The 3300-Year-Old Tape Measure

I love the fact that the measurements used by builders in Japan still are based on the shakkan-ho system that's been around since the 13th century BC. Japan went to the metric system in the 20th century (AD), and the shakkan-ho has been actually banned since 1961, but it's still firmly entrenched in building and real estate You can see the little arrows on my tape measure at 91 centimeters, which is three shaku. One tatami mat, or jo, is three shaku by six shaku (or one ken, or 182cm), and every measurement in our house plan is based around that. For the metrically challenged, one shaku is 11.93 inches, so think of a tatami mat as six by three feet.)

The plans are in centimeters, but every measurement you see is divisible by that 91cm measurement. The halls are 91cm wide (post to post); the kitchen is 2.73 by 3.64m; the dining room 3.64 x 4.55m. If you want to add something or cut something? You have to do it in increments of that scale.

The jo is a very human measurement. It is just the amount of space a person at rest would need, which is why, I suppose, we think of it as the size of graves. Though I suppose for people like my brother-in-law Jim, who at 205cm has grown beyond a size anyone imagined 3300 years ago, it might seem a bit small. One jo will also be the floor space of our toilet, the tokonoma, closets, the wood stove space. Two of them will make up the size of the bath, the stairs, etc., etc. Only the living room will actually have a tatami floor.

When I first arrived in Japan, tatami was everywhere. Many houses, if they had the space would have one Western-style room, with wooden floors, stuffed chairs covered in plastic, ugly throw rugs and a collection of kitsch. It was a formal place for visitors and was always chilly, as if they'd just dragged the entire room out of cold storage. It was where you'd be served coffee in dainty cups along with Western sweets. (If you were entertained more familiarly in the tatami room, it would be green tea and Japanese wagashi.) Now, it's the exact opposite, and in most houses--at least the ones that have them--the tatami room is usually the little-used one, where one drinks tea and sits uncomfortably in the role as "visitor" in a pristine time capsule.


I want our living room to stay the way it is now, a place to kick back on that soft surface, stretch out, roll around if you want. I want to watch people come into the room, sit around the low table, and slowly melt as they relax. M and I laugh about how often people have fallen asleep during afternoons of eating, drinking and talking. I want to keep experiencing those times when the tatami's just been redone, and you can breathe in the smell of the green rush straw as it slowly dissipates over weeks and months. The room is eight jo, plus a four-jo wood-floored engawa, and we're determined to keep the "human-ness" of this room in the new place. So, other than the sliding shoji doors, we refused to do anything--like the popular raised floor--that would set it off from the other rooms.