Disclosed is a method of producing a composite material suitable for the manufacturing of gypsum wallboard and ceiling tile applications, produced by co-calcining dihydrate (gypsum) to hemihydrate/stucco and cooking of unmodified/raw starch to cooked starch together. The method disclosed improves the standard wallboard and ceiling tile processing techniques thereby lowering the manufacturing cost of both products. The co-calcining of gypsum and the unmodified starch together eliminates the calcining of dihydrate ground gypsum (powder natural or synthetic gypsum) and cooking of unmodified starch (powder) separately prior to using the materials in the wallboard and ceiling tile formulations. The unmodified starch can be also added to the gypsum rocks during the grinding and calcining process to produce composite material. Furthermore, unmodified starch can be added to the wet synthetic gypsum such as FGD (flue gas desulphurization etc.), dried or dried and calcined together. The use of composite material in both product formulations eliminates or minimizes the processing steps and lowers the energy cost by partially or completely replacing standard hemihydrate/stucco and starch during the processing.