Minnan and Hakka Tulou. Functional, Typological and Construction Features of the Rammed Earth Dwellings of Fujian (China)

ABSTRACT

This research is focused on tulou, collective dwellings of Fujian (China), built with rammed earth and wood. Except for the evident variation in size and in shape between different tulou, all of them apparently share a similar design and layout features and also the scientific literature on this topic does not highlight substantial differences among them. Despite the generic uniformity, it is however possible to clearly distinguish two groups of tulou, built by different populations and reflecting different life styles and dwelling ideas: the Minnan and Hakka tulou. Starting from this new assumption and through a systematic analysis of eight significant case studies, in this paper it is proved for the first time that the functional differences, already partly recognized by previous studies, can be clearly linked to the typological and construction ones as well as. Thanks to this new methodological approach, in the future it will be possible to set up the analysis of this vast heritage in a more orderly manner, allow a greater integration of various disciplinary research and plan a “Manual on tulou restoration”, intended as a guide for restoration and dissemination of the knowledge regarding the original materials and techniques of tulou.

KEYWORDS:

• Adobe
• China’s old dwellings
• Chinese vernacular architecture
• collective houses
• Fujian Tulou
• Hakka tulou
• Minnan tulou
• pisé
• rammed earth

Acknowledgments

The research started thanks to the University International Mobility Grant provided by Roma Tre University (announcement 2018–2019; undergraduate: E. Colafranceschi; tutors: E. Pallottino, P. Porretta; host institution: College of Civil Engineering, Fuzhou University, China) and is part of the numerous scientific collaboration activities promoted by the Sino Italian Center, inaugurated in Fuzhou in 2016 in collaboration between Roma Tre and Fuzhou University.

The authors would like to thank C. Nuti (Department of Architecture, Roma Tre University, Rome, Italy); B. Briseghella (College of Civil Engineering, Fuzhou University, China); H. Varum (College of Civil Engineering, Porto University, Portugal); M. Togni (Department of Agricultural, Food, Environmental and Forestry Sciences and Technologies, University of Florence, Italy). We also thank the Geotechnical Laboratory of the Department of Civil Engineering of the Roma Tre University (coordinator A. Lembo Fazio) for the physical and mechanical characterization tests of the analysed soils and Y. Wei (Department of Architecture, Fuzhou University, China) for the support in the translations from Chinese to English.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

¹. Tulou are usually organised in rural villages along mountain streams; the rivers provide communication and trade routes and the necessary water resources for cultivating fields, which are suitably terraced and shaped for agricultural production. The main crops grown for trade are hemp, tobacco, tea and sugar cane; food crops include rice, potatoes, beans, wheat and maize and fruit plants. Traditional agriculture still relies on rotational crops for the best yield from the land.

². The building site and tulou layout — orientation, directional axis, etc. — were usually selected according to the Chinese traditional architectural planning, based on the principles of fengshui.

³. As noted by Benevolo (1989, 33), most of the Chinese words using the ideogram “土” («earth») allude to a defensive character and refer to the first military structures made of raw earth. We would like to take this opportunity to point out that a specific study is currently underway to trace possible derivations of the tulou from other Chinese constructions, the tubao, whose presence in Fujian is attested from the 10th century onwards. These constructions were also made of rammed earth and wood, but unlike the tulou, they were exclusively military buildings, as indicated by the etymology of the term: tǔ “土” («earth») and bǎo “堡” («fortress»). A possible typological evolution is hypothesized, according to which the residential function may have been progressively integrated with an exclusively defensive function. The literature on the subject, although fragmented and uneven, does not exclude this possibility (see, among others, the presentation by Dai 2011).:

⁴. The Minnan are also called Fulao. They are both descended from the Han people, who originated from the central plains of the Hangue River in northern China. Due to severe famine and constant fighting with the Mongols, the Han people began to migrate to southern China at the beginning of the 4th century and reached Fujian province around the 10th century. The ethnic subgroups, to whom the construction of the tulou is owed, reached this territory through two different migratory routes: the Minnan arrived from the southern coast and then settled on the estuary of the main waterways; the Hakka instead crossed the Wuyi mountains and settled along the river valleys (for more on the history of migration see, among others: Bielenstein 1959; Knapp 2000, 223; Zhou and Dong 2015).

⁵. Although the most up-to-date literature clearly suggests avoiding the indication Hakka tulou if it generically refers to all tulou (Huang 2009, 109–110; Zheng et al. 2008, 84), the widespread persistence of this custom is still noted today.

⁶. Huang’s 1982 dissertation, published in 1984 (1984a;1984b), ignored the existence of the type of tulou typically attributable to the Minnan. It was only after visits with Zeng Wuyuan, director of the Cultural Relics Office in Zhangzhou, that Huang studied and published for the first time two examples belonging to the «inhabitants of southern Fujian» (Er Yi Lou, in Hua’an district, and Shu Zi Lou in Yunxiao district; see Huang 1988). It should be noted that Huang, in his more recent studies (see, e.g., Huang 2003;2009, 110; 2020, 89), clearly underlines the functional differences and the different dwelling idea linked to the tulou of the Minnan and those of the Hakka, but does not directly link these characteristics to the construction and structural aspects; the latter are in fact analysed separately by him only when he describes the single case studies.

⁷. The most extensive survey of tulou comes from the studies of Huang who, in his most recent monograph, subdivides them by shape (Huang 2009, cf. chap. 2, A Rich Variety of Tulou Forms, 35–79) and selects them according to the exceptional nature of individual models (The most famous Tulou, The first Tulou under the “National Preservation Project”, The largest Tulou, The smallest in diameter of the Circular Tulou, The earliest Tulou, The tallest Tulou, The most spectacular Tulou, etc. cf. chap. 5, Outstandinng Marvels of Fujian Tulou, 121–180), and then analysing some specific aspects (defensive, construction, stylistic-decorative, related to the philosophy of fengshui, etc.); it should be noted that only in chap. 2 does Huang suggest a generic subdivision between Minnan and Hakka type, from a functional point of view. The other studies that offer a systematic classification are the text by Greco (2003), in which, however, a specific cataloguing principle is not stated, and the report for the candidature of the tulou as a World Heritage Site (Zheng et al. 2008) where, in line with the aims of the study, the earthen buildings are mainly selected according to their state of conservation, integrity and patrimonial value, and are described by settlement, in chronological order.

⁸. The study compared four pairs of Minnan and Hakka models, associated by size (Figures 6–13). It should be noted that only a few of the selected case studies — Er Yi Lou, Zheng Fu Lou, Zheng Cheng Lou, Cheng Qi Lou — are included in the UNESCO World Heritage List, since these are generally those that have been most transformed in recent times (see par. 5 below). It is worth mentioning that all the drawings published here are original elaborations by the authors (all rights reserved), based on the main sources available (Huang 2009; Zheng et al. 2008), with direct verification through punctual surveys; in particular, the He Xing Lou tulou was the subject of a direct and detailed survey by E. Colafranceschi and B. Fiocchetti. All the plans have been drawn with a uniform graphic criterion and are supported by graphic diagrams in order to facilitate the comparison between the different models; for more details on the examples analysed, see Colafranceschi (2019).

⁹. The texts that deal most clearly with this aspect are those by Huang and the report for the candidature of the tulou as a UNESCO World Heritage Site (we also refer to these studies for the most up-to-date bibliographical references). It should be noted that differences between the Minnan and Hakka tulou are found in most cases. However, Huang admits the possibility of structures typically made by one population but inhabited by the other (Huang 2009, 114). Finally, it should be noted that the typification presented here necessarily has the limits inherent in all cataloguing processes: due to the very large number of existing models, there are exceptions and some case characterised by singularities and hybridities between the two types considered.

¹⁰. Gallery type is a partially inappropriate definition because this expression is commonly used to indicate, from a typological point of view, houses in which the common distribution corridor gives access to the individual housing units and not, as in this case, to the individual rooms. The definitions unit type and gallery type or type with corridor are used by Huang (2009) and Zheng et al. (2008).

¹¹. In the literature, the study of the defence system usually focuses on the description of the different devices used in the tulou without a systematic comparison between the two different types (Huang 2009, 213–226).:

¹². This feature is noted in most cases, although some tulou of small size, with a simplified structure, do not include other shared functions besides the ancestral hall.

¹³. The overhang, in general, improves the mechanical behaviour of the radial beams because, as is well-known, it reduces the bending moment between the two supports.

¹⁴. In some cases, for example in the tulou of Er Yi Lou which was the subject of in-depth research (Figure 20), the structural pitch does not coincide with the width of the house, which is in fact articulated, on each floor, by several rooms defined by a succession of radial bearing walls, placed in communication with each other.

¹⁵. The above considerations are based on purely qualitative reasoning which it is hoped, in the continuation of the research, can be verified with appropriate structural calculation models and presented in further papers in collaboration with B. Briseghella and C. Nuti. It should be noted that some studies have already been completed on the mechanical and seismic behaviour of structures: (Briseghella et al. 2020; Fiocchetti 2019; Frangedaki et al. 2020).

¹⁶ This substantial difference between the two tulou families is also never clearly highlighted in the literature.

¹⁷. The outer surface of the wall is built with a gentle incline, while the inner one is stepped and decreases with each story.

¹⁸. Particle size analysis were carried out by the authors through sieving and sedimentation processes on several raw earth samples: five samples taken from the outer walls of several tulou (Zheng Fu Lou, 1913, Yongding County; He Xing Lou, 1943, Yongding County; Cheng Qi Lou, 1628–1644; Qiaofu Lou, 1962; Shize Lou, 1931, Gaobei settlement, Yongding County) and three samples of tubao (Shaung Xing Bao, Zhi Mei Bao, Jingde Tang Bao, Datian County).

¹⁹. The mass of the structure provides “inertia” against daily temperature fluctuations: it absorbs thermal energy during warming periods and emits thermal energy as temperatures drop, improving building comfort and conditions for preservation and storage in regions, such as western and southern Fujian, which experience temperature fluctuations throughout the day, especially during summer. The use of massive rammed earth acts as a heat sink and is therefore particularly effective for summer cooling. It should be noted, on the contrary, that during winter months these structures have a constant temperature of 5–6 degrees, well below today’s standards for comfortability (Ueda 2012). The thick earth wall also has the peculiar effect of adjusting the interior humidity (Huang 2020, in part. chap. 9, Habitable Inner Environment, 214).

²⁰. The present study is the result of an ongoing research conducted by the Department of Architecture of Roma Tre University: E. Pallottino, P. Porretta (scientific directors), E. Colafranceschi, C. Nuti (for structural aspects), in collaboration with the College of Civil Engineering, Fuzhou University, China and College of Civil Engineering, Porto University, Portugal. The paper is the result of the joint work of the authors; in particular, pars. 1, 2, 3, 5 are to be attributed to P. Porretta, 4 to E. Colafranceschi, 6 to E. Pallottino.