The invention relates to structural panel systems with at least a four-layered generally in-plane sidelap, at least a three layer generally in-plane sidelap, or corner sidelaps of various layers, and methods for manufacturing and assembling structural panel systems with these types of sidelaps. The structural panels may be provided with an edge having a "lower lip" with two layers, and an opposite edge having an "upper lip" with two layers. Individual panels may be coupled together by placing the upper lip of a first panel over the lower lip of an adjacent panel, thus creating an un-joined sidelap. The lips may have nested portions for helping to place one lip over the other. The panels may be operatively coupled through various couplings configurations, such as fasteners, welding, cutting the sidelap, or the like. The present invention improves the shear strength of the structural panel system and reduces costs.