No structure shall be erected or used, premises used, or lot changed in size or shape except in conformity with the requirements of this section, unless exempted by this chapter or by statute.
The following shall apply when calculating dimensional requirements:
181.4121. 
Lot area. Lot area shall be determined by calculating the area within a lot, including any area within the lot over which easements have been granted, provided that no area within a street shall be included in determining minimum lot area.
181.4122. 
Frontage. Frontage shall be measured in a continuous line along the side line of a street between the points of intersection of the side lot lines with the street.
A. 
Frontage for a corner lot may be measured either to the point of intersection of the extension of the side line of the rights-of-way or to the middle of the curve connecting the side line of the intersecting streets.
B. 
If a lot has frontage on more than one street, the frontage on one street only may be used to satisfy the minimum lot frontage.
181.4123. 
Lot width. Lot width shall be determined by measuring the diameter of the largest circle which can be located at all points along a continuous but not necessarily straight line from the lot frontage to the principal structure on the lot (or the front yard setback if there is no structure) without the circumference intersecting the side lot lines.
181.4124. 
Corner clearance. On a corner lot in any district, in order that visibility is unobstructed at intersections, no sign fence, wall, tree, hedge, or other vegetation between three and eight feet above the established street grades shall be erected, placed or maintained within the triangular area formed by the intersecting street lines and a straight line adjoining such street lines at points which are 20 feet distance from the point of intersection measured along such street lines.
181.4125. 
Lot Shape. No lot in a residential zoning district shall be created to be so irregularly shaped or extended that it has a lot shape factor less than .40. In determining the lot shape factor for rear lots, the formula shall not include the perimeter or area of the access strip. The access strip shall be defined as that section of a lot which connects the buildable area of a rear lot with its frontage. For the purposes of determining a lot shape factor, access strips shall be measured from where the side lot lines meet the frontage line and end where the side lot lines widen to the minimum required frontage width of the zoning district in which the lot is located. The lot shape factor is defined as the lot area multiplied by 16 and divided by the square of the lot perimeter.
Lot Shape Factor Formula: P = lot perimeter and A = lot area.
Lot Shape Factor = 16(A)/P2
181.4126. 
Front yards. Front yards shall be the distance, measured in a straight line, between the lot frontage and the nearest point of the principal building or any structure attached to the principal building, including garages. A lot having frontage on two or more streets shall have two or more front yards, each of which shall comply with the requirements of the front yard provisions. In no case shall any building or structure be located closer to the sideline of a street than the minimum required front yard.
181.4127. 
Side and rear yards. Side and rear yards shall be the distance, measured in a straight line, from the nearest point of any principal building or structure to each side or rear lot line.
181.4128. 
Merging of Nonconforming Lots. Nonconforming lots held in common ownership with contiguous lots shall be considered merged for zoning purposes
181.4131. 
Height in feet shall be the vertical distance measured from the mean of the finished ground level adjoining the entire structure to the highest extension of any part of the structure.
181.4132. 
Structures such as smokestacks, chimneys, flagpoles, silos and other similar structures; the architectural elements of a building such as cupolas, steeples; wind energy systems authorized under this chapter, and temporary testing towers for the purpose of testing the wind speeds to determine the potential for wind energy turbines, are exempt from the height restrictions of this chapter, except that testing towers shall be-allowed for a period not to exceed two years from its installation, except as this time may be extended by special permit from the Planning Board.
On a corner lot in any district, in order that visibility is unobstructed at intersections, no sign fence, wall, tree, hedge, or other vegetation between three and eight feet above the established street grades shall be erected, placed or maintained within the triangular area formed by the intersecting street lines and a straight line adjoining such street lines at points which are twenty feet distance from the point of intersection measured along such street lines.
181.4211. 
Toolsheds, patios, small-scale ground-mounted solar energy systems and similar facilities and structures not exceeding 120 square feet may be located in any portion of a rear yard, provided that they are set back three feet from the side or rear lot line and, further, provided that not more than 25% of the total side or rear area is covered by buildings. Vegetation or other visual screening shall be provided to screen solar energy systems. Toolsheds, patios, gardens, small-scale ground-mounted solar energy systems, and similar facilities and structures greater than 120 square feet must comply with Section 181.416, Table of Dimensional Requirements.
181.4212. 
Uncovered steps, walkways, ramps or terraces, bulkheads, chimneys, eaves, roof overhangs, cornices, signposts, and pedestrian lighting shall be exempt from the setback requirements.
181.4213. 
Swimming pools, associated uncovered decks, and freestanding decks or patios shall be set back at least six feet from any front, side or rear lot line, and not within the front yard setback.
181.4214. 
Driveway setbacks shall comply with Section 181.76 of this chapter as well as applicable regulations under City Code.
181.4215. 
Walls or fences are permitted, provided that no wall or fence shall exceed six feet in height in a front yard; stockade-type fences shall not exceed six feet in height and chain-link-type fences shall not exceed eight feet in height; provided, however, that exceptions to this section may be authorized by special permit from the Board of Appeals.
181.4216. 
Front yard exception. In the RB and RC Districts, the Board of Appeals may authorize by special permit a front setback less than that required in Section 181.416, where at least 50% of the existing buildings fronting on the same street on the same block and within a distance of 150 feet of the applicant's lot have less than the required front yard depth. The Board of Appeals may authorize the average front yard depth in this area, but in no case shall a structure be set back less than 10 feet. The burden of showing that a lesser setback is justified under this section shall be on the applicant.
The minimum lot frontage for a lot may be reduced to fifty feet per lot, provided that each lot front is entirely on a cul-de-sac with a right-of-way layout radius of 67.5 feet or greater and, further, provided that no more than five such reduced frontage lots shall have frontage on a cul-de-sac and, further, provided that each such lot shall have twice the lot area required. (See also Section 181.75, Rear Lots.)
When permitted herein, more than one principal structure may be erected on a lot, subject to the following conditions:
181.4231. 
No principal structure shall be located in relation to another principal structure on the same lot, or on an adjacent lot, so as to cause danger from fire;
181.4232. 
All principal buildings on the lot shall be served by access ways suitable for fire, police, and emergency vehicles;
181.4233. 
All of the multiple principal buildings on the same lot shall be accessible via pedestrian walkways connected to the required parking for the premises, and to each principal building.
Where a district boundary line divides any lot existing at the time such line is adopted, the regulations of any district in which the lot has frontage on a street may be extended by special permit from the Board of Appeals not more than 30 feet into the other district; provided, however, that residential uses may be extended as of right into the other district not more than 30 feet.
181.4251. 
Purpose. The purpose of the infill lot provision is to facilitate the reuse of vacant, condemned, or substandard property within existing urban or blighted areas as single-family dwelling units; to reduce vagrancy, litter, abandoned or substandard structures; to lessen density and promote single-family owner occupied homeownership in urban areas, and to improve the neighborhood character.
181.4252. 
Applicability. In the RB District, pursuant to special permit and site plan review from the Planning Board, an existing lot with at least 5,000 square feet may serve as the location for a single-family dwelling. Any of the dimensional requirements of this chapter, including but not limited to, lot frontage, width, and building setbacks, may also be reduced or eliminated by this special permit, provided that the Planning Board makes a determination that the proposed dwellings are consistent in scale and setbacks with abutting structures, and those in the immediate neighborhood. The Planning Board may impose conditions for the use of such infill lots, including, but not limited to, landscaping and maximum lot coverage.
181.4253. 
Eligibility Requirements.
A. 
Infill lots must have frontage on an existing approved way and which the Planning Board determines to provide suitable access to the buildable portion of the lot. Approved ways include a public way or a way which the City Clerk certifies is maintained and used as a public way, or a way shown on a plan thereto approved and endorsed in accordance with the Subdivision Control Law (SCL).[1] A paper street is not an approved way.
[1]
Editor's Note: See MGL c. 41, §§ 81K to 81GG.
B. 
The subdivision of a parcel that was existing at the time of the adoption of this section (April 21, 2021), in order to create an infill lot is not permitted.
C. 
Infill lots shall be served by both public sewer and public water in all districts.
D. 
The approval of an infill lot special permit does not preclude or supersede existing deed restrictions, easements, rights of access, etc. It is the responsibility of the property owner and/or applicant to prepare and ensure that a site plan complies with said conditions.
Notwithstanding the provisions of Section 181.416 (Table of Dimensional Requirements), structures in the C, AI, and I Districts may exceed the stated maximum height with the issuance of a special permit from the applicable special permit granting authority (SPGA), provided the SPGA makes a finding that additional height is necessary to accomplish the intended purpose of the structure and is not injurious to the surrounding uses.
The Planning Board may grant a special permit allowing the exceptions from the provisions of this chapter described in Sections 181.4271 through 181.4273 for principal and accessory uses and structures proposed on lots in the Commercial Recreation District (CR) and the University District (FSU) if such lots have an area of greater than 40,000 square feet. The Planning Board may grant the special permit upon written findings, in its decision, that the lot and the exceptions applied for meet the criteria for issuance of a special permit described in Section 181.94. In granting the special permit, the Planning Board may impose conditions on building and on site design in order to ensure that the site and the building, on completion of the proposed project, is compatible with the architectural and landscape design of properties in the surrounding neighborhood and consistent with the improvement of the CR or FSU District.
181.4271. 
Notwithstanding the provisions of Section 181.31, Principal Uses, the Planning Board may permit more than one principal use including residential use on a single lot and more than one principal use in a single structure.
181.4272. 
Notwithstanding the provisions of Section 181.415, One Structure per Lot, the Planning Board may permit more than one principal structure on a single lot.
181.4273. 
Notwithstanding the provisions of Section 181.416, Table of Dimensional Requirements, the Planning Board may permit structures with a front setback of less than 15 feet and a height no greater than 100 feet.