Chapter 17.34 — RULES OF MEASUREMENT

Sections:

• 17.34.010 Measuring fractions. 17.34.020 Measuring distances. 17.34.030 Measuring height.

• 17.34.040 Measuring lots. 17.34.050 Measuring floor area and floor area ratio. 17.34.060 Measuring lot coverage. 17.34.070 Determining lot frontage. 17.34.080 Measuring setbacks. 17.34.090 Measuring signs.

Whenever this code requires calculation of distances or the number of parking spaces, dwelling units or other aspects of development or the physical environment expressed in numerical quantities, and the result of a calculation contains a fraction of a whole number, the results will be rounded as follows:

A. General Rounding. Fractions of one-half or greater shall be rounded up to the nearest whole number and fractions of less than one-half shall be rounded down to the nearest whole number, except as otherwise provided.

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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B. Exception for State Affordable Housing Density Bonus. The calculation of fractions related to permitted bonus density units for projects eligible for bonus density pursuant to California Government Code Section 65915 or any successor statute, and Chapter 17.29, Density Bonus, any fractional number of units shall be rounded up to the next whole number. (Ord. 23-4 § 5 (Exh. A))

A. Measurements Are Shortest Distance. When measuring a required distance, such as the minimum distance between a structure and a lot line, the measurement is made at the closest or shortest distance between the two objects.

B. Distances Are Measured Horizontally. When determining distances for setbacks and structure dimensions, all distances are measured along a horizontal plane from the appropriate line, edge of building, structure, storage area, parking area, or other object. These distances are not measured by following the topography or slope of the land.

C. Measurements Involving a Structure. Measurements involving a structure are made to the closest support element of the structure. Structures or portions of structures that are entirely underground are not included in measuring required distances.

D. Measurement of Vehicle Stacking or Travel Areas. Measurement of a minimum travel distance for vehicles, such as garage entrance setbacks and stacking lane distances, are measured down the center of the vehicle travel area. For example, curving driveways and travel lanes are measured along the center arc of the driveway or traffic lane.

E. Measuring Radius. When a specified land use is required to be located a minimum distance from another land use, the minimum distance is measured in a straight line from all points along the lot line of the subject project, in all directions.

Figure 17.34.020. Measuring Distances

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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(Ord. 23-4 § 5 (Exh. A))

A. Parapet or Flat Roof. For buildings with a parapet or flat roof, building height is measured from the average level of the highest and lowest points where the vertical plane of the exterior walls touch existing or finished grade, whichever is lower, to the highest point on the roof, the top of the parapet wall, the wall coping of a flat roof, or the deck line of a mansard roof.

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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B. Sloped Roof. For buildings with a hipped, gabled, gambrel, or other sloped roof design, building height is measured from the average level of the highest and lowest points where the vertical plane of the exterior walls touch existing or finished grade, whichever is lower, to the highest point on the highest ridge.

Figure 17.34.030(A). Measuring Building Height

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• C. Stories. In measuring the number of stories in a building, the following rules shall apply:

  1. An interior balcony or loft shall be counted as a full story if its floor area exceeds one-half of the total area of the nearest full floor directly below it or if it is enclosed on more than two sides.

  2. A basement shall be counted as a full story if the vertical distance between finished grade and the finished surface of the floor above the basement is more than four feet at any point.

  3. A story shall not exceed twenty-five (25) feet in height from the upper surface of the floor to the ceiling above.

4. An attic is not considered a story provided it is unconditioned, unfinished, and less than seven feet at its highest point with an average height not exceeding four feet.

Figure 17.34.030(B). Measuring Building Stories

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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D. Fences and Walls. The height of fences, walls, and other landscape structures shall be measured as the vertical distance from the midpoint between the highest and lowest natural grade immediately adjacent to both sides of the fence or wall to the highest point of the fence or wall.

Figure 17.34.030(C). Measuring Height of Fences or Walls

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E. Decks. Deck height is determined by measuring from the average elevation of the ground below the deck to the top of the floor of the deck directly above the ground below.

Figure 17.34.030(D). Measuring the Height of Decks

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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F. Antennas. The height of antennas shall be measured as described in Section 17.22.270, Wireless telecommunication facilities. (Ord. 23-4 § 5 (Exh. A))

A. Lot Width. Lot width is the horizontal distance between the side lot lines, measured at right angles to the lot depth at a point midway between the front and rear lot lines.

B. Lot Depth. Lot depth is measured along a straight line drawn from the midpoint of the front property line of the lot to the midpoint of the rear property line or to the most distant point on any other lot line where there is no rear lot line.

Figure 17.34.040. Measuring Lot Width and Depth

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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• C. Average Slope. The average slope of a parcel is calculated using the following formula: S = 100(I)(L)/A, where:

  1. S = Average slope (in percent).

  2. I = Contour interval (in feet).

  3. L = Total length of all contour lines on the parcel (in feet).

  4. A = Area of subject parcel (in square feet). (Ord. 23-4 § 5 (Exh. A))

A. Areas Included in Floor Area Measurement. The floor area is measured as the sum of the gross horizontal floor areas of a building measured from the exterior face of exterior walls, or from the centerline of a wall separating two buildings. Areas included and excluded from floor area are listed below.

1. Included in Floor Area Measurement.

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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a. All habitable space (as defined in the building code) that is below the roof and within the outer surface of the main walls of principal or accessory buildings or the centerlines of party walls separating such buildings or portions thereof.

• b. Interior walkways or corridors, interior courtyards, walkways, paseos, or corridors covered by a roof or skylight.

c. In the case of a multistory building that has covered or enclosed stairways, stairwells or elevator shafts, the horizontal area of such features shall be counted only once at the floor level of their greatest area of horizontal extent.

2. Excluded From Floor Area Measurement.

a. Mechanical, electrical, and communication equipment rooms that do not exceed two percent of the building’s gross floor area.

• b. Bay windows or other architectural projections where the vertical distance between the lowest surface of the projection and the finished floor is thirty (30) inches or greater.

• c. Any areas that satisfy the landscape and open space base zone requirements.

d. A building or structure consisting of nonusable floor space such as a garage, carport, or storage shed.

e. Unfinished attics, crawlspaces, and basements shall not be included unless converted and finished as usable floor space.

Figure 17.34.050. Measuring Floor Area

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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B. Floor Area Ratio (FAR). The floor area ratio (FAR) is the ratio of the floor area, excluding the areas described below, of all primary and accessory buildings on a site to the site area. To calculate the FAR, floor area is divided by site area, and typically expressed as a decimal. For example, if the floor area of all buildings on a site totals twenty thousand (20,000) square feet, and the site area is ten thousand (10,000) square feet, the FAR is expressed as 2.0. The following are excluded from floor area in calculating FAR.

1. Underground Areas. Floor area located below finished grade.

2. Parking. Parking areas located below finished grade or finished floor of habitable space where the vertical distance between finished grade and finished floor is less than six feet.

3. Small Accessory Structures. Accessory structures up to one hundred twenty (120) gross square feet.

4. Unenclosed Porches. Porches where at least one of the longest dimensions is unenclosed. (Ord. 25-7 § 3; Ord. 23-4 § 5 (Exh. A))

The footprints of all principal and accessory structures, including, but not limited to, garages, carports, covered patios, and roofed porches, shall be summed in order to calculate lot coverage. The following structures shall be excluded from the calculation:

A. Unenclosed and unroofed decks, uncovered patio slabs, unroofed porches, landings, balconies and stairways with an elevation of less than eighteen (18) inches above finished grade;

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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• B. Eaves and roof overhangs projecting up to three feet from a wall;

• C. Trellises, pergolas, and similar structures that have roofs that are at least fifty percent (50%) open to the sky with uniformly distributed openings;

• D. Swimming pools and hot tubs that are not enclosed in roofed structures or decks; and

• E. One small, nonhabitable accessory structure under one hundred twenty (120) square feet. More than one small nonhabitable accessory structure shall be included in lot coverage.

Figure 17.34.060. Determining Lot Coverage

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(Ord. 23-4 § 5 (Exh. A))

A. Corner Lot. The front of a lot is either of the two lines adjacent to the streets as platted, subdivided, or laid out, except that the front lot line shall be that line which is obviously the front by reason of the prevailing custom of the other buildings on the block. If such front is not evident, then, as determined by the community development director, either may be considered the front of the lot, but not both.

B. Through Lot. The front of a through lot abuts the street that neighboring lots use to provide primary access. (Ord. 23-4 § 5 (Exh. A))

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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A setback line defining a required setback is parallel to and at the specified distance from the corresponding front, side, or rear property line, as shown in Figure 17.34.080(A): Determining Setbacks—Interior Lot, and Figure 17.34.080(B): Determining Setbacks—Corner Lot. Required setbacks shall be unobstructed from the ground to the sky except where allowed pursuant to this title, subject to compliance with the building code. All required setbacks shall be determined by their relationship to the front of a lot.

Figure 17.34.080(A). Determining Setbacks—Interior Lot

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Figure 17.34.080(B). Determining Setbacks—Corner Lot

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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The following special regulations for determining required setbacks apply when a lot abuts a proposed street or alley:

A. Setback Abutting Planned Street Expansions. If a property abuts an existing or proposed street for which the existing right-of-way is narrower than the right-of-way ultimately required for the street, the required setback shall be established from the future right-of-way rather than the property line.

B. Setbacks Abutting Alleys.

1. If a side lot line abuts an alley, the yard shall be considered an interior side yard rather than a corner side yard.

2. In computing the minimum setback for any lot where such setback abuts an alley, no part of the width of the alley may be considered as part of the required setback.

C. Flag Lots.

1. The panhandle portion of the lot shall be excluded when determining the required setbacks and yards.

2. The planning commission may waive the minimum setback requirements of existing units after review of the location of the proposed panhandle, the width of the landscape area and the location of buildings in the vicinity.

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

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D. Exceptions. In unusual cases, the community development director shall have the authority to establish the location of the setback and yard standards in relation to any existing or proposed buildings or structures. (Ord. 23-4 § 5 (Exh. A))

The calculation of measurements related to signs are described in Chapter 17.27, Signs. (Ord. 23-4 § 5 (Exh. A))

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.

Disclaimer: The city clerk’s office has the official version of the St. Helena Municipal Code. Users should contact the city clerk’s office for ordinances passed subsequent to the ordinance cited above.

City Website: www.cityofsthelena.gov

Hosted by General Code.

The St. Helena Municipal Code is current through Ordinance 26-4, passed May 12, 2026.