Things You Need to Know About Glulam

Seven thousand years ago, our ancestors began building nests in wood. From the enlightenment of civilization in the Xia and Shang dynasties to the grandeur of the Weiyang Palace in the Han dynasty, from the Daxing City in the Sui dynasty to the majestic Mingtang during the reign of Empress Wu Zetian in the Tang dynasty, from the "Yingzao Fashi" (Building Standards) in the Song dynasty to the prosperity of the Forbidden City in the Ming and Qing dynasties, Chinese wooden architecture has carried a thousand years of civilization and a thousand years of grandeur.

In 2020, the fight against the COVID-19 pandemic witnessed the rapid response capabilities of prefabricated modular buildings and highlighted the importance of a healthy, comfortable, and livable high-quality living environment for human health. Breathable green buildings will bring positive impacts to humanity. With the development of science and technology, modern wood treatment technologies for fire resistance, rot prevention, and insect prevention have become increasingly sophisticated, and glued laminated timber (GLLT) can now be used in mid- to high-rise and large-span timber-framed buildings. In China, a relatively large-scale, mature, and standardized development environment has been initially established. GLLT structures, through their innovation and technology, are bringing lasting and positive effects to the construction industry.

Glued laminated timber (GLT) is a type of wood product made by gluing together layers of glued laminated timber, no more than 45mm thick, along the grain. It can be used for door and window lintels, primary and secondary beams, columns, and heavy-duty trusses. Custom sizes of GLT can be manufactured. Common high-quality GLTs include Douglas fir, red pine, and Finnish wood, while more affordable options include Scots pine. GLT requires high-grade materials and is made from kiln-dried boards.

In the production of glued laminated timber (GLLT) components, the assembly process is optimized based on the veneer grade, allowing for the optimal use of inferior materials. High-grade veneers are used in areas requiring high strength (such as the edges of tension zones), while lower-grade veneers can be used in low-stress areas (such as near the neutral axis). Timber containing knots generally has a lower strength grade and can be used in compression areas or areas near the neutral axis where stress is relatively low. Furthermore, the cross-sectional shape of the timber component can be designed according to its stress conditions, even including curved and arched GLLT beams. The advent of GLLT has significantly improved the utilization rate of timber resources.

Glulam not only retains the ideal natural characteristics of solid lumber but also overcomes the problems of difficult drying, natural defects, cracking, deformation, and poor dimensional stability associated with large-section natural timber. It offers more efficient use of wood, higher structural strength, better fire resistance, and more aesthetically pleasing architectural designs, making it widely used in the construction of public buildings such as libraries, schools, visitor centers, and swimming pools. Glulam has greater strength and stiffness than other structural materials of the same size and is much lighter, weighing only 1/5 to 1/4 the weight of concrete of the same volume. Therefore, it can achieve spans exceeding 20 meters without the need for intermediate supporting components, creating ultra-large spaces. In terms of fire resistance, glued laminated timber is typically used in large-section heavy timber structures. The fire resistance mechanism of heavy timber structures relies on the formation of a carbonized layer on the surface of the wood during combustion, which slows down the rate of combustion. Heavy timber structures use large-section engineered wood materials, and these large-section timber components retain their strength for a longer time than metals when exposed to fire. Meanwhile, due to the flexible specifications of glued laminated timber products, the high degree of factory prefabrication, high construction efficiency, and ease of repair and relocation, it is more suitable for the field of prefabricated buildings.

Jinbosheng Glulam and Crafts

Qualified glued laminated timber (GLLT) products undergo a series of processes including material selection, cutting, finger jointing, planing, gluing, curing, mortise and tenon joint processing, sanding, quality inspection, and packaging. Jinbosheng GLLT maintains a moisture content of 8%-15% for its plywood, with a thickness not exceeding 45mm (40mm for hardwood species). The moisture content difference between adjacent boards should not exceed 3%. Furthermore, the surface finish and temperature of the plywood, as well as the ambient temperature and humidity of the splicing site, are controlled according to the characteristics of different adhesives. All control data for each batch of GLLT products are archived and traceable, demonstrating a complete and rigorous gluing quality control system. The company has been recognized as a "High-Tech Enterprise" and a "Prefabricated Building Industry Base." In addition, it has formed strategic partnerships with domestic and international design teams, focusing on both traditional mortise and tenon joints and modern large-scale structural joints, and has pioneered the establishment of a timber structure building engineering research center to strive for excellence.

Adhering to the corporate spirit of "wise progress and far-reaching goals," Jinbosheng strives to provide customers with high-quality products and improve processing precision and efficiency. In recent years, the company has invested heavily in introducing world-class advanced timber structure building production lines, such as the German Hundegger K2i and the German Schmidler S6 Plus. At the same time, it has also introduced the Italian Biesse Rover A 1359 ATS small beam and column, door and window processing center (with an accuracy of ±0.2mm) and HC24 straight and irregular beam gluing machine to achieve international standard production technology.

Source: National Innovation Alliance for Timber Structure Industry