Whenever district boundaries follow streets or highways, the center lines of the right-of-way of such streets and highways shall be considered the district boundaries. Whenever district boundaries on the Zoning Map follow natural features such as streams or waterways, the center of such natural features shall be considered to be the district boundaries.

Whenever district boundaries are so indicated that they apparently follow lot lines, such lot lines shall be considered the district boundaries.

Where a district boundary line does not follow streets, streams or lot lines, its position shall be shown on the Zoning Map by a dimension expressing its distance in feet from a street line or other boundary line as indicated or by use of the scale appearing on the Zoning Map.

Where a district boundary line divides a lot in single ownership at the time of the passage of this chapter, the standards for the less restricted portion of such lot shall extend not more than 50 feet into the more restricted portion, provided that the lot has frontage on a street in the less restricted district.

In case of uncertainty as to the true location of a district boundary line in a particular instance, the Board of Appeals shall render a determination with respect thereto.

No building shall be erected, reconstructed or altered, nor shall any open space surrounding any building be encroached upon or reduced in any way, except in accordance with the yard, lot area and building location regulations of this chapter for the district in which such building is, or is proposed to be, located or where such open space or land is located. No building shall be erected, constructed, reconstructed or altered, and no land or building or part thereof shall be used for any purpose or in any manner, except as permitted for the district in which such building or land is located.

No yard or other open space surrounding any building located in conformance with this chapter shall be considered as providing the requisite yard or open space area for another building. Likewise, no yard or open space on one lot shall be considered as providing a yard or required open space for a separately owned building on any other lot.

The regulations listed for each district are hereby adopted as prescribed for such district, subject to the provisions of other applicable sections of this chapter, and, unless otherwise indicated, shall be deemed to be the minimum requirements in every instance of their application.

Existing lots of record. A permitted or conditional use may be constructed or placed on any lot of record where provided for in the various districts even if said lot is less than the minimum area required for building lots in the district in which it is located, provided that the following conditions exist or are met:

Number of structures on a lot. No more than one principal structure on a lot shall be permitted unless lot area and yard requirements are met for each, including street frontage, except under the following conditions:

Corner lot. On a corner lot in any district where a front yard is required, a yard shall be provided on each street equal in depth to the required front yard on such street. One rear yard shall be provided on each corner lot, and the owner shall designate the rear yard on his application for a permit.

Through lots. Where a single lot under individual ownership extends from one street to another parallel or nearly parallel street or alley, the principal structure shall be erected to face the street on which those adjoining structures face.

Visibility at street corners. On a corner lot in any district where a front yard is required, no fence, wall, hedge or other structure or planting more than three feet in height shall be erected, placed or maintained which obstructs visibility of vehicular traffic within the triangular area formed by the intersecting street right-of-way lines and a straight line joining said lines at points 30 feet distant from the point of intersection, measured along said lines.

Front yard exception. When a vacant lot in any district is situated between two improved lots, the front yard of the vacant lot shall have a depth equal to the average depth of the front yards of the two adjoining improved lots, but not less than 20 feet from the street right-of-way or 50 feet from the road center line, whichever is greater.

Transition yard requirements. Where a residential district abuts a nonresidential district, there shall be provided in the nonresidential district for a distance of 50 feet from the district boundary line a front yard at least equal in depth to that required in the residential district. Where the side or rear yard in a residential district abuts a side or rear yard in a nonresidential district, there shall be provided along such abutting line or lines in the nonresidential district a side or rear yard at least equal in depth to that required in the residential district. In no case, however, shall the abutting side or rear yard be less than 10 feet.

Projections into required yards. Such projections are permitted only as follows:

Walls, fences and hedges. The yard requirements of this chapter shall not prohibit any retaining wall nor any fence, wall or hedge otherwise permitted, provided that in any residential district such fence, wall or hedge shall be no closer to any front lot line than two feet and shall comply with visibility at street corners as provided in this section.

Screen planting. Any use required by this chapter to be screened shall provide a fence, screen or landscaping sufficient to obscure such use from view from abutting properties or from the public right-of-way. Plans and site design for the installation of such fencing or screening as is required by this chapter shall be reviewed and approved by the Planning Board prior to issuance of a zoning permit. Any fencing or screening installed in accordance with this section shall be maintained in good order to achieve the objective of the same. Failure to maintain fencing or to replace dead or diseased plant materials shall be considered a violation of this chapter.

Width of side yard may be reduced. When authorized by the Board of Appeals, the width of one side yard may be reduced, provided that the sum of the width of the two side yards is not less than the required minimum for both side yards, and further provided that the distance between the proposed structure and any structure, existing or proposed, on an adjacent lot is not less than the required minimum sum of the width of the two side yards. Such reduction may be authorized only when the Board of Appeals finds it to be warranted by the location of existing buildings or conditions or where it is conducive to the desirable development of two or more lots.

Accessory buildings. The number, height and location of accessory buildings shall be as follows:

Additional height requirements. No building or structure shall have a greater number of stories nor have an aggregate height of a greater number of feet than is permitted in the district in which such building or structure is located, except that the height limitations of this chapter shall not apply to belfries, church spires or other structures which are not used for human occupancy; nor to chimneys, ventilators, skylights, water tanks and necessary mechanical appurtenances usually carried above the roof level; nor to silos or other farm structures; nor to flagpoles, monuments, electrical transmission towers and cables. Such features, however, shall be erected only to such height as is necessary to accomplish the purpose for which they are intended. No advertising devise of any kind whatsoever shall be inscribed upon or attached to that part of any structure which extends above the height limitations.

Additions. A nonconforming structure or use which existed prior to the adoption of this code shall not be added to or enlarged unless such nonconforming structure or use is made to conform to the regulations of the district in which it is located.

Expansion of properties. A structure on a nonconforming lot, which was conforming prior to the adoptions of these regulations, will be permitted to be expanded/altered under the following circumstances:

Changes. A nonconforming structure or use may be changed or altered to provide a structure or use otherwise permitted in that district as provided in this chapter.

Discontinuance. Whenever a nonconforming structure or use has been discontinued, vacated or abandoned for a period of one year, any future structure or use shall be in conformity with the provisions of this chapter.

Removal. If any nonconforming structure or use is hereafter removed, the subsequent use of the land or structure shall conform to the requirements of the district in which it is situated.

Validity of permit. Any nonconforming structure or use for which a permit has been lawfully granted and on which construction, installation or location has been started and diligently prosecuted before the effective date of this chapter may be completed.

Wellhead Protection Overlay District. In addition to the other provisions within this section, any use, building or structure which existed lawfully at the time of enactment of the W-O District amendments may be continued unless those existing uses, buildings or structures add new specific activities which are regulated in § 300-15, or those existing uses, buildings or structures expand existing activities that would result in the site plan review criteria being exceeded. Any such addition or expansion shall be done in conformance with the regulations of the W-O District.