A box for a plumbing fixture includes first and second side panels, an end panel, and first and second corner panels, which are interconnected at parallel joints. In a first configuration, the box is collapsed and generally planar, the first side panel being folded at a central crease closer to a forward end than a rearward end thereof, and the second side panel being folded at a central crease closer to a forward end than a rearward end thereof. In a second configuration, the box is expanded such that (a) a cavity is defined between the first side, second side, end, first corner, and second corner panels, (b) the first and second side panels are generally planar, and (c) a sum of angles between the end and first corner panels and between the end panel and second corner panels is greater than 180 degrees.