Also known as a set back line, a building line is the distance from the ends and the sides of a city lot beyond which building construction is not allowed to extend. The exact location of the building line is determined by the municipality in which the lot is located and may vary depending on local zoning laws that apply in that section of town. The institution of designated building lines is helpful in laying out the platting or positioning of city blocks and the city streets connecting those blocks for city streets in both commercial and residential areas. From this perspective, a building line makes it easier to incorporate plans for inclusion of utility lines, sidewalks and still maintain a uniform look to the area.
It is important to note that the local jurisdiction determines the type of building line that will apply to a given area of the municipality. Typically, building construction in business districts must comply with lines that take into account the need for rail traffic, roads, and even pedestrian traffic within the immediate area. In like manner, residential areas will prohibit construction of fences and other structures along the front of housing lots, making it possible to allow space for the installation of sidewalks in those neighborhoods.
While the building line along the front of a city lot is likely to be the same for every lot in the immediate area, there may be some exceptions. For example, a municipality may allow a health facility such as a hospital to extend construction such as a covered receiving area closer to the street, while requiring that a business a few blocks away limit construction to areas further back on the lot. The intended use for the structure may play a role in determining the location of the building line, with concerns for the safety of citizens being considered along with allowing for uniform platting, or mapping a layout, of the area.
In some nations, it is not uncommon for a building line to also be identified as provisions in wills or deeds, Housing developments and planned neighborhoods often have some input into where a set back line for a given street is established, making it easier to maintain the look and feel of the development. Changing a building line is usually not an easy task, but it can be done with the approval of the local zoning commission. Changes are rarely granted simply because a property owner requests them. Should the commission find there are significant benefits for either granting an exception to allow construction beyond the current line, or that shifting the line would in some way improve the prospects for a given geographical area of the city, the chances of an adjustment taking place are greatly enhanced.