‘Tree house’ takes use of wood in building structures to new heights

Wood is increasingly valued as a more sustainable building material

There is increasing interest in the use of wood in civil engineering projects. It is sustainable – coming from renewable sources. It provides carbon storage and its lighter weight reduces transport costs. It is also durable and can lead to shorter construction times. Research indicates that wood in buildings is beneficial for people’s health and wellbeing.

The drawback is that costs are typically higher than for buildings constructed from steel and concrete. Furthermore, because structural elements like columns are larger, they reduce available space. Together these make it more difficult to generate a viable business case for wooden high-rise buildings. Currently, a small number of wooden towers have been built in Europe, but the maximum height achieved is around 80m.

How to make the business case viable?

This was the challenge facing Royal HaskoningDHV structural designers in their work with developer Provast, London-based PLP Architecture and local architect ZUS to win an international competition for a new mixed-use tower at Rotterdam Central station.

“We therefore investigated how we could maximise the use of wood while ensuring the building would be financially viable”, concluded Walter van Adrichem, structural engineer at Royal HaskoningDHV.

The solution developed by Royal HaskoningDHV is for a part-timber structure with a concrete core. The first 10 floors housing offices, restaurants and meeting rooms are constructed using steel and concrete. This maximises space and allows flexibility with large, open-span areas. The main construction material for the remaining floors is wood. This is where apartments are located and all columns, floors and beams are constructed from cross-laminated timber. At 140m-high, the Tree House is set to be the tallest hybrid structure in the Netherlands.