Building a Foundation for Long-term Success: Glued Laminated Timber and Low Carbon Building in China

Glued laminated timber (GLT) is a sustainable, low carbon building material used as load-bearing structural beams, trusses, and columns. Its aesthetics, safety, durability, strength, and versatility make it popular with architects and developers around the world.

GLT originated in Germany in the late 19^th century, but its use was limited. Innovations throughout the 20^th century, particularly adhesive innovations, made it more durable and versatile. For example, better adhesives opened up its use in more humid environments, such as ice-skating rinks, sports halls, and storage buildings. Other innovations, such as CNC machining of finger joints boosted productivity, enabling product size flexibility and more efficient use of wood.

Red lines show where Henkel Loctite certified structural adhesives are used in GLT and FJT products

Mature and Industrialized

In parallel, standards for GLT and structural adhesives emerged to contribute to the maturing and industrialization of GLT. For example, in Europe EN 14080 Timber structures - Glued laminated timber standard and glued solid timber and EN 301 Adhesives, phenolic and aminoplastic, for load-bearing timber structures; Classification and performance requirements.

Today GLT and glued solid timber (GST) are used widely as a safe load-bearing material in residential and commercial construction, particularly in Europe. (See Figure 1 above for illustrations). As a result, GLT production capacity in Europe is large and growing steadily. According to the latest Holzkurier survey, 3 million m³ of GLT will be produced in Austria and Germany alone in 2021. It is a record-breaking volume.

Expansion is also evident in other parts of Europe, North America, and Australia. The trend becomes visible in recent news from GLT manufacturing equipment vendors via sales in Slovenia, Poland, Canada, US, Australia, and Sweden.

GLT Bonded with Certified Adhesives

As this brief history of GLT shows, adhesives and standardization were indispensable to its success. There are currently four kinds of certified adhesives approved for GLT manufacturing, specifically polyurethane(PUR), emulsion polymer isocyanate (EPI) and formaldehyde-based resins melamine-urea-formaldehyde(MUF) and phenol-resorcinol-formaldehyde (PRF).

Only one of these adhesive technologies was developed right from the start to provide  healthier indoor air quality and zero adhesive-related formaldehyde emissions. Only one originated with a vision of sustainability, to cure at room temperature, and to drive high-quality, flexible production. That one is the Henkel Loctite one-component PUR (1C-PUR) line of adhesive solutions.

Henkel Loctite 1C-PUR adhesive solutions are certified to national standards, such as ANSI 405 Standard for Adhesives for Use in Structural Glued Laminated Timber, AS/NZS 4364 Timber - Bond performance of structural adhesives, and EN 15425  Adhesives - One component polyurethane (PUR) for loadbearing timber structures - Classification and performance requirements.

It is a Type 1 adhesive approved for service classes 1,2, and 3, as defined in the standards above, as well as others such as ISO 12578. Each service class defines specific wood moisture content and climatic conditions that control where finished GLT products may be used (typically defining conditions for safe indoor use, covered outdoors, and uncovered outdoors).

Henkel Loctite 1C-PUR solutions are used by well-established manufacturers in Europe, as well as market leaders in other parts of the world. Recent examples of buildings featuring GLT made with Henkel’s certified 1C-PUR adhesives include the stunning Shane Homes YMCA at Rocky Ridge in Alberta, Canada, the iconic Swatch headquarters in Switzerland, the Yanqing National Sliding Centre built for the Winter Olympics 2022 in China, and the Macquarie University Incubator building in Australia (See images on Australian Sustainable Hardwoods (ASH) website.

China’s Low Carbon Era, Carbon Peak Goals, and GLT

China has a long history of structural timber innovation and architecture. It is evident in archaeological discoveries of ancient palaces, and in the preserved remains of traditional Chinese gardens, temples, and residences.

The use of timber in China was interrupted in the late 20^th Century to replenish domestic forests. Consistent effort to grow forest stock over the years means that the country is now on track to reach a forest stock volume of 19 billion cubic meters by the end of 2025, according to Xinhua. It is part of China’s 14th Five-Year Plan, covering the years 2021-2025, for the protection and development of forests and grasslands.

Forest development is part of China's efforts to fulfill its commitment to peak carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060, according to Xinhua. Government policy in China is focused on long-term energy saving, environmentally friendly, sustainable development.

Support is emerging for modern timber construction from industry associations, research institutes, universities, and government agencies. Furthermore, GLT is included in GB 50005 Standard for design of timber structures, issued by the Ministry of Housing and Urban-Rural Development of PRC.

Unlike the past, the timber used today is GLT made with softwood from sustainably managed forests in Europe and Canada (timber that is FSC-certified or PEFC-certified). There is a growing number of reference projects, such as the Tianfu International Conference Center in Chengdu, which features circa 4,000 m³ of GLT. It was designed by Tanghua Architect & Associates. Other examples of buildings featuring GLT are located in Tianjin, Shandong, and Yangzhou.

Ensuring Safety and Quality

Henkel Engineered Wood expects the GLT industry in China to develop similarly to markets abroad where industrialization, standards, and certification processes ensure safety and quality over the long term.

Milestone ahead include acceptance of several standards, such as GB/T 26899 Structural glued laminated timber; growing the number of manufacturers providing certified GLT and availability of qualified GLT for use in all three service classes.

As milestones are reached, opportunities will emerge to provide safe and sustainable GLT in commercial buildings and large-scale public buildings.

By selecting Henkel Engineered Wood as a partner for certified 1C-PUR structural adhesives, manufacturers benefit from its long-term experience with testing and approval processes in multiple regional markets. For decades it has worked with established sawmill owners in Europe, as well as GLT manufacturers of all sizes on three continents.

Henkel Engineered Wood assists in increasing productivity of GLT production lines, without compromising quality and safety. In this way, Henkel’s customers are able to access domestic and international regulated markets, become long-term suppliers of renewable certified load-bearing timber products, and be leaders in the era of sustainable, low carbon construction.