(a) As of right. Lawful preexisting nonconforming single-family dwellings and two-family houses may be altered, reconstructed, extended or structurally changed as a matter of right upon a determination by the Building Commissioner that a proposed alteration, reconstruction, extension or change would not increase or intensify the existing nonconforming nature of the dwelling or house in question. Upon such a determination, an application to the Board of Appeals for a special permit need not be made, and the owner may apply to the Building Commissioner for a building permit.

(b) By special permit. Upon a determination by the Building Commissioner that a proposed alteration, reconstruction, extension or structural change to a lawful preexisting nonconforming single-family dwelling or two-family house would increase or intensify the existing nonconforming nature thereof, the owner of such dwelling or house shall be required to apply to the Board of Appeals for a special permit to allow such alteration, reconstruction, extension or structural change. The Board may grant a special permit to allow such alteration, reconstruction, extension or structural change; provided, however, that the Board determines, by a finding under MGL c. 40A, § 6, that the proposed alteration, reconstruction, extension or structural change shall not be substantially more detrimental to the neighborhood than the existing nonconforming structure or use; and provided, further, that any such special permit shall comply with the requirements of the Zoning Ordinance of the City of Marlborough, as may be amended from time to time, including but not limited to § 650-12, entitled "Nonconforming uses," as well as § 650-59A(1) pertaining to the powers and duties of special permit granting authorities. Application for a special permit to allow such alteration, reconstruction, extension or structural change shall be made to the Board pursuant to the procedures set forth in Subsection C(5) of this § 650-58.

See Permitting for information on permits.