Kagami-tenjō

What kagami-tenjō means

A kagami-tenjō is a ceiling of flat boards laid edge to edge without battens or coffers, forming a single smooth surface like a mirror. The joints between boards are kept inconspicuous, and the broad surface is often painted.

In the Buddha halls and lecture halls of Zen temples, a great dragon painted on a kagami-tenjō is a well-known sight, the cloud-dragon painting filling the ceiling being a defining feature of Zen interiors.

It differs from other ceilings in how the surface is made. A coffered ceiling sets boards between a grid of ribs, a batten ceiling supports boards on parallel battens, and an woven ceiling uses thin woven boards or bamboo. A kagami-tenjō shows no such lines, only the surface itself.

Reading the records and the building

Records state that a ceiling is kagami-tenjō and may note what is painted on it. The Ginryukaku of Kosanji in Onomichi, Hiroshima, a small pyramid-roofed pavilion projecting over a garden pond, is recorded with a board-floored room under a kagami-tenjō painted with a dragon and a frame finished entirely in silver, an unusual design that echoes the dragon ceilings of Zen temples.

On site, look up for any lines of coffers or battens. A single flat surface without them is a kagami-tenjō. Where it is painted, the subject and artist are often given in the record or in the temple's own materials.