神社仏閣・設計、施工、文化財修復、三重県桑名市の小島建設。

About Japanese carpentry

Carpentry in Japan is a traditional craft that dates back over a thousand years. For example, the oldest standing structure in the world is a tower in Nara named “Horyuji” that was built in 607 AD; one of the oldest companies in Japan is a group of carpenters which traces their history to 578 AD, with 40 generations of owners.

The Japanese word for carpenter is “daiku” (大工) which, when translated literally, means “big construction.” There are several different types of traditional carpenters in Japan, as there are overseas. The most common of these are sukiyadaiku (数奇屋大工) who focus on residential carpentry and teahouses; “sashimonoshi” or “tateguya” (数奇屋大工 or 建具屋) who focus on furniture and cabinets; and “miyadaiku” (宮大工) who focus on building and maintaining large structures, such as shrines and temples.

The Japanese style of carpentry uses several methods in construction, namely the use of jointing wood without nails. With this in mind, it is easy to understand that the methods used in construction rely heavily on craftsmanship and know how. The character of wood, how it will be used and where are the guides which drive this style of carpentry. Furthermore, the natural strength of the materials and various techniques must be heeded in order to advantageously suit what is being built.

Japanese carpenters rely on a number of tools and methods in their craft. They must understand the nature of the wood they are using and apply it accordingly. Therefore, they must also be familiar with a myriad of tools and the construction methods that match the wood in order to shape and form it appropriately. It is from the blending of materials, tools and understanding the purpose of the structure that the Japanese carpenter is world renowned for.

Wood and Materials

Originally, Asian carpenters relied on Chinese geomancy (Feng shui or 風水) for wood choices. Where trees grew, the locations of the sun, rivers, the direction of the wind, etc. all relied on an ideal called Shishin (四神 ) referring to the four directions on the compass and the gods that represent them.

While this is an outdated practice that is rooted in Confucianism, there are viable points to consider when choosing wood. For example trees exposed to long periods of sunlight have thicker and denser bases in them from sprouting, thus the wood from these trees are hard and sturdy. Things such as wind, slope of the terrain, water drainage and soil quality all contribute the quality of the wood that a tree develops as it grows. It from that influence that the grain and nature of the wood is obtained, and one can literally tell in what conditions a tree grew in by judging the wood quality.

In choosing wood, one has to pay particular attention to the grain of the wood and density in order to suit where it is used best. For example, pillars or “hashira” (柱) need to be made of dense and straight wood in order to best support weight. From that trees with the densest consistency and straightest wood grain are chosen. For beams or “hari” (梁) are best made from trees that have a slight bend in them, with one side thicker than the other, but have a straight core and thus are suitable for supporting more weight. Wood that has a very prominent curve in the grain are best used for beams and pillars that will be required to be set at slop and hold weight at multiple points. Wood that is porous is best used for non-structural components, while the grain can be best fitted to the way that it is carved.

Another aspect of wood choice to consider is the way the wood will dehydrate over time, or “shrink.” The location from a log from which the wood is cut determines this, as planks cut from the outer portion of a log will tend to warp and upwards in a “C” curve, while wood cut from the middle will tend to split at the middle and warp outward away from the center. Wood with twisted grains tend to splinter and crack, then warp away from the center of the crack regardless of where it occurs.

to be continued....