The National Audit Office report into botched external wall installations deals a body-blow to the benefits of retrofit and industry reputation for quality. 

A staggering 98% of external wall installations funded by ECO4, the fourth iteration of the Energy Company Obligation scheme and the Great British Insulation Scheme were found to be substandard. 

In the majority of cases there was a risk of water getting behind the external insulation boards thanks to issues such as insufficient coverage of the insulation by the eaves leading to internal damp and mould. Other problems included insufficient ventilation being left for gas boilers, leading to the risks of carbon monoxide poisoning and exposed electricity cables.