Section 27-501. Wall signs

(a)  Limitations. Wall signs shall not extend
  beyond the top or ends of the wall surface  on  which  they  are  placed
  unless  meeting all the requirements of this code regulating roof signs,
  projecting signs, or ground signs as the case may be. Wall  signs  shall
  not  project  beyond street lines except as permitted in subchapter four
  of this chapter.
    (b)  Materials.  Inside  the  fire  districts,  wall  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  wall  signs  exceeding  five hundred square feet. in
  facing or display area 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. Wall signs shall be constructed and supported to  resist
  loads  acting  in  any  direction  on  the  sign  in accordance with the
  provisions of subchapter nine of this chapter. Attachment  shall  be  by
  means  of  metal  anchors,  bolts,  or similar devices. Wooden blocks or
  anchorage with wood used in connection with screws or nails shall not be
  used, except in the case of wall  signs  attached  to  buildings  having
  walls of wood.
    (d) Fire department access. Wall signs that are, or have been, erected
  to  cover  doors  or  windows  required by this code for fire department
  access to existing buildings shall be provided  with  access  panels  as
  required  by  section  27-292  of article two of subchapter four of this
  chapter. Existing wall signs shall be altered or otherwise  arranged  to
  comply  with  this  requirement  on  or  before December sixth, nineteen
  hundred seventy.