The purpose of this regulation is to implement the Orinda general plan which envisions maintaining the semi-rural character of the city and providing a variety of housing sizes. (General Plan Sections 2.1, 2.1.1-A, 2.1.2-E and 3.1.4-C) This chapter's regulation of the relationship of house size to lot size is intended to:

A.

Preserve and perpetuate the established relationship of structures and spaces characteristic of Orinda's residential setting, where relatively small homes are surrounded with generously sized areas of natural and landscaped open grounds;

B.

Assure that the scale of residential development responds to the limitations created by constrained lot sizes or the degree of the lot's slope, or both;

C.

Minimize the out-of-scale appearance of large homes relative to their lot size and to other homes in a neighborhood;

D.

Minimize the environmental damage of tree removal and grading which may result from over-building; and

E.

Expand the range of house size to accommodate housing needs and preserve and enhance diversity of housing.

(Ord. 99-5 § 2 Exh. A (part))

For the reasons set forth in Section 17.6.1, the size of a proposed new home or expansion of an existing home, including an expansion to accommodate an accessory dwelling unit in conformance with Section 17.3.4, shall be established as set forth in this section.

A.

Lots Under Twenty Thousand Square Feet. No single-family residence on a lot of less than twenty thousand (20,000) square feet may exceed the values shown on the schedule found in Section 17.6.8 entitled "Maximum Allowable Home Size Without Design Review Approval for Lots Less Than 20,000 Square Feet" except as provided in Subsection D below. The "Maximum Floor Area" values shown on that Section 17.6.8 schedule shall be increased by five (5) square feet for every linear foot of open space abutting the lot proposed for development, provided at least 75 linear feet of open space abut the lot proposed for development. For the purposes of this section, "open space" must not contain any buildings within 35 feet of the lot proposed for development. "Open space" includes EBMUD watershed property, PG&E transmission line rights-of-way, golf course fairways, East Bay Regional Park District parkland and portions of City parks in a natural state.

B.

All Other Lots. No single-family residence on a lot of twenty thousand (20,000) square feet or more may have a floor area exceeding the product of .20 times the net parcel area of the lot except as provided in Subsection D below.

C.

Large Homes. The maximum floor area for a single-family residence shall not exceed seven thousand (7,000) square feet, regardless of lot size except as provided in Subsection D below.

D.

Design Review. An applicant may elect to seek approval to exceed the maximum allowed sizes described in Subsections A—C, above, through a design review application to the City. Such applications shall be granted only if exceeding the maximum allowed sizes described in Subsections A—C, above, will not cause or contribute to inconsistency with the City's Basic design review standards (Section 17.30.5) or any other applicable design review standards.

(Ord. 05-01 § 2; Ord. 99-5 § 2 Exh. A (part))

(Ord. No. 10-03, § 2(exh. A), 4-20-10; Ord. No. 10-10, § 2(exh. A), 1-4-11; Ord. No. 17-03; § 2(Att. A), 8-1-17)

The floor area of a single-family residence shall be calculated as follows:

A.

The floor area shall include the total horizontal area of each floor within the exterior walls of all buildings on a lot, including attached and detached primary and accessory dwelling units, buildings, garages, carports (measured by total roof area), storage spaces and any enclosed space with a seven-foot or greater ceiling height, and as measured at the exterior face of the enclosing walls. The area of a fully enclosed atrium shall be calculated as interior floor area.

B.

The floor area shall exclude:

1.

Attics and lofts, and/or portions of attics and lofts, which have less than an eight-foot ceiling height as measured from the top of exterior framing elements;

2.

Basements where the finished floor level directly above is less than four feet above the finished grade on all sides or basements where the finished floor level directly above is less than two feet above the finished grade on all but one side;

3.

Building recesses as follows:

a.

On existing residences, balconies, porches, decks or other structures, (except carports) where the longest dimension is unenclosed;

b.

On proposed construction, only portions of building recesses recessed less than eight feet deep where at least one of the longest dimensions is unenclosed; and

c.

On existing residences and proposed construction, up to 150 square feet of covered porches.

(Ord. 05-01 § 3: Ord. 02-03 § 9; Ord. 99-5 § 2 Exh. A (part))

(Ord. No. 10-10, § 2(exh. A), 1-4-11; Ord. No. 17-03; § 2(Att. A), 8-1-17)

The calculation of floor area set forth in Section 17.6.3 shall be adjusted as appropriate under the following provisions:

A.

Garage Adjustment. The floor area of a garage shall be excluded from the calculation of floor area to a maximum of four hundred (400) square feet. Any garage floor area in excess of four hundred (400) square feet shall be included in the calculation of floor area in Section 17.6.3.

B.

Interior Volumes. In calculating floor area under Section 17.6.3, any space with an exterior height of seventeen (17) feet or greater, measured from finished floor level, shall be doubled.

(Ord. 02-03 § 10; Ord. 99-5 § 2 Exh. A (part))

The provisions of this chapter shall not apply to the following projects:

A.

Additions of newly created habitable space which are to be fully contained within the building envelope of any existing conforming or legally nonconforming single-family residential structure, as determined by the Zoning Administrator; and provided that no approvals for either a new residence or an exterior addition have been granted within the past five years from the time of the application under this exemption. Examples include excavation and improvement of areas behind the skirt walls of hillside homes, improvement of attic spaces, and limited exterior changes such as the addition of windows, doors and dormers not exceeding four feet in height.

B.

Any addition or accessory structure of less than two hundred (200) square feet, provided that no approvals for either a new residence or an exterior addition have been granted within the past five years from the time of the subject application, and neither an exception or variance is requested.

(Ord. 05-07 § 4: Ord. 99-5 § 2 Exh. A (part))

(Ord. No. 10-03, § 2(exh. A), 4-20-10)

When an addition to an existing home involves the complete demolition of an existing accessory structure, that previously existing floor area shall not be counted as existing space and its replacement shall be viewed as newly constructed space.

(Ord. 99-5 § 2 Exh. A (part))

"Net parcel area" means the total horizontal area included within the property lines of a parcel, excluding area within vehicular rights-of-way and vehicular easements which serve four or more parcels. Generally, all public streets and private streets serving a total of four or more lots are to be excluded from net parcel area calculations, while shared driveways may be included.

(Ord. 99-5 § 2 (Exh. A (part))

Maximum Allowable Home Size For Lots Less Than 20,000 sq. ft.

Note: The "Maximum Floor Area" as listed below excludes the first four hundred (400) square feet of garage and/or carport roof area, but includes all such garage/carport areas in excess of the first four hundred (400) square feet. Application of the design review standards of Chapter 17.30 may result in homes that are either smaller or larger than the maximum floor areas listed below.

(Ord. 99-5 § 2 (Exh. A (part))

(Ord. No. 10-03, § 2(exh. A), 4-20-10; Ord. No. 17-03; § 2(Att. A), 8-1-17)