Building cost in Richmond upon Thames: 2026 rates.
Richmond's mix of Edwardian villas, riverside cottages and St Margarets terraces produces a wide cost spread: rear extensions £3,000–£4,200/m², loft conversions £75k–£145k, full refurbs £2,500–£3,700/m² on 2026 rates. Conservation coverage is dense around Richmond Green, Kew and Twickenham Riverside, Article 4 directions remove PD on most protected streets.
| Project type | Typical 2026 cost |
|---|---|
| Rear extension | £3,000–£4,200/m² |
| Loft conversion (total) | £75,000–£145,000 |
| Full refurbishment | £2,500–£3,700/m² |
| Basement (per m²) | £5,000–£7,800/m² |
All figures exclude VAT (20% on most refurb/extension work), professional fees (8–14% typical), party wall awards and statutory costs.
- Richmond Local Plan policy LP14 protects views, scale and materials in conservation areas
- Kew, Richmond Green, Petersham and Twickenham Riverside are Article 4 zones
- Detached Edwardian stock supports larger PD extensions than terrace boroughs
- Trees with TPOs are common, works near canopy add £3–8k of arb fees and method statements
- Party Wall Act 1996 awards on detached stock are less frequent, but riverside terraces almost always trigger awards
Tree, conservation and riverside flood-zone constraints are the cost drivers, front-load pre-build budget and planning fee work.
Frequently asked, Richmond upon Thames
How much does a rear extension cost in Richmond?
A 25m² rear extension on a Richmond Edwardian semi typically costs £85,000–£150,000 on 2026 rates, plus VAT, design fees and any statutory costs. Conservation-grade timber windows, lantern glazing and TPO-protected gardens push toward the top of the band.
Can I build a basement in Richmond?
Richmond's policy permits single-storey basements under the original footprint subject to engineering sign-off, but restricts excavation under gardens and protected trees. Most basement projects in Richmond require full planning and an arboricultural impact assessment.
What does a Richmond loft conversion cost?
A standard rear-dormer loft on a Richmond terrace runs £75,000–£110,000; L-shape with ensuite £100,000–£135,000; hip-to-gable on a detached house £120,000–£170,000. All exclude VAT, design fees and party wall costs.
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