Section 27-503. Roof signs

(a)  Location. Roof signs shall be set back a
  minimum of six feet from the face of the walls of the building on  which
  they are erected.
    (b)  Materials.  Inside  the  fire  districts,  roof  signs  shall  be
  constructed entirely of noncombustible materials except as permitted  in
  sections  27-506 and 27-507 of this article. Outside the fire districts,
  the framework of roof signs exceeding fifteen  hundred  square  feet  in
  facing  or  display  area  or  having any part more than sixty-five feet
  above grade shall be constructed of noncombustible  materials,  and  the
  facing  of  such  signs  shall be noncombustible, except as permitted in
  sections 27-506 and 27-507 of this article.
    (c) Supports. Roof signs shall be constructed and anchored  to  resist
  loads  acting  in  any  direction  on  the  sign  in accordance with the
  provisions of subchapter nine of this chapter. Such signs  shall  be  so
  constructed as to leave a clear space of at least seven feet between the
  roof and the lowest part of the sign, and at least five feet between the
  vertical supports thereof.