A net vault is a compound rib vault in which the ribs intersect so that both triangular and polygonal vault cells are created. The pattern recalls the meshes of a fishing net, which gives the vault its name. The points where ribs cross are called nodes; the central node is the keystone, and a single vault may contain several.
Where it comes from
The net vault belongs to the late Gothic. In that period the role of the rib shifts: it is no longer primarily a structural member carrying loads down to the piers, but above all a means of design. Displaying craftsmanship becomes the point. The same development produced the related fan vault and the cellular vault.
Characteristics
- A dense rib pattern that dissolves the division into bays, so the vault reads as one continuous surface along the whole length of a space
- Extra ribs — besides transverse arches, wall arches and diagonal ribs there are tiercerons and liernes with no springing of their own
- Multiple keystones, often carved and painted
- Masonry webs between the ribs, usually thin, in brick or tufa
Late Gothic churches across central Europe and the Low Countries contain net vaults in numbers; in the nineteenth century they returned in the Gothic Revival, frequently imitated in plaster with no structural function.
Maintenance points
- Cracks running along the ribs point to deformation of the structure — walls spreading, or a settling foundation. That is work for a structural engineer, not a plasterer
- Never load a vault from above. Storage or a walkway on the extrados belongs on a separate structure
- Water ingress is the greatest enemy. Moisture from a failed roof covering washes lime mortar out of the joints and destroys any decorative scheme
- Repair with a lime-based mortar; hard cement cracks at the junctions and traps moisture
- Investigate before plastering or painting; medieval decoration often survives under later coatings
Related terms
- Vault rib
- Lierne
- Keystone
- Cellular vault
- Vault bay
- Vault web
- Gothic architecture
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