Chapter 8.232 — S105 DISTRICT (COMBINING DISTRICT, MIDCOAST)

The following regulations shall apply in any single-family residential district with which the “S-105” District is combined.

The minimum building site width shall be an average of 75 feet.

The minimum building site area shall be 20,000 sq. ft.

The minimum setbacks shall be:

The maximum parcel coverage shall be 0.25 (25%).

Parcel coverage shall include all: (1) buildings, (2) accessory buildings, or (3) structures such as patios, decks, balconies, porches, bridges, and other similar uses which are eighteen (18) inches or more above the ground.

a. The maximum building floor area shall be established according to the following table, except as provided by subsection b.

The maximum building floor area shall include the floor area of all stories of all buildings and accessory buildings on a building site. Maximum building floor area specifically includes: (1) the floor area of all stories excluding uninhabitable attics as measured from the outside face of all exterior perimeter walls, (2) the area of all decks, porches, balconies or other areas covered by a waterproof roof which extends four (4) or more feet from exterior walls, and (3) the area of all garages and carports.

• b. Up to 200 sq. ft. of covered parking floor area shall not be counted toward the limitations set forth in subsection a. for any substandard lot that is (1) smaller than 4,500 sq. ft. in area, (2) not in common ownership with contiguous lots, and (3) developed with an affordable (very low, low, or moderate income) single-family residential unit, i.e., subject to income and cost/rent restriction contracts with San Mateo County.

• c. In addition to the limitations set forth in subsection a., permit 250 sq. ft. bonus building floor area for any parcel whose substandard lots are voluntarily merged in accordance with the provisions of San Mateo County Board of Supervisors’ Resolution No. 068386, Exhibit G.

(Prior code § 6300.14.50 Amd Ord. 4553; 05/24/11 - CA Coastal Commission certified 08/24/12, eff. In Coastal Zone 09/07/12)

The amount of parcel area covered by impervious structures less than eighteen inches (18”) in height is limited to ten percent (10%) parcel size (not to exceed 1,170 sq. ft. for residential uses). Impervious structures include, but are not limited to, non-porous driveways, decks, patios, walkways and swimming pools.

An exception to the limit may be granted by the Director of Planning and Building for select development upon finding that off-site project drainage, i.e., runoff, will not exceed that amount equivalent to 10% (parcel size). The runoff equivalent of 10% (parcel site) could be achieved by directing runoff to on-site porous areas or through the use of detention basins. The applicant shall submit a professionally prepared site plan showing topography, drainage, and calculations which demonstrates this finding can be made. The exception provision applies to:

• a. Non-residential development, and

• b. Residential development, only if the Director of Planning and Building determines that the exception is necessary for compliance with site planning and design requirements.

(Prior code § 6300.14.60 Amd Ord. 4553; 05/24/11 - CA Coastal Commission certified 08/24/12, eff. In Coastal Zone 09/07/12)

The maximum building height shall be established, as follows:

• a. Up to 30% Slope. Where the average slope of the parcel area covered by the main residence is less than 30%, maximum building height is 28 feet.

• b. 30% Slope or Greater. Where the average slope of the parcel area covered by the main residence is 30% or greater, maximum building height is 28 feet, unless increased by the Design Review Committee.

The Design Review Committee may increase the maximum building height to 33 feet for either:

• (1) The center 40% of the house, or

• (2) The downslope wall. Where the downslope wall height limit is increased to 33 feet, maximum building height for the house shall be the plane formed by connecting the maximum upslope wall height (28 feet) with the maximum downslope wall height (33 feet).

Building height shall be measured as the vertical distance from any point on the natural grade to the topmost point of the building immediately above.

Finished grade, measured at the outside face of exterior perimeter walls, shall not significantly deviate from the natural grade, to the satisfaction of the Design Review Committee.

Where Zoning Regulations Chapter 8.300, Flood Hazard Areas, requires an elevated building, as defined in Section 8.300.030(8), building height shall be measured as the vertical distance from the “base flood elevation,” as identified on the applicable Flood Insurance Rate Map (FIRM), to the topmost point of the building immediately above.

Chimneys, pipes, mechanical equipment, antennae, solar panels and similar features may exceed the height limit to a maximum of 36 feet as required for safety or efficient operation.

The maximum plate height for a garage on a downhill slope that is allowed by Section 8.340.030 to extend into the front setback shall be 10 feet. Plate height shall be measured as the vertical distance from any point on the floor to the bottom of the lowest ceiling joist where the framing of the roof begins. No second story shall be allowed above or below any portion of such garage.

(Prior code § 6300.14.00-6300.14.80 Ord. 3980: 08/08/00)

New residential development shall conform to either the daylight plane or façade articulation options described in this section, as determined by the project applicant.

• a. Daylight Plane Option

The daylight plane shall be established on two opposite house sides, i.e., either from the front and rear setback lines, or from the side setback lines, as determined by the project applicant and approved by the Design Review Committee.

The daylight plane shall be measured from the setback line at natural grade, upward a vertical distance of 20 feet, and then inward at an angle of 45° until the maximum building height is reached.

Cornices, canopies, eaves, roof overhangs, chimneys, fire escapes, stairways; landing places; uncovered porches, and similar architectural features may extend into the daylight plane at the front, side, or rear yard, to the extent allowed by Zoning Regulations Section 8.340.010.

Chimneys, pipes, mechanical equipment, antennae, and similar equipment may extend into the daylight plane up to a maximum of 36 feet as required for safety or efficient operation.

Dormers, gables and other architectural features located in the center 60% of the house may extend into the angled portion of the daylight plane, subject to Design Review Committee approval, provided that:

• (a) The combined length on any building side does not exceed 40% of the length of that building side, and the height of such features does not exceed 24 feet.

• (b) The combined length on any building side does not exceed 30% of the length of that building side, and the height of such features does not exceed 28 feet.

• b. Facade Articulation Option

Facade articulation shall be provided on all building sides, and is subject to approval by the Design Review Committee. Facade articulation is intended to break up the appearance of shear walls through the placement of projecting or recessing architectural details, including decks, bays, windows, balconies, porches, overhangs, and cantilevered features.

In order to approve proposed facade articulation, the Design Review Committee must find that: (1) all building facades are well articulated and proportioned, and (2) each building wall is broken up so as not to appear shear, blank, looming or massive to neighboring properties.

(Prior code § 6300.14.70-6300.14.90 Renumbered Ord. 4553; 05/24/11 - CA Coastal Commission certified 08/24/12, eff. In Coastal Zone 09/07/12)

Development related grading, e.g., site preparation, shall not occur between October 15 and April 15 in any given year unless the applicant demonstrates to the satisfaction of the Director of Planning and Building and Building Official that the development site will be effectively contained to prevent erosion and sedimentation, and that such site containment has been established and is ongoing. Site containment shall include, but not be limited to, covering stored equipment and materials, stabilizing site entrances and exposed slopes, containing or reducing runoff, and protecting drain inlets.

Prior code § 6300.14.100 Ord. 4553; 05/24/11 - CA Coastal Commission certified 08/24/12, eff. In Coastal Zone 09/07/12)