This dataset contains the raw experimental results generated in the characterisation of mycelium-based composite (MBC) insulation materials. It includes primary measurement data for laboratory-produced specimens (MBC A) and two commercially sourced materials (MBC B and MBC C), covering thermal conductivity measurements, liquid water absorption by immersion, surface wettability (contact angle) measurements, and mould susceptibility assessments. The mould dataset includes individual specimen ratings after 28 days of incubation across five temperature and relative humidity conditions, as well as ratings after subsequent liquid-water exposure. All files report unprocessed specimen-level results used to generate the figures and statistical summaries in the associated publication.