This paper aims to investigate interfacial fracture toughness between concrete and polymer-cement mortar (PCM) in an external wall tile structure under various shear to tensile stress ratio by using interface elements in a finite element method (FEM). A constitutive material model of interface elements was developed, and its corresponding values that have a relation to the interfacial fracture toughness were calibrated with three four-point bending set-ups and one high shear test. Then, the developed interface element was verified by applying to analyze the failure of tiles in the tiled column compression test. With this method, the interfacial fracture toughness of the current interface was successfully obtained for the whole range of the shear to tensile stress ratio. Finally, the result is further discussed with the other interfaces, consisting of cementitious materials.