Tuesday, February 7, 2012

Orphan: Story of the Gazebo (IV)


Last post we took a look at some different Chinese approaches to framing structures with hip rafters and no ridge. Most of those systems employed purlins carried by crossbeams. Today I'd like to take a look at some Japanese approaches to the same problem.

In the smallest and simplest structures, like a garden gazebo, or azuma-ya, there are two common solutions seen. One of those is like the western common rafter framing approach using common rafters and possibly rafter struts. Here's one example using a common rafter supported roof, hips directly atop posts, with a couple of purlin rings:



Exterior:



If struts are employed, it is more than likely that a drop ceiling will be fitted to present a rather less cluttered appearance:



Note the interior corner bracing, a wise idea with common-rafter roofs.


The exterior:




Another approach is to extend the king piece all the way to the ground. In some azuma-ya, the entire roof is supported by just a central post, as in this example, built around a tree:


A different sort of garden umbrella.

Then there are pavilions of more substantial design, often carrying heavy tile roofs - here are a couple of the more famous examples, both octagonal:


I love the triple-tier rafters at the eave:


A two-tier roof example:


When you're building to last for several hundred years, and therefore use the highest quality materials, the structural systems can get complex - by necessity. The Japanese tend not to skimp when it comes to the hip rafters:


To bear heavy loads over time, the double roof is typically the answer in traditional Japanese framing practice. Here, the hip 'field' rafters, which define the exterior shape of the roof, have been fitted and you can see the notches on the purlins to carry the common 'field' rafters:


Another example of new construction, with a handsome tile roof:


Then there are the less common reciprocally supported roof structures, a variant form of roof framing in which the Japanese are acknowledged as lead developers. The Bunraku Puppet Theater, designed by architect Ishii Kazuhiro, is undoubtedly the ultimate example. From the outside, the theater presents a circular form with its roof, and a 12-sided polygon (dodecagonal) with its base:


 The roof framing is supported by heavy reciprocal beams:


 The finished structure from the inside - a reciprocal rafter system atop a reciprocal tension ring:


This structure, due to the extremely long support posts, has a second reciprocal tension ring lower down the wall.

And finally, a look at polygonal pavilions in Japan cannot be complete without a look at the most famous hexagonal structure of all, the Sazaedō (栄螺堂) located in Aizu-Wakamatsu. A sazae (栄螺) is a type of snail, Turbo cornutus, known in English (in a literal translation from the Latin) as a Horned Turban snail. They are a delicacy in Japan. The shape of the temple, you see, is a tapered regular hexagon - with a helicoidal double rampway inside:




The ceiling inside at the top is of coved form:


An amazing structure! Mitsuo Inoue, in his fine work Space in Japanese Architecture (1985), describes Sazaedō's function as follows:

"Along the ramps were represented the Avalokiteśvaras of thirty-three places of pilgrimage. The worshiper proceeded by the front ramp to the top and then descended via a different ramp to the exit at the back of the building. In the short time it took to make this ascent and descent, the worshiper could accomplish the 'equivalent' of the traditional pilgrimage to the thirty-three temples housing the image of Avalokiteśvara in Western Japan with much less trouble. This was indeed a unique idea, and is particularly surprising because traditional Japanese architecture never did advance to the stage of three-dimensional spatial compositions. The Sazaedō is an exception."

And Sazaedō remains a unique structure in Japan and one I have long been very interested in visiting. Imagine framing such a thing! Wow! It was conceived as an idea in 1712 by a priest, and built to completion in 1780. Since then it has suffered fire and earthquake and at least one complete rebuild, but it is still going strong.

All for today. In the next post in this series I'll share some drawings I've been doing of a polygonal pavilion. Thanks for dropping by and comments are always welcome.

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