Bay window
A bay window is a multi-panel window that projects outward beyond the external wall of a building. This outward projection forms a bay or interior recess and is supported by a sill height wall. Bay windows are typically rectangular or polygonal, and the most common internal angles are 90°, 135° and 150°.
Bay windows are a prominent feature of Victorian domestic architecture but were originally incorporated into designs during the English Renaissance period as a means of making a room appear larger, providing better views and admitting more natural light than a window which was flush with the wall line.
The interior recess created by a bay window can be used for storage by enclosing the lower area, or as a window seat with the addition of cushions and other soft furnishings. Alternatively, it can be used as a space to display decorative items, plants, and so on.
However, a bay window can require more heating or cooling to maintain a comfortable internal temperature due to the increased surface area of glazing. Consideration must also be given to the structural stability of the building foundations, as they must be capable of supporting the protruding windows and roof above.
In modern architecture, bay windows underwent a revival to become a characteristic feature of the Chicago School. Today, bay windows can be found in all types of domestic architecture as well as in apartment buildings.
There are several variations, including:
- Canted: A bay window with a flat front and angled sides.
- Bow: A bay window which is curved or arc-shaped.
- Oriel window: This is a bay window found on an upper floor, typically supported from below by a corbel or bracket. This type of window allows the floor space to be extended without the dimensions of the foundation needing to be changed.
- Mashrabiya: Highly decorative enclosed balconies that are characteristic of Arab architecture.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Restoring Abbotsford's hothouse
Bringing the writer Walter Scott's garden to life.
Retired firefighter cycles world to raise Grenfell funds
Leaving on 14 June 2025 Stephen will raise money for youth and schools through the Grenfell Foundation.
Key points for construction at a glance with industry reactions.
Functionality, visibility and sustainability
The simpler approach to specification.
Architects, architecture, buildings, and inspiration in film
The close ties between makers and the movies, with our long list of suggested viewing.
SELECT three-point plan for action issued to MSPs
Call for Scottish regulation, green skills and recognition of electrotechnical industry as part of a manifesto for Scottish Parliamentary elections.
UCEM becomes the University of the Built Environment
Major milestone in its 106-year history, follows recent merger with London School of Architecture (LSE).
Professional practical experience for Architects in training
The long process to transform the nature of education and professional practical experience in the Architecture profession following recent reports.
A people-first approach to retrofit
Moving away from the destructive paradigm of fabric-first.
International Electrician Day, 10 June 2025
Celebrating the role of electrical engineers from André-Marie Amperè, today and for the future.
New guide for clients launched at Houses of Parliament
'There has never been a more important time for clients to step up and ...ask the right questions'
The impact of recycled slate tiles
Innovation across the decades.
EPC changes for existing buildings
Changes and their context as the new RdSAP methodology comes into use from 15 June.
Skills England publishes Sector skills needs assessments
Priority areas relating to the built environment highlighted and described in brief.
BSRIA HVAC Market Watch - May 2025 Edition
Heat Pump Market Outlook: Policy, Performance & Refrigerant Trends for 2025–2028.
Committing to EDI in construction with CIOB
Built Environment professional bodies deepen commitment to EDI with two new signatories: CIAT and CICES.
Government Grenfell progress report at a glance
Line by line recomendation overview, with links to more details.
An engaging and lively review of his professional life.
Sustainable heating for listed buildings
A problem that needs to be approached intelligently.
50th Golden anniversary ECA Edmundson apprentice award
Deadline for entries has been extended to Friday 27 June, so don't miss out!
CIAT at the London Festival of Architecture
Designing for Everyone: Breaking Barriers in Inclusive Architecture.