Mount Pleasant City Zoning Code
SUBCHAPTER M
RULES OF INTERPRETATION AND MEASUREMENT
§ 156.1590 GENERAL RULES OF INTERPRETATION.
(A) This part, § 10.02, and § 10.06 establish rules for interpreting provisions in this chapter.
(B) In their interpretation and application, the regulations in this chapter, including the various zoning district regulations, are the minimum requirements adopted for the promotion of the public health, safety, and welfare.
(C) For purposes of interpreting this chapter, the following definitions of word use apply:
(1) Words used in the present tense include the future tense;
(2) Words used in the singular include the plural and words used in the plural include the singular;
(3) Words of one gender include the other genders and firms, partnerships, and corporations;
(4) The word “person” includes a corporation, firm, company, partnership, association, organization, or public or private authority, as well as an individual;
(5) The words "shall" and "must" are mandatory;
(6) The words "may," "should," and “encouraged” are permissive;
(7) The word “used” or “occupied” as applied to any land or building shall be construed to include the words “intended, arranged, or designed to be used or occupied.”
(8) The phrase "used for" includes "designed for," "intended for," "maintained for," and "occupied for;"
(9) The words “such as,” “includes,” “including,” and “for example” mean “including, but not limited to” or “by way of example and not limitation,” unless otherwise provided;
(10) The term "structure" includes the term "building;" and
(11) The word “lot” includes the words “plot” or “parcel.”
(D) This chapter contains tables, illustrations, and graphics, which are designed to assist the reader in understanding the provisions of this chapter. However, to the extent that there is any inconsistency between the text of this chapter and any tables, illustrations, or graphics, the text controls.
(E) Where this chapter permits or requires an act on the part of an "owner," "lot owner," or “property owner” and a particular lot or tract of land is owned by several persons, whether in indivision, partnership, joint venture, or other form of joint ownership, the act shall be taken on behalf of, and with the express consent of, all such persons.
(F) Any reference to a statute, provision of the Mount Pleasant Code of Ordinances, other laws or regulations, reference documents, technical manuals, or other documents refer to the most recent versions of those documents, including any amendments or updates to the statute, Town Code, law, regulation, or other document.
(G) In computing any period of time, refer to § 10.06(C) unless specifically provided in this chapter.
(Ord. passed 1-14-25)
§ 156.1591 INTERPRETATION OF ZONING MAP.
(A) Unless expressly stated otherwise in the associated rezoning ordinance, the boundaries of zoning districts extend to the centerline of all adjacent rights-of-way.
(B) Where uncertainty exists with respect to the boundaries of districts shown on the Zoning Map, the following rules of interpretation apply:
(1) Boundaries indicated as approximately following corporate area lines, shall be construed as following the corporate area lines;
(2) Boundaries indicated as approximately following lot lines shall be construed as following the lot lines;
(3) Where the boundary of a district follows a stream, lake, or other body of water, the boundary line is deemed to be at the limit of the jurisdiction of the town, unless otherwise indicated; and
(4) Where a district boundary line divides a lot, the town may require a survey to establish the precise location of the district boundary line. The regulations for each district apply to the portion of the lot located in that district.
(Ord. passed 1-14-25)
§ 156.1592 CONFLICTING PROVISIONS.
(A) Zoning district hierarchy.
(1) When base or floating zoning district and overlay zoning district provisions conflict, the provisions of the overlay zoning district control.
(2) When planned zoning district and overlay zoning district provisions conflict, the provisions of the planned zoning district control.
(B) Conflicts between zoning code standards. When generally applicable standards in this chapter conflict, the more restrictive standard controls.
(C) Stricter standards in this chapter. In accordance with S.C. Code § 6-29-960, where this chapter imposes a greater width or size of yards, courts, or other spaces; a lower height of buildings or smaller number of stories; a greater percentage of lot to be left unoccupied; or otherwise imposes higher standards than are required in any other state statute or local ordinance or regulation, the provisions of this chapter control.
(D) Stricter standards in state statutes or local ordinances or regulations. When the provisions of any state statute or local ordinance or regulation require more restrictive standards than required by the regulations of this chapter, the provisions of such statute govern.
(E) Conflicts with private restrictions.
(1) It is not intended by this chapter to interfere with, abrogate, or annul any easements, covenants, or other agreements between parties.
(2) Where this chapter is more restrictive or imposes higher standards than a private restriction, this chapter controls.
(3) Where a private restriction is more restrictive or imposes higher standards than this chapter, the private restriction controls if properly enforced by a person having the legal right to enforce the restrictions. The town does not enforce private restrictions.
(4) However, the town may cease processing an application if it has actual notice of the existence of a recorded covenant that is contrary to, conflicts with, or prohibits the activity for which an applicant requests approval (see § 156.1099).
(Ord. passed 1-14-25)
§ 156.1600 PURPOSE.
This part establishes rules for measurement or calculation of Zoning Code standards, such as lot area and height.
(Ord. passed 1-14-25)
§ 156.1605 GENERALLY.
This subpart describes how to measure a build-to line, which is regulated in Subchapter B and Subchapter H.
(Ord. passed 1-14-25)
§ 156.1606 HOW TO MEASURE BUILD-TO LINES.
(A) A build-to line is a set building line on a lot where a building façade must be located. In certain instances, the build-to line is expressed as a range (e.g., between 20 feet and 30 feet from the front lot line) within which the building façade must be located.
(B) A build-to line is located parallel to the adjacent street right-of-way.
(C) A build-to line is measured from the back of the curb to the face of the building. If a curb is not present, a build-to line is measured from the edge of the pavement.
(D) Awnings and canopies may encroach beyond a build-to line.
(Ord. passed 1-14-25)
§ 156.1610 GENERALLY.
This subpart describes how to calculate building coverage, which is regulated in Subchapter B and Subchapter C.
(Ord. passed 1-14-25)
§ 156.1611 HOW TO CALCULATE BUILDING COVERAGE.
(A) Measurement. Building coverage is:
(1) Expressed as a percentage of lot area; and
(2) Calculated by dividing the total area (in square feet) of all building footprints within a lot by the total lot area (in square feet), and multiplying the result by 100.
(B) Exceptions. The calculation of building coverage excludes buildings that are located completely below the finished lot grade, such as subgrade basements.
(Ord. passed 1-14-25)
§ 156.1615 GENERALLY.
(A) This subpart describes how to calculate residential density, which is regulated in Subchapter B and Subchapter C.
(B) Density for residential uses is expressed in dwelling units per acre of land.
(Ord. passed 1-14-25)
§ 156.1616 HOW TO CALCULATE MAXIMUM DENSITY.
(A) Generally.
(1) The calculation of maximum density:
(a) Is based on the gross area of all land within the boundaries of a residential project, including land designated for support of the development; that is, all areas for lots, parking areas, drives, roads, drainage and utility easements, rights-of-way, sign easements, entrance structure easements, and lands designated for private recreation;
(b) Includes freshwater wetlands; and
(c) Does not include tidally influenced saltwater wetlands.
(2) Other land area located within a parcel's boundaries, but outside of the residential project boundaries not used for residential use, shall not be included for the purpose of calculating residential density except as provided in division (A)(3) below.
(3) In mixed use projects where non-residential uses are provided in conjunction with, and are functionally integrated into, the residential uses, the total area within the project boundaries of all such uses may be used to calculate density.
(B) Accessory dwelling units. Accessory dwelling units are not included in the calculation of density.
(C) Calculation. To calculate the maximum number of dwelling units or bedrooms, as applicable, allowed in a development, multiply the gross lot area by the maximum density standard for the zoning district. See Table 156.1616-1 through 156.1616-2: Example Calculation of Maximum Density (Dwelling Units per Acre).
(D) Rounding. When density calculations result in a fraction, the allowed number of dwelling units or bedrooms, as applicable, is rounded down to the next lowest whole number.
Key: max = maximum allowed | du = dwelling unit | ac = acre | sf = square feet | |
District | R-1 District |
Density (max.) | 3 du/ac |
Gross site area | 779,421 sf |
Example calculation of maximum density | |
Step 1: Convert lot area to acres (1 ac = 43,560 sf) | 779,421 sf / 43,560 sf = 17.89 ac |
Step 2: Multiply gross lot area (in acres) by the maximum density | 17.89 ac x 3 du/ac = 53.67 = 53 du (rounded) |
Key: max = maximum allowed | du = dwelling unit | ac = acre | sf = square feet | |
District | R-3 District |
Density (max.) | 6 du/ac |
Gross site area | 14,810 sf |
Example calculation of maximum density | |
Step 1: Convert lot area to acres (1 ac = 43,560 sf) | 14,810 sf / 43,560 sf = 0.33 ac |
Step 2: Multiply gross lot area (in acres) by the maximum density | 0.33 ac x 6 du/ac = 2.03 = 2 du (rounded) |
(Ord. passed 1-14-25; Am. Ord. 26021, passed 4-17-26)
§ 156.1620 GENERALLY.
This subpart describes how to calculate gross floor area, which is regulated in Subchapter B and Subchapter C.
(Ord. passed 1-14-25)
§ 156.1621 HOW TO CALCULATE GROSS FLOOR AREA.
(A) Gross floor area (GFA):
(1) Is measured from the inside perimeter of the exterior walls of the structure, without deduction for the thickness of internal walls;
(2) Includes the total horizontal area of all floors of a structure, including interior balconies, mezzanines, corridors, stairways, ramps, closets, columns, and other features; and
(3) Excludes shafts with no openings and interior courts. A “court” is an open, uncovered space, unobstructed to the sky, bounded on three or more sides by exterior building walls or other enclosing devices.
(B) The floor area of a structure or portion thereof without exterior walls is the useable area under the horizontal projection of the roof or floor above.
(Ord. passed 1-14-25)
§ 156.1625 GENERALLY.
(A) This subpart describes how to measure building and structure height and allows exceptions for certain structures or elements.
(B) Unless necessary to meet drainage or other applicable requirements of this code, lots shall not be filled in order to artificially increase building height.
(Ord. passed 1-14-25)
§ 156.1626 HOW TO MEASURE HEIGHT.
(A) Height regulated in feet. Where this chapter regulates height in feet, the height of a structure is the vertical distance measured from grade plane to the average height of the highest roof surface.
(B) Height regulated in stories. Height, where not regulated in feet, is regulated in stories.
(1) A story is measured:
(a) From top to top of two successive finished floor surfaces; and
(b) For the topmost story, from the top of the highest finished floor to the top of the ceiling joists or to the top of the roof rafters if there is no ceiling.
(2) An attic counts as a story if it contains habitable attic space, as defined by the Building Code.
(3) To be considered a half-story, as defined in Subchapter N, the floor area with head room of five feet or more shall not exceed 50% of the total floor area of the story below it.
(4) The ground level component of an elevated building is considered a story if it is at least seven feet in height, as specified in the definition of “story” in Subchapter N.
(Ord. passed 1-14-25)
§ 156.1627 EXCEPTIONS.
(A) The purpose of this section is to allow a certain category of features to exceed the maximum height limitation for buildings and structures that would otherwise be unreasonably restrictive. These features shall not accommodate human occupancy and shall be the minimum necessary to achieve a specified purpose.
(B) The following projections are exempt from the height limitations of this chapter to the extent established below:
(1) Any chimney or antenna on a building;
(2) Church spires or the sanctuary portion of a building associated with a place of worship;
(3) Belfries, cupolas, and domes not intended for human occupancy;
(4) Smokestacks;
(5) Aerials;
(6) The judicious application of portions of a building containing or shielding from view electrical or mechanical equipment;
(7) Elevator penthouses;
(8) Masts;
(9) Construction cranes or ships; and
(10) Other similar elements, such as decorative railings.
(C) These projections may be constructed in accordance with other regulations or ordinances of the Town of Mount Pleasant or of other jurisdictions, such as the Federal Aviation Administration.
(D) Telecommunications towers are subject to the height limits specified in Subchapter C, Part 7, Subpart 7.2.
(E) Any areas intended for human occupancy, such as rooftop decks, pergolas, and the like shall not exceed the height limitations of this chapter, unless otherwise specified in this chapter.
(Ord. passed 1-14-25)
§ 156.1630 GENERALLY.
This subpart describes how to calculate impervious surface coverage, which is regulated in Subchapter B and Subchapter C.
(Ord. passed 1-14-25)
§ 156.1631 HOW TO CALCULATE IMPERVIOUS SURFACE COVERAGE.
(A) Impervious surface coverage is:
(1) Expressed as a percentage of lot area; and
(2) Calculated by dividing the total area of all impervious surfaces within a lot by the total lot area, and multiplying the result by 100.
(B) When a lot contains tidally influenced saltwater wetlands/marsh or open water beyond the delineated SCDES-BCM critical line, impervious surface coverage is calculated using only the "high ground" of the lot and specifically excluding the wetlands/marsh or open water.
(Ord. passed 1-14-25)
§ 156.1635 GENERALLY.
This subpart describes how to measure lot area, lot width, and lot depth. Subchapter B and Subchapter C regulate these metrics.
(Ord. passed 1-14-25)
§ 156.1636 HOW TO CALCULATE LOT AREA.
(A) The area of a lot:
(1) Is calculated in square feet by multiplying the lot depth by the lot width; and
(2) Does not include any portion of a road right-of-way.
(B) When a lot is irregularly shaped, the calculation method varies based on the lot shape and the information available (see www.mathopenref.com/polygonirregulararea.html)
(Ord. passed 1-14-25)
§ 156.1637 HOW TO MEASURE LOT WIDTH.
(A) Measurement.
(1) The width of a lot is the horizontal distance between the side lot lines, measured:
(a) Parallel to the front lot line; or
(b) In the case of a curvilinear street, parallel to the chord of the arc between the intersection of the side lot lines and the front lot line.
(2) The zoning district minimum lot width must be met at the front lot line, except as specified in division (B) below.
(B) Lots on cul-de-sacs. For lots located on a cul-de-sac, the zoning district minimum lot width must be met at the front setback for the district.
(Ord. passed 1-14-25)
§ 156.1638 HOW TO MEASURE LOT DEPTH.
The depth of a lot is the average horizontal distance between the front and rear lot lines, measured generally parallel to the side lot lines.
(Ord. passed 1-14-25)
§ 156.1645 GENERALLY.
(A) Purpose. This subpart describes how to measure yards and setbacks. Subchapter B and Subchapter C regulate these metrics.
(B) Required yards cannot overlap. Required yards provided for one structure shall not be used to meet yard requirements for another structure.
(C) Setbacks for lots subject to design review process. For lots subject to Subchapter H, setback distances from lot lines with street frontage are determined through the design review process, using a build-to line of between 20 and 30 feet.
(D) Setbacks for lots in the Old Village Historic District. For lots located within the Old Village Historic District (see Subchapter B, Part 4, Subpart 4.3), setback distance is determined during the certificate of appropriateness (COA) review process, with consideration of existing conditions and setbacks of adjacent lots.
(E) Setbacks for postage stamp lots. Normal setback and yard requirements do not apply to lot lines for “postage stamp” lots subdivided pursuant to the provisions of § 155.047(C)(1)(a). The setback and yard requirements of the zoning district classification apply to the perimeter of the larger parcel in which these lots are located.
(F) Setbacks for the subdivision of lots with more than one dwelling unit. Normal setback and yard requirements do not apply to lot lines for lots resulting from the subdivision of lots with more than one dwelling unit pursuant to the provisions of § 155.047(C)(1)(b).
(G) Determinations and interpretations. When making determinations or, if necessary, interpretations under this subpart, the Zoning Administrator shall consider the following characteristics of the lot and surrounding lots:
(1) The orientation of existing or proposed buildings containing the principal use;
(2) The orientation of adjacent buildings and other buildings along the street;
(3) The location of a dwelling’s curtilage;
(4) Means of gaining safe access;
(5) The relative dimensions of the lot and yards;
(6) Delivery of services to the lot, including mail and trash collection;
(7) Setbacks on surrounding lots; and
(8) Other features related to site design and safe circulation.
(Ord. passed 1-14-25)
§ 156.1646 LOT ORIENTATION, YARDS, AND SETBACKS.
(A) A front yard is adjacent to the front lot line, and is typically located along a street. A rear yard is adjacent to the rear lot line, and is generally located parallel to the front yard. Side yards are adjacent to side lot lines, and are generally located perpendicular to the front and rear yards.
(B) Figure 156.1646-1: Typical Location of Yards and Setback Lines illustrates yards and setback lines on typical lots. Setback lines are located parallel to the associated lot line. The Zoning Administrator determines the location of yards and setbacks on irregularly shaped lots using the criteria specified in this section and in § 156.1645(G). Figure 156.1646-2 depicts the typical location of yards and setback lines on two types of irregularly shaped lots, marsh front lots and flag lots.
(C) Typically, the shorter lot dimensions are considered the front and rear lot lines and the longer lot dimensions are considered the side lot lines. This provides the most buildable area on a lot. However, where a lot has street frontage that is wider than the lot is deep and was platted prior to adoption of the Town Zoning Code on August 13, 1979:
(1) The front yard setback may be applied along the street frontage, and the rear yard setback along the parallel lot line (longer side). The side yard setbacks may be applied on lot lines of adjacent parcels (shorter side) when consistent with the lots on either side of the subject lot or the majority of the lots within the block; and
(2) The principal structure must conform with the setback adjustment. If any portion of an existing or proposed principal structure does not comply with the adjusted setbacks, a variance to allow the establishment of setbacks must be approved by the Board of Zoning Appeals.
(D) In the case of new construction on a corner lot, the owner may establish the location of the front and rear yards based on preference of orientation, taking into consideration orientation of adjacent structures and existing development patterns.
(Ord. passed 1-14-25)
§ 156.1647 HOW TO MEASURE SETBACKS.
Setbacks are measured from the lot line to the closest projection of any portion of a building or structure, except for encroachments as allowed by § 156.1651.
(Ord. passed 1-14-25)
§ 156.1648 FRONT YARDS AND SETBACKS.
(A) Definition.
(1) A front yard is an open, unoccupied space on a lot (except for encroachments as allowed by § 156.1651) that generally faces a street and extends across the entire width of a lot between the side lot lines.
(2) For lots without frontage on a street, the front lot line is the lot line where access to the lot is provided.
(3) The horizontal distance between the principal structure and the front lot line shall be at least equal to the minimum front setback for the zoning district in which the lot is located (see Subchapter B).
(B) Front setbacks on double frontage lots. For double frontage lots, the front setback requirements apply along both streets as illustrated in Figure 156.1648-1: Front Setbacks on Double Frontage Lots.
(C) Average front setbacks.
(1) The minimum front yard setback requirement for dwellings does not apply on any lot where the average setback of existing buildings located, wholly or in part, within 100 feet on each side of such lot within the same block and zoning district and fronting on the same side of the street, is less than the minimum required setback.
(2) In these cases, the setback on such lots may be less than the required minimum setback, but not less than the average of the setbacks of the aforementioned existing buildings.
(Ord. passed 1-14-25)
§ 156.1649 REAR YARDS AND SETBACKS.
(A) A rear yard is an open, unoccupied space (except for encroachments as allowed by § 156.1651) that extends across the entire width of a lot between the side lot lines.
(B) The horizontal distance between the principal structure and the rear lot line shall be at least equal to the minimum rear setback required for the zoning district in which the lot is located (see Subchapter B).
(C) The horizontal distance between an accessory structure and the rear lot line shall be at least equal to the minimum rear setback required for the type of accessory structure (see Subchapter C, Part 4).
(Ord. passed 1-14-25)
§ 156.1650 SIDE YARDS AND SETBACKS.
(A) A side yard is an open, unoccupied space (except for encroachments as allowed by § 156.1651) that extends from the front yard to the rear yard.
(B) The horizontal distance between the principal structure and each side lot line shall be at least equal to the minimum side setback required for the zoning district in which the lot is located (see Subchapter B).
(C) The side yard setback requirement applies where a side yard abuts a street (corner lot). However, accessory buildings shall not be located closer to the street than the front yard setback line of the adjacent lot.
(Ord. passed 1-14-25)
§ 156.1651 ENCROACHMENTS.
(A) This section specifies allowed encroachments into required yards.
(B) REQUIRED YARD means that portion of any yard constituting the minimum area required in any zoning district, but excluding that portion of the yard in excess of the minimum required area.
(C) Items such as sills, eaves, belt courses, window air-conditioning units, chimneys, cornices, ornamental features, and bay windows may protrude into a required yard a distance not to exceed 24 inches; provided, however, a bay window projection is limited to maximum span length of ten feet along the exterior wall of the building.
(D) Items such as open fire escapes; elevators; outside stairways leading to a building entrance, but not to an uncovered porch or deck; balconies; and outside air-conditioning units and propane/heating oil tanks may be permitted to project into the required yard for a distance of not more than four feet, when so placed as to not obstruct light and ventilation, but in no case closer than three feet from the property line.
(E) Uncovered porches and uncovered decks may encroach into a required rear or side yard not more than 40% of the required setback, but no closer than three feet from the property line; except that when a zero-lot line provision is in effect, the 40% reduction applies to the minimum required distance between structures. No additional encroachments for outside stairways is allowed.
(F) Ramps for ADA accessibility may encroach into any required yard and do not have a minimum setback from a lot line.
(G) Minor accessory uses and structures may encroach into any required yard and do not have a minimum setback from a lot line (see Subchapter C, Part 4).
(Ord. passed 1-14-25)
§ 156.1660 GENERALLY.
(A) This subpart describes how to measure the required minimum separation distance between certain conditional and special exception uses specified in Subchapter C, Part 3, Subpart 3.3.
(B) Depending on the regulated use, Subchapter C, Part 3, Subpart 3.3 specifies a minimum separation distance between the new regulated use and:
(1) Certain zoning districts; and/or
(2) Certain sensitive land uses, such as residential uses.
(Ord. passed 1-14-25)
§ 156.1661 HOW TO MEASURE SEPARATION DISTANCE.
Measurements shall be taken in a straight line from the nearest portion of the lot line where the new regulated use is proposed to the nearest portion of the lot line or zoning district boundary line of the uses and districts from which the regulated use must be separated.
(Ord. passed 1-14-25)
