A curved window frame (Dutch: “bolkozijn”) is a window frame constructed with one or more arched or bowed elements instead of straight lines. It adds architectural distinction and is commonly found in historic buildings, churches, and high-end contemporary designs.
Types of Curved Window Frames
- Round-topped (arched) — a rectangular frame with a semicircular or segmental arch at the top, the most common type in traditional architecture
- Gothic arch — a pointed arch frame typical of medieval and ecclesiastical buildings
- Eyebrow arch — a shallow, gentle curve at the top of the frame
- Bow window — a frame that curves outward from the building facade in a smooth arc, creating a projecting bay
- Bullseye (oculus) — a fully circular frame, often used as a decorative accent window
Construction Challenges
Building a curved window frame requires specialised skills:
- Timber frames — wood must be steam-bent or laminated from thin layers glued over a form to achieve the desired curve
- Metal frames — steel or aluminium sections are rolled or pressed to the required radius
- Glazing — curved frames may require curved glass (hot-bent or cold-bent) or segmented flat panes fitted into a multi-part frame
- Weatherproofing — sealing curved joints demands precision to prevent water ingress
Application
Curved window frames are used in:
- Restoration of historic and listed buildings where original arched windows must be replicated
- Churches, public buildings, and institutional architecture
- Contemporary residential designs seeking visual impact
- Dormer windows and gable features
When specifying a curved window frame, key considerations include the exact radius, the number of opening sections, glass type (single, double, or triple glazing), and compliance with thermal performance standards. Custom manufacturing is typically required, as standard window catalogues rarely include curved options.
Related Terms
- Arched lintel
- Bay window
- Dormer window
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