RH are residential house districts. They are intended to recognize, protect, conserve and enhance areas characterized by dwellings in the form of houses, usually with one, two or three units with separate entrances, and limited scale in terms of building width and height.
Such areas tend to have similarity of building styles and predominantly contain large units suitable for family occupancy, considerable open space, and limited nonresidential uses. The RH Districts are composed of five separate classes of districts.
Update: on September 16th 2021, California passed Senate Bill 9 to allow property owners 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.
There are few types of RH districts in San Franscisco, based on the number of dwelling units and size of the setbacks allowed:
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 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(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.
RH-2 Districts: Two-Family.
These Districts are devoted to one-family and two-family houses, with the latter commonly consisting of two large flats, one occupied by the owner and the other available for rental. Structures are finely scaled and usually do not exceed 25 feet in width or 40 feet in height. Building styles are often more varied than in single-family areas, but certain streets and tracts are quite uniform. Considerable ground-level open space is available, and it frequently is private for each unit. The Districts may have easy access to shopping facilities and transit lines. In some cases, Group Housing and institutions are found in these areas, although nonresidential uses tend to be quite limited.
RH-3 Districts: Three-Family.
These Districts have many similarities to RH-2 Districts, but structures with three units are common in addition to one-family and two-family houses. The predominant form is large flats rather than apartments, with lots 25 feet wide, a fine or moderate scale and separate entrances for each unit. Building styles tend to be varied but complementary to one another. Outdoor space is available at ground level, and also on decks and balconies for individual units. Nonresidential uses are more common in these areas than in RH-2 Districts.
RH-1(D), RH-1, and RH-1(S) Districts.
For buildings that submit a development application on or after January 15, 2019, the minimum rear yard depth shall be equal to 30% of the total depth of the lot on which the building is situated, but in no case less than 15 feet. Exceptions are permitted on Corner Lots and through lots abutting properties with buildings fronting both streets, as described in subsection (f) below. For buildings that submitted a development application prior to January 15, 2019, the minimum rear yard depth shall be determined based on the applicable law on the date of submission.
Rear yards are provided at grade level and at each succeeding level or story of the building.