A decking system for placement on a subassembly having at least two spaced
apart joists. A plurality of elongated tubular elements for placement in
lateral interlocking engagement with each other transversely of and
spanning the distance between the joists. Each of said plurality of
elements having a top portion, a bottom portion, and first and second
side walls connecting said top and bottom portions. The top portion
extends laterally beyond the first side wall and has formed thereon a
downwardly extending longitudinal flange. The bottom portion extends
laterally beyond the second side wall and has formed thereon an upwardly
extending longitudinal wall defining an upwardly opening channel adjacent
the second side wall adapted to receive therein a watertight relation the
downwardly extending longitudinal flange. The bottom portion having
formed therein a plurality of apertures intermediate the second side wall
and the upwardly extending longitudinal wall, adapted for the insertion
of fasteners therethrough for engagement with the joists.