Extension cost estimator
Select your project type, size and finish level for an indicative all-in cost range based on typical 2026 UK design-and-build rates. For deeper context, read our guide on rear extension costs or build-only vs design & build.
Finish level
Indicative all-in range (2026 UK rates)
£55,000 – £80,000
Based on ~£2,200–£3,200/sqm for rear extension at mid specification. Professional fees, surveys, party wall and abnormal ground conditions are not included.
Disclaimer: Indicative only, not a quote. Every property differs — access, structure, finishes and planning route change cost. Book a consultation for a scoped estimate.