Singapore: Nanyang Technological University mass-timber building shows signs of mould

The building that hosts Singapore's Nanyang Technological University (NTU), known as Gaia and made of timber has shown signs of mould.  As the spokesman of the university had stated mould appeared at the walls of the last three floors of the building, making them reconsider their decision to import timber into their environment, which is tropical with high rate of humidity. The students described the mould as white flakes, likewise dust, and alongside the staff expressed discomfort, while one of the staff avoided his office because he is afraid of respiratory issues that might occur.

Considering the structure, it was completed last May, and it is a 43,500-square-meter building. The university’s business school is located there, made of 7,600 cubic meters of cross-laminated timber (CLT). The CLT was manufactured by the European supplier Stora Enso in Austria. Gai building is one of the 20 buildings made of mass timber in Singapore, alongside NTU’s "The Wave" sports hall. It should be mentioned that the building consists of 25 classrooms, 13 seminar rooms, 12 lecture theaters and an auditorium of 170 seats.

However, the chief of Architecture from NTU and the architects from RSP Architects Planners & Engineers who is the lead architect of Gaia, suggest that the structural integrity of the building is not considered to be at risk, while they believe that a comprehensive mould treatment and preservation program that is in place will ultimately solve the problem. It should be noted that the maintenance and preservation program is very extensive and includes reapplying sealant to the timber, adjusting the air-conditioning, and advising staff to keep windows closed to minimize condensation.

In addition, they encourage students and staff to report any other mould issue they might have noticed, while at their end, inspections and maintenance of the building are underway.  A spokesperson of the International Wood Culture Society pointed out that the tropical climate of Singapore is unique as it rains over 180 days per year, hence, the timber constructions need special considerations and the buildings out of timber must be treated with appropriate coats to avoid rot and mould.

Last year, while Singapore was experiencing heavy rain, and the building was under assembling construction, workers had to remove water from exposed surfaces that hadn't been sealed yet. They have been coated with a hydrophobic layer before shipping, but because of the pandemic there were disruptions to global shipping and the elements were shipped in 29 batches over 639 days between September 2019 and June 2021. Therefore, the mass timber building expert Kevin Hill argues that these delays may have contributed to mould issues and this is the reason that Stora Enso company characterized Gaia, as a test case of timber structures moisture management. Moreover, Hill claims that other mass timber buildings in the city have been successful and there is no reason to overreact about the decision to use mass timber to construct the NTU’s building.