Posted on: September 03, 2015

Insane Japanese Carpentry

Tools and techniques differ by country but are especially different in Japan.

Every country is different, but few are more different from the U.S. than Japan, at least in terms of the hand tools and techniques used in construction. And why not? Japan is far away and developed its building traditions independently from the West, long before the U.S. existed.

Japan, like the U.K. and most of Europe has a long tradition of timber framing, a method that fell out of favor in this country after the 1830s, when a carpenter in Chicago invented balloon framing—an early form of stick framing that has evolved into the platform or Western framing we use today. In Japan, timber framing never died out and is still relatively main stream. While a small number of Japanese carpenters continue to use traditional methods—primarily for restoration work and building temples—the majority have been forced to adopt modern equipment, substituting simple joints cut by computer-controlled machines for complicated ones cut by hand.

The videos below show traditional and modern examples of Japanese framing.

The tradesmen in the video below are testing the fit of a four-way mortise and tenon joint. The way the pieces connect and are held together with wedges is simply insane—in a good way. This kind of joinery is used only for high-end projects, such as temples. That said; joinery is more common in Japan than in the U.S., where timber-framing was long ago replaced by stick framing. Japan stuck with their version of timber-framing, modernizing it without completely doing away with the use of joinery. House frames are typically produced in factories with CNC machines cutting the joints. Framers in the U.S. and Canada build the house. A Japanese framer is more of an assembly worker—assembling piece that were cut off-site.

Scarfs were traditionally used to turn short pieces of timber into longer beams. Once assembled, this very cool scarf will probably be as strong as any part of the beam (video below). The rabbets on the ends of the pieces hold the wide faces flush. The box joint-like keys provide strength and keep the narrow faces flush then the beam is under load. Knock out the pin and you can disassemble the joint. Impressive!

Not every Japanese timber-framed building is assembled with joinery; the one in the video below is being assembled with metal connectors—which makes sense given the frequency of earthquakes in Japan. Once assembled, the walls of this house will essentially be a series of moment frames. I’ve seen similar methods used in heavy timber construction in the U.S.

Interesting use of framing connectors in the video below. Our joist and beam hangers are “outies”; these hangers are “innies”. I like the way everything fits and pins together—like the pieces of a puzzle.