Bay width is the distance between two parallel rows of columns, walls or trusses in a building. The term originates from church architecture, where the nave (bay) forms the main space, but it is also used in general building construction to describe the clear span between primary structural elements.
Bays in construction
A bay is an elongated section of a building bounded on each side by loadbearing elements:
- Nave (centre bay) — the central, often tallest part of a church or hall
- Aisle (side bay) — the lower spaces flanking the nave
- Single bay — a building with just one span (such as a barn or warehouse)
The bay width largely determines the span of the floor and roof structures and therefore the size of beams, trusses and purlins.
Application
- Church architecture — the ratio between nave and aisle widths defines the spatial character
- Industrial buildings — the bay width determines the clear span and thus the usability of the space
- Residential construction — in traditional houses the bay width is typically 5 to 7 metres
- Agricultural buildings — in farmhouses the bay width determines the layout of the timber frame
Typical dimensions
In residential construction, bay widths generally range from 5 to 7 metres. In industrial buildings they can reach 30 metres or more, depending on the structural system.
Related terms
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