Houses are usually built directly on the ground rather than on piles. They were traditionally made out of upright wooden shingles notched together or bound with hemp rope and creepers without the use of nails, and thatched with teak leaves or cogon grass. In some parts of China the Hmong live in houses made out of adobe or stone after the Chinese fashion; in Laos and Thailand some have adopted the Thai style of housing. Richer households may be able to invest in zinc or polystyrene roofing, while poorer families may have to construct their houses entirely out of pieces of split bamboo and rough matting. The traditional village numbered only about seven houses, but today, owing to reasons of security and the need for intensive cultivation of the land, villages of between seven and fifty households are more common. They are often arranged in a horseshoe pattern just beneath the crest of a mountain, and are, if possible, sheltered by a belt of forest and located close to a source of water. New villages are carefully sited according to the principles of a geomantic system aimed at ensuring a fundamental harmony between man and the forested environment. Water is often piped down the mountain to the village through a series of semitroughs formed out of lengths of split bamboo, and is collected, usually by women, in wooden or metal buckets. In some areas wells are maintained, or tap systems have been constructed. Usually tall clumps of cooling bamboo, peach, or banana are maintained near the village, while the neighboring slopes are devoted to herbal gardens. Raised wooden granaries are constructed near each house to protect against scavengers; small chicken coops or stables may also be built. Pigs traditionally are not penned but left free to clear the village of refuse. In some villages shops are maintained, often by Chinese traders.