A method of assembling panels, an elongated rail, and a rail and cap assembly for assembling panels are disclosed. A one-piece elongated rail comprises a bottom, a pair of sides extending from the bottom, a pair of walls located between the sides and perpendicular to the bottom, and a central channel floor extending between the parallel walls and parallel to the bottom. A central channel is formed between the walls and delimited by the central channel floor. Two lateral channels are each formed between one of the sides and one of the walls. The assembly includes the rail and a cap, the cap having a top and an opposite projection configured for insertion in the central channel of the rail. The rail and the cap may be made by extrusion. The method involves adjoining panels to the rail and mounting the cap thereon.
