Working file A0
UK house archetype retrofit cost (2026)
Four UK archetypes drive most retrofit decisions: Victorian solid wall, 1930s cavity semi, 1960s system-built, post-2000 new build. Capex envelopes for each in 2026.
The English Housing Survey shows roughly a third of the stock is pre-1919 solid wall, a third is 1919-1944 (including the modal 1930s semi), and a third is post-1944. The four archetypes here cover the bulk of decisions a homeowner will face.
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 A0]
By Oliver Wakefield-Smith, Founder, Digital Signet. Corrections to oliver at digitalsignet dot com.