OSB boards: characteristics and application of the material

Today oriented particle board (OSB) is widely used in construction. The technical characteristics and structure of the material provide it with reliability, lightness, high strength, certain aesthetic properties and affordability. The article describes in detail the characteristics and application of OSB, as well as the features of working with them.

What is OSP: composition, structure, production features and varieties

Externally, OSB boards noticeably differ from MDF and chipboard due to the structural features. In the production of the material, thin and long wood chips are used, which are oriented longitudinally in the outer layers, and transversely in the inner layers. Even in cases where the orientation is not very obvious, the OSB can be recognized immediately by large, compared to other wood boards, pressed elements. The length of the chips in the plate is 75-150 mm, and the width is 15-25 mm. Due to this orientation of the chips, the OSB board acquired properties that significantly expanded its field of application.

The original name of the material is OSB (oriented strand board), which is translated from English and means “oriented strand board. In Russia, both abbreviations are used - OSB and OSB. In some cases, you can hear the contraction of the RSD, which is nothing more than a transliteration of the English abbreviation.

OSB is produced by pressing flat wood chips mixed with a binder. For this, special equipment is used, first of all, modern high-tech pressing lines. Large plants in the USA and Europe use ContiRoll - continuous press lines.

The production process for OSB boards takes place in several stages:

The main manufacturers of OSB boards are Canada, Austria, the USA, and the Baltic states. OSB production lines were opened in China, however, due to the not very high quality of the plates, Chinese products did not become popular. In the period from 2012 to 2016, the production of oriented particle boards was launched in Russia, where, with the proper quality of the material, it was possible to achieve a lower cost.

Varieties of OSB slabs

Depending on the quantitative and qualitative parameters, OSB boards are divided into 4 classes.

• OSB-1. Due to the lower moisture resistance compared to plates of other classes, it can be used exclusively in dry conditions in unloaded structures.
• OSB-2. The material is used for the construction of structures, with the provision of a bearing load on them. It is used exclusively in dry conditions.
• OSB-3. The most common class of materials in decoration and construction. It can withstand load bearing and has the optimal ratio of price and functionality. Technical characteristics of the OSB-3 plate ensure the use of the material, including in wet conditions.
• OSB-4. These are the most durable and expensive materials. Increased reliability allows the use of material in building structures with high loads in wet conditions.

In this case, the term "dry conditions" implies that air humidity at a temperature of 20 ⁰C, only a few weeks a year can exceed the threshold of 65%. The term "wet conditions" implies that air humidity at a temperature of 20 ⁰C, only a few weeks a year can exceed the threshold of 85%.

Strength characteristics of the OSB

The strength characteristics of OSB boards may vary slightly depending on the manufacturer. However, there are standards by which manufacturers work and their products must comply with them. Most often you can find plates made according to the European standard EN 300.

Mechanical properties of OSB boards according to EN 300:

Moisture resistance and moisture permeability of OSB plates

For the production of OSB boards, natural wood is used, which cannot but respond to moisture and any atmospheric changes. Slabs of all classes, including OSB-3 and OSB-4, are not waterproof. Only glue that does not lose its qualities when in contact with water is waterproof. However, the stove itself must be completely isolated from direct moisture. With the direct hit of moisture on the plate, its increase in volume and deterioration of strength characteristics are observed.

To determine the resistance of the panels to moisture, a parameter such as swelling is used. To determine it, the plate is immersed in water for 24 hours, and then the degree of its increase is calculated in connection with the amount of absorbed water.

As can be seen from the table, OSB boards of classes 3 and 4 demonstrate the smallest degree of swelling and, as a consequence, the highest moisture resistance. It is this material that is recommended to be used in the manufacture of building structures of various types.

Vapor permeability of OSB plates

Vapor permeability remains an important characteristic of OSB boards, of which there is much debate. In this case, various methods of calculating this indicator can be used.So, a number of manufacturers use the indicator in the marking: Water vapor permeability, μ (dry / wet). The value of this indicator can be written as: 200/150. This is a comparative coefficient of vapor permeability of the plate in the dry and wet state. But it only shows how much worse the OSB cooker conducts steam compared to air.

The above example shows that a stove conducts steam 200 times worse than air. Knowing this value, using special formulas for calculating the vapor permeability, it can be determined that the vapor permeability coefficient of OSB is 0.0031 mg / (m · h · Pa).

The result clearly demonstrates that the oriented particle board has extremely low vapor permeability, comparable with the same property of foam glass or linoleum on a fabric basis. The whole problem lies in production technology. OSB cooker is not wood, but a mixture of wood and resins, which have low vapor permeability.

Workability OSB boards

Due to its composition and structure, oriented particle boards give in to various types of processing. Allowed planing, turning, drilling, grinding, sawing and milling. OSB can be processed with both stationary and portable electric and manual carpentry tools, which are recommended to be equipped with carbide blades.

In the process of working with OSB boards, the following conditions must be observed:

• use of tools with sharpened carbide blades;
• maximum attention to level tooling;
• reliable fixation and ensuring a smooth ledge of the canvas;
• reduced tool speed during sawing.

One of the key aspects of working with oriented particle board is to ensure safety for life and health. The dust released during mechanical manipulations is a strong carcinogen, therefore it is strongly recommended that any work with OSB be carried out in work clothing, it is imperative to use a mask or respirator and choose tools with a suction. It is highly desirable that the room has supply and exhaust ventilation.

The ability of OSB boards to hold fasteners

The combination of high density and fiber OSB provides all the conditions for high-quality retention of fasteners - the fixation strength even at the outer edge of the panel is quite high. All types of fasteners suitable for wood-based panel materials, including self-tapping screws, nails and staples, are allowed. Fixing fasteners can already be 10 mm from the edge of the plate without fear of breaks or delamination of the material. In extreme cases, it is possible to hammer nails at a distance of 6 mm from the edge, however, special care is required.

Oriented particle boards of all four classes have good nails. However, one should be aware that there are certain requirements for fasteners used for mounting panels. The length of the fastener should exceed the plate thickness by at least 2.5 times, but should not be less than 50 mm. If you need to use staples, you need to pay attention to the thickness of the bracket wire, it must be at least 1.53 mm.

According to the DIN 1052-2 standard for OSB plates, it is recommended to use stainless steel or galvanized steel fasteners. Certain requirements are imposed on the shape of the nails - the best option is nails with a flat head and thread, a groove or an annular groove. Due to the high resistance to pulling, excessive deepening of the nail head into the plate is not allowed. When using nail guns during installation, the use of special glasses and strict adherence to safety procedures are necessary.

Bonding and staining ability of OSB boards

For oriented particle boards, the use of high-quality paints used for natural wood surfaces is acceptable. To obtain an aesthetically attractive and lasting result, when processing OSB, a number of certain requirements must be observed:

• Mandatory priming before painting.When using sanded boards, primer mixes must be applied in two layers due to the increased ability of the sanded OSB to absorb paints, drying oil and stain.
• The use of primers with certain properties. For OSB, it is desirable to use formulations that provide a high level of protection against mold. Plates are also very susceptible to staining, however, it does not provide good protection of the material from moisture, and therefore is not used so often.
• Easy sanding of the surface after applying each coat of primer or paint. This treatment provides an even distribution of the coloring compositions and an attractive appearance of the panels.
• The use of waterproof, long-lasting paints. The optimal solution for oriented particle boards is to apply a top coat using varnishes or glaze paints based on acrylic.

Bonding OSB panels is possible with any adhesive used for wood. Grinding the surface before gluing will significantly increase the bond strength.

OSB biological resistance

OSB boards have sufficient biological resistance, but with prolonged exposure to high humidity and temperature extremes, the risk of mold damage to the material increases. First of all, it concerns panels made of spruce or aspen shavings - wood chips from pine and maple demonstrate higher resistance to mold.

To protect the OSB board from the effects of fungi and bacteria, the additional use of moisture-proof materials, as well as the use of paints and varnishes with protective properties, are required.

OSB affected by mold due to the negative impact of the external environment.

Ecological purity of material

One of the controversial issues in the technical characteristics of OSB boards – the harmfulness and toxicity of the material to humans. Indeed, melamine-formaldehyde, urea-formaldehyde and phenol-formaldehyde resins are used as binders for OSB, which release free formaldehyde when exposed to high temperatures. That is why there is an opinion that this material is more dangerous than chipboard and plywood. However, this is nothing more than a delusion.

The fact is that the content of glue and resins in the composition of oriented particle boards does not exceed 3% - for chipboard this figure is 12-14%. Thus, manufacturers managed to achieve formaldehyde emission (emission) of no more than 8 mg per 100 grams of dry board. Some experts argue that even if OSB boards are made in violation of environmental requirements, they will have lower formaldehyde emissions than particleboard and even plywood. In addition, today formaldehyde resins are increasingly being replaced with glue based on MDI - aromatic diisocyanate, which has an extremely low toxicity. But the cost of these materials is higher. Continuous improvement of the technology for creating OSB can significantly increase the environmental friendliness of the material.

In Europe, OSB boards are divided into three groups according to the level of formaldehyde emitted:

• E1 - up to 0.1 ppm, when converted to mg / m³ it will be - 0.125 mg / m³;
• E2 - 0.1 - 1.0 ppm, when converted to mg / m³ it will be - from 0.125 - 1.25 mg / m³;
• E3 - 1.0 - 2.3 ppm, when converted to mg / m³ it will be - from 1.25 - 2.87 mg / m³.

It is allowed to use materials with a formaldehyde emission level of E1 - E2 in construction. Materials with an emission level of E3 are prohibited for production.

No matter how environmentally friendly the material is, the release of formaldehyde, in a certain amount, still occurs. Most of all, it stands out during the first year of operation of the material.

Fire safety OSB

To determine the fire safety of the material, classification by the degree of combustibility is used according to GOST 30244-94.

• Class G-1 (low combustible). Materials with a degree of damage over the area of ​​not more than 65% with a degree of destruction of not more than 20%. The temperature of the flue gas during combustion does not exceed 135 degrees. Drops of the melt are not formed.
• Class G-2 (moderately flammable). A group of materials, the degree of damage of which during combustion is not more than 85%, the degree of destruction does not exceed 50%, and self-burning is a maximum of 30 seconds. Flue gas temperature - up to 235 degrees. The formation of drops of molten material is unacceptable.
• Class G-3 (normally combustible). Combustibility characteristics are similar to class G-2 - with a discrepancy in self-combustion (300 seconds) and flue gas temperature (450 degrees).
• Class G-4 (highly combustible). Materials of this class have a degree of damage in area when burning more than 85%, the degree of destruction is more than 50%, and self-burning is more than 300 seconds. The temperature of the flue gas exceeds an indicator of 450 degrees.

Due to the wood chip board included in the OSB, it is highly flammable, which forces it to be classified as G-4. To increase fire safety in rooms lined with OSB boards, as well as structures made of this material, it is recommended to install a layer of refractory material - for example, mineral wool. In addition, manufacturers are striving to increase the flammability class of oriented particle boards by adding flame retardants (boric acid) to the composition or by additionally impregnating the panel with fire retardants.

Heat transfer resistance

The resistance of building materials to heat transfer is an indicator of their ability to retain heat and not allow cold. Heat transfer resistance is especially relevant for residential buildings. For OSB, this indicator is directly dependent on the thickness and density of the plate.

Scopes of OSB plates

As a structural material, an oriented strand board is used on a par with plywood, and as a finishing material it competes with MDF, fiberboard and wood-laminated plastics. High manufacturability and reliability ensured the full use of OSB boards in the following areas:

Cladding and wall cladding

The material is resistant to deformation and is compatible with any decorative and facing materials. Depending on where you plan to use OSB - for exterior or interior decoration - panels of a certain class are selected.

Laying the sub floor

OSB is suitable for flooring seamless floors on a wooden base over wooden beams or a seamless floor on a concrete base. Compatible with any sound insulating and heat insulating materials. In lightweight building structures, OSB boards are used as an independent floor covering.

Production of a solid base for roofing

Due to their sufficient strength and elasticity, oriented particle boards withstand severe wind loads. They are used for any roofing materials, but most often for flexible tiles.

Production of supporting structures (I-beams)

Rigidity OSB ensures the reliability of any structure, resistance to displacement and deflection of any structural elements, as well as the absence of creaks.

The construction of removable formwork for concrete work

For repeated use, the formwork is made of polished or laminated OSB.

SIP panel manufacturing

Oriented particle board acts as the outer layers, between which expanded polystyrene is laid.

Packing material

OSB often serves as a raw material for the manufacture of containers for various cargoes, including large ones.

Quick-release constructions

The construction of quick-folding structures, billboards, temporary barriers.

Furniture manufacture

OSB plates of various thicknesses (except for OSB-1 class panels) are used for the manufacture of both functional and decorative elements - backs and seats of chairs, cases and back walls of cabinets and chests of drawers.

Oriented particle boards have an impressive list of advantages, including increased strength, reliability, lightness, ease of processing and a high degree of environmental friendliness compared to materials of a similar composition and structure.Subject to all the rules and standards for working with OSB panels, a long service life of elements and structures without any changes and destruction of the material is possible.

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