Engineering expert helps builders adopt innovative timber for construction

Research provides information for designers looking to use sustainable materials without sacrificing strength or structural integrity.

Image of a building constructed from cross-laminated timber

Cross-laminated timber offers a strong material for building construction that is more sustainable and less expensive than concrete or steel, according to a U of A expert whose research provides helpful information for engineers and designers. (Photo: Supplied)

Wood construction is fast becoming a leading contender in the race for sustainable building.

As a result, the number of tall wood buildings in North America is expected to increase in the coming years. According to a recent market analysis report, the global market for cross-laminated timber, or CLT, will grow to more than $2 billion in 2028 from just over $800 million in 2021.

CLT consists of at least three layers of wood panel glued together at perpendicular angles, with enough strength to support structures up to 18 stories high. First developed in Europe about 30 years ago, it has only recently become popular because it is made from a renewable resource, and has a much lower carbon footprint compared with other common building materials.

But since CLT is relatively new, some designers of larger buildings are hesitant to adopt it, says Ying Hei Chui, a University of Alberta specialist in mass timber construction. Many are unsure of its properties and how to put panels and beams together to ensure structural integrity.

A rendering of a building frame (Photo: Supplied)

That’s where Chui’s research comes in. He and his team provide designers with the information they need to use CLT with confidence, supported by a $4-million grant from the Natural Sciences and Engineering Research Council.

“There's really no difference between where you would use CLT and where you would use steel and concrete — it's just a different way to design,” says Chui, NSERC Industry Research Chair in Engineered Wood and Building Systems in the Faculty of Engineering.

“But not a lot of research has been done to evaluate the performance of the material in tall buildings,” he adds, where the forces exerted between materials are much higher than in lower buildings. He is aiming to fill that gap.

Because wood is softer than concrete and steel, it might take more fasteners in a given situation to attach wood components, whereas it will likely take a smaller number of fasteners to attach steel and concrete.

And because designers tend to be more conservative when dealing with a new material, he says, that can drive up costs.

“Let’s say the engineering analysis recommends the need to use perhaps 10 bolts to attach a beam to a column. The designer might not be comfortable with that and will go with 16 instead. That means your material costs go up, especially if the beam and column sizes have to increase to fit all these fasteners.”

However, CLT does have one other crucial cost-saving advantage, says Chui. Prefabricated wood panels can be assembled in the factory, whereas steel and concrete construction has to be done largely on site. It's a much faster process.

“So what could take six months with steel and concrete might take only two or three months with wood, providing a much quicker return on investment.”

The bottom line is that the more knowledge Chui can supply to designers about the properties of CLT and the forces exerted between components, the more likely they will be to consider using the material.

“There's still a lot of information that needs to be developed to give designers confidence.”