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RH-1 Districts: One-Family.

These Districts are occupied almost entirely by single-family houses on lots 25 feet in width, without side yards. Floor sizes and building styles vary, but tend to be uniform within tracts developed in distinct time periods. Though built on separate lots, the structures have the appearance of small-scale row housing, rarely exceeding 35 feet in height. Front setbacks are common, and ground level open space is generous. In most cases the single-family character of these Districts has been maintained for a considerable time.

RH-1(D) Districts: One-Family (Detached Dwellings).

These Districts are characterized by lots of greater width and area than in other parts of the City, and by single-family houses with side yards. The structures are relatively large, but rarely exceed 35 feet in height. Ground level open space and landscaping at the front and rear are usually abundant. Much of the development has been in sizable tracts with similarities of building style and narrow streets following the contours of hills. In some cases private covenants have controlled the nature of development and helped to maintain the street areas.

RH-1(S) Districts: One-Family with Minor Second Unit.

These Districts are similar in character to RH-1 Districts, except that a small second dwelling unit has been installed in many structures, usually by conversion of a ground-story space formerly part of the main unit or devoted to storage. The second unit remains subordinate to the owner's unit, and may house one or two persons related to the owner or be rented to others. Despite these conversions, the structures retain the appearance of single-family dwellings.

Update: on September 16th 2021, California passed Senate Bill 9 to allow property owners to go though a FAST PERMIT process to split a single-family lot into two lots, add a second home to their lot or split their lot into two and place duplexes on each. The last option would create four housing units on a property currently limited to a single-family house. You can find a friendly description of SB-9 law in this article.

Want to get your permits fast?

Answer these few questions about your project to find out if you may qualify to benefit from California's new State Bill 9 that lets homeowners to add more units on their property or even to split their lot.


The following requirements for side yards shall apply to every building in an RH-1(D) District. Any lot width of less than 33 feet as described herein shall refer only to substandard lots of record as defined in Section 180 of this Code.

Minimum side yards:

(1)   For lots with a width of less than 28 feet: none

(2)   For lots with a width of 28 feet or more but less than 31 feet: one side yard equal to the amount by which the lot width exceeds 25 feet, or the same total amount in the form of two side yards, one of which shall be at least three feet;

(3)   For lots with a width of 31 feet or more but less than 40 feet: two side yards each of three feet;

(4)   For lots with a width of 40 feet or more but less than 50 feet: two side yards each of four feet;

(5)   For lots with a width of 50 feet or more: two side yards each of five feet.

Where, however, if the building does not exceed 25 feet in height, any side yard required by subsection above to be more than three feet in width may be reduced to three feet if the width of the other side yard is increased by the same amount as the first one is reduced.

Buildings may be built to the common line of two adjoining lots if a side yard having a width of not less than the combined width of the two side yards required above for each lot is provided on each such lot on the opposite side.

Only those obstructions specified in Section 136 from San Francisco Code are permitted in a required side yard. No motor vehicle, trailer, boat or other vehicle can be parked or stored within any such yard, except as specified in Section 136.

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CityStructure Untapped Development Potential report for homeowners

City of San Francisco
San Francisco Planning Department