Spacer pins

Spindle-shaped terracotta nails or pegs designed to support vertically set tiles at a distance from a masonry wall and thus create the void for wall heating systems. The pointed or chisel-shaped end were inserted directly in the mortar of the walls, while the opposite end typically contains grooves to hold the vertical tiles. Spacer pins were popular in parts of Asia Minor, Cyprus, and Crete, and were also used in Spain and North Africa, among other places.

Spacer tubes / bobbins

Cylindrical terracotta studs placed between the wall and vertically hung terracotta tiles to create a hollow space in which the hot gas coming from the hypocaust could circulate. The spacers as well as the tiles were attached to the wall by T-shaped iron nails, driven through the hollow centre of the spacer. This type of wall heating was popular in south Gaul and Britain, and examples have also been found in Asia Minor, Spain, Romania, and Corinth, among other places.