Fenêtre en baie

A bay window is a window space projecting outward from the main walls of a building and forming a bay in a room. A bay window is a type of window that protrudes from the external wall of a building, creating a bay or alcove inside the room. It typically consists of a central windowpane, called a fixed sash, flanked by two or more smaller windows, known as casement or double-hung windows. The arrangement creates a panoramic view of the outside, allows more natural light to enter the room, and provides additional space within the room. Bay windows are often designed to extend beyond the exterior wall, forming a small nook or seating area inside, which can be used for various purposes such as reading, display, or simply enjoying the view. They are commonly found in residential buildings, particularly in living rooms, dining areas, or bedrooms, but can also be seen in commercial or public structures. Bay window is a generic term for all protruding window constructions, regardless of whether they are curved or angular, or run over one or multiple storeys. In plan, the most frequently used shapes are isosceles trapezoid (which may be referred to as a canted bay window) and rectangle. But other polygonal shapes with more than two corners are also common as are curved shapes. If a bay window is curved it may alternatively be called bow window. Bay windows in a triangular shape with just one corner exist but are relatively rare. A bay window supported by a corbel, bracket or similar is called an oriel window. "Rawashin" is a traditional and distinctive style of corbelled bay window in Jeddah, Saudi Arabia (e.g., as on the frontage of Nasseef House). Most medieval bay windows and up to the Baroque era are oriel windows. They frequently appear as a highly ornamented addition to the building rather than an organic part of it. Particularly during the Gothic period they often serve as small house chapels, with the oriel window containing an altar and resembling an apse of a church.