Working file M1
Fabric-first retrofit cost (UK 2026)
Fabric-first retrofit cost in 2026: EWI, IWI, cavity, loft, floor, glazing. PAS 2035 sequences this stratum before ventilation or heating.
Why fabric first
PAS 2035 sequences the fabric stratum first so that ventilation rates and heat-pump sizing follow the post-improvement heat-loss calculation. A heat pump sized against the pre-fabric house is the single most common over-spec in the UK installer base.
Measures
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 M1]
By Oliver Wakefield-Smith, Founder, Digital Signet. Corrections to oliver at digitalsignet dot com.