An extension support member includes a bracket or web having a first planar portion or leg, a second planar portion or leg, an acute, concave angle between the first planar portion or leg and the second planar portion or leg, and a bend or backbone joining the first planar portion or leg to the second planar portion or leg. The extension support member also includes is a first mounting portion or tab joined to the second planar portion or leg via the bend or backbone at a first, convex obtuse angle and a second mounting portion or tab joined to the first planar portion or leg via the bend or backbone at a second obtuse, convex angle. The first mounting portion and the second mounting portion are located at opposite ends of the bracket or web.