A duplex is a type of residential building that contains two separate housing units within one structure , usually with their own entrances and living spaces.

Core definition

  • In real estate, a duplex is one building divided into two distinct homes, either side-by-side or stacked (one upstairs, one downstairs).
  • Each unit typically has its own entrance, kitchen, bathroom(s), and living areas, so two households can live independently in the same structure.
  • Because it houses two units, a duplex is considered a form of multifamily housing rather than a single-family home.

How a duplex is laid out

Common configurations include:

  • Side‑by‑side: Two mirror-image units share a central wall, each with its own front door and sometimes separate driveways or garages.
  • Up‑down (stacked): One unit occupies the ground floor and the other is directly above it, with separate entrances and often separate addresses or unit numbers.
  • Shared outdoor space: Yards, patios, or parking can be fully shared, divided by fencing, or allocated to each unit.

Regional meanings of “duplex”

The exact meaning can shift a bit by region:

  • North America: Usually means a building split into two separate homes or apartments, each with its own entrance.
  • UK usage: “Duplex” can mean an apartment on two floors (a two‑level flat) within a larger building.
  • Australia: Can refer to a semi‑detached style home where two attached houses share a wall, often called a duplex or semi.

How a duplex differs from other homes

  • Versus single‑family home: A single‑family home has only one dwelling unit, while a duplex has two within the same structure and lot.
  • Versus townhouse: Townhouses are often in rows, each on its own lot, each owned separately; a duplex is usually one lot with two units under one owner.
  • Versus twin home: Twin homes look like duplexes but are on two separate lots with a property line through the shared wall.

Why duplexes are popular now

With housing costs high in the mid‑2020s, duplexes are trending as flexible options for both living and investing:

  • Owners can live in one unit and rent the other to offset their mortgage (a “house hack”).
  • Investors like duplexes as entry‑level multifamily properties, often cheaper and simpler to manage than larger apartment buildings.
  • Cities encouraging “gentle density” sometimes update zoning to allow more duplex construction on lots that once allowed only single‑family homes.

Information gathered from public forums or data available on the internet and portrayed here.