The ornamental design for a loftflooringsystemsupportleg, as shown and described.
FIG. 1 is a front view of a loft flooring system support leg;
FIG. 2 is a side view of a loft flooring system support leg;
FIG. 3 is a top down view of a loft flooring system support leg; and,
FIG. 4 is an isometric view of two loft flooring system support legs configured on joist and having a spanning element configured from the top of one loft flooring system support leg to the other loft flooring system support leg.
The joists and spanning elements shown in FIG. 4 are shown in broken lines for the purposes of illustrating environmental structure and form no part of the claimed invention.