Giuseppe Fallacara is an architect and full professor in architectural design at the Polytechnic University of Bari where he leads the New Fundamentals Research Group. He focuses his research on stereotomy, a construction technique based on stone that suffered from the 20th-century diffusion of concrete and steel. I interviewed him to understand more about this technique, which could play a central role in the sustainable development of our cities thanks to digital tools and parametric architecture.
Giuseppe Gallo: Stereotomy is an ancient and incredibly intelligent technique that we seem to have forgotten in the last century. Can you explain its meaning?
Giuseppe Fallacara: We can explain Stereotomy easily by analysing its etymology. As anyone involved in this research knows, it comes from two Greek terms: Stereos, solid, and Tomé, cut. The word atom derives from Tomé, preceded by the privative alpha, to mean something impossible to cut: the minimum entity. Stereos has a more complex etymology. When we normally speak of solid, we can mean either a Platonic solid, then a geometry, or something resistant.
Thus, the definition of Stereotomy for technical simplicity in architecture and construction is the art of translational cutting of resistant materials, such as stone and wood. But in reality, if we delve into its etymology, we come to discover a quality of the sky, the place of the fixed stars, which the Greeks called Stereoma.
When the ancient Greeks described the sky, which we still today call the celestial vault, they spoke of Stereoma, a term that in Latin will take meaning of firmament. Similarly, the meaning of the Latin word firmitas relates to a place that the ancients observed as immutable, always equal to itself. For those civilisations, the sky is a solid place because the stars do not move and it is the deities’ home, described in the shape of a dome.
Already the ancient Egyptians, observing the Milky Way, interpreted a curvilinear nature of space that led them to the idea of the sky as a vaulted space. Their findings of meteorite fragments composed of extra-terrestrial metals in the Sahara desert strengthened their idea of a celestial vault made of resistant metals, of the same nature as the stars. A meaning, common to the Greeks and other populations, also testified in the bible, where the mosaic Tabernacle, therefore the cap of the sky, goes by the name of Stereo.
This vision of the world, covered by solid curved matter, immutable like the fixed stars that represent it, naturally triggers in the philosophers’ mind the idea of the vault, and therefore their desire to read in the composition of the stars a celestial coffered ceiling, a place of divine geometries.
This is where stereotomy comes from. The same idea, translated into architecture, becomes the art of building vaulted systems made of small parts.
G.G.: When was stereotomy born and how did this technique develop before the 1900s?
G.F.: Stereotomy codification happens around 1500 in France; I say codification because it did not originate in France. It is a Middle Eastern art coming from Mamluk architecture, which arrived in Europe thanks to the Crusaders.
We do not have any treatise before 1500, when Philibert de l’Orme, the architect of the French King, published Le Premier tome de l’Architecture. He dedicated the third chapter of his treaty to stereotomy, which, since then, develops in France, but not in other regions of Europe such as Italy.
For a long time, Italy will remain marginal in the evolution of stereotomy; this is because of a substantial difference in technical culture, favoured more in France. In Italy, the treaties are those that Leon Battista Alberti dedicates to the culture of drawing, to style and not to construction techniques. The only one in our country who will address the subject is Guarino Guarini, an Italian architect close to French culture, who will write about stereotomy in his treatises. Something underlined by Portoghesi. Guarini does not call it stereotomy but Architettura Gettata, meaning architecture made through double orthogonal projections.
In the 1900s, we preferred other approaches to this complicated stone technique, less appropriate to cast iron, reinforced concrete and steel. Thus, the architecture and construction industry forgets stereotomy.
G.G.: What are the basic requirements of a stereotomic architecture?
G.F.: To build sub-specie stereotomica, architecture must respect three invariants. The first is a geometric invariant: it is necessary to describe the vaulted space geometry. Second is the cut invariant: it is necessary to divide the geometry into discrete portions, represent them geometrically first and produce them later, by cutting a solid material. The third invariant is static: the vault must stand upright by itself.
Not all cut and set constructions respect the static invariant. Similarly, not all vaults are stereotomic, because they do not respect the second invariant. Take, as an example, vaults built in shapeless stone vaults, where there is no precise geometry of the blocks: a discrepancy that we compensate for with mortar.
G.G.: How did your research start? Why did you choose to focus your research on digital stereotomy?
G.F.: My research begins in Bari, in Apulia, one of the two Italian regions, together with Sicily, where people traditionally build using squared stone; this derives from our stones, soft limestone suitable for this kind of work, especially in Salento.
In our region begins a geological continuity that reaches Noto, where there are materials with the same characteristics as those of Salento. On the contrary, in the rest of Italy, where these materials are rarely present, people usually build with bricks, and stone is mainly cladding.
This attention to regional quality derives from the vision of Professor D’Amato, who based the Bari school of architecture on the study of our architectural Genius Loci. To study the evolution of this type of construction, I could only choose stereotomy.
G.G.: Can we speak today of a renaissance of stereotomy? And if so, how did it happen?
G.F.: Certainly yes, the forerunners of the stereotomy rediscovery of this discipline are above all architectural representation academics, who studied stereotomy as a historical precedent of Monge’s geometry. This happens mainly in two places, La Sapienza in Rome and the IUAV in Venice: Riccardo Migliari, Mario Docci and Paolo Portoghesi in Rome, Camillo Scolari and Massimo Trevisan in Venice.
In Italy, however, none investigated stereotomy in the architectural design context: the one that suits its best, since the purpose of its codification is not intellectual speculation, but the construction of architecture.
This also happens because, as we have already seen, in Italy architectural design means above all drawing, theory, and philosophy. Other countries are more oriented towards making, building, and experimenting.
When 20 years ago, I interviewed my friend Camillo Trevisan, I asked him: «In your opinion, can this science have a follow-up in architectural design?» He replied, «no, I don’t think so».
We in Bari believed in it, bringing stereotomy back to the architectural design field over 20 years, starting from D’Amato’s research up to those of my group, which exploits the potential of digital in the study and the development of stereotomy.
G.G.: Earlier you talked about reinforced concrete, a material that, besides generating high levels of emissions, has negatively affected several areas of southern Italy and many Mediterranean suburbs. This has also negatively affected the presence of specialised builders: masters capable of physically creating these architectures. What future do you see for these figures, also given the digital manufacturing new potential?
G.F.: You have touched on a point that is central to the evolution of architecture. A point where issues such as environmental, energy, social and economic sustainability can converge, in particular for the Mediterranean countries.
Why am I saying this? After the second war with the economic boom, there was immoderate growth of our urban centres. This was also possible thanks to reinforced concrete, a relatively easy-to-use material, often used empirically, without calculations and any building permits. A condition that has favoured illegal activities and landscape destruction.
60, 70 years later, we have a huge problem, both aesthetic, because obviously, our suburbs are terrible, all over Europe, but also because these structures are collapsing. You can go on repairing the iron rods with the blue paint for another ten years, but under the plaster, there will be problems we will have to address soon.
In the meantime, our historic centres built in stone are still there. This is a truth for all to see. We can say that historic centres are dark and damp, but these are problems on which it is possible to work to improve housing performance, and their stone always responds well, even after centuries.
There are many reasons we should go back to building in stone. First, we traditionally quarry the stone under the construction site. So, it is a zero-kilometre material, with almost no necessary transformation to use it. The tools used to cut it are electric, and they do not emit CO2. Of course, it is necessary to think about how to produce this energy with eco-sustainable systems, but that is a general issue.
Furthermore, you do not need steel. It is a compression structure that can be eternal. Stone ages well, and the older it gets, the more beautiful it becomes.
Stone is perfect for building architecture with great thermal inertia, a solution suitable for hot countries and therefore for the Mediterranean, where, thanks to the design of internal microcirculation of the air, it is possible to cool homes without using air conditioning. I live in a house built like this, and I don’t have air conditioning.
This return to stone, necessary because of the failure of reinforced concrete, is therefore not a romantic look at the past. We can study and reinvent traditional forms thanks to digital and parametric architecture methods.
It is difficult to conceive large-scale stone structures, but when we are considering human scale, houses, small buildings, and small-scale infrastructure, stone is the best choice ever.
Reinforced concrete is a composition that requires an incredible amount of processing and with this fashionable idea of recycling it, cutting the pillars and extracting the irons, I wonder: what is the expenditure of energy?
On the contrary, architecture made with reclaimed stone has always existed everywhere in the world. It is an activity that man has always done. Stone is eternal, we can reuse indefinitely it.
To achieve this transition, we need skills that reinforced concrete has cancelled, so it is necessary to start again with skilled workers and teams of architects-builders, figures capable of bridging the gap between design and construction.
We need this new figure, which I call architect adauctus, enlarged: a new architect capable of designing and building, also thanks to robotics and CNC.
G.G.: How has digital stereotomy evolved in your direct experience? What was your approach?
G.F.: When I started 20 years ago, my first approach to stereotomy was trying to transfer the works covered in the treatises onto digital models. The stereotomy treatises on stereotomy are very complex pages of double orthogonal projection drawings. Not all architects can interpret and understand the drawings. So my effort at the time was to reconstruct those two-dimensionally represented elements in 3D. Something even relatively simple, but which no one was doing.
Later, I realised the parametric qualities of these models, so I investigated the parameters and their influence on the geometric transformation of shapes. This transition from a rigid model to an elastic one was much more complicated because there was no parametric design software. We tried a lot of them. Deepening the study, I realised that, besides the global parameters, there were also local parameters relating to micro-conditions of decoration, and block cutting.
Of course, with the parametric game, there was the ability to invent new spaces and shapes. When, in this modelling game, you change a shape; it becomes yours, and as a designer you feel the desire to realise what you have thought, to verify its static behaviour. A criticism of this work was about the static fragility of these structures, together with the difficulty in building them, so the third moment of my research was to start physically building the vaults. To do this, we got in touch with some of the largest French architectural restoration companies, which can work stone as before the 20th century and with whom we still collaborate.
G.G.: You have discussed physical models, but is it possible to simulate the behaviour of a stereotomic vault?
G.F.: Besides software, along our path, we experienced great difficulties in finding engineers able to solve static and mechanical problems. The complexity of describing vaults with CAD tools comes with the difficulty of calculating these structures. So much so that our first studies, carried out together with French mechanical engineers, were hybrid experimentation. This is because there was no adequate system for transferring information between our modelling software and their analysis tools, so we had to create hybrid models.
More recently, we found new pieces of software that allow us to work on the vaults in an integrated way, but starting from a geometric model, it is still difficult to find a program able to certify the static quality of similar structures. Computing the three-dimensional models of vaulted spaces is a complex problem, and involves delicate work not easily developed as an algorithm.
On the other hand, there is the great capacity of the vaulted spaces made with wedge-shaped ashlars to withstand large loads. Proof of this is the traditional vaults still visible in the Apulian countryside: dry stone architectures made empirically, which stand the test of time.
In the past, we have had several challenges with structural engineers. We built vaults with unlikely shapes and we asked them how much load they would hold. It was interesting because times that they believed would have collapsed at 100kg of cargo collapsed at 10 tons. An abysmal distance, which however expresses the great resistance of the vaults and underlines the importance of building physical models.
Today, looking at contemporary architectural research, we see a large spread of pavilions, physical models often made to show the muscles of architectural researchers. Yet that of physical models is one of the essential characteristics of stereotomic culture, with the substantial difference that in stereotomy the physical model is a moment of experimentation preparatory to the final construction, without which the pavilion loses its essential meaning.
G.G.: What is the value of stereotomy within contemporary architectural education?
G.F.: Stereotomy is a discipline that architecture students should study from the earliest years because it combines static, materials science, form, three-dimensional modelling, and the ability to compose spaces in a single discipline.
Even if contemporaneity pushes us towards hyper-specialisation, I have always been against this trend. From my point of view, to train competent architects and return to building quality architecture, it is necessary to move towards the unification of knowledge. Of course, it is also possible to get into specialisations, but it can happen even after graduation.
However, in the beginning, there is a need to understand the phenomena of construction science, with disciplines that are globalising. To do something innovative, the student must achieve a real vision of the world of construction, something that the teaching of stereotomy allows with a naturalness that other disciplines, albeit equally valid, do not contemplate.
Stereotomy brings students to acquire a historical perspective that shows the absolute continuity of architectural evolution and how architecture always originates from the same things. The construction technique and practical problems: starting points of more courageous intellectual speculations.
Therefore, my advice is to include stereotomy within any architectural study plan.
I noticed that the Italian school is turning towards a more pragmatic approach, towards learning by doing. This approach will find more space among the younger generations than those sixty or seventy years old, born and trained along another school.
G.G.: Despite the Italian birth thanks to the genius of Luigi Moretti, even in our country, parametric architecture struggles to find space. Why?
G.F.: From my point of view, things could find the right appeal in all cultural areas, only if we explained them well. The problem is that there is a lack of understanding, and this creates internal divisions. In Italy, we still pay for the war between Portoghesi and Zevi. Therefore when we discuss the goodness of parametric architecture, we put it in opposition to the study of history. This is insane because when Luigi Moretti invents a method for the parametric analysis of architecture, he starts with research on the architectures of Guarino Guarini and other masters of the Italian tradition. If we understand this continuity, we cannot place Luigi Moretti as a point of discrimination between tradition and innovation, but as a point of union.
G.G.: How has the role of the architect changed during your career? What do you wish for in the future?
G.F.: For our south, for our school of architecture, I would have imagined a much greater acceleration towards digital already 25 years ago, 30 years ago, but it did not happen. I started working on CAD when I was a student, and even then, there was a cultural restraint on the subject. Even today, after 27 years, I hear students from all over Italy telling me, my professor still wants me to draw by hand because he believes in the goodness of this method. Assuming that I have no problem, nor do I criticise manual drawing, I think that there is still strong resistance to the evolution of the discipline in the academic field. If, on the one hand, in the space of 20 years, digital tools transformed architectural firms, hit in full by a digital wave that has swept drafting machines and analogue instruments. On the other hand, at least in Italy, the older professionals who often lead architectural firms have little or no digital awareness: victims of change rather than supporters of it.
Therefore, I hope that the next architects are proficient in tools management, for this to happen our universities must push a lot in this direction, and train architects aware of the use of means that allow us to build optimised architectures from a constructive, ecological and economic point of view.
Looking at the last twenty years, I would have preferred a different evolution, but like all great revolutions, whoever brings them first must pay the pledge of a great change. In the future, I hope this change is more aware. It will be necessary to explain its evolution, first by teaching the history of the digital within the history of architecture.
As just as there was the history of architecture and the history of science, you must teach the history of digital architecture. Where do we come from, and why this was done, otherwise we will force future professionals to repeat history and experience where we have been. The university has a role; it has that of illustrating everything that has been there, in order not to make mistakes, and then carry on this flow, which must never be an end to itself. Digital architecture is a problem if it becomes a keyword, and rather it is a means of making the architecture at its best.
