What drives flat renovation cost?
Five main factors. First, scope: cosmetic refresh, full strip-out or structural reconfiguration. Second, age and condition: pre-1939 stock often hides asbestos artex, dated wiring and unvented soil pipes; ex-LA flats need fire compartmentation upgrades. Third, finish level: builders-grade kitchen vs handleless German vs bespoke joinery is a 3–4× spread. Fourth, freeholder consent and lease requirements — Listed and Article 4 buildings need parallel planning/LBC. Fifth, access: top-floor flats with no lift add 10–15% to labour for material movement.
Typical flat renovation scope and cost
Cosmetic refresh (decoration + flooring + appliances): £15,000–£35,000 over 4–6 weeks. Bathroom + kitchen replacement only: £25,000–£55,000 over 6–8 weeks. Full strip-out with new M&E, kitchen, bathroom and decoration: £85,000–£140,000 for a 70 m² flat. Structural reconfiguration (knocking through, moving bathroom): add £25,000–£50,000 and 4–6 weeks. High-spec finishes (engineered oak, stone, bespoke joinery, smart systems): add 30–50%.
Freeholder consent and party walls
Most leases require freeholder Licence to Alter for any structural work, M&E changes or removal of internal walls. Allow 6–12 weeks and £1,500–£4,500 in freeholder solicitor and surveyor fees. Party Wall etc. Act 1996 notices required for any work to walls or floors shared with neighbouring flats — typical surveyor fees £1,200–£3,500 per neighbour. Builderr coordinates Licence to Alter and party wall service in parallel with detailed design to avoid programme slippage.
