Duplexes are homes that have either been designed or renovated into separate apartments for two or more occupants. The duplex model of housing is popular with landlords who want to get the most value from their rental properties and most popular with renters in heavily populated areas where affordable living space is hard to come by.
Two-story duplex houses may be split vertically or horizontally. The most common vertical split is a firewall built through the middle of the home that separates the unit into identical two-story apartments. The most common horizontal split renders the entirety of the upstairs and downstairs into two separate apartments. Sometimes occupants of a duplex house will share some space, such as a single entrance into a foyer, a porch or a backyard.
While Dictionary.com defines a duplex as a house that has separate apartments for two families, the term is often used more liberally. Sometimes, the term duplex will be used to refer to houses that are split into three or four units (triplex or quadplex). Duplexes are often confused with condos and townhouses; the main difference is that a duplex is a free-standing structure (a house) while condos and townhouses are multiunit structures like apartments with more extensive ownership rights and responsibilities.
Older single-family homes are often bought and repurposed by landlords, but houses can also be built as duplexes. While these houses are typically owned by one person, the individual apartments can be owned separately, like condominiums. Ownership of a duplex typically includes not only the space inside the structure, but the land it sits on. In the case of dual ownership between the two units, land ownership is either split or shared.
The most obvious benefits for owning or renting a duplex home are economic. For landlords, renting to two families instead of one is typically much more lucrative. For tenants, renting a duplex is often substantially cheaper than renting an entire house. In many situations, a landlord may occupy one apartment while renting the other one out. Such proximity between landlord and tenant can provide peace of mind for both parties in the event of an emergency or a repair request.
While duplex housing is often more economically viable, it comes at the cost of some privacy for the tenants. Occupants of duplexes will always have a neighbor right through their floor, ceiling or wall similar to townhouses, condos and apartments. Issues can arise with the shared spaces like driveways and backyards. Even if all of the tenants get along, there is always the possibility that one side of the duplex will be sold off to a new, incompatible tenant.