Calculate your external wall insulation cost
External wall insulation cost per m² in Cardiff
External wall insulation by property type in Cardiff
The UK figures are current property examples; the city column applies the same moderated 18% regional weighting as the live calculator.
UK £5,000–£7,000 · avg £6,000£4,900–£6,900 · avg £5,900
UK £6,000–£10,000 · avg £8,000£5,900–£9,850 · avg £7,850
UK £14,000–£20,000 · avg £17,000£13,750–£19,700 · avg £16,700
UK £15,000–£21,000 · avg £18,000£14,750–£20,650 · avg £17,700
UK £20,000–£30,000 · avg £25,000£19,700–£29,500 · avg £24,600
Current UK system benchmarks
What can change a real Cardiff quote?
- External wall area
- EPS, mineral wool or board system
- Render or cladding finish
- Scaffolding
- Gutter and pipework changes
- Existing wall condition
Local planning considerations
For grants and energy schemes, verify the current Wales-specific eligibility rules before relying on any support assumption.
- Use Wales-specific planning, building-control and energy-scheme information where the rules differ from England.
- Terraced or constrained urban properties can add access, waste and scaffold costs that are not captured by the regional factor.
- Drainage, roof and external-work scopes should be based on the property condition rather than a generic city assumption.
How the regional model works
The live external-wall-insulation calculator uses only 18% of the broad Wales regional difference because insulation boards, fixings and render systems contain a substantial nationally priced material component. The resulting Cardiff EWI factor is 0.984× and is applied to the current £150–£200 per m² installed benchmark.
Sources
External Wall Insulation Cost: 2026 UK Guide
Published / checked: July 2026
Used for: Installed external-wall insulation cost-per-m² and property-type ranges
Frequently asked questions
How much does external wall insulation cost in Cardiff in 2026?
The current UK installed benchmark is £150–£200 per m², averaging about £175 per m². Using the same moderated regional factor as the live calculator gives a Cardiff planning rate of about £148–£197 per m².
How much is external wall insulation for a semi-detached house in Cardiff?
The current UK semi-detached example is £14,000–£20,000, averaging £17,000. Applying the moderated Cardiff model gives about £13,750–£19,700, with a modelled midpoint near £16,700.
Why is the Cardiff EWI adjustment smaller than the broad regional factor?
External wall insulation contains a large material and system component, so the live calculator applies only 18% of the broad regional difference rather than treating the entire installed price as locally variable labour.
What can make external wall insulation more expensive?
Wall repairs, scaffolding, architectural detailing, moving rainwater pipes and services, premium finishes, difficult access and larger exposed wall areas can all increase the final quote.