retrofitcost.co.ukA surveyor's working file. Q3 2026 Ofgem cap applied.
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Working file A4

Post-2000 new-build retrofit cost (UK 2026)

Post-2000 new-build retrofit cost: working capex envelope, sequenced measure cost, PAS 2035 risk path.

Working envelope (100 m² post-2000 build)

Scope is narrow. Typical capex: £11,000to£25,000(pre-grant). Net after BUS: £3,500to£17,500. The case for fabric work is usually limited; PV plus battery plus HP is the modal stack.

Sequenced cost

  • ASHP plus rads £8,000 to £14,000 net of BUS.
  • Solar PV 4 kWp £5,800 to £8,800.
  • Battery 5 kWh £3,500 to £5,250.
  • MVHR retrofit possible in well-built post-2010 stock.

Risk path

ASHPMVHRU 0.18 W/m²KU 0.15 roofU 0.18 wallU 0.22 floorPath A, post-2000 build
Surveyed 22 June 2026. Ofgem Q3 2026 cap applied (gas 7.33p, elec 26.11p, gas standing 29.04p). Next scheduled review 26 September 2026 (Q4 cap publication). [ref A4]
By Oliver Wakefield-Smith, Founder, Digital Signet. Corrections to oliver at digitalsignet dot com.