Low Density
Stacked
Duplex
Form: Two units stacked on top of each other. Units do not share floors and have separate external entrances. From the outside units will have the same appearance as a small to medium single family detached house. Entrances can be placed in the rear to keep a uniform front appearance. Stacked duplexes can be particularly well-suited for narrower lots, where townhomes may not fit.
Local presence: Duplexes can be found in Chester County but are more prevalent in neighboring counties. Nearby examples include Bryn Mawr, Montgomery County where they are commonly found near major commercial streets.
Zoning considerations: Municipalities will need to consider in which districts duplexes are allowed, parking, and minimum lot size. Additionally, municipalities can choose to allow duplexes only as two units stacked, or allow them in configurations of four, with two sets of duplexes attached by a central vertical wall, creating four units in an attached building. Allowing duplexes by-right will better enable unit construction. Additional municipal considerations as they relate to duplexes include: permitting smaller minimum lot sizes, requiring sidewalk construction and utility connections for new units, and ensuring setbacks are at an appropriate size to maintain neighborhood integrity.
Zoning ordinance examples
- West Goshen Township: Allows, as a special exception, twins (units separated by a party wall with independent outside access and open space on three sides) and duplexes (single buildings containing two dwelling units with independent outside access, and open on all sides) under semi-detached buildings in R-4 Residential District zoning. The township requires sewer connections for each semi-detached unit.
- London Grove Township: Allows duplex development by-right in all residential zoning with the exception of Agricultural Residential. In lower density zoning districts, duplexes must be developed as part of a cluster development of five parcels or more.
- Spring City Borough: Defines duplex as a unique use separate from twins, quadplexes, or townhomes. The borough allows duplex development in medium and high-density residential districts by-right.
