What Are the Limits of Timber Construction?

Researchers at Wageningen University & Research in the Netherlands have investigated both the possibilities and limitations of using biobased materials in construction. Their findings indicate that timber is a sustainable option for buildings up to 60 metres tall. Beyond this height, the advantages of timber begin to diminish compared to traditional fossil-based building materials.

Traditional construction materials, such as bricks, concrete, and steel, produce significant CO2 emissions during their production and transportation. In contrast, biobased materials like timber absorb carbon dioxide from the atmosphere as they grow and store it throughout their lifespan. Among biobased options, engineered timber, or mass timber, is the most commonly utilised choice for construction.

In high-rise buildings, architects typically rely on a large concrete column at the centre to support all the floors. The research conducted by Wageningen University, in collaboration with TU Delft, explored whether this concrete column could be replaced with a timber alternative.

However, timber is less robust than concrete, necessitating a thicker wooden column compared to a concrete one in similar structures. Moreover, as the building height increases, the required thickness of the column also escalates. According to the researchers’ model, constructing a five-storey building would require approximately 250 trees. For a ten-storey building, that number rises to 1,000 trees. When extending the height to roughly 60 metres — around 15 storeys — you would need about 4,000 trees.

For buildings taller than 60 metres, the excessive material use makes timber construction less advantageous. Nevertheless, this doesn’t mean architects should rely solely on traditional materials. A hybrid construction approach that incorporates both timber and concrete or steel can significantly reduce CO2 emissions compared to using conventional materials alone.

Want to know more about building in timber? Check out our book Tomorrow’s Timber (also available in Dutch and Spanish translation).

Photos: Wageningen University and Research