A door system including a sectional door having adjacent panels hinged for moving between a closed vertical position and an open horizontal position, the adjacent panels including at least a top panel, an intermediate panel, and a bottom panel, sets of lower rollers provided proximate the interfaces of the adjacent panels and proximate the lower extremity of the bottom panel, upper rollers carried proximate the upper extremity of the top panel, vertical track assemblies including vertical track sections and reverse angles, the reverse angles interconnecting with a header to form a door mounting system, transitional track members having first track sections and second track sections, and dual horizontal track assemblies having lower horizontal track sections and upper horizontal track sections, wherein the lower rollers are carried by the vertical track sections, the first track sections and the lower horizontal track sections and the upper rollers are carried by the second track sections and the upper horizontal track sections.