Construction Technique of Hakka Earth Building
The layout of Fujian tulou followed the Chinese dwelling tradition of "closed outside, open inside" concept: an enclosure wall with living quarters around the peripheral and a common courtyard at the center. A small building at the center with open front served as an ancestral hall for ancestry worshipping, festivals, meetings, weddings, funerals and other ceremonial functions. Ground floor plan includes circle, semicircle, oval, square, rectangle, and irregular pentagon.
The foundation of tulou building was built with paved stones on top of compacted earth ground, in two to three tiers. There is a circular drain around the top tier foundation to prevent rainwater from damaging the tulou wall.
In most cases, the weight bearing outer wall of tulou consists of two sections, the lower section is built from cut stone blocks or river cobbles held together with a lime, sand and clay mixture to a height of about one or two meters, depend upon the regional flood water level. The compacted earth wall stacked on top of the stone section. The construction of earth wall from compacted earth mixed with sticky rice and re-enforced with horizontal bamboo sticks was described first in Song dynasty building standard the Yingzao Fashi.
The walls were built inclined toward the center, such that the natural force of gravity pushes the wall together. This inward inclination method was also used in the construction of Pagoda of Fogong Temple. The thickness of the Tulou wall decreases with height as specified in Yingzao Fashi. The bottom two storeys of tulou are solid with no window nor gun hole, windows are open only from 3rd to 5th storey, because rooms at the bottom storey served as family storage rooms and the upper storeys were living quarters.
The rooftops were covered with baked clay tiles, arranged radially; insertion technique was used at regular intervals to compensate for larger circumference at the outside.( Majority of roof tiles were laid from top to bottom, the gap caused by radial layout was compensated by small sections of tiles laid in λ shape inserts). This technique allowed the tiles to be laid radially without visible gaps, and without the use of small tiles at top, larger tiles at bottom.
The eaves usually extend about two meters, protecting the earth wall from damage by rainwater pouring from the eaves.
The wooden frame supporting the rooftop had no dougong elements common in traditional Chinese building.
Circular corridors from 2nd to uppermost level were made of wood boards laid on horizontal wooden beams with one end inserted into the earth wall. The corridors are protected with a circle of wooden railing.
Stairwells are distributed evenly around the corridors, four sets of stairwells being the usual number. Each stairwell leads from ground floor to the highest floor.
Public water wells in groups of two or three are usually located at the center court; more luxurious tulou has in-house water well for each household in ground floor kitchen.
In the mountainous areas of southwest Fujian Province, there are numbers of earth buildings, either round or square，which reflect the wisdom and creativeness of the Hakkas.
The Hakkas were people who settled in Fujian from the Central Plains of China 1,000 years ago. During those years of struggle they formed their original Hakkas culture, of which the most unique is the earth buildings.
According to the the Hakkas, heaven was round and the earth was square and the earth buildings in the Hakkas area include varieties of square and round houses combined together.
Thousands of these buildings were built in the Qing Dynasty, with thick walls, ingenious structures and various functions such as protection against high winds, earthquakes and hot and cold weather. They also served as protection against enemies. All these buildings were furnished for living, storage and cooking and can accommodate a clan of hundreds of family members.
The most popular types of earthen buildings are the Round, Square, and Five-Phoenix Earth Buildings.
Ⅰ. Round Earth Building
This type of building is round in shape and divided into three classes, small, medium and big. Two thirds of the round building are three stories high and hold roughly 20 families or 100 people.
The round earth building is a "group-oriented" residence, usually with one main entrance. Its wall is usually around one meter thick. Inside the entrance is a huge central courtyard that all the doors of the rooms and inner windows open onto.
At the ground level, except the hall and the staircases, the rooms are used as kitchens and dining rooms. The rooms on the second floor are used for storage. The rooms on the third floor are used as bedrooms. The rooms in each level are identical. In the front of each room, there is an open round hallway and usually there are four staircases to move from one level to another.
Ⅱ. Five-Phoenix Building
Five-Phoenix Buildings (Wu Feng Lou) are the most representative of Hakka traditional Central China culture as they are built according to the Central China imperial court pattern. The Five-Phoenix Building has the following characteristics: It has a central axis with central hall, at least one upper and one lower hall; left-right symmetrical rooms (houses); in front of the house, a large field and pond; the front houses are lower and the back houses are higher from ground level.
The Five Phoenix represents five different types of "birds" in five different colors: Pink, Yellow, Green, Purple, and White. It also represents the North, East, South, West and Central section, thus the name Five-Phoenix.
The Five-Phoenix Building is usually built facing a river and on a slope. At the back of the building, there is usually a vegetable garden. The front pond is used for washing, irrigating the garden, and for aquaculture. The roof is usually made of green "Wa" (roof tiles), and the walls tend to be white.
At present most old earth buildings have fallen into disrepair while only a few elderly people still know how to construct them using the original techniques.
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