The dataset consists of (1) measurement data from an outdoor test stand involving a number of different internal insulation systems and surface treatments. The placement outdoor makes it possible to take into consideration the wind driven rain on the behaviour of the different systems and treatments (2) files with risk prediction of fungal growth (3) test results from Mycometer tests and pH-measurements (4) Photo documentation for identification of fungal growth (5) Delphin 6 models and results of Delphin simulations (6) Appendics with background information for Delphin simulations Overview of data files to be found in ’RIBuild data WP3_DTU Outdoor test unit' as part of this dataset. Further details to be found in Jensen, N.F., Odgaard, T.R., Bjarløv, S.P., Andersen, B., Rode, C., Møller, E.B. (2020). Hygrothermal assessment of diffusion open insulation systems for interior retrofitting of solid masonry walls. Building and Environment (In Review) Data on hot box cold box experiments with a solid wall wooden beam end combination is to be found in the data sets 'RIBuild: Hotbox coldbox experiment with solid wall in combination with wooden beam ends at KU Leuven' (https://zenodo.org/deposit/3890050) and 'RIBuild: Hotbox coldbox experiment with solid wall in combination with wooden beam ends at TU Dresden' (https://zenodo.org/deposit/3904836)