The ornamental design for a loftflooringsystemsupportleg, as shown and described.
FIG. 1 is an isometric view of a loft flooring system support leg;
FIG. 2 is an isometric view of a loft flooring system support leg;
FIG. 3 is a side view of a loft flooring system support leg;
FIG. 4 is a front view of a loft flooring system support leg;
FIG. 5 is a top down view of a loft flooring system support leg; and,
FIG. 6 is an environmental isometric view of the loft flooring system support leg.
The broken lines shown in FIGS. 1, 2 and 4 illustrate portions of the loft flooring system support leg and form no part of the claimed design. The broken lines showing of the spanning elements, in FIG. 6, represent the environment of the claimed design and forms no part thereof.