Plywood is a material that many associate with an inexpensive substitute for natural wood. This is a misconception – there are different types of wooden plywood on the construction market, made from different types of wood, including exotic species. This is a very popular building material, which is often used in the manufacture of furniture with an unusual shape. It is also used in the construction industry. The material is in demand due to its low price, in contrast to solid wood products.
What is plywood
Plywood is a composite board made up of several cross-glued layers of sliced or peeled veneer. The number of layers varies, but usually it is odd. If a manufacturer is trying to create really strong plywood, they can also insert a single metal layer between the individual wood layers. The main advantage of plywood over classic wood is its dimensional and shape stability. Although it can be processed in the same way as solid wood, there are practically no situations where it somehow twists or changes shape in any other way, as is often the case with solid wood. Huge slabs of different thicknesses are made from the material, which allows the use of plywood sheets for a variety of purposes..
Features of plywood production
In the manufacture of plywood boards, a technology is used based on the following stages:
- Initially, logs used in production are soaked in warm water. This makes the wood softer, due to which it is better fed to further processing..
- Veneer is made from blanks with certain parameters, which then goes through the stage of leveling and drying.
- The next step is to sort the veneer. The surface is cleaned of all kinds of defects, then sheets with a given size are created. There is an established procedure for collecting veneer sheets, which are subsequently fastened to each other..
- After the completion of the drying stage, the edges of the boards are cut to the required size, and the front surface is sanded, and a decorative layer is also applied to it (if necessary).
How veneers are obtained for plywood
For this, different technologies are used. The most common is circular stubble cultivation. The method consists in a circular rotation of the workpiece, from the surface of which a special knife removes a thin layer. The resulting wood layers are unfolded into a tape, cut into separate sheets and processed further. In some cases, peeling technology is used with the use of eccentric rotation of the workpiece, which allows you to create interesting patterns at the moment when the knife crosses the annual layers.
A less used technology is flat planing. This method creates a veneer with a specific pattern. Veneer can be tangential and radial. The differences between them lie in the location of the processing plane along the radius of the log and the type of pattern formed by the wood structure. In the manufacture of veneer in this way, wood of the highest quality is used, which does not have any defects. In special cases, sawing is used. To implement the technology, the wood is not subjected to special processing, due to which a natural pattern is obtained on the finished product, and the color of the board remains natural.
Plywood board is a material with unique mechanical and chemical properties. The physical properties of plywood are also high. Let’s consider them in more detail:
- Biological resistance. In the manufacture of the material, an adhesive composition with a phenol-formaldehyde content is used, due to which the products become unattractive to fungi and harmful microorganisms. Due to lamination, as well as careful processing of the ends, high-quality protection against adverse weather conditions is provided. This allows building materials to be used even outdoors..
- Chemical properties. Laminated plywood sheets are acid and oil resistant. After contact with various chemicals, the surface will only partially lose color. At the same time, it is not recommended to allow the interaction of building material with nitrates and chlorine. Wood swells and loses strength from contact with organic solvents (acetone, gasoline). For this reason, boats made of plywood sheets are processed only with the use of safe compounds..
- Refractoriness. Plywood is wood and is therefore classified as flammable (the risk of fire increases when exposed to temperatures above 400 ° C). By impregnation with various special chemical compounds or inorganic substances, it is possible to improve the refractory characteristics of the building material.
- Soundproofing. The building material is characterized by a relatively low density, therefore, it does not have high acoustic performance. However, a rubber gasket that is placed between the plates improves sound insulation..
- Environmental friendliness. The ecological purity of raw materials is another important advantage. The material is easy to process, does not harm the environment, is safe for humans.
Types of plywood
There are coniferous and deciduous types of plywood. The material is waterproof or dry-resistant.
There are such types:
- Plywood for indoor use (not suitable for wet rooms), used for the production of musical instruments, toys, furniture or interior doors.
- Waterproof structural plywood is used in the construction industry for the production of formwork, load-bearing and reinforcing elements of buildings, for the manufacture of forms, tiles. If we want to use different types of moisture-resistant plywood in places with high humidity, we need to create additional protection using a special impregnation.
- Surface treated construction plywood is provided with phenolic foil on both sides and covered with a waterproof protective layer along the edges. The material is excellent for all types of concrete work, they are most often used on formwork elements and as flooring of trucks.
- Low-flammability plywood is excellent for interior decoration of public buildings. They provide security at airports, train stations, trams.
The choice of plywood – what to consider
Among the important points is the building material class. It is manufactured in four grades. Each class is designated by numbers from 1 to 4. The best quality is a board with number 1 – no defects. It is intended for widespread use, but especially in places where high aesthetics and workmanship are required. It can be used, for example, as a floor covering or wall paneling. Lower grade materials are intended for use as elements invisible from the outside.
Choosing plywood for the floor
Leveling of floors is carried out using plywood sheets with different thicknesses. The choice of plywood thickness is an important point. When laying on a relatively flat surface, sheets 8-10 mm thick are used. For surfaces with significant differences, thicker materials (12 mm) are used. Builders do not recommend using sheets with different thicknesses in the same room.
Plywood can be laid on various substrates:
When laying on a screed, it is necessary to control the level of its moisture. Only a dry base is suitable for laying plywood boards. To determine the dryness of the concrete screed, it is necessary to spread the polyethylene film around the perimeter of the floor, pressing the edges tightly. If after 2 days no condensation has formed, then the screed is dry and is suitable for mounting a plywood board.
If the sheets are laid on a floor made of wood or concrete, then the strength is practically irrelevant. In the case of lags, the situation is more serious. In such a situation, a high-strength plywood board is used, with a thickness of 12 to 16 mm. To choose the distance between the lags, you need to evaluate the hardness and thickness of the plywood board. The thinner the sheet, the shorter the distance. However, even when using thick sheets, it is not recommended to make too large a distance, so that after a while you do not get the effect of a “squeezed” floor..
For what purposes plywood is most often used
The use of building materials is relevant for many manufacturing and construction industries. The first thought is often related to plywood furniture. Full-fledged cabinets or individual elements are made of this material. Warehouse or office furniture, as well as countertops, are made from thicker sheets. For the production of some furniture items, a thin plywood board (3 mm) is used. For example, it is used as the back upholstery for wardrobes. In the field of construction, building materials are used in the production of panels for formwork systems, as well as structural elements of scaffolding.
Plywood made of wood is a completely safe material, both for health and for the environment (sometimes building materials are called “eco-plywood”). Therefore, it is often used for decoration, for example, when erecting partitions, during the installation of suspended ceilings, steps for staircases, various types of cladding of large flat surfaces..