Every new and existing principal structure on a premise shall have the address number affixed thereto. The numbers shall be 6 inches in height for structures built per the provisions of the IBC with the exception that individual dwelling units in multi-family structures are allowed numbers to be a height of 3 inches. The numbers for buildings constructed per the provisions of the IRC shall be 4 inches in height. The numbers shall be of visible from the public right of way and of contrasting color from the principal structure. Where required by the fire code official, address identification shall be provided in additional approved locations to facilitate emergency response. Where access is by means of a private road and the building address cannot be viewed from the public way, a monument, pole or other approved sign or means shall be used to identify the structure. Address numbers may be required to be increased in height and stroke width at the direction of the Fire Code Official. Address identification shall be maintained.