CHOOSE WOOD

The barriers

Despite of all the advantages, the use of wood to construct tall buildings faces challenges. One challenge is the need to win the minds of people: no one should find it amazing that 30 story buildings can be made of wood. Another challenge is that the costs of timber buildings are still higher than a traditional steel and concrete construction, although that should change as timber buildings become more massive. The third challenge is that there are myths surrounding the use of wood, especially in the case of fires and earthquakes.

This last point is probably the easiest to demystify. Burning a log is not easy, as anyone who has tried to light a fire for a barbecue can attest. There are all kinds of techniques to do this, ranging from using rolled paper to wood splinters and sticks. Only when the fire is strong enough can a trunk burn – and it will burn slowly. The same happens with solid wood panels: they don`t catch fire easily and when they do, they burn slowly and in a predictable way.

Earthquakes are another cause for concern. However, earthquake forces are proportional to a structure’s mass, so heavy steel and concrete structures experience greater forces. Wood-frame construction is substantially lighter than other types of construction and has a high strength-to-weight ratio. In addition, thanks to the connections by means of nails and fixings, the wood-based building systems designed correctly dissipate the energies of an earthquake better. In short, wood buildings are more flexible and less susceptible to collapse if any part of the structure fails.

Wood production can be implemented sustainably. The cultivation of fast-growing forests and proper management is essential to achieve large-scale production that facilitates timber construction. According to Michael Green's calculations, enough wood is grown in North America in 13 minutes to build a 20-story building.

Another barrier lies in the construction codes, which in many places do not allow the use of wood for buildings over four floors high. In August 2018, Oregon became the first US state to change its building code to allow the construction of wooden buildings. In contrast, the United Kingdom banned, as of December 21, 2019, all combustible coatings in buildings over 18 meters high, including wood. While the decision was made in response to the tragedy of the fire at the Grenfell tower in London, where 72 people died in a fire, the coating in that case consisted of two sheets of aluminum that sandwiched a combustible core of polyethylene.

When one is told that something is so spectacular that it can change the world, skepticism seems a natural reaction. It may be that the wooden skyscrapers will remain a promise. But the arguments are convincing enough to at least develop the construction of wooden buildings in parallel with the materials that already exist.