During WWI, the US Army tested chemical weapons, including mustard gas, at a research center inside Washington, DC. At the end of the war, the left over materials, including unexploded shells and glass canisters of mustard gas, were buried and forgotten, and many houses were built on the site, near American University. American University sold some of the property for the home of the Korean Ambassador’s residence. As more and more evidence was discovered, the Army Corps of Engineers began an investigation, finding wide spread contamination, with high levels of arsenic, throughout the area. One of the most contaminated sites turned out to be the Korean Ambassador’s residence, so the Army Corps removed all the vegetation and top two feet of soil, and paid to have a new garden constructed. As part of this, I was hired to design and build a Korean style pavilion.
Korean style architecture is similar in some ways to Japanese architecture, since much of early Japanese Buddhist architecture came to Japan from China through Korea, but they evolved slightly differently over time so for me this was an opportunity to try to understand their common roots. Unfortunately, I couldn’t find too much in English on Korean carpentry, but I found a number of pictures of Korean style buildings, including open pavilions. Both Korean and Japanese architecture use what is sometimes called hip gable roofs, with a downward curve of the roof line and an upward flare at the corners. However, in Japanese roofs this upward curve usually begins at the corner of the building, while in Korean buildings there is a continuous arc along from corner to corner. To get the shape of the roof, Japanese buildings usually have a double roof structure, with low pitched finish rafters at the eaves and steeper rough rafters bent to purlins. Traditional Korean buildings had roof rafters and eave rafters at different pitches, with the curve smoothed out by building up clay, into which tile was bedded. Japanese buildings usually have parallel rafters, buts Korean usually employ what are called fan rafters, since the rafters radiate from the corner like the ribs of a fan.
Laying out and constructing such a roof is very complicated. All the joinery has to be cut in advance, and involves a number of compound angles. In addition, the curved roof surface adds another layer of difficulty. Fortunately, there are traditional techniques for laying out all of the angles using the Japanese framing square, or sashigane, and also methods of laying out everything on the floor to figure out the curves and make patterns for the various parts. All of these techniques have been worked out in Japanese traditional carpentry, and were originally handed down orally from master to apprentice, or in what were known as ‘secret scrolls.’ Fortunately, carpentry manuals with modern versions of these are now available in Japan, and I own a number of them. They have many detailed drawings and clear step by step instructions but trying to understand them was a challenge and meant many hours with a dictionary. The article from Timber Framing goes into the layout and joinery in more detail. It was certainly a challenge, and very interesting and educational in many ways, but I had a tight deadline and not too much help, and the Army Corps of Engineers was not too sympathetic to my desire to do everything as authentically as possible, so it was pretty stressful.
Article, Timber Framing, September 2002, describing layout and joinery.
Construction photos--photos of construction process