The earthen buildings known as tu lou are made of rammed earth and timber with neither concrete nor steel. A Hakka saying has it that one bowl of rammed earth is worth a bowl of meat. The main material is a mixture of fine laterite, fine sand from the river, silt from the bottom of paddy fields and even re-cycled ancient wall mud. After these materials are thoroughly mixed together, quality brown sugar, whisked egg white and the strained liquid from sticky rice soup are added and a new turn of mixing begins. The resultant material is then used for the earthen buildings. The ingenious Hakkas use this method to compensate for the lack of raw materials normally used for building.
As well as providing a defense from enemies, the tu lou has the following advantages: quakeproof, fireproof, theft proof, good ventilation and day lighting. Also due to their thickness, the earthen walls help to provide thermal insulation and preservation, which makes the building warm in winter and cool in summer.
The Influence of Ba Gua
Originally, the Hakkas came from central China and were influenced profoundly by traditional Chinese culture. Earthen buildings were created using the ba gua (Eight Trigrams) theory, more widely known in the West as Feng Shui, which was thought to be the essence of ancient Chinese culture. From a more practical point of view, as the Hakkas usually lived in barren and remote hilly environments, they needed to defend themselves from wild animals as well as other clans.