The present application is generally directed to multifunctional flashing devices suitable for installation of lap siding. Flashing devices include a flashing section, a removable supporting section, and one or more alignment features configured to facilitate positioning of the flashing devices adjacent to an installed course of lap siding. The flashing devices may be fastened to a building substrate adjacent to an installed course of lap siding, at locations corresponding to butt joints of an additional course of lap siding. The supporting sections of the flashing devices are configured to retain and support additional cladding elements in position for installation. When the additional cladding elements have been fastened to the building substrate, the supporting section may be removed from the flashing section.