Double-bay system

A partial plan of a church using the double bay system (Speyer Cathedral). The nave in the center uses large vaults (green), while side aisles use half-sized vaults (blue).The nave exhibits the alternation of supports (black), where the supports carrying the large vault are thicker than the ones only carrying the smaller vaults

In architecture, the double bay system (or engaged system) is the arrangement commonly found in Romanesque architecture, where the internal space of basilicas is subdivided into three spaces, the nave and two side aisles, with aisles having half the width of the nave. This arrangement required the ribbed vaults to be twice smaller as well, so supports in the side aisles had to be spaced at half the step of the supports in the nave.

Double bay system inside the Speyer Cathedral

Double-bay systems in Romanesque churches are almost always reflected in the alternation of supports, usually between compound piers and round columns, although some researchers see to purely decorative alternation in some buildings, like the Ely Cathedral.

Sources

• Davies, N.; Jokiniemi, E. (2008). Dictionary of Architecture and Building Construction. Elsevier/Architectural Press. ISBN 978-0-7506-8502-3. Retrieved 2024-12-23.
• Hoey, Lawrence R. (1989). "Pier Form and Vertical Wall Articulation in English Romanesque Architecture". Journal of the Society of Architectural Historians. 48 (3). University of California Press: 258–283. ISSN 0037-9808. JSTOR 990431. Retrieved 2024-12-23.

Further reading

• McKinne, Jane Elliott (1985). The Church of Sta. Maria and S. Sigismondo in Rivolta d'Adda and the Double-Bay System in Northern Italy in the Late Eleventh and Early Twelfth Centuries Reference (PhD thesis). UC Berkeley.