A bay window is a projecting window assembly that extends outward from a building, increasing interior space and natural light.

A bay window is a window structure that projects outward from the exterior wall of a building, typically consisting of three or more window panels set at angles. This design creates additional interior space while allowing more natural light to enter the room compared to a flat window.

In construction, bay windows may be supported by cantilevered framing, brackets, or foundation elements depending on size and load requirements. They are commonly used in residential construction but also appear in certain commercial and mixed-use buildings. Proper structural support, insulation, and weatherproofing are critical to ensure performance and durability.

From a design and building envelope standpoint, bay windows require careful detailing at rooflines, flashing, and transitions to prevent air and water infiltration. When properly constructed, they enhance architectural character, improve views, and increase usable interior space without expanding the building footprint.

Bay windows were historically used to bring in more daylight before electric lighting—and they often became prized seating or reading areas inside homes.

• Apron (Driveway/Window)
• Awning Window
• Egress Window