trade tricks

There are a few things that are done to ensure that the wood lasts as long as possible, which includes cutting a slot the length of all the keshou-bashira, or "fancy" posts (the ones at the corners that hold most of the weight, as well as ones that are clearly visible, or ones that are open to the elements, like the ones holding up the large eave over the entrance). This is to allow them to expand with the humidity of summer and contract with the drier winters--without cracking.

There's also a very thin space just outside the walls that connects to a similar space running just under the roof. This allows a flow of air to run from the base of the walls through these spaces to the very top of the roof, which is built with a vent to allow its dispersal. There's another layer inside the wall that mirrors this.

The carpenter told me they do this because they think that one of the reasons that wood in old Japanese houses lasted so long was that--since an outside wall post, for example, had open faces to both the outside and the inside--that the air actually flows through the wood. Since we all know that wood breathes, that makes sense to me.

This layer of air is supposed to replicate the conditions that allow a free air flow. According to the carpenter, this started about twenty years ago, and most of the best builders (a minority) require it.