External wall insulation can help reduce condensation and penetrating damp by keeping walls warmer and better protected from the weather. For best results, insulation should be installed alongside proper household ventilation, in line with PAS 2035 retrofit best practice. This may include background trickle ventilation, mechanical extract ventilation in wet rooms such as bathrooms and kitchens (DMEVs), or whole-house systems such as Positive Input Ventilation (PIV). This balanced approach helps control moisture levels, improve indoor air quality, and reduce the risk of mould.