RULES OF MEASUREMENT
202 RULES OF MEASUREMENT This section provides the rules of measurement for the dimensional standards and locational characteristics within the Ordinance.
A. Build-To Dimensions 1. A build-to line (BTL) is the set dimension on a lot, measured from the applicable lot line, where a certain percentage of building frontage shall be located. (Figure 2-2)
2. A build-to zone (BTZ) is an area on a lot where a certain percentage of the building frontage shall be located, measured as a minimum and maximum range from the applicable lot line. (Figure 2-3)
3. A build-to percentage specifies the percentage of the length of the build-to zone that is occupied by a building facade. Facade articulation, such as window or wall recesses and projections, is not counted against the required build-to percentage, so long as the variation does not exceed two feet of depth or projection.
B. Building Height 1. For a vacant parcel of land, building height shall be measured from the average, existing-grade elevation where the foundation of the structure is proposed. This method of building height applies to all structures unless specifically exempted by this Ordinance. For an existing structure, building height shall be measured from average grade taken from the outermost four (4) corners of the existing foundation. In all cases, building height shall be measured to the top of the highest point of the existing or proposed roof or structure. This distance shall exclude spires, chimneys, flag poles, and the like, as described in item 2 below. (Figure 2-4). For any property or structure located in a special flood hazard area, as shown on the official FEMA Flood Insurance Rate Maps (FIRMs), building height shall be measured from base flood elevation, and where freeboard, as defined in Section 201, is being utilized or proposed, such freeboard area, not to exceed five feet, shall be excluded from the building height calculation; provided, however, that the Rhode Island Coastal Resources Management Council design elevation maps may be used by an owner or applicant to establish a base flood elevation for a property that is higher than the official FEMA FIRMs.
2. The following structures or parts thereof are exempt from maximum height limitations, unless otherwise limited by any height restriction imposed by any airport authority, port authority, or other similar federal, state, or local authority.
a. Public utility poles, towers, and wires. This does not include wireless telecommunication towers and wind turbines that are regulated separately by this Ordinance.
b. Water tanks and standpipes.
c. Building appurtenances such as chimneys, parapet walls, skylights, steeples, flag poles, smokestacks, cooling towers, elevator bulkheads, fire towers, monuments, water towers, stacks, stage towers, or scenery lofts, tanks, ornamental towers and spires, rooftop accessory structures, stair towers, recreational facilities, necessary mechanical appurtenances, or penthouses to house mechanical appurtenances. However, building appurtenances shall be eligible for this exemption only if they meet the following standards: i. The footprint of all building appurtenances shall not exceed 50% of the total floor area of the roof.
ii. All mechanical appurtenances or penthouses to house mechanical appurtenances roof equipment shall be set back from the edge of the roof a minimum distance of one foot for every two feet by which the equipment extends above the roof.
iii. The Downtown Design Review Committee may waive these regulations pertaining to rooftop mechanical equipment in the D-1 District to permit up to 100% of the roof to be covered by such structures.
3. A story is that portion of a building between the upper surface of any floor and the upper surface of the floor next above, including any portion of a building used for human occupancy between the topmost floor and the roof. A basement is counted as a story, but a cellar is not. (Figure 2-5)
C. Caliper Tree caliper is the diameter of a tree trunk, measured at six inches above the adjacent ground.
D. Grade A reference plane representing the average of finished ground level adjoining the building at all exterior walls. When the finished ground level slopes away from the exterior walls, the reference plane is established by the lowest points within the area between the building and the lot line or, when the lot line is more than six feet from the building, between the building and a point six feet from the building.
E. Gross Floor Area (GFA) The sum of the gross horizontal area of the floors of a building measured from the exterior face of exterior walls or from the centerline of walls separating two buildings, but not including interior parking spaces, loading spaces for motor vehicles, or any space where the floor to ceiling height is less than six feet.
F. Impervious Surface and Pervious Surface Coverage Impervious surface coverage is a measure of intensity of land use that represents the portion of a site that is occupied by structures, pavement, and other impervious surfaces that do not allow for the absorption of water into the ground. Regardless of the surface treatment, all areas designated or used for parking or access to parking shall be considered impervious surfaces. Pervious surface coverage represents the portion of a site that allows for the absorption of water into the ground.
1. Maximum impervious surface of a lot is calculated as the percentage of all impervious surface area of the total area of the lot.
2. Maximum impervious surface of a specific yard is calculated as the percentage of all impervious surface area of the total yard area. Yard area is defined in item O below. In the case of front yards only, the roofed area of a porch shall not be counted towards the impervious surface in that area of a lot.
3. Minimum pervious surface of a lot is expressed as a minimum square footage, regardless of lot size.
G. Lighting 1. Luminaire Height The total height of a luminaire is measured to the top of the pole or luminaire, whichever is higher, from grade. (Figure 2-6)
2. Footcandle A footcandle (FC) is a unit of illumination produced on a surface, all points of which are one foot from a uniform point source of one standard candle. Footcandle is measured utilizing a direct reading, portable light meter mounted in a horizontal position.
H. Lot A lot is the basic development unit for determination of lot area, depth, and other dimensional regulations; or a parcel of land whose boundaries have been established by some legal instrument such as a recorded deed or recorded map and which is recognized as a separate legal entity for purposes of transfer of title. The following describes the types of lot configurations: (Figure 2-7)
1. An interior lot is a lot other than a corner or through lot, bounded by two interior side lot lines.
2. A corner lot is a lot situated at the junction of, and abutting on, two or more intersecting streets.
3. A through lot is a lot which fronts upon two parallel streets, or which fronts upon two streets which do not intersect at the boundaries of the lot.
I. Lot Area The total area within the boundaries of a lot, excluding any street right-of-way, usually reported in acres or square feet. (Figure 2-8)
J. Lot Building Coverage That portion of the lot that is or may be covered by buildings, accessory buildings, and other structures covered by a roof.
K. Lot Depth The distance measured from the front lot line to the rear lot line. For lots where the front and rear lot lines are not parallel, the lot depth is an average of the depth. (Figure 2-8)
L. Lot Line A line of record, bounding a lot, which divides one lot from another lot or from a public or private street or any other public or private space and includes: (Figure 2-9)
1. A front lot line is the lot line separating a lot from a street right-of-way. The front lot line of a corner lot may be any one of the lot lines abutting a street. A front lot line for a through lot is one or both lot lines that abut a street. On a lot that does not abut a developed right-of-way, the front lot line shall be considered that lot line which is oriented towards the site access.
2. A rear lot line is the lot line opposite and most distant from the front lot line, or in the case of triangular or otherwise irregularly shaped lots, an assumed line at least ten feet in length entirely within the lot, parallel to and at a maximum distance from the front lot line.
3. An interior side lot line is a lot line that is perpendicular or approximately perpendicular to the front lot line and abuts another lot.
4. A corner side lot line is a lot line that is perpendicular or approximately perpendicular to the front lot line.
5. A street lot line is a lot line that abuts a street.
M. Lot Width Lot width is the horizontal distance between the side lot lines measured at right angles to its depth along a straight line parallel to the front lot line at the minimum front setback line. (Figure 2-8)
N. Sign Dimension Measurement 1. Measurement of Sign Area Sign area is measured as follows: (Figure 2-10)
a. For signs on a background, the entire area of the background is calculated as sign area, including any material or color forming the sign face and the background used to differentiate the sign from the structure against which it is mounted. Sign area does not include any supports or bracing.
b. For signs consisting of freestanding letters or logos, the sign area is calculated as the total area of each square, circle, rectangle, or triangle, or combination thereof, which encompasses each individual letter or logo. Sign area does not include any supports or bracing.
c. Window signs printed on a transparent film and affixed to the interior or exterior of a windowpane are calculated as individual letters or logos, provided that the portion of the transparent film around the perimeter of the individual letters or logos maintains 100% transparency of the window.
d. The sign area of a three-dimensional, free-form, or sculptural (non-planar) sign is calculated as 50% of the sum of the area of the four vertical sides of the smallest cube that will encompass the sign.
2. Measurement of Sign Height For freestanding signs, height is calculated as the vertical distance measured from grade adjacent to where the sign is to be installed to the highest point of the sign. (Figure 2-11)
O. Yards and Setbacks A yard is the open space area between the building line of a principal building and the adjoining lot lines. A required setback is the required minimum distance a principal building shall be located from a lot line, which is unoccupied and unobstructed by any portion of a principal building or accessory structure, unless permitted by this Ordinance, and may be equal to or lesser than a yard. A setback is located along a lot line for the minimum depth specified by the zoning district in which such lot is located. A build-to zone or build-to line is considered a required setback. (Figure 2-12)
1. Front Yard and Front Setback A front yard is located between a principal building line and the front lot line, extending the full width of the lot. A front setback is the required minimum distance per the zoning district that a principal building shall be located from the front lot line. The front setback extends the full width of the lot between side lot lines measured perpendicular to the front lot line. For the purposes of determining a front setback, if a porch extends the full width of the building, the front of the porch shall be considered the building line.
2. Interior Side Yard and Interior Side Setback An interior side yard is located between a principal building line and the interior side lot line. An interior side setback is the required minimum distance per the zoning district that a principal building shall be located from the interior side lot line. The interior side yard and interior side setback extend along the interior side lot line between the front and rear yard and setback, measured perpendicular to the interior side lot line. For rowhouse developments, the interior side yard and interior side setback are applicable to end units only.
3. Corner Side Yard and Corner Side Setback A corner side yard is located between a principal building line and the corner side lot line. A corner side setback is the required minimum distance per the zoning district that a principal building shall be located from the corner side lot line. The corner side yard and corner side setback extend along the corner side lot line between the front yard or front setback and the rear lot line, measured perpendicular to the corner side lot line.
4. Rear Yard and Rear Setback A rear yard is located between a principal building line and the rear lot line. A rear setback is the required minimum distance per the zoning district that a principal building shall be located from the rear lot line. The rear yard and rear setback extend between interior side lot lines, measured perpendicular to the rear lot line. In the case of a corner lot, the rear yard and rear setback extend between the interior side lot line to the required corner side setback for the lot, measured perpendicular to the rear lot line.