No building or structure in a mobile home park shall be constructed to a height of more than twenty-five (25) feet above the ground, and no mobile home shall be placed in such a manner as to be directly above another one. This provision shall not be construed in such a manner as to prohibit a two (2) story mobile home, nor a mobile home designed in such a manner that a second story may be attached to the lower portion after the lower portion has been placed in position on the mobile home site.