Duplex homes may be side by side or stacked. Within these two main categories, there are many different possible types such as single story or multi-story that can further be divided into ranch and mansion styles. A duplex home may feature two adjoining garages in the center of the design or have them at either end. Of course, some duplex housing doesn't include any garages within the design, but have only entry doors. Some duplex homes feature the entry doors in the middle of the house plan with one large covered roof over them.
Centered entries or garages may be horizontally level with the rest of the design, or the main housing units could be placed back from them. Typically, in side-by-side duplex homes, either the entries or garages form a shared wall between the two separate housing units. This type of duplex design can reduce the amount of noise between the units, as living area walls or floors aren't shared. A duplex home plan may place focus on providing the least amount of transferable noise between the two separate housing units, or it may have a more basic design of a completely shared wall or floor.
A side-by-side duplex with entries that are also part of the main building and not set back or forward will have a shared wall that may transfer noise quite easily. If these side-by-side duplex homes are multi-story types, the shared wall may divide bedrooms, bathrooms or other main living areas. Similarly, in stacked duplexes, a horizontal shared area, which is the ceiling of the lower unit and the floor of the upper one, may more easily transfer sound through the main living spaces.
Mansion, or block-style, duplexes may be either side by side or stacked in their home plan. Many of these are both, as they have multiple stories and adjoining entries. Of all of the different possible designs for duplex homes, this type is often the most difficult to tell that it's multi-family housing. Only looking at the two separate entry doors under the single roof at the front of the building reveals the "secret."
Ranch-style duplex homes are often more clear in their dual housing format. These single story, side-by-side duplexes typically have a reverse floor plan design that is quite obvious from the outside. The entries may feature separate, covered porches or paths to each front door.