The audits found: • 98% of homes with external wall insulation have major issues: 92% have defects that will negatively affect the insulation’s performance, often creating the risk of water ingress and mould; 6% have immediate health and safety risks, such as inadequate ventilation, and may also have other major issues requiring remediation. Between 22,000 and 23,000 homes are likely to be affected.15 • 29% of homes with internal wall insulation have major issues: 27% have defects that will negatively affect the insulation’s performance, often creating the risk of condensation and mould; 2% have 14 C&AG’s Report, paras 2.2 to 2.4 and Figure 10 15 C&AG’s Report, para 2.2 and Figure 10 11 immediate health and safety risks, such as inadequate ventilation and poor electrical safety, and may also have other major issues. Between 9,000 and 13,000 homes are likely to be affected.16 The Department does not have an estimate of how many additional homes retrofitted after mid-January 2025 are likely to have major issues, so the total number of homes affected will be higher than we set out in this report.17