Bay (architecture)

In architecture, a bay is the space between architectural elements, or a recess or compartment. The term bay comes from Old French baie, meaning an opening or hole.

Examples

The spaces between posts, columns, or buttresses in the length of a building, the division in the widths being called aisles. This meaning also applies to overhead vaults, in a building using a vaulted structural system. For example, the Gothic architecture period's Chartres Cathedral has a nave that is "seven bays long." Similarly in timber framing a bay is the space between posts in the transverse direction of the building and aisles run longitudinally.
If there are no columns or other divisions but there are regularly-spaced windows, each window in a wall is counted as a bay. For example, Mulberry Fields, a Georgian style building in Maryland, United States, is described as "5 bay by 2 bay," meaning "5 windows at the front and 2 windows at the sides".
A recess in a wall, such as a bay window.
A division of space such as an animal stall, sick bay, or bay platform.
The space between joists or rafters, a joist bay or rafter bay.

The Japanese ken and Korean kan are both bays themselves and measurements based upon their number and standard placement. Under the Joseon, Koreans were allocated a set number of bays in their residential architecture based upon their class.