Any increase in area, lot coverage, frontage, width, yard or depth requirements shall not apply to a lot for single-family and two-family residential use which at the time of the lot's recording, or endorsement, whichever occurred sooner, was not held in common ownership with any adjoining land, conformed to then-existing zoning requirements, and had at least 5,000 square feet of area and 50 feet of frontage. For the purpose of this section, lots shall not be considered to be held in common ownership with adjoining land if each single lot of record adjoins another solely along the rear lot line of each lot, so long as each such lot has frontage on an improved public way constructed (or adequately bonded to be constructed) to the City's specifications, or on an improved private way constructed to the City's specifications. For the purpose of this section, lots shall not be considered to be held in common ownership with adjoining land if each lot has at least 5,000 square feet of area and 50 feet of frontage and was not held in common ownership as of January 1, 1980.

The Zoning Board of Appeals may grant a special permit for the division of any single lot of record containing two or more residential dwelling buildings existing continuously since 1954, provided they be divided into separate lots, each of which contains a separate residential dwelling building and the Zoning Board finds that the division is made in a way to maximize the use of the proposed lots, specifically access, parking and yard area.

Change or substantial extension of the use.

Change from one nonconforming use to another, equally appropriate or more appropriate nonconforming use.

The Zoning Board of Appeals may grant a special permit to reconstruct, extend, alter, or change a nonconforming structure in accordance with this section only if it determines that such reconstruction, extension, alteration, or change shall not be substantially more detrimental than the existing nonconforming structure to the neighborhood. The following types of changes to nonconforming structures may be considered by the Zoning Board of Appeals:

The reconstruction, extension or structural change of a nonconforming structure (except nonconforming single- and two-family residential structures) in such a manner as to increase an existing nonconformity, or create a new nonconformity shall require a variance; provided, however, that the extension of an exterior wall at or along the same nonconforming distance within a required yard shall require the issuance of a special permit from the Board of Appeals.

Any of the following circumstances shall not be deemed to increase the nonconforming nature of said structure:

In the event that the Building Inspector determines that the nonconforming nature of such structure would be increased by the proposed reconstruction, extension, alteration, or change, the Board of Appeals may, by a finding (which shall not require a supermajority required by MGL c. 40A, §  6), allow such reconstruction, extension, alteration, or change where it determines that the proposed modification will not be substantially more detrimental to the neighborhood than the existing nonconforming structure.

A nonconforming use or structure that has been abandoned, or not used for a period of two years, shall lose its protected status and be subject to all of the provisions of this chapter.

Notwithstanding the above, a nonconforming structure that has been abandoned, or not used for a period of two years, may reestablish its protected status upon the grant of a special permit by the Board of Appeals.