A welded structural assembly and method, in one form, includes an upper substrate, a lower substrate adjacent the upper substrate, a fastener, and a sealing member. The fastener includes a shank portion, a first head portion, and a second head portion. The shank portion extends through the upper substrate and into the lower substrate. The shank is welded to the lower substrate. The first head portion has an outer periphery and an underside. The second head portion is frangibly coupled to the first head portion. The sealing member is disposed under the first head portion between the upper substrate and the first head portion. The sealing member contacts the underside and extends beyond the outer periphery such that the sealing member extends radially outward beyond all points of the first head portion.