Centering

Centering (or Center), as an architectural term, is the temporary support placed under vaults and arches to sustain them while in process of building; usually a frame of woodwork. In Norman architecture, in which the vaulting is constructed with rough, unhewn stones, the centering was covered with a thick layer of mortar, in which the stones were imbedded, so that when the centering was removed it remained adhering to the under surface of the vault, exhibiting an exact, impression of the boards on which it was spread. In Ireland hurdles were used in-stead of boards over the centering, and their; impression frequently remains on the plaster.