A legal nonconforming building or structure existing at the time of the adoption of this title may be continued and maintained except as otherwise provided in this chapter.

A legal nonconforming building or structure shall not be added to or enlarged in any manner unless the building or structure, including additions and enlargements, is made to conform to all of the regulations of the district in which it is located; provided, that from and after the time of enlargement or addition the off-street parking requirements of the district in which the building or street is located are met and further encroach into any required setback beyond the building line established by the existing building or structure. However, if a building or structure is legally conforming as to use, but legally nonconforming as to yards or height or off-street parking space, the building or structure may be enlarged or added to; provided that, the enlargement or addition complies with the off-street parking requirements of the district in which the building or structure is located. No legally nonconforming building or structure shall be moved in whole or in part to another location on the lot unless every portion of the building or structure is made to conform to all of the regulations of the district in which it is located. Nothing in this section shall prohibit the expansion of the legal nonconforming use if the property is for a single-family dwelling and any expanded use complies with yard, height, lot coverage and use requirements for LDR zoning.

The legal nonconforming use of a legal nonconforming building or structure may be continued, except in all residential districts, and a legal nonconforming building or structure which was arranged and designed, and which is used for a use permitted only in a commercial or industrial district, shall be removed or it shall be altered and converted to a legal conforming building or structure designed and used for a use permitted in the district in which it is located, within 1 year after the termination of the respective periods of time set out hereinafter. Such periods shall be computed from the effective date of the ordinance codified herein. The following are established as the reasonable periods for amortization of the normal, useful life of each class of building and type of construction above the foundations, the types of construction being defined and specified in the current building codes adopted by the City of Rapid City:

A legal nonconforming building, structure or portion thereof, which is or hereafter becomes vacant and remains unoccupied for a continuous period of 1 year shall not thereafter be occupied except by the uses which conform to the use regulations of the district in which it is located.

Where an individual lot is held in separate ownership and complies with all applicable zoning and subdivision requirements, except for the minimum lot size requirement of the zoning district in which it is located, such lot may be developed for any permitted uses or conditional uses specified in that zoning district except for duplex or multi-family development.

Nothing herein contained shall require any change in the overall layout, plans, construction, site or designated use of any development, building, structure or part thereof, for which official approvals and required building permits have been granted before the enactment of this title. If the construction, conforming with such plans shall have been started prior to the effective date of the ordinance codified herein and completion thereof carried on in a normal manner within the subsequent 1-year completion except for reasons out of the builders control.