In architecture, a bay is the space between architectural elements, or a recess or compartment. bay comes from “Old French baee,” meaning an opening or hole.
A bay is an opening, a built space or a building element delimited by two vertical supports constituting the main support points or the centerpieces of a construction (pillars, columns, arches, trusses, beams, etc.).
The “bay” in the original sense of the term is an opening (bay) ordered with other openings and which together are covered with an architrave in the respect of a Greek architectural order.
The “full bay” succeeding the architrave is the set of solid masonry forming a horizontal band on the façade bearing or not a building, in the structure of a Roman aqueduct for example, between the bays, the arches of two levels , two floors.
Starting from the use of the term “bay of vault”, more generally, the word “bay” designates in architecture a division of a room, that is to say a polygonal plane covered space whose supports of the wall in elevation are located at the vertices of this polygon in plan.
The following types of bays are encountered:
The “rhythmic bay” is a group formed by a main bay, generally covered by a semicircular arch, framed on each side by two superimposed secondary bays, real or feigned (niches, tables, etc.). one under the transom level of the main bay, the other above. It corresponds to an arcade definition.
The wooden “bridge bay” is originally the crossing opening between two piles covered by spars, the bridge arch bay on massive pile is the bridge portion between two piles (also called arch) .
The “bay of vault” is the part of a nave, a vessel of building between two points of main supports or two lateral arches (which are at the origin of the concept of bay).
The “gallery bay” is a fraction of gallery arcade or not, vaulted or not.
The “bay of height” is the portion between two farms of a height in a building.
The “floor bay” is the part of a building floor that fills the opening between two beams that face each other.
The “bay of balusters” is a row of balusters filling the opening between two columns or pedestals.
The “gate bay” is a row of bars filling the opening between two pillars or between two pilasters.
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 (between ribs), in a building using a vaulted structural system. For example, the Gothic architecture period’s Chartres Cathedral has a nave (main interior space) 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.
The openings for windows in a wall. For example, in Georgian style, at Mulberry Fields, the building is described as a “5 bay by 2 bay facade,” meaning a “5 windows by 2 windows” exterior.
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.
East Asia
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.
Source From Wikipedia