A comparative study was conducted on the properties of lightweight cementitious composites (LWCCs) mixed with four types of filler particles; EPS beads, dry-expanded plastic microspheres, hollow glass microspheres, and fly ash cenospheres. Thermal conductivity was tested using the transient plane source method. Results showed that thermal conductivity of LWCCs are dictated by the volume of lightweight functional filler (LWF) used and are insensitive to the type of LWF....