All buildings heretofore erected and hereafter erected shall be provided by the owners thereof, in a conspicuous place thereon, the line of the street upon which the building fronts, with the correct number of that building to the plan herein adopted, which number shall be in Arabic figures and shall be either painted upon some good and substantial material, and shall be sufficiently large and distinct as to be easily read from the street. Numbers written or printed upon paper or cardboard, or written with chalk or with pencil, shall not be a compliance with this section, but those buildings for the purposes of this section shall be deemed the same as though they had no number at all.
('71 Code, § 92.03)