911 does prescribe certain minimum standards specific to address plaques to guarantee ease of visibility. These include the mandatory requirement for all principal structures to display house numbers such that the bottom of the house number sign is at least one foot off of the ground. The house number sign blades have to be a minimum of 4” and a maximum of 9” in height. The lettering shall be a minimum of 3” high in reflective material and in contrast to the sign’s background color. 911 also requires that obstructions, including but not limited to snow, be removed to ensure the sign is visible for a distance of not less than 50 ft in both directions. The number plaques can either be mounted flat on the wall facing the addressed street or no more than 50 ft from the edge of the street shoulder, whichever is closer to the street. These are some general requirements and the 911 standards may vary across locations. Please be sure to check what applies to your situation.