A slab is fabricated of concrete positionable adjacent to a side wall of a manufactured home. The slab has a periphery. The periphery forms a lower flange. A dome is positioned upon the slab. The dome has a flat face. The flat face is positionable in contact with the side wall. The flat face is formed with an opening in facing contact with the side wall. The dome has a peripheral flange remote from the opening. The peripheral flange of the dome is concentric with and smaller than the peripheral flange of the slab.