Liimpuitu

Liimpuitu is a wood-based panel produced by bonding multiple thin sheets of wood veneer with adhesive. The veneers are layered with their grain directions alternating across adjacent layers, which improves strength and dimensional stability compared with solid timber. The result is a lighter, more uniform panel that is widely used in construction and manufacturing.

Manufacture involves peeling or slicing logs into veneers, drying them, and bonding the layers under heat and pressure. Common adhesives include phenol-formaldehyde and urea-formaldehyde resins; exterior grades use moisture-resistant formulations. Panels come in various thicknesses and grades, with interior plywood for indoor use and exterior plywood designed to withstand weather when sealed. Typical thickness ranges from about 3 to 40 mm, with the number of veneers increasing with thickness.

Applications include construction (walls, floors, roofs), furniture, cabinetry, flooring underlayment, and packaging. Interior liimpuitu provides a smooth surface suitable for finishing, while exterior grades offer enhanced durability under weather exposure. The material combines strength, light weight, and workability, making it a versatile alternative to solid wood and some other engineered woods.

Limitations include moisture sensitivity if not protected, potential emissions from some adhesives, and the need to select appropriate grade and thickness for load-bearing uses. When sourced from responsibly managed forests, liimpuitu is considered a renewable material with a relatively low carbon footprint compared with many other panel products.

Liimpuitu is governed by standards that specify bonding quality, mechanical properties, and dimensions for plywood used in structural and non-structural applications. European and North American standards and certifications cover these panels, with various grades for interior and exterior use. See also laminated veneer lumber, glue-laminated timber, and cross-laminated timber.