Vietnamese Yin-Yang Tile (Ngói Âm Dương)

The Vietnamese yin-yang tile (ngoi am duong) is a thin, curved, handmade clay roof tile laid in alternating rows, one set face up and the next face down, like the two halves of the yin-yang symbol. It is closely associated with the Tay and Nung peoples of the northern border provinces, and in some parts of Vietnam ordinary red clay roof tiles are called yin-yang tiles because of their concave and convex shape.

Laying

The name comes from the way the tiles are placed: alternate tiles face up and down. Concave tiles form channels that carry rainwater, and convex tiles cap the joints between them. This is the same pan-and-cover principle used for Chinese, Roman and Spanish curved tiles and for split-bamboo roofs elsewhere in Southeast Asia.

Production

Two documented craft centres give a picture of the process:

• Quynh Son and Long Dong communes, Bac Son district, Lang Son province: about 50 households have made the tiles for over a century. Clay from wet rice fields is kneaded with water, cut into pieces about 1 cm (0.4 in) thick, pressed in wooden moulds, sun-dried for one to two months and fired in round wood kilns for about 10 days. Kiln operators judge temperature by smoke colour. One kiln firing of about 10,000 tiles is enough for a three-compartment house.
• Lung Ri hamlet, Cao Bang province: 23 of 80 Nung households still make tiles. Clay is soaked for 10 days, kneaded by buffalo for 4-5 days, rested, sieved, cut into 1 cm sheets and wrapped around cylindrical wooden moulds, each producing four tiles. The blanks dry for 30-40 days, then 16,000-20,000 tiles are fired together for seven days and nights and cooled in the kiln for two to three weeks. Lung Ri was recognised as a traditional craft village in 2024.

Performance

Makers and reporters describe the tiles as light, waterproof and heat-resistant, keeping houses warm in winter and cool in summer. Published sources give no reliable lifespan figure.

Status

Factory-made tiles, metal sheet and other materials have taken most of the market, and makers report shortages of suitable clay. Vocational classes have been organised to pass on the skill, and the villages are promoted for craft tourism. Contemporary Vietnamese architects also reuse traditional clay tiles in new buildings.