Wood is going to return as a construction material. It is no longer the former inflammable material – that could set half a Mediaeval town on fire. It now lends itself to modern, performant and sustainable constructions. Timber construction represents a true revolution.
Timber construction, new opportunities
Recently, change.inc again devoted attention to timber construction (link in Dutch). For quite some time, wood as a construction material had an unfavourable connotation: it burned easily. Stone, cement, concrete and iron had a much better reputation. Moreover, wood was looked upon as untrustworthy – its construction properties varied a lot. Each kind of timber is different, there may even be major differences within one species. From the fifteenth century onwards, the new materials surpassed timber – that only survived in wooded areas.
But now, we witness the reverse development. Firstly, we can now much better control wood’s strength as a construction material – through new techniques. Moreover, concrete has a major disadvantage. Its production emits lots of carbon dioxide. In terms of CO2 emissions, the concrete and cement construction trades are among the major emitters. We find different figures in literature – they vary from 5 to 10% of mankind’s yearly emissions. An appreciable amount. Less than motorized transport, but much more than aeroplanes. Interesting, and all the more so as an alternative arrives at the horizon.
In short, wood needs to overcome two problems. The strength and the fire safety problem. Of course, part of the fire safety problem can be overcome by impregnating the wood. But just as important is the thickness of the beams. Thick beams will only be affected on the surface by a fire, and therefore will retain their constructive properties.
We overcame the strength problem through the development of CLT, Cross Laminated Timber. CLT consists of surfaces glued to each under high pressure. Cross-constructed, with the grain in adjacent layers perpendicular to each other. It consists of thick, strong and stable beams and panels – and yet, light in comparison with the concrete alternative. In constructing CLT, we remove any defects and weak spots; therefore, we know exactly how strong the final product is. Because of the development of CLT, we can now construct high-rise buildings from wood. The highest existing building in the world now measures 86 metres; but plans are in development for wooden buildings of over 100 metres.
Wood is much lighter than concrete – five times as light, exactly. Moreover, we can easily process wood; those two properties render to wood very good properties for industrial and prefab constructions. In the factory, we can construct wooden panels to measure – making recesses for sockets, piping and wiring, windows and doors. With the implication that work on the construction site itself can be done very fast. Moreover, because of the low weight of the construction material, we could very well place wooden floors on top of existing buildings. An opportunity hardly explored so far.
But from its past, wood earned a bad reputation. Now is the time to reset that. In principle, we can apply wood anywhere in homes and buildings: as a constructive and as a finishing material. In principle, if wood is being used as a building’s constructive material, this doesn’t need to be shown. Although it is much more appealing if it shows. Timber construction may make a quick start.
Timber construction on the rise
Examples abound. Like Haut (pronounced like hout, the Dutch word for wood), a 73-metre high-rise flat in Amsterdam. A wood-hybrid construction, meaning that concrete is still partly used as the constructive material. And the new headquarters of DPG Media in Amsterdam, headquarters of a number of media; also, a wood-hybrid building. Rotterdam will catch up, constructing the residential complex Sawa. And near Eindhoven a wood-hybrid building will be constructed, with two high-rise flats, 100 and 130 metres high.
One of the Dutch banks, the Triodos bank, already houses in a largely wooden office. And there are more initiatives. The company Sustainer Homes builds affordable wooden homes. They already built quite a number of them, and now plan to build entirely wooden neighbourhoods. Major construction companies have also entered this market. Heymans and BAM, two major Dutch construction companies, already have wooden homes for sale. Amsterdam for its part is planning a wooden neighbourhood consisting of 700 units. Timber construction is on the rise!