The irori: fire sunk in the floor

The irori is a square, stone-lined pit sunk into the floor of a traditional Japanese house, burned with wood or charcoal, and for most of a kominka's working life it was the one fixture the household could not do without. The anatomy of a kominka names it as the heart of the plan in a single line; this card opens that line out.

What it is, physically

The pit sits at or near the centre of the main room, lined in stone against the fire and framed by the timber floor around it. Over the fire hangs the jizaikagi, an adjustable pothook, often an iron rod running through a length of bamboo, raising and lowering a kettle or pot and sometimes finished with a carved counterweight shaped like a fish. The whole fixture is simple: a hole, a stone lining, a hook, and whatever burns in it.

More than heat

Heating a room was only the first job. Fish and other food were skewered and set in the ashes or buried to cook; wooden lattices hung above the hearth dried clothes, grain and foodstuffs in the rising warmth; and before electric light reached the countryside, the fire was the room's lamp as much as its stove. Seating around the irori was not arbitrary either: the place furthest from the house's entrance, the doma, was named the yokoza and reserved for the head of the household, a small piece of social architecture built around a hole in the floor.

What the smoke did to the house

The black skin on a kominka's beams, visible in the anatomy of the frame overhead, is not neglect; it is the hearth's second job. Smoke from the fire below carries tar that works into the beams and the thatch of the roof, and that tar makes both insect-resistant and waterproof over time. A roof that has been smoked for decades by its own hearth is, in a real sense, treated timber, cured by the house's daily fire rather than by any product applied afterward.

Why most of them went cold

Charcoal and wood burned in an open room produce fine particulate matter and carbon monoxide, and long exposure to open hearth smoke has been associated with higher rates of eye conditions including cataracts and glaucoma among those who lived closest to it for years. That health cost, set against the spread of the enclosed kamado cookstove (in the Hokuriku region, irori cooking held on until kamado became widespread in the 1950s), is the practical reason the sunken hearth went cold in most houses still standing: a safer, more contained way to cook replaced a fixture that had done several jobs at once but asked a daily price in the air of the room. Where an irori survives today, it is often in open-air museums, inns, preserved houses and the odd public waiting room, kept for the record rather than the daily meal.

Reading one in a surviving house

A visitor who finds a cold irori in a preserved kominka can still read its history without lighting it. The black ceiling directly above the pit is usually the darkest point in the house, a rough map of where the smoke rose most often and most directly. The stone lining tells its own story of use: a lining cracked and refired many times over has done real daily work, where a clean, sharp-edged pit more often marks a hearth rebuilt or restored for display. The floor level either side of the pit, lower where people worked and higher where they sat, is the same line the anatomy of the kominka reads in the frame above, so the hearth and the floor plan explain each other at a glance.

The card, filed

The irori did four jobs from one hole in the floor: heat, cooking, light and, through its smoke, a slow treatment of the roof above it. It cost the household exposure to smoke every day it burned, and that cost is the plainest reason the enclosed stove replaced it once one was available. Read beside the kominka's frame, the hearth is the part of the house that explains the black beams overhead and the particular quiet of the rooms that have let it go cold.