An architectural term used for the divisions of a facade or an interior space as defined by features such as windows, arches and columns. In timber framed buildings the term is used to describe the space between a pair of vertical posts linked by a horizontal tie beam. The length of a bay in a timber framed building can vary considerably, but usually corresponds to the length of a room.
The mid 18th century facade of Quorn House, Hingham, with three bays and a slightly advanced central bay with a pediment. (© NCC)