Building cost in Lambeth: 2026 rates.
Lambeth's Victorian terrace and Edwardian semi stock, Clapham, Brixton, Herne Hill, Streatham, supports a cost band of £2,800–£3,900/m² for rear extensions, £68k–£130k for lofts, and £2,300–£3,500/m² for full refurbs on 2026 rates. Quote spreads of 15–25% on the same scope make builder quote review one of the highest-ROI homeowner cost expert interventions.
| Project type | Typical 2026 cost |
|---|---|
| Rear extension | £2,800–£3,900/m² |
| Loft conversion (total) | £68,000–£130,000 |
| Full refurbishment | £2,300–£3,500/m² |
| Basement (per m²) | £4,700–£7,400/m² |
All figures exclude VAT (20% on most refurb/extension work), professional fees (8–14% typical), party wall awards and statutory costs.
- Lambeth conservation areas include Clapham Old Town, Stockwell Park, Lansdowne Gardens, Herne Hill
- Side-return + rear wrap-arounds dominate the kitchen extension market across SW4 and SE24
- Lambeth's basement SPD restricts excavation under gardens and listed terraces
- Party Wall Act 1996 awards typically £900–£2,300 per adjoining owner
- Builder market is deep, quote competition consistently saves 10–18% on shortlisted quotes
Lambeth's competitive builder market is the homeowner's biggest cost lever, get three written quotes, level them, and challenge the spread.
Frequently asked, Lambeth
How much does a Clapham side return extension cost?
A 15m² side return on a Clapham Victorian terrace costs £70,000–£115,000 on 2026 rates, plus VAT, design and statutory costs. Cost spread is driven by glazing spec (Crittall versus aluminium), structural opening size and finished floor specification.
Are loft conversions common in Lambeth?
Yes, Lambeth's terrace stock is well-suited to rear-dormer, L-shape and Mansard lofts. Mansards usually require planning even outside conservation areas; rear-dormer lofts often qualify for permitted development on non-Article 4 streets.
How much should I budget for a full Lambeth refurbishment?
A full strip-and-reinstate of a 120–160m² Lambeth terrace house typically costs £300,000–£550,000 on 2026 rates, plus VAT, fees and any extension cost. Adding a side-return + loft conversion to the same project pushes the all-in figure to £550k–£850k.
Know what your project should cost. Before you build it.
One UK working day response. Fixed-fee proposal, VAT inclusive. No retainer. No obligation.