House Extension

 Updated: 15 August 2026  |  By QuoteMyRenovation House extension cost in London in 2026 range from £60,000 for a small single-storey rear extension to £380,000+ for a large wrap-around at premium specification. London extension costs run 20-40% above the UK national average, driven by higher labour rates, constrained sites, planning complexity, and the complications of period London properties. […]