As early as 1925, Junkers also experimented in his own building developments with industrial forms of construction, and there, too, he chose metal rather than concrete. He attempted to produce a prefabricated building that could be assembled according to serial principles, applying the basic findings he had made in the field of aircraft construction. Aesthetic and formal considerations took a back seat behind physical and technical requirements. His most successful achievement in building engineering, the so-called “Junkers lamella hall”, was developed and marketed by the department for steel construction.
Only when he was 50 years old did the qualified engineer Hugo Junkers address the task of building aircraft, however, a discipline in which he was to gain international fame. At that point in his life, he was the father of seven children; he had already developed the first two-stroke opposed piston gas engine and the calorimeter; he had founded six companies; and he had a full professorship for thermodnamics at the University of Technology in Aachen. It was there that he was motivated by his colleague Hans Reissner to take an interest in aviation. In 1910, he had already patented the so-called “thick wing”, and five years later, he succeeded in creating the first all-metal plane. With his urge to apply himself to research, and aided by the economic development of the Junkers works, more than 30 different aircraft models were developed and constructed during his lifetime, the best-known of which were the Junkers F13 and Junkers Ju52, nicknamed “Tante Ju”.
In 1919, Junkers initiated the first air route between Dessau and Weimar and played a participatory role in a number of airlines. The company Junkers-Luftverkehr AG, founded in 1921, merged with Deutscher Aero Lloyd in 1926 to become the German Lufthansa.
In the 1920s, other spin-off and start-up companies were founded in Germany as well as in the Soviet Union, the US, Sweden and Turkey. The concern retained its base in Dessau, however, which at that time can be seen as a Mecca for engineers and technicians. When the Bauhaus was invited to establish itself in that prosperous city in 1925 – with strong support from Junkers – the company increasingly applied itself to the industrialization of building construction.
In 1924, under the direction of the architect Ottokar Paulssen, the steel construction department of the Junkers plant applied for its first patent: for the so-called “bar grid”. In the following years, a civil-law dispute with the Zollbau Syndicate came about on account of the alleged strong similarity of the Junkers system to that of Zollinger. Before the Junkers concern was caught up in the world economic crisis as well, Junkers himself managed to develop the lamella hall as a successful product and to market it worldwide.
A tragic turn of events for Hugo Junkers and his consortium was the seizure of power in Germany by the Nazis, whose intrigues and threats he felt as early as 1930. Within a few months, Junkers was first dispossessed, then ousted from Dessau and finally, on 3 February 1934, his 75th birthday, placed under house arrest in his holiday home in Bayrischzell. Exactly one year later, Junkers died in Gauting near Munich.
The first structure that could be referred to as a “lamella hall” was the so-called “Benzin-schuppen” or “fuel shed”, built on the company’s site in Dessau at the beginning of 1925. At that time, the construction still consisted of two rib types of different length which formed a non-hierarchic triangular grid (ill. 5). This corresponded closely with the initial patent application of 1924 (ill. 6). Apparently, this first hall met with great acclaim. After a loading test ordered by the building authorities and passed with flying colours, Paulssen informed Junkers that the persons who had inspected the structure “showed a keen interest in the construction and expressed their conviction that it possesses great potential.” And indeed, they were to be proved right.
When arch-shaped lattice grids are exposed to asymmetric loading – from wind or snow on one side, for example – the grid members are subject to bending. With weaker cross-sections or a lack of bracing, this can lead to lateral deflection on the non-loaded side of the arch. In contrast to other contemporary buildings, however, the Junkers halls re-quired neither bracing with stays nor a two-
dimensional curvature of the overall structure to overcome this problem. Instead, the individual grid members were optimally adapted to the load-bearing behaviour of arch construction and rigidly connected.
As part of the technical development, the construction team about Paulssen was able to draw on the progressive know-how gained from the rapid advances made in aircraft construction (ill. 4). Long-year experience in design and construction, using thin metal sheets that acquire their overall rigidity through the process of bending, together with the appropriate connection of the individual elements, logically leads to a vertical orientation of the cross-sections; i.e. the formation of “lamellae”. To increase the rigidity of these members (without increasing their structural depth) and in particular to enhance their lateral stability, the upper and lower edges are bent at an angle. The rigid connections of the individual lamellae are achieved with one or two pairs of bolts at each point of intersection (ill. 2).
The Zollinger system and the lamella halls of Junkers are related in their triangulated and lattice-grid structural make-up. As barrel-vaulted forms of construction, they are also subject to the structural need for a rigid cross-section. The differences between the two can be seen in the node points, the construction of which varies considerably because of the materials used – wood and steel. The rigidity of the Zollinger form of construction is ensured solely by bars alternately continuing through a node (ill. 1). In addition, the load-bearing capacity of the Zollinger structure depends on the bracing effect of the roofing.
In 1928, the legal battle over Zollinger’s accusation of plagiarism by Junkers was ended. Zollinger backed down and agreed to an economic collaboration under the name of Junkers-Zollbau.
While the Treaty of Versailles imposed tight economic constraints on German industry, around 1924, Junkers found scope to set up a company in Turkey. In order not to have to hand over the erection of the production plant to a third party, he instructed the company’s building management to optimize the lamellahall type technically and economically so that it could be shipped as a modular system within a few months and erected virtually anywhere in the shortest of time.
The springboard for the further development of these structures was the “Benzinschuppen”, mentioned previously. In a working report, Paulssen recorded its load-bearing behaviour with the words: “The main load is borne by the diagonal lamellae, while the linking members would seem to be scarcely subject to loading.” In terms of stress distribution, the structure was further optimized by adopting the form of a barrel vault. In the longitudinal direction of a shell structure of this kind, only very small forces occur, because there is no curvature in that direction. The logical outcome of this was to use much more slender purlins (ill. 15). This was structurally of advantage, allowing the geometric simplification of the connection points and a reduction of the geometry to no more than single lamellae. It was thus no longer necessary to connect six diagonal members, but only four.
Using this modified system, two further prototypes were erected in Dessau. In order to manufacture the large numbers required for the Turkish site – at least ten halls – a pressing apparatus was specially developed (ill. 8).
In 1926 –27, at three locations in Turkey, large-area production halls were erected in a very short time. On the partially rough terrain, the modular unit construction system offered great advantages. In some cases, the lamellae and purlins were transported into remote regions using pack animals (ill. 9).
Following the success of this initial project, the first segmental-arch roof with tension rods as well as a multibay construction, consisting of three round-arch roofs, were erected – again on the company’s own works site. Smaller commissions in the Dessau area followed, such as the roof over the dining hall of a well-known hotel in the town centre and the outer enclosure of a bolt factory in Finsterwalde.
The end of the patent dispute in 1928 and the engagement of the engineer Wilhelm Klingenberg as head of the steel construction department mark the beginning of the worldwide proliferation of Junkers halls. Klingenberg implemented the change from Z- and S-section to C-section lamellae (ill. 7), which simplified their manufacture because the new form could be pressed in a single process (ill. 8).
Around 1930, a final modification of the lamella geometry was made – from a shaped cross-section to flat metal junctions (ill. 15).
At the same time, the standardization of the halls proved to be decisive for their economic success. Klingenberg developed the structures into products that clients could order as finished objects. Modular design and flexibility nevertheless allowed the creation of many different forms. The first customers in other European countries were quickly found, too. In the case of Britain, not only the finished products were sold; licence and patent rights were granted for the manufacture of halls as well. Further contracts followed in Brazil, Venezuela and even New Guinea (ill. 12). In all, roughly 170 halls and roofs were constructed in accordance with the Junkers system, 120 of them by the British licence holder. As part of a current research project at the University of Technology in Munich, a full mapping of the structures is being attempted, at least for those built in Germany.
The motivation for this were the halls standing on the former military airport in Oberschleiss-heim outside Munich, which are now used by aero clubs (ills. 15 –17). The structures are in a multibay form of construction and were built with lamellae 2.75 m long. The three arched roofs were lined up next to each other and have an effective floor plan of approximately 130 ≈ 30 m. The halls are listed structures subject to conservation order, although one of the three arched sections of the eastern hangar was lost some decades ago, and the others are in a critical state. The halls that are still standing are now being analysed with a view to their retention and rehabilitation.
After being expelled from Dessau, the Junkers research department and the motor works were relocated in Allach, Munich. Here, too, two production halls exist – the last constructional token of the plant that once stood there.
In Dessau itself, four of the 15 former halls are still in use. Another two are marked by having stood empty for many years. An early version of the all-metal form of construction, dating from 1929, extended some years later and used for industrial purposes until 1996, is the last surviving structure of the former calorifier works of Hugo Junkers and the steel construction department that were located there. After 2010, despite protests from notable organizations, the municipality removed these factory buildings, which, until then, had survived more or less in their original form. A small listed hangar from the nearby town of Köthen was removed in 2012 and taken apart. The elements were stored on the open site of Dessau’s Museum of Technology.
An unusual form of the structure still stands in Leipzig. In 1949, the intact elements of a partially ruined pointed barrel-vault hall were re-erected on the flat roof of a publishing house. When the building complex was refurbished in 1996, the steel structure was rediscovered beneath the timber cladding. Restored and enclosed within a glass skin, it now houses the impressive conference rooms of a newspaper, the “Leipziger Volkszeitung” (ill. 18).
The lamella roof of the Opel building, dating from 1929 and also in Leipzig, was erected to increase the height of a multistorey concrete structure. Used originally as a prestigious showroom for cars, it is an almost forgotten garage today (ill. 19). One example outside Europe is in São Paolo, where a station hall built in the 1930s (ill. 14) is still used for its original purpose. Even if no trains now stop directly beneath the lamella structure and the roof has been reduced to roughly half its original length, it nevertheless forms the central entrance hall to the urban station of Brás.
In 2006, the hangar of the old airport in Liverpool was converted into the headquarters of a mail-order firm. In Skyways House, the almost 80-year-old structure curves over a modern open-plan office, creating a surprisingly up-to-date and spacious atmosphere beneath the glass-covered grid (ill. 3).
Unfortunately, examples of this kind are the exception. The structural simplicity and lightness of the surviving lamella halls are reminders of the exceptional all-round engineer Hugo Junkers. Their relevance in terms of building technology and history are reason enough to halt the destruction with which many are threatened and to preserve one of the most important witnesses to an age of industrial architecture and the early years of aviation.
