Bamboo 1: structure
Ta-ke 1: structure
Bamboo -one of the central subjects of our research here- has an uncertain place in the built world in Japan. In Columbia it has been enshrined as a structural material in the building code thanks to the celebrity of architect Simon Velez, who co-wrote the code; he is building public infrastructure with this material -essentially long-span roofs and bridges, as well as houses and chapels. In China it is being developed on an industrial scale, especially for products such as floorboards. We have visited two bamboo suppliers here (Masaji Ishida and Shoji Tanabe), who both downplayed building applications for their amazing grass. We also visited fourth generation bamboo craft master Sho chiku Tanabe, subject of a separate post.
In Ishida’s case the bumper crop -in financial terms- is edible bamboo for luxury restaurants, which requires careful husbandry. A special plot is reserved for the edible plants, almost completely thinned out compared to a ‘natural’ grove (seven metres between stalks instead of a few centimetres). The ground is covered with straw just after the harvest and then with a centimetre of earth, allowing a soft stratum in which the delicate young shoots can be harvested with ease. The mulch is added year after year, meaning that the fifty-year-old patch we saw was set in a base some 50 cm high. The ‘parent’ stalks were kept at under 5 years of age.
The other principal application -for which regular cell lengths are a premium- is for craft products such as spoons, cups and woven objects such as baskets. The raw material is extremely cheap; the objects less so (a simple fashioned cup costing 15 euros, one of Shouchiku’s creations being traded at gallery prices in the several thousands).
In the case of the building sector, Shoji Tanabe explained that people are nervous about using traditional materials for structure because of earthquakes: despite plenty of surviving buildings hundreds of years old, they seek security in modern connections and calculations. The rare architects using bamboo -such as Kengo Kuma and Kinya Maruyama- treat it as a applied rather than primary material for structure and envelope (Kinya makes spectacular forms, but they remain at the status of open shelters for the most part; Kuma-san has made a wonderful house screened by bamboo rods outside Beijing and has used bamboo as a surface material -in natural and sheet form- in projects such as the Nezu Museum, and as a translucent fibre in plastic facade panels in the Bamboo/Fibre house (some beams in this project are also made of compressed/laminated bamboo).
Bamboo is still used extensively -though invisibly- as an armature for clay plaster walls in renovations and ‘traditional’ projects. 2-3 cm centimetre rods are lashed together with smaller quarter sections and the ropes are developed in chunky knots giving more purchase for the clay, which is first slapped on in balls and then smoothed over in several layers. Always locally-sourced, the quality of the clay is paramount, therefore the experience of the craftsman will determine the result (hygrometric measuring devices and instruction manuals do not abound…).
Tanabe operates principally as a dealer and does some transformation work of the material for use in floorboards and facade panels. His workshop has a bamboo planer, a device which takes strips and shaves them to a standard width and thickness for use in floorboards, beautiful facade panels and such like. Otherwise his principal tool is a blue plaster container sunk into the ground with a metal post anchored nearby. The bucket allows him to sit at ground level (like the pit for Westerners’ feet in many restaurants) and split whole rods of bamboo on the metal spike with impressive speed. This initial split can be in half or quarters, the machines take over from there.