A quad house is a type of housing that is attached on two consecutive or perpendicular sides to two other houses, each one with private and direct entrance via their front or side garden. When facing any of the four sides of the group, they appear to be semi-detached houses. The term "quad" describes the style, and if you cut the building into quarters, each corner would be one unit. Quad houses often have a fair amount of green space around the buildings, giving each unit its own private corner and a feeling more like a house than many townhome styles.

In general, quad houses are part of a multi-family residential property, which includes other kinds of homes such as duplexes, triplexes, and even quadriplexes. A quadriplex is a home divided into four separate residences. The residences are part of one single structure, and all of them are attached to each other.

Quad houses are also used to describe stacked housing with two units on a lower floor and two units on an upper floor. They are mostly indistinguishable from other houses within a neighborhood and are similar in scale to other buildings within a neighborhood. Quads often share a common front entrance, making them look similar to a single-unit dwelling.

In summary, a quad house is a type of housing that is attached on two consecutive or perpendicular sides to two other houses, each one with private and direct entrance via their front or side garden. It is part of a multi-family residential property and can also refer to stacked housing with two units on a lower floor and two units on an upper floor.