Any contractor who quotes a £1m London home renovation without understanding the property first is either guessing or lying. That said, clients naturally want the range, so here is an honest. And cautionary. Breakdown from our recent work across NW3, TW10 and W11.
The fundamental reality is that a full-house Victorian refurbishment at £1m build value is, in 2026, roughly a 140 to 180 sqm scheme. Not the 300 sqm palatial vision. At that value, allocations usually fall as follows: 18 to 22% to demolition and substructure, 25 to 30% to shell and envelope, 15 to 18% to M&E first and second fix, 20 to 25% to interior fit-out including kitchen and bathrooms, and 8 to 12% to professional fees and planning.
“Every central London terrace hides at least one unwelcome foundation surprise. Discover it at substructure and it costs ten times what it would have cost at design stage.”
The three places projects overrun are predictable: basement discoveries (every central London terrace hides at least one unwelcome foundation surprise), sash window and heritage joinery (the cost of doing this properly is always higher than the cost of doing it badly), and specialist finishes (stone slabs and bespoke joinery that arrive at the tail of the programme and stop cheques being signed).
If your architect has produced a £1m cost plan and you are nervous about where the number lands at completion, the single best thing you can do is insist on a two-stage tender with a pre-construction services agreement. HXL prices the PCSA at a fixed fee, reviews the scheme for buildability and risk, and returns a fixed price for the build before you commit to the contract sum.
This is the point at which surprises are still cheap. Discover them later and they cost an order of magnitude more.
