Four retrofit panels were installed in-situ to assess their hygrothermal performance when applied in an exterior overclad retrofit, to a brick veneer facade. The brick veneer was constructed on load cells to measure the gravimetric moisture content of the brick layer. Prior to installing the retrofit panels, the brick facade was saturated to assess the ability of the retrofitted assembly to dry. Through retrofitted walls hygrothermal analysis using damage functions such as visible mould index, Time of Wetness, and the RHT-Index, it was found that the retrofit panels with higher permeability insulation and no interior wood sheathing layer had the lowest mould risk and would be suitable in overclad retrofit applications even if the brick is wet at the time of retrofit.