and existing buildings shall have their address numbers, building
numbers, or building identification placed in a position to be plainly
legible and visible from the street or road fronting the property. The
numbers and letters shall contrast with their background and shall be a
minimum of six inches in height for commercial buildings and three
inches in height for residential buildings. The numbers and letters
shall have a minimum stroke width of 0.5 inches (12.7 millimeters).