Abstract Composite materials containing phase change materials (PCMs) are obtained by mixing PCM microcapsules with traditional construction materials. The composite materials thermal properties, which depend on the composition, are required when dynamic simulations of building structures containing composite material with PCM are performed. In order to avoid the need of measuring density, thermal conductivity and specific heat capacity for each possible composition, in this work correlations for the estimation of these thermal properties for gypsum based composite materials with micro-encapsulated PCM are derived. The correlations, obtained on the basis of experimental measures, give the composite material thermal properties as function of gypsum, water and PCM mass and volume fractions; it is verified that the correlations for density and thermal conductivity can be applied in the whole temperature range, including both the PCM liquid and solid phases, while a correction based on the temperature is applied for the correlation for specific heat capacity to extend its validity to the phase change temperature range. The correlations fit the experimental data with an error comparable with the measurement uncertainty and, when tested on a commercial product, they are able to predict its thermal properties with good accuracy.