retrofitcost.co.ukA surveyor's working file. Q4 2026 Ofgem cap applied.
Home/Archetypes/1960s System Build
Working file A3

1960s system-built house retrofit cost (UK 2026)

1960s system-built house retrofit cost: working capex envelope, sequenced measure cost, PAS 2035 risk path.

Working envelope (80 m² system-built)

Phased deep retrofit: £48,000to£75,000(pre-grant). Net after BUS: £40,000to£67,000. The system-built premium is real and reflects survey, design and Path C fee uplift.

Construction types

  • No-fines (Wimpey No-Fines): EWI works once thermal-bridging is detailed.
  • BISF: steel frame; EWI plus careful detailing of cold bridges.
  • Concrete panel (Reema, Cornish Unit): valuation and mortgageability often the lead concern.

Risk path

ASHPMVHRU 0.18 W/m²KU 0.15 roofU 0.18 wallU 0.22 floorPath C, system-built
Surveyed 1 October 2026. Ofgem cap for 1 October to 31 December 2026 applied (gas 7.97p, elec 26.32p, gas standing 29.68p, elec standing 54.83p). Next scheduled review 25 November 2026 (January cap announcement). [ref A3]
By Oliver Wakefield-Smith, Founder, Digital Signet. Corrections to oliver at digitalsignet dot com.