What are the properties of wood-based materials
Wood-based materials are products that are manufactured by pressing wooden parts of different sizes, such as boards, rods and veneers. Used wood is also often used. Read here what different wood-based materials exist and where they are used.
The first wood-based materials were used 50 years ago in the form of chipboard and fibreboard. The use of wood-based materials has been gaining in importance since the late 1980s. The reason for this is the growing environmental awareness, since wood is a sustainable, ecological product and wood-based materials are above all a good form of “leftover recycling”.
Today it is hard to imagine the construction industry without wood-based materials. Entire prefabricated houses are already being manufactured on the basis of a frame construction and with the help of OSB cladding. In addition, wood-based materials are constantly being adapted to the changing needs of the market. The aim is to implement the increasingly precise requirements of technology with a sustainable concept.
Buy products with a seal
To make sure that the wood comes from sustainable cultivation and thus the protection of valuable biotopes is guaranteed, you should always make sure when buying products with the FSC seal (Forest Stewardship Council) or the PEFC seal (Program for the Endorsement of Forest Certification Schemes). You can then be sure that no tropical forest was cut down to produce the materials. The Blue Angel also guarantees that the chipboard is free from organohalogen compounds.
Advantages of wood-based materials
Wood-based materials made from veneers or boards can have significantly higher strengths than solid wood. In addition, the swelling and shrinking of the materials is significantly lower than with solid wood. Board-shaped wood-based materials also convince with their large surface area, and beam-shaped wood-based materials can be particularly long.
Since wood-based materials are manufactured or offered in standard dimensions, both the storage and the assembly time can be better planned.
Wood-based materials must either comply with a DIN or DIN-EN standard introduced by the building authorities or a building authority approval from the Deutsches Institut für Bautechnik, provided that they are used as follows:
- load-bearing and stiffening purposes according to DIN 1052
- Wooden structures
- Calculation and execution
- Thermal insulation, sound insulation and fire protection
Wood-based materials made from solid wood
Wood-based materials made from solid wood are usually solid wood panels that consist of composite boards and lamellas. They are carefully selected and sorted according to quality. Mainly European woods such as spruce, larch, beech, maple, alder and birch are used. Little energy is used for production, and the structure, color and proximity to nature should be preserved.
Wood-based materials made from veneers
Plywood is a wood-based material made up of layers of veneer. It impresses with its lightness and elasticity, which enables various shapes and designs during manufacture. The simple appearance also allows combinations with other materials such as glass and concrete. For example, skis, skates and snowboards are made from plywood. Those who are skilled in their craft can veneer wood themselves.
Wood-based materials made from chips
In the middle of the 20th century, chipboard became a universal product. Residual wood from the forest and the timber industry is used as the starting material. They are used both in house building and in the manufacture of furniture and are particularly affordable. Depending on the product type, they convince with good sound insulation, are only flame-retardant and moisture-resistant. OSB panels are a further development of chipboard and meet special technical requirements. Practical: OSB boards can also be painted.
Wood-based materials made from fibers
Wood-based materials made of fibers are, for example, soft and hard fiber boards, which are particularly adaptable, light and dry to build. They guarantee a cozy living environment, so that they protect you from the cold in winter and from heat in summer. In addition, the components are open to diffusion, which controls the moisture balance. They are suitable for the renovation of old buildings as well as for modern new buildings.
Lightweight panels combine low weight, high strength and maximum design freedom. This allows them to carry heavy loads, even though they are extremely lightweight themselves. Lightweight panels are a wood-based material of the future, because raw material, energy and logistics costs can be kept low.
Overview of wood-based materials
Since wood-based materials are becoming more and more popular, new, highly stressable wood-based materials can be expected in the near future. So far, however, the following materials have been used in construction:
Glulam consists of softwood boards that are dried to a wood moisture content of 12 percent and then sorted visually or by machine according to their strength. Then, as the name suggests, individual boards are stacked on top of one another and glued together. Compared to solid wood, glulam enables larger cross-sections and larger spans in construction, which is why it is mainly used in the construction of factories. Glued laminated timber is characterized by its high load-bearing capacity and its low weight. It is also dimensionally stable and dimensionally stable.
- Synthetic resin-bonded wood-based materials
Synthetic resin-bonded wood-based materials are bonded using urea-formaldehyde resins (UF), melamine-formaldehyde resins (MF), modified melamine-formaldehyde resins (MUF and MUPF), phenol-formaldehyde resins (PF), phenolresorcinol-formaldehyde resins (PRF) and polymeric diphenyl urethane diisocyanates (PMD) .
Depending on the moisture resistance of the adhesive used, the standardized wood-based materials are divided into three wood-based material classes with regard to the areas of application.
Wood material class
maximum board moisture in the state of use
Without additional fire protection equipment, the wood-based materials belong to building material class B2 (normally flammable) according to DIN 4102-1. If building material class B1 is to be achieved, a fire retardant must be added during manufacture or the surface must be coated.
- minerally bound wood-based materials
Either gypsum, cement or magnesite is used as a binding agent in the manufacture of mineral-bound wood-based materials. Cement-bonded chipboard has good sound insulation properties due to its high density of 1.2 g / cm3.
The gypsum-bonded wood-based materials are non-combustible and are assigned to building material class A2. Wood-based materials that are bound with cement belong to building material class B1 (flame retardant). One advantage of the cement-bonded chipboard is the good sound insulation properties, which is made possible by the high density of 1.2 g / cm3.
- 3- and 5-layer boards made of softwood
The panels are built from three or five glued board layers made of softwood. The wood fibers of the neighboring layers run at an angle of 90 degrees to each other. Modified melamine resins and phenolic resins are used to bond the board layers. Depending on how thick the individual layers are, the elasticity of the boards differs with the same density.
So far, all multi-layer solid wood panels can be used as load-bearing and stiffening cladding for the production of wall, ceiling and roof panels for wooden houses in panel construction according to DIN 1052-3. Some panels can also be used where the use of construction plywood according to DIN 1052-1 is permitted.
The construction veneer plywood, BFU for short, is produced by arranging the veneers crosswise and gluing them together. It is important that the veneers are arranged symmetrically to the central axis. There are no special requirements for the type of wood, it only has to meet DIN 68705-3 and no light tropical wood types such as limba or abachi may be used. Materials such as urea resins, modified melamine resins, alkali-curing phenolic resins, phenol-resorcinol resins and resorcinol resins are used for bonding.
The panels are mainly used as supporting and stiffening cladding on walls, ceilings and roofs made of wood.
- Beech construction plywood BFU-BU
The construction veneer plywood with the abbreviation “BFU-BU” is also produced by arranging and gluing the veneers crosswise. Beech wood is used for this. A layer can consist of two parallel veneers. Here, too, the veneers must be arranged symmetrically to the center plane. Alkaline curing phenolic resins, phenolic resocin resins and resorcinol resins are used as adhesives. Depending on the structure of the plywood, a distinction is made between five structure classes.
The beech veneer plywood is mainly used for special purposes such as reinforcing bridges and notches in accordance with DIN 1052-1.
Laminated veneer lumber consists of three millimeter thick peeled veneers made from softwood. Phenolic resin is used for bonding. The grain direction must either run parallel to the longitudinal direction of the laminated veneer lumber or for the most part parallel and to a small extent perpendicular to the longitudinal direction. The veneers are connected by a shaft or an overlap.
It is used where the use of glued laminated timber according to DIN 1052-1 is permitted in the technical regulations DIN 1052-1 and 1052-3 introduced by the building authorities.
- Parallam PSL veneer strip wood
Veneer strip lumber Parallam PSL is made from peeled veneer strips around 16 millimeters wide and around three millimeters thick. The wood used is either Douglas Fir (DF) or Southern Yellow Pine (SYP). A phenolic resin adhesive is used for bonding.
Just like laminated veneer lumber FSH, Parallam can also be used where glued laminated timber according to DIN 1052-1 may be used.
- Long-chip timber TimberStrand
Long chipboard TimberStrand is made from poplar chip strips glued together. The chip strips need dimensions of about 0.8 mm x 25 mm x 300 mm. An MDI polyurethane adhesive is used for bonding. Depending on the distance between the spreader and the mat surface (51 millimeters or 203 millimeters), different strength classes can be produced.
Long chipboard may be used for all designs in which the use of glued laminated timber according to DIN 1052-1 as well as construction veneer plywood according to DIN 68 705-3 is permitted in the technical regulations DIN 1052-1 and DIN 1052-3 introduced by the building authorities.
OSB flat pressed panels are among the most frequently used wood-based materials. The abbreviation OSB stands for "Oriented Strand Board" and means that there is a chip orientation, which is not the case with chipboard, for example.
The flat press plates are manufactured using either the cycle process or the continuous process. They consist of large long chips ("strands", on average about 0.6 millimeters thick, 75 millimeters to 130 millimeters long and 35 millimeters wide) lying parallel to the board surface. Phenolic resin-modified melamine-formaldehyde resin and PMDI adhesives are used for bonding. The long chips run parallel in the top layers and transversely to the direction of production in the middle layer. As a result, OSB panels have different properties in the longitudinal and transverse directions. The flexural strength in the longitudinal direction is much higher than in the transverse direction.
OSB panels are mainly used as load-bearing and stiffening cladding for wooden walls, floors, ceilings and roofs in accordance with DIN 1052-1 and -3. When using it, the provisions for calculation and execution in accordance with DIN 68763 must be complied with.
- Chipboard flat press boards for the building industry FP
Flat pressed panels are produced by pressing relatively small wood chips with adhesives, the chips preferably lying parallel to the plane of the panel. As a rule, they are made up of multiple layers or with a continuous transition in the structure. Urea resins, modified melamine resins, alkaline curing phenolic resins, polymeric diphenyl methane diisocyanates (PMDI) and tannins are used as adhesives. The panels are mainly used as load-bearing and stiffening cladding on wooden walls, floors, ceilings and roofs.
- Medium-hard wood fiber boards HFM, medium-density wood fiber boards MDF
Medium-hard or medium-density wood fiber boards are produced by pressing lignified fibers with (dry MDF) or without glue (wet HFM). In the case of the process with adhesive, mainly urea resins, modified melamine resins, polymeric diphenylmethane diisocyanates (PMDI) and tannins are used. Depending on the pressing pressure, panels are produced with a bulk density between 330 kg / m3 and 800 kg / m3.
The panels according to DIN 68754-1 with a gross density of more than 650 kg / m3 may only be used for the production of wall, ceiling and roof panels for wooden houses in panel construction.
The panels with a gross density between 330 kg / m3 and 650 kg / m3 can be used for wall and roof panels in accordance with DIN 1052-1 to 3, however, they may only be used for buckling or tilting reinforcement of the ribs and as load-bearing cladding to absorb wind loads can be used.
Wood fiber insulation boards are made from ligno-cellulose fibers using the wet process, whereby the bond is based on the felting of the fibers and their own adhesiveness. The maximum gross density is 400 kg / m3.
The panels according to DIN 68755-1 are mainly used for thermal insulation. With a correspondingly high tear resistance and dimensional accuracy (PT panels), they can also be used as plaster base panels.
- Cement-bonded flat pressed panels
The flat pressed panels consist of natural or chemically treated wood chips of the wood types spruce and fir, as well as Portland cement. They are used in all classes of wood-based materials. This means that they occur, for example, as load-bearing and stiffening paneling of the elements for wooden houses in panel construction in accordance with DIN 1052-3. But they can also be used for the outer cladding of external walls, provided that lasting weather protection is ensured.
- Plaster-bonded flat pressed boards
This type of flat pressed board consists of calcined gypsum and spruce wood chips, which serve as reinforcement. They occur as load-bearing and stiffening cladding of wall panels for wooden houses in panel construction.
Gypsum fiber boards consist of gypsum and paper fibers that are obtained in a recycling process and serve as reinforcement. Gypsum fiber boards may, for example, be used as load-bearing and stiffening paneling of wall panels for wooden houses in panel construction and for buildings in wood frame construction.
Plasterboard consists of a plaster core that is covered with cardboard. In certain cases the gypsum core is ported and may contain additives to achieve certain properties.
Plasterboard may be used as load-bearing and stiffening paneling of wall panels for wooden houses in panel construction. In addition, the panel can also be used on the outside of the exterior wall elements. To do this, however, you need a building authority approval (manufacturer's certificate).
- Wood wool lightweight panels HWL
Wood wool lightweight panels are lightweight panels made from wood wool and mineral binders such as cement or magnesite. The panels are mainly used for thermal insulation, soundproofing and fire protection. DIN 1102 applies to processing and use.
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