Special setback lines are intended to regulate the location of structures where special features such as scenic roads, geologically hazardous areas, and floodplains require setback regulations to those otherwise specified in this title.

(Ord. 2017-419 § 4, 2017; Ord. 1973-119 § 3 (part), 1973: Ord. 1967-80 § 1 (6209), 1967)

A. Purpose. Special setback lines—S are established along streets to assure the provision of space for light, air, safety, circulation, and visual amenity, and to permit or require adjustment in the location of structures to observe unusual physical conditions. Special setback lines shall be adopted and amended in conformance with the requirements of Chapter 18.74 and when adopted shall be set forth on the zoning map.

B.

Requirements. No structure shall be located closer to a street parcel line than the special setback line. In any district where the least depth or least width of yard required for such distance is greater or less than the distance set forth for any special setback line, the distance established by the special setback line shall govern.

C.

Measurement. The location of a special setback line shall be established by measurements in feet measured at right angles from the parcel line of the subject parcel.

D.

Special Building Setback Lines—S Adopted.

1.

Skyline Boulevard—No structure shall be closer than two hundred feet to the right-of-way of Skyline Boulevard, provided, however, that the architectural and site control commission may allow a reduction of the setback to no less than one hundred feet when it finds that in such a location the proposed structure will not be visible from the right-of-way of Skyline Boulevard.

2.

Alpine Road—No structure shall be located closer than seventy-five feet to the right-of-way of Alpine Road in that section of Alpine Road lying between the northerly town limits and Portola Road.

3.

Portola Road—No structure shall be located closer to the right-of-way of Portola Road in that section from the intersection with Alpine Road to the northwesterly town limits than as stipulated below:

a.

In zoning districts requiring a minimum parcel area of one acre or larger, no structure shall be closer to the Portola Road right-of-way than fifty feet; however, where a parcel has a side or rear parcel line contiguous with the Portola Road right-of-way, an accessory structure may come within twenty-five feet of the right-of-way provided the architectural and site control commission finds the structure will not be seen from Portola Road or that existing and/or proposed planting consistent with the character and quality of the Portola Road corridor will largely obscure the structure.

b.

In zoning districts requiring a minimum parcel area less than one acre, a one-story house shall observe a minimum setback of thirty-five feet and any second story addition thereto shall observe a minimum setback of forty-five feet; alternatively, a two-story house shall observe a minimum setback of forty feet. Structures which are not buildings shall adhere to the same setback requirements. Where a parcel has a side or rear parcel line contiguous with the Portola Road right-of-way, an accessory structure may come within twenty feet of the right-of-way provided the architectural and site control commission finds the structure will not be seen from Portola Road or that existing and/or proposed planting consistent with the character and quality of the Portola Road corridor will largely obscure the structure.

c.

Structures existing as of the date of adoption of the ordinance codified in this subdivision (August 28, 1991), which do not comply with the setback requirements described herein are deemed conforming structures and are not subject to the provisions contained in Chapter 18.46. For such a structure, the three-dimensional space it occupies which does not comply with the setbacks stipulated in subsection D.3.a. and b. of this section becomes a building envelope. Remodeling and rebuilding may occur within such a building envelope subject to normal design review requirements provided for in this section. In addition, the architectural and site control commission may allow architectural details to extend up to two feet from any wall surface on no more than ten percent of the building perimeter within the setbacks in subsection D.3.a. and b. of this section when such details will better ensure compatibility with the character and quality of the Portola Road corridor. This provision is not meant to allow any new construction or use in an existing structure deemed conforming under this subsection, without the required permits; all changes shall be subject to review as required in Chapter 18.46.

(Ord. 2017-419 § 5, 2017; Ord. 1991-265 § 1, 1991; Ord. 1973-119 § 3 (part), 1973; Ord. 1967-80 § 1 (6209.1), 1967)

Editor's note— Ord. 2017-419, § 5, adopted May 24, 2017, changed the title of § 18.58.020 from "Special building setback lines—S (scenic)" to read as herein set out.

A. Purpose. Special building setbacks are established along earthquake fault traces to minimize the potential loss of property and life resulting from differential movement along such traces caused by tectonic forces.

B.

Maps. The town geologic map and ground movement potential map, adopted by Resolution 2279-2006, as amended from time to time, provides the basis for required fault setbacks. Two types of setbacks are established. One type is for setbacks along the San Andreas Fault. The other type is for setbacks from fault (other than the San Andreas).

C.

Setbacks from the San Andreas Fault. The town ground movement potential map establishes required building setbacks along the active traces of the San Andreas Fault. The San Andreas Fault is a known hazard for development and it is prudent to preclude construction of buildings for human occupancy within these zones.

1.

Delineation of Earthquake Fault Zones. Earthquake fault zones define the areas along faults in which primary fault rupture may occur. The map, ground movement potential adopted pursuant to town council Resolution 2279-2006, as amended, defines the boundaries of the fault zones and labels them Pf. Where the location of the fault is known and the pattern of ground breakage is parallel to the direction of the trace, the trace is classified as a "known" trace and shown in a solid line. Where the location of the trace is less well known and the pattern of expected ground breakage is parallel to the direction of the trace, the trace is classified as an "inferred" trace and is shown in a dashed line. Where the pattern of ground breakage results in an en-echelon pattern, the trace is identified on the map as an "en-echelon" trace and shown as a series of short lines at an angle to the general alignment of the trace. An "en-echelon" trace consists of relatively short ruptures, on the order of forty feet in length, oriented obliquely to the general fault trend.

2.

Required Setbacks for Buildings for Human Occupancy. The boundaries of the Pf zones constitute the required building setback lines for buildings for human occupancy. Setbacks are based on the following measurements taken at a right angle from the fault trace. Where the location of the trace is "known", the boundary of the zone is set back from the trace fifty feet from the center line of the trace. Where the location of the trace is "inferred", the boundary of the zone is set back one hundred feet from the center line of the trace. Where the trace is characterized as an "en-echelon" trace, the boundary of the zone is set back one hundred feet from the center line of the trace.

3.

Buildings not intended for Human Occupancy. The following buildings not intended for human occupancy are allowed within fault setbacks:

a.

Buildings that do not exceed one hundred twenty square feet and are used as a tool shed, an ornamental garden structure, an animal shade structure, an agricultural building or for a similar nature and use.

b.

Other non-habitable buildings not exceeding a floor area of one hundred twenty square feet, and are of a similar nature and use may be permitted by staff or by the planning commission upon referral by staff.

D.

Setbacks from Faults (other than the San Andreas). The town ground movement potential map shows traces noted as "fault (other than the San Andreas)." While the location and future movement of these faults is less certain than for the San Andreas Fault, it is still prudent to make certain that buildings for human occupancy do not cross such faults.

1.

Construction of new buildings for human occupancy within one hundred feet of such mapped fault traces shall be supported by a site-specific geologic investigation that demonstrates to the satisfaction of the town geologist that the structure is not underlain by the suspected fault. This investigation must include recommendations for specific geotechnical measures, including appropriate seismic design criteria and minimum setback requirements, to mitigate potential adverse impact from the mapped fault trace and the estimated potential for some degree of displacement along the fault trace alignment.

2.

Construction of new buildings not for human occupancy shall comply with required front, side and rear setbacks.

E.

Modification of Requirements. When geologic studies acceptable to the planning commission demonstrate that delineations of the San Andreas Fault setback zones or the location of faults (other than the San Andreas) are incorrect, the planning commission may approve modifications to the geologic map and/or the ground movement potential map.

(Ord. 2010-387 § 8, 2010; Ord. 1988-227 § 1, 1988; Ord. 1973-119 § 3 (part), 1973; Ord. 1967-80 § 1 (6209.2), 1967)

Editor's note— Ord. 2010-387, § 8, adopted Oct. 27, 2010, changed the title of § 18.58.030 from "Special building setback lines—EF (earthquake fault)" to "Special building setbacks along earthquake faults."