A building panel structure is disclosed, in which composite building panels are used to form a structure. A composite building panel is disclosed which includes a core and a coating applied over the core. In some embodiments the core consists of a frame and one or more than one insulating structural block. The insulating structural blocks can be encapsulated polystyrene (EPS) foam blocks. In some embodiments the coating includes an inner scratch layer and an outer main brown layer. The inner scratch layer can be formed of at least two layers. The outer main brown layer can include a fiberglass mesh embedded into the outer main brown layer. A method of forming a building panel structure is disclosed which includes forming a core using a frame and one or more than block, applying an inner scratch layer to the core, and applying an outer main brown layer over the inner scratch layer.