Box Flue

A brick of four terra cotta tiles which were joined together to conduct the furnace-heated air of a Roman (hypocaust) heating system. The tiles were joined at the edges and open at the top and the bottom. The air was directed through them up the walls to escape at the eaves. The exposed faces of the box-flue tiles were often decorated in relief to provide a key for the wall plaster which normally covered them.

[Latin tubulus’, box tile]. A term denoting the hollow box-shaped terracotta tiles which were joined together to form passages in the walls and roofing of Roman imperial buildings, especially baths, to carry furnace-heated hot air up from the hollow hypocaust floors.

A brick of four terra cotta tiles that were joined together to conduct the furnace-heated air of a Roman (hypocaust) heating system. The tiles were joined at the edges and open at the top and the bottom. The air was directed through them up the walls to escape at the eaves. The exposed faces of the box-flue tiles were often decorated in relief to provide a key for the wall plaster which normally covered them.