By now, most people have become aware of the exclusionary effects of single-family only zoning.  Cities and states have started to flip the concept of single-family only zoning on its head.  Cities like Minneapolis and Seattle and states like Oregon, California and Minnesota have passed (or are considering) legislation essentially outlawing single-family only zoning.  In these states and cities, laws or ordinances now permit additional dwelling types, such as accessory dwellings (i.e., granny-flats), duplexes, triplexes or quadplexes in areas that were formerly zoned exclusively for single-family detached dwellings.  These ordinances and laws are intended to remove land use and housing regulations that have served as economic, social or racial barriers for certain classes or groups of residents, by increasing access to more diverse or affordable housing options in areas previously off-limits.  Surprisingly, these laws and ordinances have broad-based support from disparate groups ranging from developers, home builders and chambers of commerce to housing or social service providers and activists (see YIMBYs).

By way of background, beginning in the early 1900s, communities started zoning most of their land exclusively for single-family detached dwellings. In fact, today communities have not just one, but several of these single-family only zones.  The only real differences between a community’s single-family only zones relate to permitted density (i.e., number of dwellings units per acre) or dimensional standards (i.e., area, setback, coverage) for single-family detached dwellings.  All other dwelling types are expressly prohibited.

States and communities are now reexamining this century-old approach to regulating land use and housing.  In addition to permitting single-family detached dwellings by right in these zones, states and communities are now beginning to relax use (i.e., housing types), density or dimensional standards to permit certain other compatible dwelling types.  In California, up to two accessory dwellings (also known as in-law units or backyard cottages) are now permitted to be constructed on lots with single-family detached dwellings.  While one of these accessory dwellings, known as a junior accessory dwelling unit, is permitted to be located within the walls of a single-family dwelling, the other is permitted to be detached from the principal dwelling.  Therefore, lots that formerly were limited to one dwelling unit are now permitted to have up to three dwelling units.  In fact, there are firms specializing in converting garages into additional living spaces.

In Minneapolis, duplexes and triplexes are now permitted to be constructed within formerly single-family only zones.  In order to ensure that these newer and denser dwelling types are consistent and compatible with the existing and predominate single-family detached dwellings, the new housing types must comply with certain dimensional standards regulating building size, height and setback.  Additionally, there are limitations in the design or location of fire escapes, mechanical equipment and building additions.

To a lesser extent, the Pennsylvania Municipalities Planning Code enables zoning and land use regulations to provide diverse housing opportunities.  Sections 604(4) and 604(5) expressly state that zoning ordinances are intended to provide for housing via a variety of “dwelling types encompassing all basic forms of housing, including single-family and two-family dwellings, and a reasonable range of multifamily dwellings in various arrangements.” Further, Section 503(1.1) expressly permits land development plan exemptions for the:  (i) conversion of an existing single-family detached dwelling or single family semi-detached dwelling into not more than three residential units; and (ii) the addition of an accessory building (e.g., accessory dwelling) on a lot or lots subordinate to an existing principal building (dwelling).

In light of recent events, we anticipate that more and more states and communities will be following suit to examine or modify their single-family only zones to be more inclusive.