Duplex (building)

A duplex house plan has two living units attached to each other, either next to each other via townhouses or above each other like apartments. By contrast, a building comprising two attached units on two distinct properties is typically considered semi-detached or twin homes but is also called a duplex in parts of the Northeastern United States. The term 'duplex' is not extended to three-unit and four-unit buildings, as they would be referred to with specific terms such as triplex and fourplex or quadplex/quadruplex. Because of the flexibility of the term, the line between an apartment building and a duplex is somewhat blurred, with apartment buildings tending to be bigger, while duplexes are usually the size of a normal house. In dense areas like Manhattan and downtown Chicago, a duplex or duplex apartment refers to a maisonette, a single dwelling unit spread over two floors connected by an indoor staircase. Similarly, a triplex apartment refers to an apartment spread out over three floors. These properties can be quite expensive and include the most expensive property in Manhattan as of 2006 (according to Forbes Magazine), a triplex atop The Pierre hotel. In this context, an apartment locating on one floor only may be called a simplex. In the United Kingdom, the term duplex is more often used by property professionals such as architects and estate agents and refers only to a flat or apartment on two floors connected by an inner staircase though many newer apartments have open-plan designs including mezzanines. In Australia, a duplex is often considered a residential building containing two homes that share a common central wall. As such they are usually a mirror image of each other in layout. Also referred to as a maisonette in South Australia. A paired home is two homes that share a wall and have opposite side entries. The whole building is designed to look like one single larger home. Unlike a front to front duplex, the paired home helps provide more privacy for the homeowners. In urban planning, the term duplex is used more specifically. Major Canadian cities sometimes use the term duplex to refer specifically to a building with one unit built above another. Edmonton defines 'Duplex Housing' as 'development consisting of a building containing only two Dwellings, with one Dwelling placed over the other in whole or in part with individual and separate access to each Dwelling'. Calgary defines Duplex Dwelling as 'a building which contains two Dwelling Units, one located above the other, with each having a separate entrance'. Toronto proposes in their new Zoning Bylaw to define 'Duplex Building' as a building that has only two dwelling units, and one dwelling unit is entirely or partially on top of the other dwelling unit. Halifax defines Duplex Dwelling as 'the whole of a dwelling that is divided horizontally into two separate dwelling units, each of which has an independent entrance'.