Except as specifically provided herein, this bylaw shall not apply to structures or uses lawfully in existence or lawfully begun, or to a building or special permit issued before the first publication of notice of the public hearing on an amendment which may relate to such permit. It shall apply to any change or substantial extension of such use, to any construction, reconstruction, alteration, or relocation of such building or structure and to any building or special permit if the work so authorized has not commenced within six months of issuance.

A building or structure lawfully erected or located prior to the publication of first notice of a public hearing for an amendment of this bylaw shall not be affected by such amendment, even though such building or structure would thereafter no longer conform to this bylaw. Such building or structure shall not be reconstructed, extended, or altered except upon issuance of a special permit, as provided in Article XIII; however, non-conforming single-or two-family residences may be constructed, extended, or altered as long as such reconstruction, extension, or alteration does not increase the non-conformance thereof. Additions extending the non-conforming aspect at a distance less than required by this bylaw shall be deemed an increase in non-conformance.

When the non-conforming use of any building, structure, including signs, or premises has been or shall be discontinued for a period of two years, it shall not be reestablished, and the future use thereof shall be in conformity with this bylaw.