We don’t normally think about zoning and the impact it can have on our neighborhood, but occasionally questions arise about what all these different terms mean. Here is a breakdown of what zoning we have in our neighborhood and what other types of land use can impact our zoning.
RS20
RS20 zoning is the zoning for most of our neighborhood. This zoning type is intended for single-family residential development at a variety of densities. These districts may be applied to preserve the character of developed residential areas that are predominately single-family in nature and recommended to remain so by the general plan. These districts also may be applied to establish single-family character in developing areas at densities recommended by the general plan.
Designed for relatively low to moderate intensity single-family development, these districts are appropriate for implementing the residential low-medium policies of the general plan. These districts may also be appropriate within selected areas of natural conservation policy, with urban services. The RS20 and RS15 districts may be applied along edges of areas classified within residential low density policy that have suitable physical characteristics and good street access.
RS20 zoning allows for one single family unit on 0.5 acre of property. For the vast majority of lots in our neighborhood, you would only be able to add one home on our lots, which range from 0.9 acre to 0.5 acre, with the frontages and property line offsets required by law on each side.
Secondary dwellings are currently only allowed on RS20 within parts of town that have an additional policy overlay that enhances what can be done in a particular area. A DADU (Detached Accessory Dwelling Unit) Overlay would allow residents to build smaller, secondary dwellings in RS20 zoning (more on that below).
R20
R20 zoning allows for either: two single family dwelling units OR one single family dwelling unit and a DADU. This could be 2 single family homes or a single family home and a DADU. The R20 district is intended either for established residential subdivisions where the pattern of development contains both one-and two-family structures. Intended for low to moderate intensity one-family and two-family development, these districts are appropriate for implementing the residential low-medium density policies of the general plan. These districts also may be appropriate within those areas of natural conservation policy that are environmentally suitable and have urban services.
R20 zoning in our neighbor does exist sparsely, but currently it is along the southern edge of our area at W Due West Ave and Cash Lane. However, we do have a fair number of instances in the neighborhood where secondary dwellings pre-exist as part of the mass reclassification of zoning across Nashville in 1974. Before then, our whole neighborhood was classified as R20, with some lots still having multiple units sprinkled throughout the neighborhood. So while our neighborhood is zoned as RS20, we do have areas where the use looks like R20.
DADUs
A Detached Accessory Dwelling Unit, or DADU, is a small, single family residence on a property with an existing home on a residential lot that is at least 15,000 sq ft (0.34 acres). These secondary dwellings are often used as homes for aging parents, children saving for their first homes or other flexible uses for the homeowners. The living space of a DADU cannot exceed 700 sq ft, and the height of a DADU cannot exceed the height of the principal house on the lot. You can have one additional accessory structure (e.g., a storage shed) on your property, not to exceed 200 sq ft.
Currently in Nashville, DADUs can only legally be built within the Urban Design Overlay. The “legally” distinction is important, because we have a handful of illegal DADUs in our neighborhood already. At the time of this writing, Metro Council is exploring ways to either expand the Urban Design Overlay to include our neighborhood or to change the zoning code to allow DADUs in RS20 zoning. The second option would be part of a broader effort to simplify zoning in Nashville and to try and better codify some of the oddities of where short-term rentals are allowed, how they are used, and to address broader concerns about land use flexibility in single-family zoning.