What it covers
Free lead-gen calculator (extension, loft, refurb, new build); paid RIBA design-and-build engagement behind it.
What it costs
From £1,750/m² (basic 2026 new build floor; up to £3,000/m² for high-spec).
What changed recently
All four calculators refreshed for 2026 £/m² rates; guidance still advises +15% consultants and +8% statutory/contingency on top of the headline rate.
Where it fits in a UK knockdown rebuild
Use Urbanist Architecture as one input among several when sizing a KDR. The calculator on this site cross-checks against BCIS, FMB, and HMRC simultaneously so no single reference drives the headline. For the live worked example, see the calculator; for every figure's primary source, see the sources ledger.
Primary source
Verified 2026-06-21 against the source URL above.