Last edited 20 May 2019


The term ‘bay’ has numerous applications in the construction industry.

  • When used in relation to a window, (as in ‘bay window’), it describes a part of the construction (in plan and elevation) that protrudes outwards from the main building line and is partly or wholly glazed. Bay windows take various shapes such as curved, rectilinear, polygonal etc.
  • An elevation can also be divided into bays, whether these are subtle, eg delineated by rainwater pipes or movement joints, or created by more three-dimensional features such as a crenulated configuration of the walls.
  • A bay in a building can also describe an internal area that is demarcated by structural elements. For example, in a building that comprises a grid with columns spaced at 6m-centres in both x- and y-directions, the result on-plan will be the creation of bays measuring 6m x 6m – assuming measurements are taken to the grid centre-lines.
  • Bay can also refer to an area that is connected to and forms a small annexe to a larger area, such as a subsidiary area used for some function connected to the activity of the main area, e.g a loading bay.
  • Bay (or bays) can also refer to single parking spaces that are created by painted lines on the ground.

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