A.   For the purpose of this chapter, allowable density is defined as the maximum number of dwelling units permitted per gross acre of land.  The maximum allowable density shall be based upon and established by the average slope of a property, calculated in compliance with paragraph C.  The maximum allowable density based on the average slope shall be as set forth in Table 20.206.060.A:
TABLE 20.206.060.A
Average Slope
Maximum Allowable Density
TABLE 20.206.060.A
Average Slope
Maximum Allowable Density
Less than 10%, inclusive
2.2 units/acre
10.1 to 20%
1.6 units/acre
20.1 to 25%
1 unit/acre
25.1 to 30%
1 unit/5 acres
Greater than 30%
1 unit/ 20 acres
   B.   The maximum dwelling unit yield based on the maximum allowable density mathematical sum shall be considered maximum potentials and not an entitlement, right or vested right to develop.  Other factors and individual property characteristics will affect and may reduce the yield, including but not limited to: physical constraints, floor-area ratio (§ 20.206.060.D.); compliance with design guidelines, engineering design standards, hillside development standards; and performance criteria such as access, emergency response standards, and sensitive grading techniques and volumes.
   C.   Calculating the maximum allowable density for any parcel or group of parcels under common development application within the Hillside Residential zoning district shall involve the following steps.  Establish allowed density based on average slope:
      1.   Alternative 1 – Average slope of the parcel or group of parcels. For Alternative 1, the average slope shall be calculated in compliance with § 20.206.050.E.2.  For example, a one hundred (100)-acre parcel which has an average slope for the entire parcel of twenty-five percent (25%) would yield a maximum of one hundred (100) units.
      2.   Alternative 2 – Use of slope categories.  Cumulative land areas of a site corresponding to the slope categories identified in Table 20.206.060.A may be used to calculate site maximum density in compliance with the method established in § 20.206.050.E.2. Land areas within established slope categories which are not proposed for development shall be excluded from the final density calculation, said areas to remain undeveloped and set aside as natural open space and deed-restricted from any future development pursuant to the provisions of § 20.206.090.E of this chapter. The units/acre density used in the calculation shall correspond with the steepest slope category within the area proposed for development.  For example, on a one hundred (100)- acre parcel, of which sixty (60) acres has an average slope of more than thirty percent (30%), ten (10) acres are between 25.1 to 30 percent average slope, ten (10) acres are between 20.1 to 25 percent average slope, ten (10) acres are between 10.1 to 20 percent averge slope, and the remaining ten (10) acres are under ten percent (10%) average slope; let's assume you select the use of the land area within the two lower average slope categories. The cumulative land area of twenty (20) acres from the two slope categories of less than ten percent (10%) average slope and 10.1 to 20 percent average slope can be used to calculate an allowable density of thirty-two (32) units (1.6 units/acre X 20 acres = 32 units).
      3.   As an alternative to the Hillside Residential density calculation procedures contained in § 20.206.060.C.1 and 2, development proposals approved through a development agreement or specific plan (as provided for in state law) may have a greater density than that allowed by the slope density formula(s) provided that the proposal complies with all other criteria of the Hillside Residential (HR) zoning standards, including exceptions, and also provided that the maximum number of units does not exceed 2.25 times the highest number calculated under the slope density formulas.
   D.   For the purposes of this chapter, floor-area ratio (FAR) is defined as the ratio of gross building floor area on a pad to the total land area of the pad. For purposes of this definition, gross floor area shall include the square footage of all structures on a pad, as measured from the outside of the exterior walls. Gross floor area shall not include the first six hundred (600) square feet of attached garages, decks, balconies, covered patios, the total combined square footage of any and all accessory structures and detached garages up to six hundred (600) square feet inclusive, and attics that do not exceed a height of five (5) feet as measured from the top of ceiling joist (floor) to the bottom of the ridge beam (ceiling).  For detached dwelling units, after constraints and performance criteria have been addressed to develop a maximum yield, the maximum yield for a development is further affected by average FAR and shall be based on Table 20.206.060.B.  For attached dwelling units, the maximum yield shall be irrespective of the FAR.
TABLE 20.206.060.B
Dwelling Unit Yield
Maximum FAR
Maximum units
80% of maximum
70% of maximum
60% of maximum
   E.   Physical constraints are the on-site circumstances and resources that will be protected consistent with policies in the General Plan or other regulatory requirements.  Factors that require special consideration are as follows:
      1.   U.S.G.S. blueline streams and potential habitat areas for endangered species;
      2.   Areas greater than thirty percent (30%) slope greater than one (1) acre as determined by § 20.206.050.E.;
      3.   Liquefiable soils, Alquist-Priolo Zones, and faulting; and
      4.   Large, mature native trees including but not limited to Coastal Live Oak, Sycamores, Willow, or Black Walnut.
(Ord. 1079, passed 11-2-04; Am. Ord. 1101, passed 5-15-07)