The purpose and intent of this title is to lessen congestion in the streets, to conserve health, to secure safety from fire, flood, panic and other dangers, to provide adequate light, air and space, to prevent overcrowding of land, to avoid undue concentration of population, to encourage housing for persons of all income levels, to facilitate provision of transportation, water supply, drainage, sewerage, schools, parks, open space and other public requirements, to conserve the value of land and buildings, including the conservation of natural resources and the prevention of blight and pollution of the environment, to encourage the most appropriate use of land throughout the city, and to preserve and increase amenities by the promulgation of regulations to fulfill these objectives.

The interpretation and application of the provisions of this title shall be held to the minimum requirements adopted for the promotion of the public health, safety, comfort, convenience and general welfare. It is not intended by this title to repeal, abrogate, annul or in any way to impair or interfere with any existing provisions of the law or ordinance or any rules, regulations or permits previously adopted or issued, or which shall be adopted or issued pursuant to law relating to the use of buildings or premises, nor is it intended by this title to interfere with or abrogate or annul any easements, covenants or other agreements between parties; provided, however, that where this title imposes a greater restriction upon the use of buildings or premises or upon the height of buildings or requires larger yards, or other open spaces, than are imposed or required by such existing provisions of law or ordinance, or by such rules, regulations or permits, or by such easements, covenants or agreements, the provisions of this title shall control.

No building shall, after the effective date of the ordinance from which this title derives, be erected, constructed or placed; no existing building shall be moved, altered, rebuilt, converted, added to or enlarged; and no land shall be used for any purpose other than listed as permitted uses in each zone except in conformance with the requirements set forth in this title; nor shall any required open space or yard contiguous to any building be encroached upon or reduced in any manner. In the event of any such unlawful encroachment or reduction, such building or uses are in violation of this title, and the certificate of occupancy shall automatically become void.

The provisions of this title shall not apply to customary local utility distribution or collection lines for water, gas, telephone or electric service. All facilities such as pumping stations, repeater stations and electric substations which require a building above grade shall be subject to the yard requirements.