Udatsu

What an udatsu is

An udatsu is a small wall raised at the gable end or above the roof of a Machiya. In a street where houses stand eaves to eaves, it exists to stop fire running sideways from one building to the next.

One kind projects from the upper wall towards the street. The Tsuzuki sake shop in Ehime Prefecture, built in 1887, is described as standing on the street with plastered gable ends and these walls projecting on both street-facing sides. The Ueno Residence in Shiga Prefecture, from the late Edo period, is described as having a latticed centre to its upper front, plastered flanking bays with a barred window to the east, and these walls at both ends.

The Tamura tea shop in Nara Prefecture, from the later Edo period, is described as a townhouse entered from the eaves side, two storeys, gabled and pantiled, with a projecting eaves beam across the front, these walls to either side, and a large barred window upstairs.

Since the purpose is fire resistance, the walls are plastered over. All three descriptions mention plaster in the same breath.

A mark of standing

Because they are the part of a house most visible from the street, these walls came to signal the owner's position. The gatehouse of the Inaba Residence in Kyoto, from the late Edo period, is described as unusual for a building of its kind in having two storeys with the upper one projecting forward, and a gabled pantiled roof carrying these walls, so that it resembles the main house of a townhouse. The entry reads it as displaying the standing of a wealthy merchant, and notes that it stands where the road gives a clear view of it.

That description also points to the second kind. One rises as a continuation of the upper wall; the other stands on the roof itself, set across the ridge and often given a small roof of its own.

A Japanese idiom is sometimes attached to the word. The records treat the part as a matter of fire protection and outward standing, and following what a given entry actually says is the safer basis for writing about a building.