Cavity wall insulation
Cavity walls were standard in UK homes built between 1920 and 1990. Insulating them is typically the most cost-effective retrofit measure, with payback periods of 2 to 5 years.
Cornerstone guide
Is cavity wall insulation worth it?
An honest 2026 cost / benefit answer. Install cost by house type, grants available, savings vs gas and electricity bills, and when cavity wall insulation makes sense (and when it doesn't). Includes a 5-question eligibility check for your house.
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