A construction system definable in terms of an X, Y, and Z coordinate axes which provides a first part having a hollow four-walled web elongate in the Z axis, having a securement flange on the upper XZ base of the elongate Z axis member; and a second part having at least one open end for complemental engagement of the first part wherein the second part may fit over distal ends of said first part in which a cross-section of the second part is generally that of the first part, but wide and tall enough to allow the first part to slip within the second part, and said second part having an opposite end of said opening, wherein said second part securing the first part to a structural support.