Except as otherwise provided in this article, the lawfully permitted use of land or buildings existing at the time of the adoption of this chapter, including uses of land or buildings under a special permit heretofore issued by the Board of Appeals, may be continued, although such use does not conform to the standards specified in this chapter for the zone in which such land or building is located. Said uses shall be deemed nonconforming uses, except as otherwise provided by § 300-177.

Where no building is involved, the nonconforming use of land may be continued; provided, however, that no such nonconforming use shall be enlarged or increased, nor shall it be extended to occupy a greater area of land than that occupied by such use at the time of adoption of this chapter, unless specifically allowed by other provisions in this chapter, nor shall any such nonconforming use be moved in whole or in part to any other portion of the lot or parcel of land occupied by such nonconforming use at the time of adoption of this chapter; provided, further, that if such nonconforming use of land or any portion thereof ceases for any reason for any continuous period of more than 90 days or is changed to a conforming use, any future use of land shall be in conformity with the provisions of this chapter. No nonconforming use of land shall be changed to another nonconforming use.

A building that is conforming in use but does not conform to the height, yard or land coverage requirements of this chapter shall not be considered to be nonconforming within the meaning of § 300-172. No permit shall be issued that will result in the increase of any nonconformity in height, yard, space or land coverage.

If any building legally nonconforming in use shall be destroyed by any means, it may be repaired or reconstructed to the same size and on the same location or at the location specified for new buildings in the district in which such use is located. All repairs or reconstruction for such nonconforming use shall be completed within two years of the date on which the destruction occurred.

Regardless of any other provisions of this chapter, every sign which, after the adoption of this chapter, may exist as a nonconforming use in any district shall be discontinued and removed or changed to conform to the standards of said district within a period of two years from August 19, 1958. Subject to the provisions of this section, all of the provisions of this article shall apply to every nonconforming sign. Signs for which a special permit has been issued are not considered nonconforming signs.

Any building, extension or alteration for which a permit has been duly granted, the construction of which has been started before August 19, 1958, and the ground story framework of which, including the second tier of beams, has been completed within one year after the adoption of this chapter or amendment thereto, may be completed in accordance with plans on file with the Building Inspector, provided that such construction is diligently prosecuted and the building is completed within two years of the adoption of this chapter.

Any use lawfully existing on August 19, 1958, in the district in which such use is classified herein as a special permit use shall, without further action, be deemed to be a conforming use in such zone (see § 300-170).

It is the intent of this section that all office uses in residential structures should be clearly incidental and accessory to the main use. All such existing offices in residential structures which are legally conforming at the time of the adoption of this section may continue, provided that a special use permit has been granted by the Zoning Board of Appeals in accordance with standards set forth in § 300-76. Application for such special use permit must be made within 90 days of the adoption of this section.