The international construction industry is moving away from carbon- producing materials, such as steel and concrete, in favour of more sustainable materials.

Engineered wood offers a multitude of benefits, including being a more sustainable and cost-effective material while offering shortened construction time with customisable, stronger and uniform panels.

According to the United Nations Environment Programme, the built environment accounts for 39% of gross yearly carbon emissions globally. This comprises operational carbon, ongoing carbon emissions from day-to-day use and embodied carbon.

Engineered wood serves as a more sustainable construction material because timber sequesters carbon, York Timbers chair and University of Pretoria (UP) senior lecturer Dr Schalk Grobbelaar explains.

Trees capture carbon during their growth phase and the wood formed will continue to retain carbon when used in construction.

Grobbelaar explains that, as the growth rate of trees slows down, forestry companies have optimised the harvesting age of trees to ensure that growth is maximised before replanting.
By removing the tree, using the wood and planting a new tree, more carbon is absorbed and stored. This process maximises the trees’ carbon sequestration capabilities while providing more wood for construction.

Engineered wood construction uses large timber components or premanufactured panels or units that can be assembled on site.

Engineered wood products include glue-laminated timber, laminated veneer lumber, cross laminated timber, plywood, mass plywood, nailed laminated timber, doweled laminated timber and parallam.

Premanufactured units can increase construction speed while reducing the construction site’s environmental impact in terms of pollution regarding land, noise and dust.

Units can be made to the exact size required, allowing for the manufacturing of large, engineered wood components, which is not always possible when using ordinary timber. The structures can also be erected quicker because bigger components are used.

“As the rotation age of trees are also coming down, trees today are generally smaller which limits how big planks produced from that tree are. Engineered wood does not have that limitation,” adds Grobbelaar.

Further, since engineered wood is made from a combination of weak and strong pieces, it can create components that have a more uniform strength and improved stability.

Trees have various defects, which can weaken the wood, but engineered wood involves using different planks together; therefore, a weak spot on one plank is supported by a stronger plank.

The strong and the weak components cancel each other out, resulting in a component that is almost as strong as a plank without any defects, explains Grobbelaar.

Local Construction Needs
The local construction industry does not typically rely on wood for construction. As a result, very few architects or engineers will specify timber in structures. Production capacity is also low compared to international standards; thus, economies of scale are not optimised.

However, the local industry can integrate engineered wood products into structures on a small scale, particularly where it is easy and cost effective to replace usual construction products with engineered wood.

South Africa has limited skills to undertake large projects, but he adds that it can increase its engineered wood construction knowledge over time and, consequently, its adoption rate.

UP offers practical training sessions to “inspire the students” and provide practical experience in working with wood.

Grobbelaar emphasises the importance of such training because many architects, engineers and developers do not consider wood because they have never worked with it.

York Timbers Multidisciplinary Chair
The York Timbers Chair in Wood Structural Engineering is a strategic partnership between forestry company York Timbers and UP.

Its objective is to establish a multidisciplinary research programme focused on the structural engineering of wood products within the context of a sustainable, timber-based built environment and the wood-based bioeconomy in South Africa and Africa.

“Our near-term objectives aim to increase awareness of timber construction, developing research capacity and training capacity,” says Grobbelaar.

This is achieved through collaborating with industry partners, arranging training sessions, appointing lecturers and researchers, performing research and marketing timber construction, he elaborates.

The organisation also participates in joint community-based projects to provide students with an opportunity to design and build timber structures.

Grobbelaar explains that, previously, there was little interest in timber research and training, but interest is steadily growing from various parties, including industry partners that want to be involved.

Currently, researchers of the organisation are preparing proposals for research specifically on timber. The organisation will appoint a dedicated architect and researcher for timber.

“We are also appointing interns to create the basket capacity for the researchers to do more research and, through the internship process, we give students practical exposure to timber,” he concludes.