Opus spicatum


Opus spicatum, literally "spiked work," is a type of masonry construction used in Roman and medieval times. It consists of bricks, tiles or cut stone laid in a herringbone pattern.

Uses

Its usage was generally decorative and most commonly it served as a pavement, though it was also used as an infill pattern in walls, as in the striking base of the causeway leading up to the gate tower at Tamworth Castle. Unless the elements run horizontally and vertically, it is inherently weak, since the oblique angles of the elements tend to spread the pattern horizontally under compression.

Firebacks

Herringbone work, particularly in stone, is also used to make firebacks in stone hearths. Acidic flue gases tend to corrode lime mortar, so a finely-set herringbone could remain intact with a minimum of mortar used. Usk Castle has several fine examples.
The herringbone pattern produces opposing shear plane faces, increasing the relative surface area and therefore rendering it a more sound design for mortar and brick.

Examples

The herringbone method was used by Filippo Brunelleschi in constructing the dome of the Cathedral of Florence.
Herringbone brickwork was also a feature of Gothic Revival architecture.