Continuation of nonconforming use. Any use of land, or a building or structure or part thereof, existing at the time this chapter or any amendment hereto becomes effective, may be continued, although such building or structure or use does not conform to the provisions of the district in which it is situated.

Discontinuance of use. When a nonconforming use has been discontinued for not less than one year or destroyed wholly or in part by fire or other cause, it may be reconstructed if construction begins within one year. After this period it shall not be reestablished, and future use shall be in conformity with the provisions of this chapter.

Change of nonconforming use. No nonconforming use shall be changed to other than a conforming use for the district in which it is situated.

Maintenance of a nonconforming use. A nonconforming use is hereby required to be maintained in such condition as will not constitute a danger of the safety, health or general welfare of the public. Alterations and extensions of the nonconforming use may be authorized by the Board of Appeals following a public hearing, provided that such alterations or extensions do not violate any provisions of this chapter regarding yards, lot area or lot coverage for the district in which it is situated, or to increase any existing violation of such provisions.

Temporary permits may be issued by the Zoning Enforcement Officer for a period not exceeding one year for nonconforming uses incident to housing and construction projects, including such structures and uses as storage of building materials and machinery, the processing of building materials, and a real estate office located on the tract being offered for sale, provided such permits are conditioned upon agreement by the owner or operator to remove the structure or structures or use upon expiration of the permit. Such permits may be renewed upon application to the Board of Appeals and proof of hardship shown for an additional period not exceeding one year.

Except as may otherwise be permitted by this chapter, it shall be unlawful to conduct any temporary outdoor sales from the right-of-way of any roadway, yard or parking lot.

"Temporary" shall mean businesses that are transportable and not located on the vendor's own property.