Insulation leads UK — find every retrofit opportunity in your patch

EWI is a thermal layer fixed to the outside of a building, typically 90–150mm of mineral wool or expanded polystyrene plus a render or brick-slip finish. It is the dominant retrofit measure for solid-wall homes — usually pre-1920 stock with no cavity to inject. Cost £4,000 for a small terrace to £25,000 for a large detached. EWI delivers the biggest single SAP-point uplift available, often moving a property two full EPC bands. Internal wall insulation (IWI) is the alternative where planning, listing or aesthetic constraints rule EWI out — cheaper material cost but loss of internal floor area. Filter Retrofit Radar to property-age pre-1920 and wall-type "solid" to surface the EWI cohort directly.

Three EPC fields tell you. Wall type "cavity" or "filled cavity (uninsulated)" means a cavity exists. Construction year between roughly 1920 and 1990 is the typical UK cavity-wall era. The recommendations panel lists "cavity wall insulation" as a measure if the cavity is unfilled. Retrofit Radar surfaces all three — filter to wall-type cavity, age 1920–1990, and recommended measures including "cavity wall insulation". The remaining qualifier is on-site: a borescope check confirms the cavity is wide enough (usually 50mm+) and free of debris. Around 5 million UK homes have unfilled cavities; CIGA-certified installers fit them in a single day at £400 to £1,500 per dwelling. Conversion is fastest among privately rented homes flagged with the recommendation.

TrustMark is the UK retrofit quality body; PAS 2035 is the BSI standard for whole-house retrofit design and project coordination. You need it for any government-funded retrofit work — ECO4, Warm Homes Plan, the now-closed GBIS — and for cost-cap exemption claims under MEES. PAS 2030 is the install-side companion specification covering the actual installation work. If you only fit privately funded measures (a homeowner paying cash for cavity-wall insulation), TrustMark plus PAS 2030 is sufficient. If you want to be on the rails for the £13.2bn Warm Homes Plan funding flow, PAS 2035 plus a registered Retrofit Coordinator on every project is non-negotiable. Retrofit Radar flags properties with active grant eligibility automatically.

Yes. The property-type filter accepts terraced (mid and end), semi-detached, detached, flats and bungalows. For insulation work this is decisive: cavity-wall installers ignore solid-wall pre-1920 stock; EWI installers ignore mid-terrace where two of four walls are party walls; loft-insulation installers ignore top-floor flats. Combine property-type with construction year and wall-type filters to land precisely on the cohort you fit. A typical EWI installer filters to detached and end-of-terrace, pre-1920, solid wall — that combination cuts a 5,000-property patch down to 200–400 high-conversion candidates. The full filter set is documented on the how-it-works page; export-to-CSV preserves every filter you set.

Three live grant streams in May 2026. ECO4 — open through 31 December 2026 — funds insulation and heating upgrades for low-income households, routed via TrustMark and PAS 2030 installers. The Great British Insulation Scheme closed to new applications on 31 March 2026 after delivering around 130,800 measures; past tense for new work. The Warm Homes Plan — £13.2bn confirmed at Spending Review 2025 — is being rolled out through FY 2025-26 to 2029-30 with delivery mechanisms still being finalised. For private MEES retrofit work, no direct landlord grant exists; the cost is the landlord's, capped at £10,000 per property under the MEES cost-cap rule, with a Property Value Adjustment to 10% for sub-£100k homes.