An impost (in German Kämpfer) is the architectural element above a pier, wall or capital where an arch begins to curve. This point is also called the springing or the spring of the arch.
Structure
- The impost marks the transition between the vertical, load-bearing part and the curved arch.
- This transition is often marked by a projecting, moulded band: the impost moulding.
- The impost moulding visually emphasises the point where the arch springs.
Application
The impost transfers the load of the arch to the support below, such as a pier or wall. In this way the impost connects the load-bearing masonry with the arch construction above it and ensures a clear transfer of forces.
Related terms
- Arch
- Springing
- Spring
- Keystone
- Pier
- Corbel
Want to learn more about construction terms? Visit our knowledge base at fredsdiyplans.com.