Glazed tile

Glazed tile (Chinese: 琉璃瓦) was used in China since Tang dynasty as building material for roof top. In Song dynasty, the manufacture of glazed tile was standardized in Li Jie's "Architecture Standard". In Ming dynasty and Qing dynasty, glazed tile became ever more popular for top tier buildings, including palace halls in the Forbidden City, and ceremonial temples (for example Heavenly Temple).

There are two main types of Chinese glazed tiles, glazed tubular tile and glazed plate tile. Glazed tubular tile as moulded into tube shape on a wooden mould, they cut in two halves along its length into two tubular tiles, each semicircle in shape. A tube shape clay mould can be cut into four equal parts, with cross section a quarter of a circle, then glazed into four plate tire.

Glazed plate tiles are laid side by side across, and one overlapping on top of the other. In Song dynasty, the stardard for overlap was 40% overlap, and was increased to 70% overlap in Qing dynasty. With Song style 40% overlap, it was not possible to have triple tile overlap, there was a 20% gap between the first plate tile and the third plate tile, hence if a crack developed in the second tile, water leak was inevitable. One the other hand, with Qing dynasty style 70% overlapping, the first plate tile was overlapped 70%, 40% and 10% by the second, third and fourth tile respectively; thus even the second or/and the third tile developed cracks, there would be no rain leakage.

Glazed tubular tile used at the eave edge is called eaves edge tubular tile. It has an outer end made into round shape top, often moulded with pattern of dragon. Eave edge plate tile has its outer edge decorated with triangular shape end to facilitate rain fall.