Engineered wood
Engineered wood, also called mass timber, composite wood, man-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, veneers, or boards of wood, together with adhesives, or other methods of fixation to form composite material. The panels vary in size but can range upwards of and in the case of cross-laminated timber can be of any thickness from a few inches to or more. These products are engineered to precise design specifications, which are tested to meet national or international standards and provide uniformity and predictability in their structural performance. Engineered wood products are used in a variety of applications, from home construction to commercial buildings to industrial products. The products can be used for joists and beams that replace steel in many building projects. The term mass timber describes a group of building materials that can replace concrete assemblies. Such wood-based products typically undergo machine grading in order to be evaluated and categorized for mechanical strength and suitability for specific applications.
Typically, engineered wood products are made from the same hardwoods and softwoods used to manufacture lumber. Sawmill scraps and other wood waste can be used for engineered wood composed of wood particles or fibers, but whole logs are usually used for veneers, such as plywood, medium-density fibreboard, or particle board. Some engineered wood products, like oriented strand board, can use trees from the poplar family, a common but non-structural species.
Alternatively, it is also possible to manufacture similar engineered bamboo from bamboo; and similar engineered cellulosic products from other lignin-containing materials such as rye straw, wheat straw, rice straw, hemp stalks, kenaf stalks, or sugar cane residue, in which case they contain no actual wood but rather vegetable fibers.
Flat-pack furniture is typically made out of man-made wood due to its low manufacturing costs and its low weight.Types of products
There are a wide variety of engineered wood products for both structural and non-structural applications. This list is not comprehensive, and is intended to help categorize and distinguish between different types of engineered wood.Wood-based panels
Wood-based panels are made from fibres, flakes, particles, veneers, chips, sawdust, slabs, wood powder, strands, or other wood derivate through a binding process with adhesives. Wood structural panels are a collection of flat panel products, used extensively in building construction for sheathing, decking, cabinetry and millwork, and furniture. Examples include plywood and oriented strand board. Non-structural wood-based panels are flat-panel products, used in non-structural construction applications and furniture. Non-structural panels are usually covered with paint, wood veneer, or resin paper in their final form. Examples include fiberboard and particle board.Plywood
, a wood structural panel, is sometimes called the original engineered wood product. Plywood is manufactured from sheets of cross-laminated veneer and bonded under heat and pressure with durable, moisture-resistant adhesives. By alternating the grain direction of the veneers from layer to layer, or "cross-orienting", panel strength and stiffness in both directions are maximized. Other structural wood panels include oriented strand boards and structural composite panels.Oriented strand board
is a wood structural panel manufactured from rectangular-shaped strands of wood that are oriented lengthwise and then arranged in layers, laid up into mats, and bonded together with moisture-resistant, heat-cured adhesives. The individual layers can be cross-oriented to provide strength and stiffness to the panel. Similar to plywood, most OSB panels are delivered with more strength in one direction. The wood strands in the outermost layer on each side of the board are normally aligned into the strongest direction of the board. Arrows on the product will often identify the strongest direction of the board. Produced in huge, continuous mats, OSB is a solid panel product of consistent quality with no laps, gaps, or voids. OSB is delivered in various dimensions, strengths, and levels of water resistance.
OSB and plywood are often used interchangeably in building construction.Fibreboard
and high-density fibreboard are made by breaking down hardwood or softwood residuals into wood fibers, combining them with wax and a resin binder, and forming panels by applying high temperature and pressure. MDF is used in non-structural applications.is manufactured from wood chips, sawmill shavings, or even sawdust, and a synthetic resin or another suitable binder, which is pressed and extruded. Research published in 2017 showed that durable particle board can be produced from agricultural waste products, such as rice husk or guinea corn husk. Particleboard is cheaper, denser, and more uniform than conventional wood and plywood and is substituted for them when the cost is more important than strength and appearance. A major disadvantage of particleboard is that it is very prone to expansion and discoloration due to moisture, particularly when it is not covered with paint or another sealer. Particle board is used in non-structural applications.Structural composite lumber is a class of materials made with layers of veneers, strands, or flakes bonded with adhesives. Unlike wood structural panels, structural composite lumber products generally have all grain fibers oriented in the same direction. The SCL family of engineered wood products are commonly used in the same structural applications as conventional sawn lumber and timber, including rafters, headers, beams, joists, rim boards, studs, and columns. SCL products have higher dimensional stability and increased strength compared to conventional lumber products.Laminated veneer
is produced by bonding thin wood veneers together in a large billet, similar to plywood. The grain of all veneers in the LVL billet is parallel to the long direction. The resulting product features enhanced mechanical properties and dimensional stability that offer a broader range in product width, depth, and length than conventional lumber.Parallel-strand
consists of long veneer strands laid in parallel formation and bonded together with an adhesive to form the finished structural section. The length-to-thickness ratio of strands in PSL is about 300. A strong, consistent material, it has a high load-carrying ability and is resistant to seasoning stresses so it is well suited for use as beams and columns for post and beam construction, and for beams, headers, and lintels for light framing construction.Laminated strand
Laminated strand lumber and oriented strand lumber are manufactured from flaked wood strands that have a high length-to-thickness ratio. Combined with an adhesive, the strands are oriented and formed into a large mat or billet and pressed. LSL and OSL offer good fastener-holding strength and mechanical-connector performance and are commonly used in a variety of applications, such as beams, headers, studs, rim boards, and millwork components. LSL is manufactured from relatively short strands—typically about long—compared to the strands used in PSL. The length-to-thickness ratio of strands is about 150 for LSL and 75 for OSL.I-joists
s are ""-shaped structural members designed for use in floor and roof construction. An I-joist consists of top and bottom flanges of various widths united with webs of various depths. The flanges resist common bending stresses, and the web provides shear performance. I-joists are designed to carry heavy loads over long distances while using less lumber than a dimensional solid wood joist of a size necessary to do the same task. As of 2004, approximately 81% of all wood light framed floors were framed using I-joists.Mass timber
Mass timber, also known as engineered timber, is a class of large structural wood components for building construction. Mass timber components are made of lumber or veneers bonded with adhesives or mechanical fasteners. Certain types of mass timber, such as nail-laminated timber and glue-laminated timber, have existed for over a hundred years. Mass timber enjoyed increasing popularity from 2012 onward, due to growing concern around the sustainability of building materials, and interest in prefabrication, off site construction, and modularization, for which mass timber is well suited. The various types of mass timber share the advantage of faster construction times as the components are manufactured off-site, and pre-finished to exact dimensions for simple on-site fastening. Mass timber has been shown to have structural properties competitive with steel and concrete, opening the possibility to build large, tall buildings out of wood. Extensive testing has demonstrated the natural fire resistance properties of mass timber primarily due the creation of a char layer around a column or beam which prevents fire from reaching the inner layers of wood. In recognition of the proven structural and fire performance of mass timber, the International Building Code, a model code that forms the basis of many North American building codes, adopted new provisions in the 2021 code cycle that permit mass timber to be used in high-rise construction up to 18 stories.Cross-laminated timber
is a versatile multi-layered panel made of lumber. Each layer of boards is placed perpendicular to adjacent layers for increased rigidity and strength. It is relatively new and gaining popularity within the construction industry as it can be used for long spans and all assemblies, e.g. floors, walls, or roofs.