of KT2 and the surrounding London postcodes from our Dartford base. Recent projects sit close to the Thames and Richmond Park. 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.