A wooden city
At the time when Pliny the Elder (23 – 79 CE) mentioned the Macedonian city of Xylopolis (Ξυλόπολις,), in the 4th book of the Naturalis Historia (Natural History), neither Romans nor Greeks could ever imagine that almost 20 centuries later, “wooden city” will reflect the concept of cities and metropolises being subordinate to nature instead of hostile, and made from wood not concrete.
Indeed, the conception of buildings and whole towns made of wood is as old as time itself. In the past, villages and towns comprised only wooden buildings. However, when the industrial age dawned, cast iron and steel were worshipped, and at the present time, modern cities favor concrete and glass, whereas postmodern cities adore aluminum and polymers. Wood building materials used to be pushed out as risky, stolen from nature, flammable, perishable and not durable. Architects promoting wood used to be perceived as charming freaks.
So it took Glenn Murcutt, Australian architect who loves wood, to win the Pritzker Prize 2002 (equivalent of the Nobel Prize in architecture) and make architecture critics and architects aware that wooden buildings do not bring shame. The emancipation of wood as a building material has been fostered by a substantial progress of wood preservation methods, which allowed to minimize its main disadvantages: flammability, inhomogeneity as well as susceptibility to warping and biological corrosion.
Successive Pritzker Prize winners are also fascinated with wooden architecture: Peter Zumthor (2009), Eduardo Souto de Moura (2011), Wang Shu (2012) and Shigeru Ban (2014). Remarkably, wooden buildings began to prevail among national pavilions at EXPOs, held in Hanover (2000), Aichi (2005), Zaragoza (2008), Shanghai (2010) and Milan (2015). By the way, at that time, Poland also exhibited architectural gems in the form of pavilions reflecting aesthetics and symbolism of wood.
Inspired by the traditional Far East clamp structure, the wooden pavilion of Japan for the Expo 2015 exhibition in Milan (proj. arch. Atsushi Kitagawara)
Technology - how to build a 160-meter-high wooden dome
In the 1860s, the technology of gluing wood layers (lamellae, facing boards), already known for quite a long time, quickly progressed towards obtaining large wooden elements free of main disadvantageous features: flammability, inhomogeneity that causes warping and dimensional constraints. Glued laminated timber (glulam) entered the technological arsenal of architects and builders, and already in 1866, Josiah George Poole used this material in one of the university buildings in Southampton.
Over the next century, the largest domes built with the use of glued laminated timber reached spans of nearly a hundred meters, as exemplified by the Brick Breeden Fieldhouse situated in 1957 on the campus of Montana State University in Bozeman, USA. Soon, even larger wooden domes were constructed: that over a multi-purpose arena in Tacoma, Washington – the Tacoma Dome (160-meter diameter), and the Superior Dome, on the campus of Northern Michigan University in Marquette, Michigan, USA (163 m).
In the second half of 20th century, new types of wood-based building materials were developed:
- dowel laminated timber (dowellam, DLT),
- cross-laminated timber (CLT),
- timber-concrete composite (TCC) panels made of a layer of wood bonded to a layer of concrete,
- structural insulated panel (SIP) composites with an insulating layer,
- wood-plastic composite (WPC) made of wood fibers reinforced with plastic, used as cladding and structural elements in areas exposed to moisture.
In 21st century, improvements in wood construction started to be complemented by attempts to use again ancient technological solutions. Architects reached for aesthetical and technological inspirations drawn from historical and folk wooden constructions, such as cruck frame historically used in England; tie beam in the dou-gong system of traditional Chinese construction; historical Japanese log structures, such as azekura-zukuri or Eastern European izbicowa; natural building methods (North American cordwood masonry, Swedish cubbhus); half-timbered constructions and various types of Far Eastern reciprocal structures as well as age-old finishing solutions, such as Japanese wood impregnation yakisugi or shōsugiban.
Plyscrapers - sky-high wooden skyscrapers
Just like trees, wooden buildings have long climbed up to the sky: the church in Heddal, Norway, built in 1242, still standing, is about 30 meter-high. Slightly higher are old wooden pagodas (34 m) in Zhangye in China and Hōryū-ji in Japan. Next in line are: 37 meter-high Transfiguration Church in Kiza (Karelia, Russia), built in 1714, and Romanian Orthodox churches in Plopis, and Surdești (49 m and 54 m, respectively). There exist even higher old wooden buildings: the Sakyamuni Pagoda of Fogong Temple of Ying County, Shanxi province built in 1056 reaches a total height of more than 67 meters. The wooden tower (2013) of the monastery in the Romanian village of Săpânța nad Tisou, rises as high as 75 meters even though made with the use of traditional carpentry.
In view of the above, information provided by Yang Xuanzhi in the Description of the Buddhist Temples of Luoyang in 547 CE, sounds almost like a fairy-tale: in the year 516, there was erected a wooden pagoda 147-meter-high. It means that it was 1.5 times higher than the Złote Tarasy complex, opened downtown Warsaw, Poland, in 2007. The pagoda was visible from a distance of about 50 kilometers. Unfortunately, it was devastated by fire as a result of a lightning strike in 534.
Countless age-old wooden buildings were demolished by fire. The threat of fire deterred architects from designing wooden high-rise buildings, but this risk was minimized through improvements of the methods for wood treatment and application of fire-retardant solid building components (glulam-GLT and cross-laminated timber-CLT).
Starting from the last decade, high wooden buildings (25-55 m) have been erected in Europe, e.g. the first seven-story timber building in an urban context in Central Europe, “E3” situated in Prenzlauer Berg district, Berlin, Germany (designed by Tom Kaden and Tom Klingbeil, opened 2007) or the first eight-storyy wooden high-rise in Germany, the “H8” building in the Upper Bavarian town of Bad Aibling (designed by Architekturbüro Schankula and completed in 2011). Among wooden high-rise buildings, the most famous is Brock Commons Tallwood House, 18-story student residence at the Point Grey Campus of the University of British Columbia (UBC) in Canada (53-metre-tall; designed by Aston Ostry Architects; opened in 2017).
Apart from the aforementioned several wooden churches and pagodas, as well as radio towers erected in the 1930s in then Germany, e.g. the Gliwice Radio Tower (111 m) and a radio transmission antenna built near Mühlacker, Germany – when opened in 1934, the tallest structure ever built of wood (190-meter high; blown up 1945 by Germans to prevent its capture by the Allies in World War II), it is only recently that in wooden construction, there has been exceeded 55-meter height limit, on the way to high-rise buildings. The 21-story, 73-metre-tall HAUT apartment building at Korte Ouderkerkerdijk Street in Amsterdam, the Netherlands, is at finishing point. The 19-story, 76-meter-tall community center (Sara Kulturhus) in the city of Skellefteå, Sweden, designed by White Arkitekter, was opened in 2021. The 24-story, 84-meter-high HoHo wooden skyscraper in Vienna, Austria and 18-story, 85-meter-high Mjøstårnet, erected for office and hotel purposes in Brumunddal, Norway was opened in 2019. In Milwaukee, Wisconsin, USA, a 25-story mass timber building Ascent is scheduled for completion in 2022. More “wooden skyscrapers” are under construction (e.g. Terrace House in Vancouver, Canada, Albizia in Lyon, France)
Architects are more and more willing to design buildings that are even taller. Examples are: 40-story, 133-metre-high wooden skyscraper Trätoppen in Stockholm, Sweden (designed by Anders Berensson), 80-story, 228-metre-high wooden skyscraper River Beech Tower in Chicago, USA (designed by Perkins+Will), 80-story, 304-metre-high wooden skyscraper Oakwood in London, England (designed by PLP Architecture). Such projects are done sometimes with an eye toward future realization, every so often to promote a developer or an architectural design studio, now and then to explore technological possibilities – as in the case of the latter project, supported by a university grant from the Engineering and Physical Sciences Research Council and backed by the authority of the University of Cambridge, United Kingdom.
There has recently appeared on the horizon of technological possibilities, a wooden office building (350-square meter), designed in detail by Nikken Sekkei, yet-to-be-built by Japanese timber company Sumitomo Forestry. It was announced to be erected in the heart of Tokyo by 2041. Will it actually be built? Or is it just a “marketing ploy”? Today, it does not seem that technological limitations will prevent such a construction.
"Wooden skyscrapers" in culture and science
The fashion for “wooden skyscrapers” has become part of contemporary culture. Internet portals, magazines and newspapers have eagerly picked up the topic a couple of years ago: The Economist posted an article “Plyscrapers – Tall buildings” on the front page; Forbes published “Tree Houses: Is Wood Really the Future of Skyscrapers?; BBC Future – “Plyscrapers: the rise of the wooden skyscraper”; The Guardian – “Wooden skyscrapers could be the future of flat-pack cities around the world” and “Plyscraper city: Tokyo to build 350 m tower made of wood”. In 2018, the exhibition “Timber Rising: Vertical Visions for the Cities of Tomorrow” was presented at the at the Roca London Gallery (afterwards – also at other Roca branches with exhibition spaces).
This topic has also been taken up by scholars. For example, in 2018, Kaiser Group (KAISER GROUP + PATH ARCHITECTURE, Portland, USA) received a $250,000 Wood Innovation Grant from the USDA Forest Service to conduct feasibility research on The Spar (36-story, 91-meter-high), designed for a site in downtown Portland. At least a dozen or so similar research projects have surfaced in recent years. Actually, in 2017, there was published, the first textbook on the design of wooden high-rise buildings: ATLAS – Mehrgeschossiger Holzbau (by Hermann Kaufmann, Stefan Krötsch, Stefan Winter); its English-language edition was soon published, and the second updated edition is expected in 2021.
The concept of modern wooden buildings expands further, as already there have been developing the prospects for wooden cities and metropolises. Until a short time ago, they existed only in the imagination of architects, although – some design offices have already become famous for their visions of wooden cities, such as a wooden city Bamboo City designed by Chinese-Swiss team Penda/Precht and their design of a wooden exhibition city for the Beijing International Horticultural Expo 2019, as well as some theoretical projects – e.g. Arboria – prepared by a visualizations studio based in London, UK – Ordinary Vis (by Magnus Larsson and Alex Kaiser),
It is thanks to visionary projects, their creators, as well as teams of architects, graphic designers and researchers – all in love with wood, that year after year, there are addressed the possibilities, opportunities and needs for designing wooden cities, not only in debates at a professional level, also in the press articles. But what is it that attracts architects, scientists, journalists and some politicians, apart from the extraordinary aesthetics of wood?
First of all, these are environment and climate concerns. The postulated basic building material for cities of the future, namely glulam, contains carbon. The constructional use of wood can, therefore, be one way of capturing carbon dioxide from the atmosphere and counteracting climate change.
Secondly, the erection of buildings from prefabricated glulam and cross-laminated timber can go very fast when compared to any other construction technology (e.g. steel construction). So it becomes very cost effective where time is at stake. If a fast erection of a wooden building is profitable, the establishment of housing complex or district with the use of wood technology will also be cost-effective. Furthermore, in the event of a natural disaster, a modular prefabricated building built with the use of CLT technology makes it possible to respond immediately to emergency (e.g. homelessness or evacuation).
Thirdly, today’s CLT prefab systems allow for rapid disassembly of a building, thus facilitate prompt reconstruction. The buildings can be assembled as if it were made of building blocks and then disassembled, rebuilt, extended or reduced in size.
Obviously, the installation and finishing elements could pose problems, in terms of difficulties associated with adaptation buildings to new needs, nevertheless, at least the structural system will not be a major obstacle. Besides, wooden finishing solutions can often be quickly dismantled. Consequently, the building is flexible, easy to adapt to changing needs – in a way it is movable property. The flexibility of such buildings implies the ease of changing the building tissue on a larger scale, towards building complexes, districts or even entire cities. This is an extremely important aspect, well understood by those who have had to deal with technical hitches when demolishing concrete districts.
JAROSŁAW SZEWCZYK, Doctor of Science (DSc) Ph.D. Eng., Assistant Professor at Białystok University of Technology, Faculty of Architecture.
Graduate of the Faculty of Architecture at Białystok University of Technology (1996), Ph.D. (2006) and DSc (2012) at Warsaw University of Technology. Scientifically passionate about folk and untypical ways of building, folk stove construction and carpentry. The author of 13 books and about 200 other publications. In didactics, an advocate of teaching by inspiration. Privately an occasional marathon runner.