A. 
No building or structure shall be erected or used and no premises shall be used except as set forth in the Table of Use Regulations included at the end of this chapter.
B. 
Permitted uses and uses allowed by special permit from either the Zoning Board of Appeals or Planning Board shall be in conformity with the provisions of § 675-1170, Special permits, and shall not be detrimental or offensive or injurious to properties in the same or adjoining districts by reason of dirt, dust, glare, odor, fumes, smoke, gas, sewage, refuse, noise, vibration or danger of explosion or fire.
C. 
See § 675-1010, Site plan review, for applicability of site plan review.
A. 
Applicability. This chapter 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 required by MGL c. 40A, § 5, at which this chapter, or any relevant part thereof, was adopted. Such prior, lawfully existing nonconforming use and structures may continue, provided that no modification of the use or structure is accomplished unless authorized hereunder.
B. 
Nonconforming uses.
(1) 
The Zoning Board of Appeals may award a special permit to change a nonconforming use in accordance with this section only if it determines that such change or extension shall not be substantially more detrimental than the existing nonconforming use to the neighborhood. The following types of changes to nonconforming uses may be considered by the Zoning Board of Appeals:
(a) 
Change or extension of the use not substantially more detrimental than the existing nonconforming use to the neighborhood.
(b) 
Change from one nonconforming use to another, less detrimental, nonconforming use.
(2) 
Reversion to nonconformity. No nonconforming use shall, if changed to a conforming use, revert to a nonconforming use.
C. 
Nonconforming structures. The Zoning Board of Appeals may award 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.
(1) 
The following types of changes to nonconforming structures may be considered by the Zoning Board of Appeals:
(a) 
Reconstructed, extended or structurally changed.
(b) 
Altered to provide for a different purpose or for the same purpose in a different manner that is not substantially more detrimental than the existing nonconforming use or structure to the neighborhood.
(2) 
Variance required. Except as provided in Subsection C(4) and (5) below, the reconstruction, extension or structural change of a nonconforming structure in such a manner as to increase an existing nonconformity or create a new nonconformity shall require the issuance of a variance from the Zoning Board of Appeals.
(3) 
Special permit required. Except as provided in Subsection C(4) and (5) below, the reconstruction, extension or structural change of a nonconforming structure where there is an extension of an exterior wall at or along the same nonconforming distance within a required yard, then the Zoning Board of Appeals may award a special permit.
(4) 
Reconstruction after catastrophe or demolition. Except as provided for in Subsection C(5) below, a nonconforming structure may be reconstructed after a catastrophe or after demolition in accordance with the following provisions:
(a) 
Reconstruction of said premises shall commence within two years after such catastrophe or demolition.
(b) 
The building(s) as reconstructed shall be located on the same footprint as the original nonconforming structure, shall be only as great in volume or area as the original nonconforming structure, and shall meet all applicable requirements for yards, setback, and height.
(c) 
If the proposed reconstruction would cause the structure to exceed the volume or area of the original nonconforming structure or exceed applicable requirements for yards, setback, and/or height or cause the structure to be located other than on the original footprint, a special permit shall be required from the Zoning Board of Appeals prior to such demolition.
(5) 
Nonconforming single- and two-family residential structures. Nonconforming single- and two- family residential structures may be reconstructed, extended, altered, or structurally changed upon a determination by the Building Commissioner that such proposed reconstruction, extension, alteration, or change does not increase the nonconforming nature of said structure.
(a) 
The following circumstances shall not be deemed to increase the nonconforming nature of said structure:
[1] 
Alteration to a structure located on a lot with insufficient area which complies with all current setback, yard, building coverage, and building height requirements.
[2] 
Alteration to a structure located on a lot with insufficient frontage which complies with all current setback, yard, building coverage, and building height requirements.
[3] 
Alteration to a structure which encroaches upon one or more required yard or setback areas, where the alteration will comply with all current setback, yard, building coverage and building height requirements.
(b) 
If the Building Commissioner determines that the nonconforming nature of such structure would be increased by the proposed reconstruction, extension, alteration, or change, the Zoning Board of Appeals may, by special permit, allow such reconstruction, extension, alteration, or change where it determines that the proposed modification will not be substantially more detrimental than the existing nonconforming structure to the neighborhood.
D. 
Abandonment or nonuse. A nonconforming use or structure which has been abandoned, or not used for a period of two years, shall lose its protected status and be subject to all the provisions of this chapter.