In the construction of the 21st century, craftsmen often give preference to materials that have been able to prove themselves for decades. Among them, OSB panels can be considered the most reliable. This stands for oriented strand board. Quite often it can be found under other markings, and in Latin it is OSB. A material that was developed more than 30 years ago, and this type of finishing material will not lose its popularity even now.
When it is necessary to carry out construction or repair work, most people have a need for inexpensive and high-quality material, which is the panels.
They can last for many years, and their characteristics make it possible to use them for building residential and non-residential buildings. Everything is due to the wide potential and multifunctional features of the production of the material.
What is OSB: composition, structure, production features and varieties
Externally, OSB boards are noticeably different 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, OSB can be recognized immediately by the large, compared to other wood-based panels, compressed elements. The length of the chips in the slab is 75-150 mm, and the width is 15-25 mm. Thanks to this orientation of the chips, the OSB board acquired properties that significantly expanded its scope of application.
The original name of the material is OSB (oriented strand board), which translated from English means “oriented strand board.” In Russia, both abbreviations are used - OSP and OSB. In some cases, you can also hear the abbreviation OSB, which is nothing more than a transliteration of the English abbreviation.
OSB is produced by pressing flat wood chips mixed with a binder material. For this purpose, special equipment is used, primarily modern high-tech pressing lines. Large factories in the USA and Europe use ContiRoll - continuous pressing lines.
The production process of OSB boards sequentially takes place in several stages:
1. Sorting of raw materials . The raw materials for the production of oriented strand board are timber from such tree species as aspen, spruce, pine and poplar. After the raw materials are delivered to the production line, the logs are carefully selected.
2. Preparation of raw materials and production of chips . After sorting, mechanized debarking of the logs takes place. Next, the cleaned logs are sawn into short pieces and sent to a planing unit, where they are split into chips along the wood fibers. At the end of the stage, the chips are dried using a conveyor and sorted.
3. Preparation of the composition for pressing and molding . Wax and adhesives based on paraffin, phenol-formaldehyde or isocyanate resin and boric acid are used as a binder for OSB boards, with which the chips are mixed in stages. The resulting mixture is then transferred to a molding station, where it is rolled out and molded into a uniform carpet before being sent to the press.
4. Pressing slabs . The board is pressed under a pressure of 5N/mm2 and at the temperature required for the resin to harden – 170-200 degrees. The temperature and pressure in the pressing zone are constantly monitored. After pressing and edge trimming, the material is subjected to control measurements of thickness and density, as well as checking for defects, and then aged for 48 hours until the final polymerization of the binders.
5. Slicing and packaging . After a quality control check, the OSB fabric is cut into elements of a standard format, the edges of the elements are profiled, and the resulting boards are sent to the marking and packaging line.
The main manufacturers of OSB boards are Canada, Austria, USA, and the Baltic states. OSB production lines were also opened in China, but due to the not very high quality of the boards, Chinese products did not become popular. In the period from 2012 to 2016, the production of oriented strand boards was launched in Russia, where, with the proper quality of the material, it was possible to achieve a lower cost.
Types of OSB boards
Depending on the quantitative and qualitative parameters, OSB boards are divided into 4 classes.
- OSB-1. Due to the lowest moisture resistance compared to slabs 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 load-bearing loads placed on them. For use only in dry conditions.
- OSB-3. The most common class of material in finishing and construction. Can withstand load-bearing loads and has an optimal price-functionality ratio. The technical characteristics of OSB-3 boards ensure the use of the material even in wet conditions.
- OSB-4 . These are the most durable and expensive materials. Increased reliability allows the material to be used in building structures with heavy loads in wet conditions.
In this case, the term “dry conditions” suggests that air humidity at a temperature of 20 0C may exceed the 65% threshold for only a few weeks a year. The term “humid conditions” suggests that air humidity at a temperature of 20 0C may exceed the 85% threshold for only a few weeks a year.
The need to use specialized protective and decorative means
It is not for nothing that the specialist emphasizes the importance of using specialized protective and decorative means - this is a pressing issue.
qwerty123123FORUMHOUSE Member
A garden house was built, external finishing is OSB. Finishing is planned for next year. For now I want to paint it (with a spray gun) to protect it from precipitation (about 1-1.5 m from the ground). Do I understand correctly - you can take any acrylic paint that can be applied with a spray gun and is intended for external work?
Elizaveta Kataeva
Sales Manager
No. The fact is that the house needs not only protection from precipitation, but also protection from mold and mildew. Not all paints contain biocides, which means there is a need to use a primer that will protect the OSB from biological damage.
Since the board contains resin and adhesive components, careful surface preparation is required before painting. Often during application there is poor wetting and spreading of paints and varnishes over the surface, which ultimately affects the protective properties of the coating (wetting and spreading of paintwork materials, a necessary condition for adhesion and the formation of coatings of uniform thickness). An important factor is the degree of hiding power of the paint, because... The structure of the slab can be pronounced and a significant amount of paint will be required to obtain an even, non-translucent coating.
Advantages of specialized paints compared to conventional ones:
- They already contain biocides, which means they eliminate the need to use special primer to protect against mold and mildew;
- The line of fire-retardant paints and compounds contains anti-foam agents, which also eliminates the need to use additional primer or compound.
- They have increased adhesion, resulting in reduced consumption and the final cost of finishing work.
If you use, albeit high-quality, but universal facade paint, and don’t pay much attention to preparation, you can easily get a “ground” for a sweeping verdict.
AlisakosForumHouse Member
About 5-6 years ago I installed OSB-3 on the façade of the house in the faux-iron style and painted it with good façade paint, which guarantees 15 years of impeccable appearance. After 3-4 years, the paint began to peel off along with OSB chips. A year ago, in connection with the remodeling of the facade, the OSB was covered with inexpensive stone paint. I liked it even more in terms of coverage and strength.
Conclusion: OSB boards are not a facade material, I regret that I did not know about this, alterations are expensive.
Elizaveta Kataeva
Sales Manager
We agree that correcting poor-quality coating is labor-intensive and expensive. Therefore, we always draw the attention of our clients to the fact that preparing the OSB surface for application is an important stage. The slab should be cleaned of dirt, dust, old paint (if any) and peeling by grinding, and the surface should be dedusted. And when choosing a finishing material, it is necessary to take into account compatibility with the type of surface, with wood in general and OSB in particular.
The service life of the coating depends on the quality of the paint (the amount of film-forming substance) and the guarantee on the label does not always correspond to reality. It is best to use paints and plasters designed for processing OSB boards, since this is a guarantee that the manufacturer conducted tests on the boards.
Strength characteristics of OSB
The strength characteristics of OSB boards may vary slightly depending on the manufacturer. However, there are standards that manufacturers work by and the products they produce must comply with them. Most often you can find slabs produced according to the European standard EN 300.
Mechanical properties of OSB boards according to EN 300 standard:
| Characteristics | Test method | Plate thickness, mm | OSB-1 | OSB-2 | OSB-3 | OSB-4 |
| Bending strength – major axis, N/mm2 | EN 310 | from 6 to 10 | 20 | 22 | 22 | 30 |
| > 10 and < 18 | 18 | 20 | 20 | 28 | ||
| 18 to 25 | 16 | 18 | 18 | 26 | ||
| Bending strength – lateral axis, N/mm2 | EN 310 | from 6 to 10 | 10 | 11 | 11 | 16 |
| > 10 and < 18 | 9 | 10 | 10 | 15 | ||
| 18 to 25 | 8 | 9 | 9 | 14 | ||
| Modulus of elasticity – main axis, N/mm2 | EN 310 | from 6 to 10 | 2500 | 3500 | 3500 | 4800 |
| > 10 and < 18 | ||||||
| 18 to 25 | ||||||
| Modulus of elasticity – lateral axis, N/mm2 | EN 310 | from 6 to 10 | 1200 | 1400 | 1400 | 1900 |
| > 10 and < 18 | ||||||
| 18 to 25 | ||||||
| Tensile strength perpendicular to the plane of the slab, N/mm2 | EN 319 | from 6 to 10 | 0,30 | 0,34 | 0,34 | 0,50 |
| > 10 and < 18 | 0,28 | 0,32 | 0,32 | 0,45 | ||
| 18 to 25 | 0,26 | 0,30 | 0,30 | 0,40 |
Moisture resistance and moisture permeability of OSB boards
For the production of OSB boards, natural wood is used, which cannot fail to respond to exposure to moisture and any atmospheric changes. Boards 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 slab itself must be completely insulated from direct moisture. When moisture directly hits the slab, it increases in volume and deteriorates its strength characteristics.
To determine the resistance of panels to moisture, a parameter such as swelling is used. To determine it, the slab is immersed in water for 24 hours, and then the degree of its increase is calculated in connection with the amount of water absorbed.
| OSB class | Swelling degree |
| OSB-1 | 25% |
| OSB-2 | 20% |
| OSB-3 | 15% |
| OSB-4 | 12% |
As can be seen from the table, OSB boards of classes 3 and 4 demonstrate the lowest degree of swelling and, as a consequence, the highest moisture resistance. This material is recommended for use in the manufacture of building structures of various types.
OSB: size and advantages
The material, which you can see in our catalog in various sizes, is characterized by advantageous characteristics during operation:
| Options | Indicators |
| Density kg/m3 | 500–600 |
| Possibility of use as a structural element, that is, subflooring, roofing, etc. | Yes |
| Thermal conductivity | 0,14 |
| Vapor permeability | 0,004 |
| Flammability high, medium, low (B, C, H) | IN |
| Toxicity under normal conditions/in case of fire, high, medium, low (V, C, H) | I/O |
The high density of the product makes it heavy, which can cause difficulties when climbing to the upper floors, so it is better to give preference to products with a low density. OSB meets these requirements while maintaining increased strength.
The building material is suitable for the arrangement of:
- roofs;
- floors in apartments and houses;
- stairs;
- SIP panels;
- formwork;
- all kinds of fences.
Vapor permeability of OSB boards
Vapor permeability remains an important characteristic of OSB boards, about which there is much debate. In this case, various methods for calculating this indicator can be used. Thus, a number of manufacturers use the indicator in labeling: Water vapor permeability, μ (dry/wet). The value of this indicator can be written as: 200/150. This is the comparative coefficient of vapor permeability of the slab in dry and wet states. But it only shows how much worse the OSB board conducts steam compared to air.
The above example shows that the stove conducts steam 200 times worse than air. Knowing this value, using special formulas for calculating 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 oriented strand board has extremely low vapor permeability, comparable to the same property of foam glass or fabric-based linoleum. The whole problem lies in production technology. OSB board is not just wood, but a mixture of wood and resins that have low vapor permeability.
Manufacturability of OSB boards
Due to their composition and structure, oriented strand boards lend themselves to various types of processing. They can be planed, turned, drilled, grinded, sawed and milled. OSB can be processed with both stationary and portable electric and manual carpentry tools, which are recommended to be equipped with hard alloy blades.
When working with OSB boards, the following conditions must be observed:
- using tools with sharply sharpened blades made of hard alloys;
- maximum attention to smooth handling of the tool;
- reliable fixation and ensuring an even protrusion of the canvas;
- reduced speed of the tool when sawing.
One of the key points of working with oriented strand board is to ensure safety for life and health. Dust released during mechanical manipulations is a strong carcinogen, so it is strongly recommended to carry out any work with OSB in special clothing, be sure to use a mask or respirator, and choose tools with suction. It is highly desirable to have supply and exhaust ventilation in the room.
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 on the outer edge of the panel is quite high. All types of fasteners suitable for wood-based panel materials can be used, including screws, nails and staples. You can fix the fasteners as early as 10 mm from the edge of the slab without fear of breaks or delamination of the material. As a last resort, you can drive nails at a distance of 6 mm from the edge, but special care is required.
Oriented strand boards of all four classes have good nailability. However, you should be aware that there are certain requirements for the fasteners used to install the panels. The length of the fastening element must exceed the thickness of the slab 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 staple wire; it must be at least 1.53 millimeters.
According to the DIN 1052-2 standard, for OSB boards it is recommended to use fasteners made of stainless or galvanized steel. There are certain requirements for the shape of the nails - the best option is nails with a flat head and thread, groove or ring groove. Due to the high resistance to pull-out, the nail head should not be too deep into the slab. When using nail guns during installation, it is necessary to use special glasses and strictly adhere to safety precautions.
Options for protecting OSB from exposure to atmospheric factors
Just a few years ago, OSB was considered an exclusively rough material that needed cladding or a curtain wall. Today an alternative has appeared.
AntForumHouse Member
4. What options are there for finishing the facade over OSB boards?
Elizaveta Kataeva
Sales Manager
The main methods used for external finishing of OSB walls:
- Siding;
- Decorative facade panels;
- Decorative stone cladding;
- Coloring;
- Plaster.
— Painting is the most common and simplest option for finishing OSB boards. However, in order for the coating to adhere well, it is necessary to pay special attention to preparing the surface before painting.
To seal joints, it is recommended to use elastic putty-sealant for OSB. After sealing, the OSB surface must be thoroughly cleaned and primed. It is recommended to use a protective primer as a primer, which will prevent the appearance of yellow-brown spots on the coating. After the primer layer has dried, it is recommended to use specialized paints for OSB.
What happens when painting is done can be seen in the example of the house of one of the participants of our portal.
— Applying plaster.
Before applying plaster, careful preparation of the surface is required, since OSB during operation can change its geometric dimensions over wide ranges, which is associated with changes in humidity and ambient temperature. If you apply plaster directly to an unprepared slab, it will soon become covered with cracks and peel off from the surface.
To prepare the surface, it is recommended to apply an elastic putty-sealant for OSB to the joints between the boards. Then it is recommended to prime the OSB surface. In this case, it is recommended to use adhesive primer or yellow spot blocking primer as a primer.
In the process of applying plaster, it is recommended to use a reinforcing mesh: apply the first layer of plaster, and embed the reinforcing fiberglass mesh into it. After the first layer has dried, apply another layer of plaster. It is recommended to use decorative plaster for OSB as plaster, which is characterized by elasticity and weather resistance. In fact, it is a “liquid” siding designed specifically for oriented strand boards. The plaster completely hides the texture of the slabs and joints, which is especially important when the facade is not framed.
If you like the “drawing”, painting or coating with primer is preferable.
Trio3FORUMHOUSE Member
Tell me the best option for my task - the non-residential premises are lined with OSB (OSB-3) tenon and groove boards from the inside, I would like to decoratively paint it with a non-covering coating (leave the structure visible, but change the color). What is better not to use, and what can you try?
Elizaveta Kataeva
Sales Manager
Leveling putties and plasters are not suitable, since they will hide the structure of the slab, but you can safely use paints for OSB. They are produced in white, tinted in pastel colors. Primer is also suitable as an independent varnish coating, when applied in 3 layers - the structure and color of the slab will be preserved, and a glossy shine will appear. To obtain a glaze coating, the primer can be tinted.
Ability of OSB boards to bond and paint
For oriented strand boards, it is acceptable to use high-quality paints used for natural wood surfaces. To obtain an aesthetically attractive and durable result, when processing OSB it is necessary to comply with a number of certain requirements:
- Mandatory priming before painting. When using sanded boards, primer mixtures must be applied in two layers due to the increased ability of sanded OSB to absorb paint, drying oil and stain.
- Application of primer coatings with certain properties. For OSB, it is desirable to use compounds that provide a high level of protection against mold. The slabs also lend themselves well to staining, but it does not provide good protection of the material from moisture, and therefore is not used so often.
- Lightly sand the surface after each coat of primer or paint. This treatment ensures uniform distribution of coloring compounds and an attractive appearance of the panels.
- Use of waterproof, durable paints. The optimal solution for oriented strand boards is to apply a finishing layer using varnishes or acrylic-based glaze paints.
Bonding OSB panels is possible using any adhesives used for wood. Sanding the surface before gluing will significantly increase the strength of the joint.
Conclusion
OSB is a universal construction and finishing material intended for use both inside and outside. It is indispensable in the construction of frame houses, as well as wherever budget finishing is needed. But the slabs themselves, being a wood derivative, also need protection from moisture and biological damage. The use of specialized protective and decorative means not only increases the presentability of the interior and facade, but also extends the service life of structures without additional financial investments.
Additional useful information on the topic of OSB can be found in one of the previous materials. And in the article about reconstruction there is an example of transforming an old log house into a modern chalet-style house with a budget facade made of OSB. The video talks about the properties, types and applications of OSB.
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Biological resistance of OSB
OSB boards have sufficient biological resistance, however, with prolonged exposure to conditions of high humidity and temperature changes, the risk of damage to the material by mold fungi increases. This primarily applies to panels made from spruce or aspen chips - pine and maple chips demonstrate higher resistance to mold.
To protect OSB boards from the effects of fungi and bacteria, it is necessary to additionally use moisture-proof materials, as well as the use of paints and varnishes with protective properties.
OSB affected by mold due to negative environmental influences.
Environmentally friendly material
One of the controversial issues in the technical characteristics of OSB boards is the harmfulness and toxicity of the material to people. 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 misconception.
The fact is that the content of glue and resins in the composition of oriented strand boards does not exceed 3% - for chipboard this figure is 12-14%. Thus, manufacturers managed to achieve the emission (release) of formaldehyde no higher than 8 mg per 100 grams of dry board. Some experts argue that even if OSB boards are produced in violation of environmental requirements, they will have lower formaldehyde emissions than chipboard and even plywood.
In addition, today formaldehyde resins are increasingly being replaced with glue based on MDI, an aromatic diisocyanate with extremely low toxicity. But the cost of these materials is higher. Constant improvement of the technology for creating OSB can significantly improve the environmental friendliness of the material.
In Europe, OSB boards are divided into three groups based on 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.
In construction, it is allowed to use materials with formaldehyde emission levels E1 - E2. Materials with emission level E3 are prohibited from production.
No matter how environmentally friendly the material is, the release of formaldehyde in a certain amount still occurs. It stands out most of all during the first year of operation of the material.
Fire safety OSB
To determine the fire safety of a material, classification according to the degree of flammability is used in accordance with GOST 30244-94.
- Class G-1 (low-flammable) . Materials with a degree of damage by area of no more than 65% with a degree of destruction of no more than 20%. The temperature of the flue gases during combustion does not exceed 135 degrees. No melt drops are formed.
- Class G-2 (moderately flammable) . A group of materials whose degree of damage during combustion is no more than 85%, the degree of destruction does not exceed 50%, and spontaneous combustion lasts a maximum of 30 seconds. Flue gas temperature is up to 235 degrees. The formation of droplets of melted material is unacceptable.
- Class G-3 (normally flammable) . The flammability characteristics are similar to class G-2 - with a difference in spontaneous combustion (300 seconds) and flue gas temperature (450 degrees).
- Class G-4 (highly flammable) . Materials of this class have a degree of area damage during combustion of over 85%, the degree of destruction is over 50% percent, and independent combustion lasts more than 300 seconds. The flue gas temperature exceeds 450 degrees.
Due to the wood chips included in the OSB board, it is highly flammable, which forces it to be classified as class G-4. To increase fire safety in rooms lined with OSB boards, as well as structures made from this material, it is recommended to install a layer of fire-resistant material - for example, mineral wool. In addition, manufacturers are striving to increase the flammability class of oriented strand boards by adding fire retardants (boric acid) to the composition or additional impregnation of the panel with fire retardant compounds.
Heat transfer resistance
The heat transfer resistance of building materials is an indicator of their ability to retain heat and keep out cold. Heat transfer resistance is especially important for residential buildings. For OSB, this indicator is directly dependent on the thickness and density of the slab.
| Plate thickness, mm | Heat transfer resistance, (m2.®C/W). |
| 9,5 | 0,08 |
| 11,0 | 0,09 |
| 12,5 | 0,11 |
| 15,5 | 0,13 |
| 18,5 | 0,16 |
Our production
The Remonstr online store offers consumers only high-quality, proven OSB boards of any size and thickness (8-12 mm). The range of products can be found in a special tab on the company’s website.
If you have any questions regarding the calculation of the material or its technical characteristics, you can always contact the store managers. Professional consultants will help you select slabs, determine the required volume and agree with the customer on the terms of delivery of the material.
We offer our customers favorable prices, safe and durable building materials and a wide range, regularly updated and replenished with new product items.
Application areas of OSB boards
As a structural material, 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 technology and reliability have 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 external or internal decoration - panels of a certain class are selected.
Laying the subfloor
OSB is suitable for laying seamless floors on a wooden base on wooden beams or a seamless floor on a concrete base. Compatible with any sound-proofing and heat-insulating materials. In light building structures, OSB boards are used as an independent floor covering.
Production of a continuous base for roofing coverings
Due to their sufficient strength and elasticity, oriented strand boards can withstand severe wind loads. They are used under any roofing materials, but most often under flexible tiles.
Production of supporting structures (I-beams)
The rigidity of OSB ensures the reliability of any structure, resistance to displacement and deflection of any structural elements, and the absence of creaks.
Construction of removable formwork for concrete work
For repeated use, the formwork is made from sanded or laminated OSB.
Manufacturing of SIP panels
Oriented strand board acts as the outer layers, between which polystyrene foam is laid.
Packaging material
OSB often serves as a raw material for the manufacture of containers for various cargoes, including large ones.
Quick disassembly structures
Construction of quick-dismountable structures, billboards, temporary barriers.
Furniture manufacture
OSB boards of various thicknesses (with the exception of OSB-1 class panels) are used for the manufacture of both functional and decorative elements - the backs and seats of chairs, cases and back walls of cabinets and chests of drawers.
Oriented strand 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 similar composition and structure. If all rules and standards for working with OSB panels are observed, a long service life of elements and structures is possible without any changes or destruction of the material.
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Scope of use
By the way, the scope of application of panels of this type is not limited to the finishing of facade walls. If they meet safety requirements and are made in compliance with all environmental standards, they can be used to make furniture and interior decoration. Such tiles will be used:
- In wall decoration, slabs based on wood chips can be used with all popular types of cladding coatings for external surfaces.
- As a removable, reusable formwork for concrete work.
- As a rigid base when creating thermal panels.
- As a subfloor - both as a continuous flooring and as load-bearing joists.
- When creating structural SIP panels, which are made of two outer layers of OSB and an inner layer of expanded polystyrene.
- As a continuous roofing sheathing, and taking into account the ability to withstand significant snow and wind loads, as well as the high degree of sound absorption and the rigidity of OSB, such items can be confidently used as a basis for various types of slate, tiles and most other roofing materials.
- In the form of a single-layer floor covering for light construction-type structures.
The areas of application of all types of tiles will be based not just on the operational potential, but also on the decorative qualities of each type of product. In certain design solutions, its use can be quite useful if you come up with an original design in such a way that it is in perfect harmony with other types of elements.
