been banned in China for buildings over six stories, but is still in continuous use for skyscrapers in Hong Kong. In the Philippines, the nipa hut is a fairly typical example of the most basic sort of housing where bamboo is used; the walls are split and woven bamboo, and bamboo slats and poles may be used as its support. In Japanese architecture, bamboo is used primarily as a supplemental or decorative element in buildings such as fencing, fountains, grates, and gutters, largely due to the ready abundance of quality timber. Many ethnic groups in remote areas that have water access in Asia use bamboo that is 3–5 years old to make rafts. They use 8 to 12 poles, long, laid together side by side to a width of about . Once the poles are lined up together, they cut a hole crosswise through the poles at each end and use a small bamboo pole pushed through that hole like a screw to hold all the long bamboo poles together. Floating houses use whole bamboo stalks tied together in a big bunch to support the house floating in the water. Fishing and aquaculture Due to its flexibility, bamboo is also used to make fishing rods. The split cane rod is especially prized for fly fishing. Firecrackers Bamboo has been traditionally used in Malaysia as a firecracker called a meriam buluh or bamboo cannon. Four-foot-long sections of bamboo are cut, and a mixture of water and calcium carbide are introduced. The resulting acetylene gas is ignited with a stick, producing a loud bang. Weapons Bamboo has often been used to construct weapons and is still incorporated in several Asian martial arts. A bamboo staff, sometimes with one end sharpened, is used in the Tamil martial art of silambam, a word derived from a term meaning "hill bamboo". Staves used in the Indian martial art of gatka are commonly made from bamboo, a material favoured for its light weight. A bamboo sword called a shinai is used in the Japanese martial art of kendo. Bamboo is used for crafting the bows, called yumi, and arrows used in the Japanese martial art kyūdō. The first gunpowder-based weapons, such as the fire lance, were made of bamboo. Sharpened bamboo javelins weighted with sand known as bagakay were used as disposable missile weapons in both land and naval warfare in the Philippines. They were thrown