A plurality of intermediate deck boards span across joists in a decking system in which each deck board includes a lower frame portion extruded of a first material and an insert body inserted into the top side of the lower frame portion which is formed of a second material. Additional extruded members are used as starting and ending rows of the deck boards and as finishing boards across the ends of the intermediate deck boards, in which each of the deck boards defines a respective portion of an upper deck surface of the assembled deck structure. The perimeter extruded members include mounting channels for mounting a railing structure thereon.