Yona Friedman’s Roofs: manuals for simple, low-cost building

Andrea Bocco1,a, Emiliano Cruz Michelena Valcárcel1,b, Laura Trovato1,c 1DIST-Politecnico di Torino, viale Mattioli 39, 10125 Torino, Italy [email protected], [email protected], [email protected]

Keywords: Yona Friedman, low-tech, low cost, bamboo construction, learning by doing.

Abstract. Since 1973, Yona Friedman, architect, born in Hungary in 1923, used the “manual” as a method of providing information to those unable to decipher technical drawings. The communication was entrusted to very schematic drawings, similar to comics, coupled with short texts. Manuals – mostly produced thanks to the support of UN agencies – were intended to transmit easy techniques regarding the basics of survival, i.e. shelter and food. The privileged recipients were slum dwellers. In his book L’architecture de survie, Friedman explained his lucid vision of an impoverished world, where in “developing” and industrialized countries alike, conditions of scarcity will be common and the question of survival will be urgent, even more so in cities. The only effective way to ensure the survival of the poor would be to support their autonomous development of feasible solutions. The manuals collected in Roofs contain a number of techniques suitable for people without building skills. Most involve the use of natural materials and include many different solutions for bamboo domes, which Eda Schaur and Yona Friedman used in the Museum of Simple Technologies they built in Madras in 1987. The techniques – chosen because of ease of use and low cost – have also important ramifications in terms of autonomy and environmental impact, and are the subject of sometimes advanced research carried out in rich countries. Therefore they may indicate a possible path towards a socially, economically and environmentally sustainable architecture. This presentation covers both the illustration of Roofs and a discussion of its current technological viability, which the authors conducted in students workshops, building a number of full-scale prototypes. The possible applications in the improvement of housing in the city and the metropolitan area of Buenos Aires are covered in paper no. 114.

Introduction Roofs is a collection of practical information on the building of roofs for the shelters of the poorest populations. It bears the acronyms UNESCO, CCSK (that is, Friedman’s Centre for the Communication of Scientific Knowledge), and UNU (United Nations University), and is still freely downloadable from UNESCO archives. [1] One of the most appreciable peculiarities of Roofs lies in the simplicity of its drawings and texts, through which Friedman meant to make himself understood by the larger amount of people, even illiterate. He had first experimented with this communication strategy in 1973, when he decided to make the contents of his theoretical text Pour une architecture scientifique [2] – a book conceived in order to enable the inhabitants in designing their own living environment, a similar engagement to that of some contemporary authors, such as Habraken and Alexander – available to children. [3] From that time through most of the Eighties, a large part of Friedman’s work consisted in composing manuals. The cartoons encouraged self-planning and self-building practices, and innate creative capacities, with the scope of empowering citizens in fields deeply affecting their lives, but from which they had been expelled by professionals and political power. Awareness would build up a convivial relationship between one’s will and the tools to follow it up. [4]

The Manuals Since 1973, Friedman collaborated with UNESCO on housing insecurity issues in big cities of developing countries; in 1976 he was a member of the preliminary commission to the first UN Conference on Habitat, to be held in Vancouver. In 1977, Friedman collected what he had learnt from such appointments in his fundamental essay, L’architecture de survie (“The architecture of survival”). [5] Friedman proposed that the spontaneous initiatives of the poor should be supported, both in housing and food provision. He also claimed that the best way to learn is from direct experience, what is denied by formal education. Friedman thought that the cartoon manual would have transmitted knowledge elements without compelling the reader to use them in a specific way: “Only those from bottom up are true solutions.” [5:74] Thanks to successful diffusion initiatives in India, in 1982 the UNU financed the establishment of CCSK, whose scope was the realisation of information tools for the improvement of living conditions in developing countries. [6] This included translating scientific knowledge into information which had to be comprehensible and usable by the poorest. The design of manuals was by far the largest activity the CCSK undertook. Architecture was just one of the many topics – they included food (production, storage and processing), health (diet, hygiene and basic care), water management (collection, conservation, treatment, irrigation), habitat, ecology, material resources, energy, self-organisation, communication, business. In all of these CCSK tried to teach simple techniques relying “more on investment of labour than cash or materials that must be bought.” [6:335] Only some of the topics were actually covered; anyhow, such ‘Encyclopaedia of survival’ [7:166] is outstanding in vision and richness, with potentially enormous ramifications: let us only think of what might be accomplished if a similar initiative were undertook now, in the age of Internet.

The Museum of Simple Technology Besides the manuals, another means of knowledge diffusion envisaged by the CCSK was the construction of a Museum of Simple Technology. Friedman conceived it as “a permanent exhibition of techniques, traditional or modern, implementable by disfavoured people in order to improve their life. The exhibits consist of artefacts used for or resulting from such techniques, accompanied by a simple and pragmatic explanation.” [8:1] He held it was crucial that all exhibits be produced at a very low cost (or, better, without any money expenditure), make use locally available knowledge, and constitute innovations bringing tangible improvement to the quality of life. Moreover, they should have been easy to understand and copy. The target group was the urban poor. The Museum building itself was supposed to embody building techniques that the slum dwellers might use to improve their shelters. Therefore materials were selected according to economy and technical appropriateness – cement and steel were ruled out (“in India, even scrap metal can be too expensive for the disfavoured”) [6:335] and the use of timber was minimised. Expenditure in labour was privileged on cash for building materials. Friedman designed several architectural projects for the Museum. One, which was not implemented, consisted in a complex of three large rooms covered by ‘ring-ball’ domes: (Fig. 1) a technology which would allow covering quite large spans without intermediate columns and using a limited amount of material, that in our opinion was never really tested, although Friedman built a few prototypes at different stages of his career. [9] [10:62] It seems to us that he can be fully credited with such technology – which is described in the manual with the same name [1:89-99] –, as already in 1959 he invented a system of ‘spherical constructions’ based on tangential joints connecting what he dubbed ‘indeterminate polygons’ (that is, circles). From a single element – a steel ring –, this system would allow to build various polyhedra, assemblable almost at will, their faces being in all cases a ring with the same diameter. [11] Translating this system in ‘low-tech’ he substituted bamboo for steel, and reduced the diameter of the rings; he even proposed that these be prefabricated handicrafts, so to obtain a low-cost building component made from local material. [10:62-64] Theoretically, rings could be the only load-bearing element in indefinite space chains: in practice though, either they are so large that they contain a full storey, or they can be used for roof structures only – which will be quite cumbersome, and will require a different vertical structure.

Fig. 1 Friedman’s sketch of an auditorium for Madras Museum, to be covered by a ring-ball roof.

Fig. 2 Some pavilions of the freshly-completed Museum of Simple Technologies, 1987.

This technology is quite different from that of the built Museum, which was erected in 1987 at the campus of Anna University, in Chennai (Madras). Eda Schaur’s and Yona Friedman’s project consisted of 13 square modules – 6 pavilions enclosed by walls and 7 covered courtyards. (Fig. 2) Walls were rather ordinary self-bearing raw and fired brick masonry, while roofs were bizarre double-domed structures, spanning 4.3 m, built of 10 cm diameter bamboo culms that had been split in eight strips, or 2.5 cm diameter whole canes. Domes were supported by an independent structure made of timber posts inserted in concrete pad foundations, and tightly tied to the domes’ base frames with vegetal rope. The technology of these domes is described in the manual Bamboo domes with suspended mat cover, [1:51-70] one of the very few containing also technical drawings. The upper dome is the load-bearing one, while the bottom one hangs from it and carries the roofing. The latter is relatively flat, which allows to keep down its surface area (just a bit more than with a flat roof, as opposed to common domes), and to employ sheets and mats for roofing. Friedman was proud of an innovation he dubbed ‘alumats’: an aluminium sheet 0.05 mm thick glued to a bamboo mat locally handcrafted – or a sandwich made of two outer mats and an aluminium sheet in between. Such an easy-to-use building product – coupling of a widely-spread, low-cost traditional technique with an also low-cost product issued from advanced industrial manufacture – is a good example of CCSK’s scientific and socioeconomic goal. ‘Alumats’ offered new performances – watertightness, heat reflection – for a flexible, lightweight building product, alternative to corrugated sheets. Upper domes supported shading screens – in the photos, one of the most appealing features of the Museum –: substantially, they were flat baskets, reducing solar irradiation on the ‘alumat’ roofing. Domes were built of long and very thin elements, easily obtainable anywhere, although not valued anymore for building purposes, in spite of their long tradition – especially in the region. The coupling of advanced scientific knowledge – e.g. on grid shells [12] – with traditional know-how – e.g. in tying rope joints – allowed Schaur and Friedman to propose a strong and lightweight roof structure, made with a minimum amount of material, and not asking for a high degree of precision from the builders. The Museum was built by basketmakers lacking previous experience in building, who lived in slums nearby. In 1988 ten more modules were scheduled, but the project was never completed. Indeed, the Museum was soon dismantled; overall, it did not operate for more than two years. Also the ambitious program of building a network of museums stayed just a charitable intention of Friedman’s. [13:21]

Roofs Roofs was probably assembled around 1991. (Fig. 3) It contains 29, mostly previously-released manuals and provides useful information for the building of low-cost roofs. Friedman thought technical innovation of roofs was an important mission: slum dwellers, although inexperienced in building, might not need assistance for erecting walls, while it would have been relevant to advise them so to substantially improve the roofs of their shelters. He observed that this part is the most difficult for the self-help builder, and therefore the most unsatisfactory both structurally and in terms of liveability – e.g. heat and noise problems due to corrugated sheets; rain leakage... These manuals constituted a remarkable case of popularisation of ‘low tech,’ and a core of a possible future encyclopaedia of building with natural materials, including ecological and low-cost solutions. (It is somehow peculiar that low-cost and ‘outdated’ building techniques – in that not based on reinforced concrete – are closer to what should today be considered as sustainable than their industrialised, post-WWII counterparts). Friedman was moved by a humanitarian and environmental urgency. He affirmed that “the society of poor world is inventing the architecture of survival.” [5:13] But, notwithstanding its wide scope, Roofs was not a complete design and/or building handbook, like van Lengen’s. [14] Friedman wanted to provide convivial tools to develop people’s skills and knowledge, and give them some agency, [15] more than giving them technical solutions. With today’s eyes, one cannot restrain from observing that scientifically grounded and habitat- improving innovations – be they exuberant grid shell domes, or appropriate technology applied to local materials – proposed by engaged technicians have often be rejected, because for slum-dwellers it is more crucial that their house resembles to the mainstream model than it performs well in terms of structural safety, comfort, usability, and even cost.

Fig. 3 The first two pages of the manual Bamboo domes with suspended mat cover.

Fig. 4 A prototype built under Schaur’s direction, at the Ahmedabad School of Architecture.

Eda Schaur’s and IL’s Contribution to Research on Bamboo Building Eda Schaur, CCSK’s deputy director, was at the same time a fellow researcher at the Institut für Leichte Flächentragwerke (IL) where she worked, among other things, on surface structures (shells). A relevant part of the IL’s work was dedicated to the possible employment of lightweight structures in developing countries. (It must also be reminded that a few years before Gernot Minke – still one of the most prominent experimenters and propagators of technologies based on natural materials – was too a fellow researcher at the IL.) The IL published one of the first books in which bamboo as a building material is examined thoroughly. [16] Its outstanding structural properties could only stimulate an inquisitive mind as Frei Otto’s, who held that research on bamboo structures was useful to understand the behaviour of vegetal thin rods, which could be employed even in large-span structures such as the Mannheim’s Multihall he designed. But, besides these advanced usages, the IL hoped that appropriate technology research on bamboo would stimulate a humane construction exploiting locally available resources – craft traditions included. [16:394] The goal was to understand how to minimise the use of material and obtain strong – even earthquake proof – structures with very thin elements. Wickerwork creates flexible and strong objects. The IL, as many other subjects wishing to promote an architecture truly adapted to human beings and the environment, had a sincere interest for traditional buildings. In fact, they noted that bent rods, subject to compression, can be found in many primitive cultures, and that baskets – an almost universal artefact – can be enlarged to become building structures. [16:304] Economic and ecological reasons are therefore found both in out-of-the-ordinary engineered grid shells and in many vernacular shelters, both temporary and permanent, such as the Tuareg tent of Southern Aïr, [17:12] mongulu huts of Baka Pygmies, and Dorse houses of southern Ethiopia. In our opinion, the bamboo dome building techniques described in Roofs are mostly the result of IL’s and Schaur’s research, while ‘ring ball’ constructions derive from Friedman’s research on the industrialisation of the building trade, as discussed above. During her appointment at the Ahmedabad School of Architecture, Schaur performed research on split bamboo structures, mainly grid shells. [16:330] She chose to work with split bamboo as opposed to whole canes, as the first can be bent easily, while the second need to have a small diameter, and to be green or duly prepared. (Fig. 4) Tests showed that the introduction of a secondary diagonal grid notably increased strength – as we have verified. Schaur tested also that traditional basket weaving techniques in view of their employment for building. A model built with thin bamboo strips by a skilled basket-weaver stood a 1000 N/m2 distributed load without significant deformation. This made her conclude that a full-scale construction would be remarkably strong. [16:336]

Our experience To conclude, we take the liberty of introducing a few observations deriving from our experience, as in the last two years we have built in five occasions reproductions and rearrangements of Schaur and Friedman’s bamboo structures, together with students and volunteers. Among these occasions, at Buenos Aires Bienal de arquitectura (2013) we realised a small exhibition where a split bamboo dome and a smaller-than-life, demonstration ring-ball construction were shown (both were built by UBA students); (Fig. 5) and as part of the Architectural Construction Studio (Politecnico di Torino, School of Architecture), students built in 2014 eighteen different models taken from Roofs and in 2015 eight split bamboo domes and two ring-ball constructions. (Fig. 6) The self-building workshop Construir con el delta held in Tigre (province of Buenos Aires) in 2014, directed by Emiliano Michelena, is described here in paper no. 114. One main reason for most of these experiences was to verify the buildability of the Roofs, or, more precisely, to check the comprehensibility of the instructions by people lacking building skills. In fact, we had noticed that Friedman’s manuals contain little explanation on how to obtain several details, such as joints, knots and cane cuts, on care to be taken because of the material’s characteristics (e.g., the opportunity to cut and make joints close to bamboo nodes, or special recommendations regarding its very small shear strength), or on the tools to employ. As one student, Tom Dagan, noticed, “Friedman’s manuals are more conceptual than practical, and some basic understanding of (or experience in) DIY is needed.”

Fig. 5 The installation at the Bienal de arquitectura in Buenos Aires. Fig. 6 Students working at 2015 workshop, PAV, Torino. Fig. 7 A few examples of joints using rope and bamboo pins.

Friedman drew his manuals for very poor and badly housed people, but nevertheless used to help themselves to solve their survival problems, and therefore skilled in some trades (maybe including some relative to bamboo); his scope was to give them information regarding new techniques which would have enriched their know-how. This is probably the reason why he was not concerned with how to implement building details, as he left the choice to self-builders according to available, or culturally appropriate, techniques and materials. But this was not the case with our students and volunteers! Generally speaking, each of the students groups was asked to build a 3x3 m prototype starting from a square framework braced at the corners (in the case of bamboo domes) or a 6 m diameter one using 1 m diameter rings (in the case of ring-ball constructions). For joints we gave preference to rope and wire – to obtain reversible joints, and because these products had been indicated by Friedman. [1:100-105] (Fig. 7) Canes were not treated, but in 2015 we were gifted high-quality, well-seasoned Phyllostachys pubescens canes. Out of these experiences we obtained some qualitative knowledge:  as largely expected, to control the geometry of a bamboo construction is not obvious, be it made with whole or split canes, as the thickness of the walls is not uniform, and the canes themselves are tapered. Experience suggests ways to fit, but a certain degree of asymmetry must be accepted. (Fig. 8) The same problem occurs with ring-balls: rings are not perfect circles, as to the above-mentioned facts the higher stiffness of the overlapping segment is added. (Fig. 9) Diaphragm parts need to be removed in order to regularise the element’s behaviour and facilitate bending.  some domes tend to settle down. (Fig. 10) Forms designed by Schaur and Friedman do not escape gravity, even though being made of extremely light elements, which are also very elastic. The question was studied in form-finding experiments on cyclic knots, particularly by Dmitri Kozlov. [18] Both configurations result in self-supporting structures subjected to tension, like big springs.

Fig. 8 A dome prototype built from Roofs (page 60, left). Fig. 9 A dodecahedron to be used as one of the components of a ring-ball structure. Fig. 10 A ‘petal’ dome prototype built from Roofs (page 131). Fig. 11 A double dome prototype built from Roofs (page 60, right).

 as it was easy to expect, it was shown that some know-how in binding is much called for. Tying points, particularly those fastening strips upon themselves to form rings, act as ‘fuses,’ so that not a single ring broke when a storm knocked down some constructions of 2015 workshop. (But those most affected by the impact with the ground were permanently deformed). The event also showed the easiness of repair of these constructions, as Friedman claimed.  domes with strips radially crossing at the top or with a ring acting as an oculus are stiffer than those whose design leaves a void at the top. Also, domed roofs (central symmetry) appeared more stable and thus generally more durable than vaulted ones (axial symmetry), because they are connected to the base framework on four sides, not just two.  some manuals propose a double roof: an upper load bearing roof, and a bottom sheltering roof, which supports a waterproof membrane, and/or a shading screen. In our experience though, the latter actually stiffened the whole structure, increasing its structural performance. (Fig. 11)  Friedman’s basic assumption that particular attention should be dedicated to the improvement of roofs, as they are the most delicate part of a building, is certainly true, but the correct execution of the vertical supports of bamboo roofs is not negligible nor obvious. The foundation ought to be stiff enough and direct contact of bamboo (or timber) poles with the ground should be avoided; the column must be able to resist horizontal load, possibly with the help of bracing elements; knots connecting posts and the dome base framework must be correctly placed, strong but elastic, and able to transfer vertical stress. We found that it is preferable to build bundle columns made of two or three culms rather than a single one, albeit with a larger diameter. However, in the occasion of the collapse of our 2015 workshop structures we noticed that the weak point was the joint between columns and ground, not the stiffness on vertical planes nor the joints connecting posts and dome framework. It was not by chance that in Madras Museum the vertical supports were inserted in a small pad foundation; while in 1985 prototypes the structure had been reinforced adding horizontal rods at the base, lying on the ground, and diagonal braces in some of the vertical planes.  in ring-ball constructions it is not easy to select the most appropriate points to tie the columns and the roof together: Friedman affirmed that these are “in spots where several rings meet and, if possible, where their tangent is near to vertical.” [1:93] In our experience, the first condition is essential; but often contrasts with the second: in other words, we could not place the posts on the rings’ tangent – only at an angle. Giving a saddle shape to the column’s end, where the connection of several rings was inserted, and binding with rope produced a fairly stiff joint. However, this solution – as it is punctiform compared to the extension of the roof, whose elements are all to be considered as load-bearing structure at the same extent – inevitably implies a measurable, yet not really detectable deformation of the construction. (Fig. 12)

Fig. 12 A ring-ball structure consisting of six-and-a-half dodecahedra and twelve tetrahedra (adapted from Roofs, page 98).

 some constructions appeared more durable than others. For instance, the dome made of intertwined circular ‘petals’ [1:127-132] performed well (after more than one year it is almost intact) because it has tangential joints (split bamboos are tied to the canes constituting the base framework, and not perpendicular to them – a position which often leads to cut slits into them). (Fig. 10) Moreover, not piercing the canes allows to possibly reuse them when the structure is disassembled. We noticed an easy onset of rot whenever water stagnation in internodes occurred, albeit for a few days. Therefore we think it is crucial to avoid exposed inflow points by design, and if possible to avoid piercing the canes at all.  the usability of the space covered by both kind of roofs is a relevant issue. Often, domes based on a square actually cover a smaller area as they stem from the middle section of the sides and the corner braces, leaving the corners unprotected: to avoid so, a different configuration should be worked out. On the other hand, ring-ball constructions cover a much larger area but the unencumbered space, free from vertical supports, is more or less the same than that obtained with the square domes.

Future Work Our experience with Friedman and Schaur’s bamboo roofs is less than extensive. Our experiments led to more questions than answers, and we plan to develop further research on this kind of constructions. To begin with, we want to measure quantitatively the phenomena occurring, something that in the haste (and excitement) of the workshops was not easy to perform – we don’t even have an exact figure for the weight of our roofs. Moreover, we would like to extend our experience building more, and more focussed, constructions. To mention just a few of our intentions: load tests on prototypes; comparison of durability and buildability of different joint shapes and materials; larger dimension ring-ball constructions; comparison – in terms of strength and durability – of split bamboo with very small diameter green bamboo; checking what happens (also in terms of wind load) if waterproofing sheet and/or shading screens are added to the roofs skeletons.

Acknowledgements First of all, we wish to thank Eda Schaur, who was so generous to accord us a one-day-long interview, without which we would not have understood many facts regarding Roofs. We acknowledge the massive technical support obtained from Angela Lacirignola, in charge of the DAD-STI laboratory at our university. Laboratori di Barriera and Parco di Arte Vivente (PAV) need to be credited for having kindly hosted our students workshops, respectively in 2014 and 2015. The bamboo employed in the 2015 workshop was granted by the grower Walter Montiglio, through Roberto Pichetto, who is working to establish a bamboo production chain in Piedmont. Last but not least, we are grateful to our publisher Quodlibet, as this paper much owes to the forthcoming publication of the Italian edition of Roofs.

References [1] CCSK, Roofs, vol. 1-2, Paris : UNESCO, [1991]. 1st volume: http://unesdoc.unesco.org/images/0008/000876/087695eb.pdf; 2nd volume: http://unesdoc.unesco.org/images/0009/000908/090863eb.pdf. [2] Y. Friedman, Pour une architecture scientifique, Pierre Belfond, Paris, 1971. [3] Y. Friedman, Comment vivre entre les autres sans être chef et sans être esclave?, 1973. [4] I. Illich, Tools for conviviality, Harper and Row, New York, 1973. [5] Y. Friedman, L’architecture de survie, Éditions de l’Éclat, Paris, 1978. [6] Y. Friedman, Centre of scientific knowledge for self-reliance, Leonardo, 4 (1986) 333-336. [7] Y. Friedman, Utopies réalisables, Éditions de l’Éclat, Paris, 1974. [8] CCSK, A Museum of Simple Technology, 1981. [9] Y. Friedman, M. Homiridis, Drawings and models, Les presses du réel, Dijon, 2010,. pp. 380- 381. [10] Y. Friedman, E. Schaur, Architetture per la gente, Spazio e Società, 50 (1992) 57-64. [11] Y. Friedman, L’industrialisation et la ville, Techniques et Architecture, 25 (1964) 176-177. [12] F. Otto et al. (Eds.), IL10 Gitterschalen/Grid Shells, Institut für leichte Flächentragwerke, Stuttgart, 1974. [13] Y. Friedman, E. Schaur, Uno strumento di crescita, Spazio e Società, 40 (1987) 86-93. [14] J. van Lengen, The barefoot architect. A Handbook for Green Building, Shelter Publications, Bolinas, 2007. [15] N. Awan; T. Schneider; J. Till, Spatial Agency. Other Ways of Doing Architecture, Routledge, London, 2011. [16] S. Gaß; H. Drüsedau; J. Hennicke (Eds.), IL31 Bambus/Bamboo, Institut für leichte Flächentragwerke, Stuttgart, 1985. [17] L. Kahn (Ed.), Shelter, Bolinas : Shelter Publications, 1973. [18] D. Kozlov, Form-Finding Experiments with Resilient Cyclic Knots, in: G. Hart, R. Sarhangi (Eds.), Bridges 2013: Mathematics, Music, Art, Architecture, Culture (conference proceedings), pp. 419-422.