Which of the following is NOT classified as a house?

The classification of structures as a "house" typically pertains to their function, purpose, and the way they are used. In this context, a portacabin used for storage is primarily designed for utility rather than as a dwelling. This establishes it as not being a house.

Sheds and garages often have residential connections; they may support household activities like gardening or vehicle storage, which tie them to domestic life. On the other hand, a factory is generally recognized as a place for industrial activities, further distancing it from the concept of a house. However, the unique role of a portacabin as a temporary or mobile structure explicitly used for storage makes it the clear candidate that does not fit the definition of a house. Thus, it stands out as not classified as a house compared to the other options.