US Patent 9739054 Two-piece track system

A fire-rated receiver channel includes at least one intumescent or other fire-resistant material strip. The receiver channel can nest with a framing member, such as metal tracks, headers, header tracks, sill plates, bottom tracks, metal studs, wood studs or wall partitions, and placed at a perimeter of a wall assembly to create a fire block arrangement. In other arrangements, a track assembly includes two nested tracks, an inner track and outer track. The assembly is designed so that the outside width of the outer track is equal to or less than the outside width of the inner track to present a substantially flush external surface for attachment of exterior sheathing elements when the assembly is used in an external wall.