A Bohemian vault (also known as a sail vault) is a shallow, dome-like masonry structure that spans a square or rectangular bay, resting on walls or beams on all four sides. It originated in Central European architecture and was widely used as a fireproof ceiling and floor system.
How It Differs from Other Vaults
Unlike a barrel vault that curves in one direction, a Bohemian vault curves in two directions simultaneously, forming a gentle dome shape:
- Barrel vault — a continuous semicircular arch extending in one direction
- Groin vault — two barrel vaults intersecting at right angles
- Bohemian vault — a shallow dome that meets the supporting walls at a horizontal line on all four sides, creating a smooth, sail-like surface
The key characteristic is its very low rise relative to its span, making it much flatter than a true dome.
Construction Method
Traditional Bohemian vaults are built using:
- Thin bricks or tiles laid in a herringbone or radial pattern
- Lime mortar with a quick initial set to allow rapid construction
- Minimal formwork — skilled masons could build these vaults freehand or with simple guide frames
- Steel or iron beams in later examples, where the vault spans between parallel I-beams
The vault transfers loads outward and downward to the supporting walls, which must resist both vertical weight and lateral thrust.
Application
Bohemian vaults are found in:
- 18th and 19th century residential and commercial buildings throughout Central Europe
- Cellar and ground-floor ceilings where fire resistance was needed
- Church and monastery interiors
- Restoration projects where original vault structures must be repaired or replicated
Modern interest in Bohemian vaults continues in restoration work and in sustainable building, where thin-tile vaulting techniques are valued for their low material use and structural elegance.
Related Terms
- Groin vault
- Barrel vault
- Thin-tile vaulting
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