Section 27-506. Temporary signs

(a) Materials. Temporary signs not more than
  five  hundred  square  feet  in  area  may be constructed of combustible
  materials. Temporary signs more than one hundred  square  feet  in  area
  shall  be  made  of  rigid  materials with rigid frames. Temporary signs
  shall be securely attached to their supports, and shall  be  removed  as
  soon  as they are torn or damaged, but in no case later than thirty days
  after their erection.
    (b) Limitations. Temporary signs of combustible  materials  shall  not
  extend  more  than  one  foot  over, or into, a street, except that when
  permitted by the department  of  transportation,  temporary  banners  or
  signs  of combustible materials may be suspended from buildings or poles
  to extend across streets, and except that temporary signs of combustible
  materials constructed without a frame may be attached flat  against,  or
  suspended  from  the  fascia  of  a canopy or marquee, provided that the
  lowest part of any such sign is at least nine feet above the  ground  or
  sidewalk level.