A three-light window is a window or facade opening divided by two vertical mullions into three side-by-side glazed lights. The word ‘light’ here means the glazed panel; three lights therefore means three panels. The shape is common in monumental facades and in modern executions as a wide shopfront.
Forms of three-light windows
- Symmetrical three-light — three lights of equal width, often with a fixed central panel
- Asymmetrical three-light — wider central panel than the two side panels, or vice versa
- Palladian window — central panel higher and arched, side panels lower with flat tops
- Diocletian window — a semicircular variant with three lights, derived from Roman thermae
- Ribbon window — a horizontal three-light running continuously along the facade
Historical context
The three-light window is a classical motif from Roman and Renaissance architecture. Andrea Palladio (16th century) made the symmetrical version famous in his villas. In Dutch step-gabled houses and English country houses, the three-light was often placed above an entrance or in the central gable.
Applications
Three-light windows are used in:
- Classical facades — as a central feature above the front door
- Church architecture — three-lights in the apse or transept
- Modern houses — as a wide facade opening with doors or fixed glazing
- Bay windows — a three-light in a projecting wall
- Office facades — often in a repeating rhythm across the elevation
Structural aspects
- Lintel and head member — must carry the load across the full width
- Intermediate mullions — may be load-bearing or merely separate the glazing
- Operable parts — often only the side lights open, with fixed central glass
- Glass thickness — large panes are usually laminated or toughened safety glass
Related terms
- Window frame
- Window
- Transom light
- Empire window
- Cross-mullioned window
- Palladian window
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