4. Cropius, Hirsch, and the Saga of the Copper House
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MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House Walter Gropius, Konrad Wachsmann Published on: Apr 23, 2021 License: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC-BY-NC-ND 4.0) MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House The Hirsch Copper House The Hirsch Copper and Brass Works (Hirsch Kupfer-und Messingwerke) were founded by Aron Siegmond Hirsch in 1906, as the extension and consolidation of an old- established family metal business based in Halberstadt, with associated enterprises in Werne, llsenberg, and Ebers-walde. The firm developed to become a major power in the German copper industry and is described as having played “a leading role in German economic life.”1 (It was at Eberswalde, incidentally, that Hirsch built a large two-story new factory, designed by architect Paul Mebes, and later published by Walter Gropius in his Internationale Architektur.)2 Hirsch not only dealt with copper ore but also with the manufacture of copper products, including such building products as copper tubing, sheeting, and roofing.3 During 1930 the Hirsch company began to experiment with the use of copper in building on a more comprehensive scale. They acquired the rights to a system of prefabrication of dwellings, invented by Friedrich Förster (originally Frigyes Förster, of Budapest) and later further developed by Förster in conjunction with Robert Krafft.4 Förster, in his original patent application of 1924,5 drew attention to the many previous attempts to design “knockdown buildings that can be readily assembled,” which had failed because of high costs or through inadequate standards of construction and performance. He then went on to claim: Recognizing the importance of such considerations I have constructed a knock- down type of building composed of structural elements that are made at the factory in the desired form and to the desired dimensions required by the purchaser. Each structural element constitutes a wall section of box-frame construction, and is adapted at its edges to be joined to other sections to provide a complete wall. The wall sections may be made up of wooden skeleton frames covered on both sides with metal sheathing. The space between the metal sheathing is filled with insulating material such as wood wool, sawdust, exelsior, or the like. The edges of the sections may carry tie bolts or equivalent forms of fastening means for easily connecting the sections together. The general construction of the sections is such that they can be readily made up at the factory and transported to the point of construction. 2 MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House The advanced nature of these proposals must here be stressed, as well as their early date, in a European context. They were developed at the very latest in early 1924, and possibly in the previous year, and therefore predated all the German steel houses by at least two years. The Förster concept moreover had no structural prototype among the German houses, or even the earlier, much-admired British models. His self-supporting metalfaced panels eliminated the need for a structural frame, but without the excessive weight of the Telford panels and with a superior degree of thermal insulation. Moreover—and here lay the most significant contribution—the entire panel could be factory made, reducing the site work to a minimum. In 1930 Förster, now working with Krafft, radically altered his concept of insulation, and a new patent application was made for a revised system that did away with the infill of insulation material and replaced it with a series of “parallel partitions of a material which is impervious to air, preferably metal.” This principle, incidentally, had already been exploited in practice in the panel system of the wooden houses produced by Holzbau A.G., a firm of house manufacturers operating under the direction of the architect Kunz, and had been published as early as 1922.6 The performance could “be further improved by lining the partition with a layer of a poor heat conductor, preferably of a fibrous material,” in order to impede vertical air movement within the panels and to eliminate the possibility of heat bridges from exterior to interior. Dramatic improvements in thermal capacity were achieved, many times that of an equivalent brick wall. Hirsch was later to claim a thermal equivalence to a 220-mm- thick masonry wall for the panels they manufactured according to this system. In Förster and Krafft’s patent application, a revised and much improved method of joining the panels was suggested in place of the original, rather primitive tie bolts. The wooden frames were beveled and bolted to a continuous U-section connector. By this device two-, three-, and possibly four-way connections were easily achieved without altering the standard panel, and at the same time heat bridges between adjacent panels were avoided. A universal jointing system was thus proposed. At the time of the revised patent application, in August 1930, Förster and Krafft gave their address as at Finow, Mark. This was the location of the Elberswalde factory of Hirsch Kupfer-und Messingwerke. Hirsch set up a sophisticated production process for the manufacture of houses on the Förster and Krafft principle, including assembly of the subcomponents to make building elements on a moving production belt, and a new division was established in the factory, the Copper House Department. A five-roomed model house war erected probably late in 1930, and it generated much interest not 3 MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House only in Germany but also in the United States, where it was studied with care by the Copper and Brass Research Association and published in the metal industry journals.7 In order to publicize this new venture, a catalog was printed, and a total of six examples of complete houses were exhibited, some at the Paris International Colonial Exhibition of 1931 (winning a “Grand Prix”) and others at the German Building Exhibition in Berlin in May of the same year.8 The “Haus in Allkupfer-Bauweise der Hirsch Kupfer-u-Messingwerke A.-G. Berlin” as exhibited was a large, two-storied structure made of wood-framed panels covered externally with copper sheets, internally with pressed steel plates, and insulated in the prescribed manner. The ceilings too were of pressed steel, suspended from wooden trusses, ready cut (with the parts numbered for ease of assembly), which carried the copper roof. The cost of the Berlin exhibition house was given as RM 10,900, and an erection time of only 24 hours was claimed. Reaction to these exhibition houses was mixed. The editor of Bauwelt magazine in a private letter9 confessed to some disappointment. He was worried about such technical problems as the heat conductivity of the copper panels; he anticipated long- term maintenance problems, particularly if the houses were erected in areas where the necessary skills and materials were lacking. He also pointed out that the price differential with conventional housing was not sufficient and—perhaps most important of all—the architectural character (more picturesque than functional) set back the cause of modern architecture by thirty years. Walter Gropius, on the other hand, in reply to an inquiry, affirmed that on the whole he was most impressed with the copper houses, was convinced that their weather-resistance was very good, and expressed his intention shortly to look into the technical aspects in greater detail.10 This general approval, as we shall see, did not preclude Gropius from having his own reservations, both about technical aspects of the copper houses and especially about their conservative architectural character. 4 MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House 4.1 Förster and Krafft, heat-insulating wall (U.S. patent application, 1930) 5 MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House 4.2 Hirsch Kupfer-und Messingwerke, copper house, 1931. 6 MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House 4.3 Hirsch Kupfer-und Messingwerke, copper house, German building exhibition, Berlin, 1931 7 MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House 8 MIT Press Open Architecture and Urban Studies 4. Cropius, Hirsch, and the Saga of the Copper House Together with the exhibition houses a handsome catalog was produced, which extolled the virtues of the copper house in a twelve-point manifesto, answering the selfposed question “Why is the copper house the best?” Attention was drawn to its precision, being mechanically assembled; its hygienic qualities; its efficient thermal insulation, which made it economical to heat; its proof against fire, lightning, and earthquake; and the fact that it could be erected in 24 hours and internal partitions could be relocated. A price list for separate components—internal and external wall panels, glazed windows, doors, insulated roof decks—was included in the catalog. Wall panels were shown to have an outer facing of rectangular-patterned copper sheets and an inner lining of pressed steel, with a choice of six “tasteful patterns,” some simulated brick or tile, others (the Englisch and Japanisch styles) with a delicate overall floral motif. These panels were modular, in 1-m increments up to a maximum of 4 m, and in two heights: 2.35 and 2.80 m. The wall unit, came complete from the factory, fully insulated with aluminium and asbestos and fitted where necessary with shuttered double-glazed casement windows (whose fanlights were remotely operated) or with doors.