Last week’s post presented the typical method of raised floor framing used in Japan, with joists laid on bearers and either subfloor or finish floor boards laid on top of the joists. However, for reasons of custom, sumptuary laws, economy, availability, or climate, it was common in many areas of Japan to forego floorboards and instead lay sugaki (簀掻), lattices of bamboo, reed, or timber lath, over the joists, to form the sugaki-yuka (簀掻床) or ‘lattice floor.’

In contrast to tight-fitting floorboards which prevent heat loss in winter and (most) drafts from coming up from under the floor, the open structure of the sugaki lets air pass freely in both directions. In the warmest subtropical regions of southern Japan, this could be desirable, as the sugaki allowed cool air from the shaded space between the floor and the ground to be drawn up into the house to replace warmer interior air as it rose into the roof space.

A bamboo *sugaki-yuka* with an inset *irori* hearth. From the Kawano house, originally in Ehime Prefecture, Shikoku, first half of the 17th century.

In colder areas where the sugaki-yuka was used but drafts were not welcome, the subfloor space was sealed off by infilling the gap between ground and floor level in the exterior perimeter walls with stones, then rendering the stones with daub, giving an external appearance very similar to the raised earthen floors (taka-doza-yuka, 高土座床) previously discussed.　 In these minka, the sugaki would also be covered with mushiro mats; even in warm climates, ‘local’ mats were still necessary, as lattice floors of any type, but especially bamboo lattice with its raised joints, are uncomfortable to sit on.

A bamboo *sugaki-yuka* partly overlaid with *mushiro*.

This type of floor is also seen in the upper ‘attic’ storeys of the famous gasshо̄-zukuri 合掌造り (literally ‘praying hands construction’) minka of Gifu Prefecture. The upper levels of these houses were used to raise silkworms by feeding them on mulberry leaves, requiring a well-ventilated environment.