KUALA LUMPUR, Aug 17 — The S$125 million (RM421 million) Gaia building at Singapore’s Nanyang Technological University, which debuted last May as Asia’s largest wooden marvel, was celebrated as both a green and gorgeous timber wonderland.

However, just over a year later, this 450,000-square-foot structure, built with sustainable timber beams and panels, is facing an unexpected challenge: mould growth on the wood.

According to Bloomberg, Gaia’s mould issue highlights the global challenges timber structures can face. Even as companies like Walmart and Microsoft champion wood for sustainable building, mouldy timber has led to health concerns, damage, and legal disputes from London to Melbourne.

While cement and steel production contributes around 14 per cent of global greenhouse gas emissions, trees absorb carbon dioxide as they grow, and using their wood in construction helps sequester that carbon. The Gaia building's supplier claims it locks away over 5,000 tons of CO2, even factoring in shipping.

Yet, what seemed like a promising eco-friendly solution has encountered a reality check in tropical Singapore, where the city experiences rain on approximately 180 days each year.

As reported, wood used in Gaia is primarily Austrian spruce, processed into mass-engineered timber — thin layers glued together to form panels and beams for columns, walls, and roofs.

The problem is that spruce is less resistant to mould compared to other wood species. In Singapore’s humid environment, with relative humidity around 80 per cent, untreated spruce is particularly prone to mould and rot, Andrew Wong of the International Wood Culture Society told Bloomberg.

"It’s essentially a climate issue,” Wong notes. "We’re in the tropics, and that demands special care.”

In fact, it’s not just the tropical regions. In the deserts, significant temperature fluctuations can lead to excessive expansion and contraction of wood, causing it to crack. In freezing temperatures, water can enter gaps and freeze, which splits timber components.

Engineers need to consider these factors when designing timber buildings, Erik L’Heureux, associate professor of architecture at the National University of Singapore said to Bloomberg, noting that each climate presents its own limitations and challenges.

It was reported that Singapore has used mass-engineered timber in over 20 projects in the past decade, with more than 30 companies involved. However, officials have not revealed whether other buildings are facing mould issues.

In contrast, Singapore’s colonial shophouses, built with regionally native hardwoods, are naturally mould-resistant. Today, sourcing chengal, the traditional hardwood used in these shophouses, is both difficult and costly, a stark difference from the 1900s when these buildings were constructed.

"It’s really expensive,” Loh Kee Soon, a lead architect for Gaia at RSP Architects Planners & Engineers told Bloomberg, adding that to use that much timber, a very large forest is needed.

Bloomberg said although thicker protective coatings could have alleviated some issues, Loh’s team opted against it due to cost and their desire to showcase the natural wood grain.

Larch, a more mould-resistant softwood, would have been more expensive, so Loh chose spruce for most of the structure and used larch for the columns most exposed to sun and rain.

There’s no denying the aesthetic appeal of Gaia. However, staff and students are increasingly worried about the health risks associated with the mould.

While the school and architect recognise that mould is a common issue in humid Singapore, they believe it’s unlikely to affect the building's structural integrity.

Nonetheless, Bloomberg notes that a "comprehensive” maintenance plans for Gaia is being implemented, which include reapplying sealant to the timber, adjusting air-conditioning, and instructing staff to keep windows closed to minimise condensation.

Experts recommend treating surfaces with bleach, applying thicker coatings on the wood, installing dehumidifiers, and running the AC continuously, although these measures itself could reduce the building’s sustainability.