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CLT
Originating in Europe, this latest engineered wood building material is made by cross-laminated timber sheets glued together. The size and thickness can be customized, and its high strength allows it to replace concrete. It is earthquake-resistant, fire-resistant, and, from a carbon emission perspective, more environmentally friendly than concrete. Large blocks of CLT can be directly cut and used for building exterior walls, floors, etc., significantly improving construction efficiency. Currently in the promotion stage in China, its long-term market prospects are promising.
I. GLT laminated timber
Made of multiple layers of glued timber, it is mainly used for beam and column structures in larger wooden buildings, hence the name glued laminated beams or columns. Its load-bearing capacity is almost comparable to that of steel beams, but it is lighter, more fire-resistant (the consensus in modern structural design is that timber structures are more fire-resistant than steel because steel softens quickly after heating and will collapse, while timber only slowly chars from the surface, forming a "protective layer" that protects the internal timber while still allowing it to bear a certain load), and more earthquake-resistant (the elastic structure of timber will not collapse even when shaken, while rigid steel connections will break and collapse during shaking, and the survival rate of being hit by timber is much higher).
The individual timber pieces before glulam assembly are called lamstocks. In many cases, each piece undergoes strength testing and is sorted to ensure the load-bearing capacity of the finished glulam.
J. Composite Beam (NLT)
Easily confused with the glued laminated beams mentioned above, NLT is a vertical timber beam where the force comes from the side. The timbers are connected by nails, but from the perspective of force distribution, they do not play a major role.
K. TJI
"TJI" was originally a trademark registered by Welwyn-Haul for I-joist, and is now commonly used to refer to I-joist. I-joist is an English word meaning "hieroglyph," and there is also a corresponding Chinese "hieroglyph"-工字梁 (gongziliang), or "工字木栅栏" (gongzimu zhilang).
Primarily used for supporting floor slabs. This material has replaced most traditional 2x12 timber frames in North American timber-frame construction.
Because: 1) the performance is more stable; 2) the thermal expansion and contraction performance is better, which reduces the possibility of cracks at the edges and creaking floors during later decoration; 3) it is easier to construct and install wiring and pipes; 4) as it is an engineered wood product, it can be made with a larger span and longer length.
Of course, TJI also has disadvantages compared to 2x12: 1) It is slightly more expensive; 2) Its fire resistance is slightly worse; 3) Its sound insulation is slightly worse.
L. Parallel veneer laminated timber (PSL)
PSL's method involves creating veneers from Douglas fir, southern pine, or boxwood, then drying and gluing them together, followed by microwave pressing. This process results in veneers several times stronger than the raw materials used, and can be made up to 20-30 meters long (the standard product is 18 meters). Therefore, compared to other materials, it simplifies and saves on many components when handling large-span designs. Its rugged industrial and postmodern style is also highly sought after by many designers.
M. Laminated Veneer Panel (LVL)
It is also called Microllam, and Microllam is also a trademark of Huihao;
LVL generally refers to engineered wood made by mechanically pressing multiple layers of veneer together in parallel.
Note: LVL is mainly used in wood-frame construction. The veneers are in the same direction along the grain. It is made of pine wood with waterproof phenolic resin, which is formaldehyde-free. It emphasizes strength, water resistance, and corrosion resistance, and has no requirements for the surface. Plywood veneers are cross-grained, and there are certain requirements for the surface. It uses urea-formaldehyde resin.
N. LSL laminated wood chip glued laminate
LSL cuts logs into long strips, then dries them. The strips are then stacked together with high-quality resin along parallel grains and processed using a steam-pressing process. Under the action of adhesives and high pressure, they are made into standard-sized boards, mainly used as lintels, end caps, and frame walls.