New horizons for wood
Image size 12 Kb After decades of waiting in the wings, wood is surging ahead to a star role as a building material. It has been used as the main material in several internationally-notable structures that were either recently completed or are now taking shape. They include modern urban milieus, the world's first wooden concert hall and the world's biggest wooden bridge - not to mention a great number of smaller objects.

Given that Finland is Europe's most-forested country, it seems incredible that for several decades wooden buildings were to all intents and purpose banned. The Finns seemed more interested in grinding the "green gold" that their forests gave them into pulp and paper than in sawing it into beams and planks. Suppliers of competing structural materials jealously guarded and expanded their turf, and soon building laws virtually ruled out the use of wood as a structural material in anything other than single-family houses.

Finally in the early 1990s, when people again awakened to a realisation of the virtues of wood, the Finnish Timber Council was created to promote this material. It had its work cut out for it, but did it well. Now wood is again respected, accepted and esteemed.

"Skill in the use of wood as a structural material had deteriorated and one of the first priorities was to tackle this problem both at university and vocational-institute level. Equally important was an extensive research and development programme that focused primarily on building systems," says the Council's managing director Pertti Hämäläinen.

Earthquake-proof wooden houses

"Finland has indisputably been a forest virtuoso," says Hämäläinen. "We know how to use forests and are masters of industries based on them. Now that we have concentrated on developing our ability to build with wood, we have been deferentially learning from the rest of the world. In America they are masters at using wood in frame structures, in Central Europe it is used for interior decoration whereas we use it for cladding exteriors. When all of these skills are combined, the result is a good wooden house, and a competitive one at that."

The open Wood Platform Construction system was adopted from the United States and further developed to suit Finnish conditions. It has proved a very competitive way of building high-class houses, be they single- or two-storey, in rows or detached.

"The beauty of Platform is that one needs only two pole dimensions to built, let's say, an entire urban milieu with a rich diversity of expression. Indeed, our aim is to make wood a leading building material in Europe, and an open construction system is the means that we have specifically chosen to achieve that goal," explains Hämäläinen.

He believes that Finnish multi-storey wooden buildings could save lives in earthquake-prone parts of the world: "A wooden building is resilient; when the earth shakes it flexes, but it does not collapse."

The ecological choice

In addition to being economically competitive, wood has another significant advantage in that it is environmentally-friendly, something that matters more and more in construction.

It is a renewable natural resource. Processing it requires very little energy and does not generate undesirable emissions. Wood waste is easy to dispose of safely.

However, the most important factor from the environmental perspective is that wood acts as an efficient carbon sink, thereby slowing down the greenhouse effect. Growing trees remove carbon dioxide from the atmosphere and break it down into carbon and oxygen. The latter is released back into the air and the former incorporated into the tree's tissues. In fact, as much as half a tree's weight is carbon. The carbon remains in the wood until it is burned or rots. Thus the more wooden buildings there are, the greater the braking effect on global warming.

Old lessons, modern city

An entire district of wooden buildings with an utterly modern expression is now under construction beside the University of Oulu in northern Finland. Behind the scheme is a research group - called Puustudio or "Wood Studio" - led by Professor of Architecture Jouni Koiso-Kanttila.

Image size 12 Kb The district will encompass about 50 two- and three-storey houses based on an open platform system and is due for completion in 2002. Some of the residents will be able to move in already soon after the turn of the millennium.

Although the new housing scheme definitely represents modern architecture, its milieu planning is based on lessons learned from the wooden buildings still to be found in parts of many Finnish towns and cities.

"The aim has been to transplant the atmosphere and milieu of those old wooden districts to this modern residential area. The streets are clearly narrower than in modern suburbs, the blocks are closed and sheltered, all of the utility spaces are in separate buildings of various sizes in the courtyards, and there are no open parking fields," says Professor Koiso-Kanttila.

Naturally, the facades of the buildings are clad in wood, which lasts centuries if correctly attached and treated.

The scheme has attracted attention elsewhere in Finland as well. In autumn 1999 similar ones had been launched in at least five other towns and cities.

The music of wood

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Even before it was completed,Sibelius Hall, a concert and congress centre in Lahti, aroused interest all over the world. So many groups of visitors were coming to see the construction site that a guide had to be employed to look after them..

It is, undoubtedly, a fascinating place in many ways. It is the only concert hall in the world that is built completely of wood and also Finland's largest wooden public building. Its acoustics were designed by the American guru Russell Johnson and the general opinion is that they will prove superior to anything else in Finland. Indeed, there are some who argue that it will beat anything in the world! Sibelius Hall will become the home of the Lahti Symphony, which under the baton of Osmo Vänskä has earned world fame. The hall opens in March 2000.

The building was designed by two young architects, Hannu Tikka and Kimmo Lintula. "It was a very challenging project. We designed the building on the material's terms and all of the wood in it is Finnish species from spruce to pine, birch and aspen. We used thousands of cubic metres of it," says Hannu Tikka.

Unique wooden bridge

Image size 16 Kb The world's longest wooden road bridge was opened to traffic near Mäntyharju in September 1999. Its three 42-metre main spans are likewise of world-record length. All in all, the bridge - which has been nicknamed Honkahimmeli or "Pine Mobile" - is 182 metres long and its deck has a surface area of 2,400 square metres. The design emerged from a competition won by the Timo Rantakokko office.

Mäntyharju is a popular location for summer cottages and wanted to replace its old steel bridge with a wooden one in order to strengthen its image as an environmentally-minded municipality.

"It definitely deserves to be called a wooden bridge, although considerable amounts of steel and concrete were used in it. Its bearing structure is entirely wood," says Professor Aarne Jutila of the Helsinki University of Technology.

"Wood is a completely competitive material also for building bridges. We expect it to last 100 years, as long as any other building material," he says.

See also:
WTF-O The hall with a sound like an instrument