Doma (earthen floor) (土間)
A doma is a space constituting the inside of a Japanese-style house.
The inner space of a traditional private Japanese house or storehouse consists of an area called "yuka" where living space is placed above the ground using flat wooden plates supported by pillars, and an area that is placed at ground level. The latter area constitutes a doma.
Tataki (a floor hard-packed with plaster), diatomite or concrete tiles are used for finishing a doma,
In old private houses, there is sometimes an area where the earth is simply exposed, and this would be the origin of the term.
It is placed nearly at ground level and lower than the other rooms constituting living space, such as corridors, living room and bedrooms, and wide doors or sliding doors are always built to allow people to come and go between the inside and outside of the house. As described below, although the same term is now used for a scaled-down version, it originally had the nature of "an indoor room used in the same way as the ground."
Water-resistant materials are generally employed considering the purpose of use,
Today, many traditional-style doma are preserved in houses of old established families. In private Japanese houses, the raised floor area supported by pillars and the doma area have been valued equally since ancient times, and connecting these two factors constitutes the basic style of such houses. The pillar placed at the critical position connecting these two parts is called a daikoku-bashira (central pillar).
In contemporary private houses, the doma has become reduced to a small space in the entrance hall provided and is simply at the boundary between the inside and outside of the house. It is simply a place to remove shoes and the important function of the traditional doma, which was to provide work space for gaining earnings, is now generally excluded from the living quarters in the house. Today, people who traditionally did their work in the doma of their own house, such as farmers and craftsmen, have increasingly come to replace the role of doma with a separate outdoor space, such as the yard, covered with a simple roof.
The original doma has a space wide enough to allow work, but contemporary ones are considered part of the entrance hall, which is around 0.825 square meters at most (depending on the size of the house).
The doma is positioned as a place intermediate between outdoor and indoor, and it is a custom in Japanese houses "to take off shoes indoors." However, it was permissible to enter the doma alone without taking off one's shoes. Therefore, the doma continues to exist as a place where shoes are to be taken off or put on. The entrance halls of Japanese houses and the entrances/exits of schools are also considered to be doma. Because a doma is treated as an outdoor place, even if descending to a doma temporarily, simple footwear such as sandals are put on.
The doma is used as a work place to take care of agricultural machines or fishing gear on rainy days. The doma provided a space of several joes (approx. 1.65 square meters per jo) to about 15 joes and people would sit on a straw mat or sunoko (a board made of thin plates positioned horizontally) or take off their shoes to stand on it.
It is assumed that the use of a doma convenient for cleaning up after doing tasks that generate trash and dust. On the other hand, in old Japanese houses of agricultural villages, the room with a wooden floor was used for daily household activities and there was no designated workplace. Therefore, the doma was probably used as a general-purpose area in such houses. In addition, a space which can be used as a wooden floor room by laying wooden plates but also used as a doma without the wooden plates are found in some traditional houses in rural areas.
Since the doma floor cannot rot and has few flammable items, the doma was naturally used for cooking, which requires much water and fire. Moreover, flame-generating equipment, such as a furnace, could be installed more easily in the doma and this is also effective from the standpoint of fire prevention. Therefore, the kitchens of many old established family houses are located at the doma.
In many traditional rural houses, the lavatory and bathing place are located in a hut separate from the main building. The kitchen is also located at a roofed place outside the main building. The kitchen is a type of under-eave structure, but because simple walls surround it, it is difficult to judge whether the kitchen is outdoors or indoors. The kitchen is called kamaya (furnace hut) in some regions because fo such structure.
Collective buildings of Gunkan-jima Island
The collective housing in Hashima Island (Nagasaki Prefecture) is a densely built housing complex. However, reflecting the age when it was built, some of the dwelling units have a rather spacious area equivalent to a doma in their entrance halls. Additionally, although they are large buildings, there is a large difference in the height between the ground level and the floor level, thus showing a transitional style.