A bound system is a layout principle in medieval church architecture in which one square bay of the nave corresponds to two (narrower) bays of the aisles. The nave and aisles are rhythmically “bound” to one another: each wide nave bay lines up with exactly two aisle bays.
Why the bound system?
The system emerged in the Romanesque period, when builders wanted to cover the nave with heavy groin vaults. At that time a groin vault was preferably built over a square plan, because square vault fields were the easiest to construct. Since the nave is wider than an aisle, one wide square nave bay had to be paired with two narrow square aisle bays.
Key features:
- Square vault fields — both the nave and the aisles are covered with square groin vaults
- Rhythmic alternation — main piers (carrying the heavy nave vaults) alternate with lighter intermediate piers
- Alternating support system — this alternation of strong and weak supports is also called the alternating system
Application
The bound system is found mainly in:
- Romanesque churches — with their heavy walls and round arches
- Early Gothic cathedrals — as a transition to the later travée (repeating bay) system
- Rhineland and Low Countries church building — where the system was used for a long time
In the High Gothic period the bound system was abandoned. The development of the ribbed vault made it possible to cover rectangular bays as well, so each nave bay once again matched a single aisle bay.
Related terms
- Bay
- Ribbed vault
- Vault
- Nave
- Pier
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