Which type of housing commonly involves two living units sharing one wall?

The concept of a semi-detached house involves two individual housing units that share a single wall, allowing for two separate living spaces within one structure. This arrangement provides certain advantages, such as reducing construction costs while maximizing land use, making it a popular choice in many urban areas. In a semi-detached house, each unit typically has its own entrance and can offer a degree of privacy and independence compared to a shared building, such as an apartment complex.

In contrast, other types of housing, such as single-family homes, are standalone units with no shared walls, which distinguishes them from semi-detached houses. Row houses consist of multiple units connected in a row, typically sharing walls on both sides of each unit, which is different from the arrangement seen in semi-detached houses. Apartments refer to units within a larger building, where multiple living spaces can be arranged vertically or horizontally, but do not share a wall in the same manner as semi-detached houses do. Thus, the characteristics of a semi-detached house distinctly align with the question about living units sharing one wall.