Section 27-326. Lintels

Lintels  over  openings  wider  than four feet in
  masonry walls, other than in walls  of  masonry  veneer  on  wood  frame
  structures,  shall  be  fire  protected as required by section 27-324 of
  this article for structural members, when the full load over the opening
  is not relieved by a masonry arch of required strength. The  members  of
  an  assembled  metal lintel that support only outer face masonry that is
  securely bonded or anchored to  backing  need  not  be  fire  protected,
  provided  that  the  inner members of the assembly support the full load
  imposed  upon  the  lintel  and  are  fire  protected  as  required  for
  structural members supporting masonry.
    (a)  Stone  Lintels.  The use of stone lintels on spans exceeding four
  feet shall not  be  permitted  unless  supplemented  by  fire  protected
  structural members or masonry arches of the required strength to support
  the superimposed loads.