Abstract: A modular building panel (10) for use in forming walls. The panel comprises: an inner foam core (36) and a frame (12) surrounding the inner foam (5) core (36). The frame (112) is provided for standing upright to provide two primary faces (18) joined by a number of side portions (20). The side portions (20) of the frame (12) are provided by structural channel members (42). The structural channel members (42) provide a perimeter around the foam core (36). The structural channel members (42) providing flange portions (96) to allow rigid connection of the panel (10) using fasteners extending through the primary faces (18) into the flange portions (98) to provide the panel with a desirable cyclone rating.