Earliest Fired Clay Roof Tiles

Fired clay tiles were one of the first manufactured roofing materials. They are heavy, fireproof and durable, and because broken pieces survive in the ground for thousands of years, they are much easier to trace than thatch or timber.

Qiaocun, China (about 2400-2200 BCE)

Excavations between 2018 and 2021 at Qiaocun, on the edge of the Loess Plateau in north-west China, recovered a large assemblage of fired clay tiles dated to the early Longshan period, about 2400-2200 BCE. A 2023 study in Scientific Reports reconstructed how they fitted together. The tiles fall into three groups:

• semi-cylindrical cover tiles (about a third of the finds);
• trapezoidal pan tiles with raised side walls (about half);
• flat pan tiles, possibly laid on rammed-earth gable walls.

Because pan and cover tiles were used together, the authors describe Qiaocun as the earliest known composite-tiled roof in the world. They estimate the roofs carried around half a tonne of tile, which needed thick walls to support it.

Early Greece

In western Eurasia, earlier ceramic tiles were flat and rectangular, with no interfitting parts. They roofed so-called corridor houses on the Greek mainland around 2650-2200 BCE. According to the Qiaocun study, interfitting parts appeared in western Eurasia roughly a thousand years after the Chinese composite tiles. The first fully interfitting Greek system identified so far is the 7th-century BCE Protocorinthian roof at Corinth.

Why composite tiles matter

Pairing a flat or dished pan with a curved cover tile is the basic principle behind the Roman imbrex and tegula, Chinese and Japanese temple roofs, and Spanish and Mission tiles today. Water runs in the pans, and the covers seal the joints between them. The Qiaocun finds show this idea existed far earlier than once thought.

Points of uncertainty

New excavations often push dates back, so "earliest" claims should be read as "earliest known". Dating relies on radiocarbon results from associated material, and reconstructions of roof layout from broken fragments involve some interpretation.