OSB or oriented strand board is a multi-layer lumber consisting of differently oriented layers of wood chips. The production technology was developed at the end of the last century in America. The USA and Canada still occupy leading positions in the manufacture of products of this type. The material is obtained by pressing at a certain temperature using synthetic resins. The length of the wood components does not exceed 140 mm with a thickness of up to 0.7 mm. The chips are laid in three layers. On the upper and lower surfaces it is placed along the length of the product, and the middle layer is laid across. As a result, a material similar to plywood is obtained, i.e., it improves the properties of natural wood in terms of moisture resistance and strength. The content of natural components in the slab is up to 95%.
Features of the production process and types of products
The slabs are not made from waste wood, but use thin-sized pine raw materials, which are specially processed to produce homogeneous chips. The logs are sorted, peeled and planed. The resulting mass is dried and laid as a carpet in two directions, impregnated with waterproof resins, and then pressed at high temperature. The finished canvas is cut in accordance with standard sizes or customer sizes.
The products are available in four types and are labeled depending on the level of moisture resistance and mechanical characteristics. The lowest performance is for OSB-1 products. They can be used in rooms with low humidity, therefore they are used in the production of furniture and for the manufacture of packaging. OSB-2 has higher strength characteristics and can be used as load-bearing structures. For conditions of high humidity, OSB-3 and OSB-4 boards are produced, which in addition are designed for significant loads.
Boards with varnished and laminated external surface are produced. Laminated products are intended for reusable formwork when performing concrete work. For high-quality joining, slabs are made with tongue-and-groove locks, both on both ends and on each side.
Advantages of oriented strand boards
The board has a smooth, homogeneous structure without knots and defects that are typical for natural materials or plywood. It does not delaminate, is not subject to deformation and has a higher level of moisture resistance. It is believed that when completely immersed in water, the product retains its shape and strength throughout the day. The environmental friendliness of the material allows it to be used in residential premises. Its use helps improve the heat and sound insulation properties of floors, walls, and roofs. In terms of strength characteristics, it is comparable to plywood and significantly exceeds chipboard and MDF. The board is quite easy to process; it can be planed, sawed and drilled with tools designed for working with wood. The surface can be painted, varnished, or covered with finishing materials. Thanks to the multidirectional layers, the lumber holds the fasteners firmly. The slabs are not susceptible to damage by wood borers and fungal infections.
Depending on the characteristics of strength and moisture resistance, lumber is used for cladding external and internal walls, floors are made from it, and used as roofing and thermal insulation materials. They are used in the construction of shelving and partitions, the interior of railway cars and other vehicles. The slabs are convenient to lay as a base for laying laminate, carpet, linoleum, and parquet.
It is difficult these days to find a person who has not heard anything about OSB (oriented strand board) boards. This sheet material is actively used in the renovation of apartments, the construction of frame buildings, the construction of roofs and formwork structures.
However, hearing and knowing are unequal concepts. Between them lies a vast field of practical experience gained as a result of long searches and mistakes.
This article will help you overcome this information space without disappointment and financial losses.
What is OSB?
Since the creation of the first OSB board, the abbreviated name of which in Russian sounds like OSB (oriented strand board) 30 years have passed. This material was developed during the era of mass construction of prefabricated frame houses. Today they are home to millions of citizens of Canada, the USA and Europe.
The wooden frame required lightweight and durable cladding that could withstand moisture and solar radiation. Traditional chipboard was not suitable for this. It is too heavy and afraid of moisture. Natural wood is suitable for exterior decoration, but its installation is low-tech (takes a lot of time). A solution was found when, instead of randomly mixing sawdust and shavings, they used the technology of oriented layer-by-layer laying of long chips. The binder for it was glue based on formaldehyde resins.
Wood chips treated with an adhesive mixture are placed in the outer layers of OSB in the longitudinal direction, and in the inner layer in the transverse direction. After this, it falls under a powerful thermal press. Here the process of polymerization (hardening) of the glue occurs and the slab turns into a durable wood conglomerate of minimal thickness and maximum strength.
Since the chips are laid in mutually perpendicular directions, the deformation of the OSB board under the influence of alternate wetting and drying is minimal. This fact is of paramount importance for high-quality wall cladding of “frameworks” and crumbles.
Summarizing all that has been said, the question of what OSB is can be answered briefly. This is glued and pressed wood chips.
Insulated ones, the creation of which would have been impossible without OSB, became the first stage in the use of the new material. Today it can be found in almost all areas of construction production.
Technical characteristics and applications
- Density of OSB boards ranges from 640 to 700 kg/m3.
- Swelling coefficient from 10 to 22% (tested by soaking in water for 24 hours).
- Flexural strength . According to the European standard EN 310, it is 20 and 10 Newton per 1 mm 2 (longitudinal and transverse bending, respectively).
- Mechanical holding capacity This material does not have an exact digital expression, but is assessed by experts as very high. This plate holds screws and nails securely.
- Paintability and adhesion . The slabs accept paint and adhesive compositions well, which allows their appearance to be varied within a wide range.
- Manufacturability . This material can be sawed, cut, drilled, nailed and sanded. The large area provides the slabs with simple and quick installation.
- Fire safety . Oriented chip boards belong to the G4 flammability group. This means that they are very fire hazardous. To reduce flammability to a level acceptable in residential construction (G2-G1), they are treated with fire retardant compounds.
The areas in which OSB board is used are very numerous:
- wall cladding for frame houses;
- SIP panels;
- base for roofing bitumen shingles;
- ceiling filing, base for installation of floor coverings;
- covering of wooden stairs;
- formwork panel structures;
- racks and stands;
- construction site fencing.
Types and sizes
There are several varieties of this material. The first level of differences relates to the class of slabs, designated by numbers from 1 to 4:
- OSB-1 – material of low strength class. Such boards can only be used in dry rooms in structures that do not bear load (furniture, cladding).
- OSB-2 — can be used for the construction of load-bearing structures in dry rooms.
- OSB-3 designed for operation under load in conditions of high humidity.
- OSB-4 designed for wet environments and intense mechanical stress.
The industry also produces special types of OSB - laminated. They can be installed indoors and can also be reused for formwork.
To install floors, tongue and groove slabs are used. At their ends special recesses and protrusions (grooves) are applied for a tighter connection.
Note that OSB-3 boards are most widely used in construction. They have reasonable cost, good installation and performance characteristics.
Manufacturers produce OSB boards in the following size range:
- (with smooth edges) 3125x2000 mm, 2800x1250 mm, 2500x1250 mm, 2440x1220 mm;
- (grooved edge) 2500x1250, 2450x590, 2440x590, 2440x1220 mm.
In retail trade, you can most often see OSB boards measuring 2.5x1.25 meters.
The thickness of this material ranges from 6 to 22 mm.
Advantages and disadvantages
The advantages of OSB boards include:
- High moisture resistance.
- Light weight.
- High mechanical strength and stability of geometric characteristics.
- Easy installation.
- Aesthetically acceptable appearance.
The disadvantages of this material include:
- Low bending strength.
- Low level of environmental safety of the products of some domestic companies.
Harm to health
This is the most “sick” topic around which there are constant debates. Manufacturers of the stoves claim that they are completely safe for health. Experts, on the contrary, are skeptical about their sanitary and hygienic properties.
Let's figure out what is the reason for such polar opinions. As we have already said, the binder in the slabs is glue containing formaldehyde. In its chemically bound state it is safe. However, during the process of pressing the boards under the influence of high temperature, the molecular chains of the glue are destroyed and gaseous formaldehyde is released into the atmosphere.
As you know, the line between poison and medicine is very thin. In low concentrations, the poison is a medicine, but in large concentrations it causes serious harm. Something similar happens with formaldehyde. The degree of its toxicity directly depends on the number of molecules in the air.
There is a concept of emission level. It is used to standardize the sanitary and hygienic qualities of OSB boards, dividing them into three classes:
- E0 - emission from 3 to 5 mg/100 grams of dry material;
- E1 - emission no more than 10 mg/100 g;
- E2 – formaldehyde emission ranges from 10 to 30 mg/100 g.
For indoor use, OSB E0 and E1 can be used. Class E2 material is intended only for outdoor installation (roofs, external wall cladding).
You will not see this classification in the sanitary certificates issued to stove manufacturers. In them, toxicity is assessed according to MPC (maximum permissible concentration). It is measured in milligrams of formaldehyde in 1m3 of room air. The permissible concentration in this case is no more than 0.003 mg/m3.
After formaldehyde in the sanitary certificate there is a long list of other toxic substances, the level of which requires checking by GOST.
At the end of the list we see a final indicator called the toxicity index as a percentage. In this case, it ranges from 70 to 120%. According to the sanitary classification, this means that the OSB board is non-toxic.
In order to protect your home from formaldehyde emissions, we recommend taking the following steps:
- Do not buy a stove of a class lower than E1.
- If there are doubts about the quality of the material, then before installation it must be kept under an open canopy for 3-4 months. During this period, the concentration of free formaldehyde will decrease several times.
- Interior finishing made from OSB boards of low toxicity class should be treated with a detoxifying primer.
- The room lined with this material must be ventilated daily.
- In summer, the room should not be allowed to overheat above +30C.
- Do not allow air humidity to rise above 70%.
Verified manufacturers and estimated prices
Since it is not difficult for a manufacturer to obtain a “fake” certificate for a low-quality domestic stove, we advise you to focus on products from trusted brands when purchasing. This group includes the trademarks Egger, Glunz, Kronospan-Bolderaja, Kalevala.
Estimated prices for materials (end 2015) produced by these well-known manufacturers are:
Kronospan-Bolderaja OSB-3 (emission class E1) size 2500*1250 mm - from 510 rub./sheet (thickness 9 mm) to 1300 rub./sheet (thickness 22 mm).
German Glunz and Egger boards of the same size and thickness are significantly more expensive - from 650 to 1800 rubles per sheet.
The average price group is represented by Russian Kalevala OSB-3 boards. They can be purchased at a price almost identical to Kronospan from 530 rubles/sheet (9 mm) to 1300 rubles/sheet (22 mm).
Finally, we traditionally note that prices for material can vary significantly depending on the region, as well as on the volume of the purchased batch.
Oriented strand board, or OSB board, is a multi-layer sheet building material obtained by processing wood waste. For its production, wood shavings are used in the form of thin chips, which are glued together using synthetic resins containing boric acid and wax. The strength characteristics of the material are achieved due to different orientations of the chips. The outer ones are laid longitudinally, and the chips from the inner layers are laid transversely.
OSB classes
OSB board is classified into 4 types. They differ in technical characteristics and performance. Each OSB class is intended for a different use:
- OSB1– this material has the lowest density. As a result, it does not tolerate contact with a humid environment. Such products are often used in the furniture industry as a rough material for creating sofa frames, which are subsequently covered with upholstery.
- OSB2- These are denser slabs, but they also do not tolerate contact with moisture well. Such products are suitable for creating various structures and cladding in rooms with moderate levels of dampness.
- OSB3- This is the most common material. It has increased resistance to mechanical stress and also tolerates high humidity. Despite many positive properties, such slabs are not designed to be constantly in water. With prolonged dampness in the environment, they can become deformed. OSB3 board is intended for use in outdoor work. To increase its protection, it is possible to coat it with paint or special impregnation.
- OSB4– the strongest oriented strand board. It can be used outdoors as it tolerates high humidity. Despite very good wear resistance, strength and moisture resistance, OSB4 is in little demand. This is due to the high cost. Its price is 2 times higher than OSB3.
Weight, thickness, size, material properties
One of the most important indicators of the stability of OSB boards is their thickness. The higher it is, the more layers it contains with different arrangements of wood chips. The thickness of the material ranges from 8 to 26 mm. The standard size of the slabs is 2500x1250 mm.
The purpose of the material is determined primarily by its thickness, as well as its class. For example, the thinnest sheets from 8 to 16 mm are used for cladding. They are suitable for creating a base for a soft roof. They can be used to cover walls. For wooden floors, sheets with a thickness of 16-20 mm are used. The thickest material is used in cases where a load of hundreds of kilograms is expected. OSB board of maximum thickness is often used for covering floors in workshops.
OSB is 2.5 times stronger than chipboard. In terms of resistance to mechanical stress, it can be compared with coniferous plywood. OSB swelling coefficient is about 10%. Thanks to this, when the slab is in water, it retains its strength characteristics throughout the day. In its manufacture, thin wood chips are used, laid very tightly. Thanks to this, the material is free of knots and voids. It is not prone to delamination because it contains a large amount of binding resins. OSB holds fasteners screwed into it 25% better than pine plywood or chipboard. Insects are not interested in the material.
Material advantages
OSB board is in very high demand in the construction industry and furniture production, as it is endowed with many positive qualities:
- High strength.
- Good elasticity.
- Homogeneous structure without defects.
- Maintains stability with short-term increases in humidity.
- Easy processing.
- Good heat and sound insulation.
- Chemical resistance.
- Resistant to mold and mildew.
OSB board is a very durable material. Its stability limit during static bending is 22 MPa. For example, for chipboard this figure is only 14 MPa. It has a modulus of elasticity at static bending of 3500 MPa (for chipboard 1800 MPa). OSB can withstand loads of several hundred kilograms, which allows it to be used in the assembly of critical structures that will be subject to serious pressure. OSB retains its integrity under any impact. The slab will remain intact when stretched and subject to fracture.
The material is lightweight and elastic. Thanks to this, it can be used for cladding curved structures. A preheated plate can be rounded to a large radius. This can be used if it is necessary to cover attic spaces.
The slab has a homogeneous structure. The chips embedded in it are very thin, due to which the surface of the slab does not have significant protrusions. The small steps between the shavings are covered with resin. The homogeneous structure ensures the strength of the material when bending. Unlike plywood, it will not begin to delaminate because it is made of small chips rather than large sheets of veneer.
The material is well processed. Its cutting is carried out,. It can be easily drilled using ordinary wood bits and crowns. They are used for fastening slabs. They can be screwed in without pre-drilling the sheet. This ensures high speed of installation work.
OSB has good sound and thermal insulation performance. OSB board is excellent for the construction of frame structures. It is often used in the manufacture of SIP panels. OSB is used for cladding attics because it tolerates moisture well compared to other materials. At the same time, it helps retain heat.
Thanks to special impregnation, as well as a high concentration of resins, which are used to secure chips in the production of OSB, it is completely immune to mold and fungi. It has a long service life.
Disadvantages of the material
OSB board, despite many advantages, is not an absolutely ideal building material. It is endowed with significant disadvantages:
- Unpleasant smell.
- Evaporates formaldehyde.
- Has low vapor permeability.
The binders used in the production of OSB boards have a characteristic odor that takes a very long time to dissipate. When covering walls or laying sheets on the floor, you need to be prepared for the characteristic smell to persist for quite a long time. With good material it disappears in a few weeks, but with cheaper material it practically does not go away even after six months. Often the problem of unpleasant odor in the room is due to the fact that OSB was chosen for outdoor use when purchasing. It uses resins with different chemical compositions as a binder. Outdoor slabs have a much more persistent odor. When making a purchase, be sure to inquire about the purpose of the material and use it correctly. OSB for external use cannot be used for internal cladding.
The main disadvantage of OSB is the release of formaldehyde fumes. This is a common problem for all sheet materials obtained from wood waste. It is worth noting that OSB emits less formaldehyde than chipboard, since not as many binders are used in the board. When using OSB for interior work, you need to ask the seller for a certificate of conformity to verify the manufacturer’s compliance with environmental requirements. Certified products have low emissions of formaldehyde and other toxic resins.
Disadvantages also include the low vapor permeability of the slabs. It can be important when laying floors. If OSB is used for cladding the attic, then this is not so significant. The fact is that the roofing pie contains special moisture-stopping membranes, which still prevent the penetration of steam
Area of use
OSB board has a very wide range of applications. It is used when performing:
- Wall coverings.
- Creation of a continuous roof sheathing.
- Laying rough floors.
- Production of SIP panels.
- Assembling removable formwork for pouring concrete.
When covering the walls, a thin slab is used. It is attached to a previously created frame made of wooden slats or metal profiles. The sheets are screwed using self-tapping screws. Most often the material is used in the construction of frame houses. It is also used to make interior partitions. Its use makes it possible to lighten the weight of the building and speed up construction.
Very often OSB is used to create roof sheathing. Soft roofing materials such as shingles are nailed onto it. You can also screw slate onto OSB. OSB board is part of SIP panels. Almost all sandwich panels are made on its basis. The material is excellent for creating subfloors. It is fixed directly to the joists, after which laminate, linoleum or ceramic tiles are laid on top.
Particularly popular is laminated OSB board, which is used to assemble formwork when pouring concrete. Thanks to the laminated layer, the board can be used repeatedly. Concrete does not stick to it, so lining with plastic film is not required. To assemble the formwork, a thick slab with a cross-section of 16 mm and above is used.
Not long ago, a new building material appeared on the construction market - oriented strand boards (OSB, OSB, OSB). They immediately gained recognition among both professional builders and private developers. The high assessment that was given to this material made from wood waste by experts is associated with its remarkable properties, which particle board and plywood, related to OSB products, cannot boast of. Although in everyday life oriented strand board is often mistaken for a special type of plywood, the characteristics of OSB are an order of magnitude superior to the properties of glued veneer sheets.
OSB3 plywood is perfect for external cladding and interior finishing of walls, installation of floors and ceilings, construction of disposable formwork and sandwich panels.
OSB is a board that was first produced in Canada. This abbreviation is an abbreviation of the English Oriented Strand Board (translated as a plate with oriented chips). It has a multilayer structure, which is similar to plywood, but its manufacturing technology differs from the production methods of the latter. Each layer, the number of which can reach 3-4 in a slab, is made of thin (less than 1 mm) and long (up to 150 mm) chips oriented in the same direction. In addition, the direction of the chips in each subsequent layer is perpendicular to the previous one. The chips are bound in the board with synthetic fibers, paraffins and resins of natural origin. OSB plywood is made by hot pressing, which turns it into a durable reinforced monolith.
Main types
There are several types of oriented strand boards.
- OSB1 – used for the manufacture of products operated at low humidity. Such products include furniture.
- OSB2 - used to create structures inside buildings, and their operation must take place in a dry environment.
- OSB3 - can be used as a structural element for interior and exterior work in environments with any level of humidity.
- OSB4 is a reinforced board that can withstand increased loads. It is used as a supporting structure.
In addition, OSB is divided according to the type of surface finishing into tongue-and-groove, varnished and laminated. Plates with this type of coating are most suitable for interior work.
In most construction and finishing works, OSB3 boards are used due to the most balanced combination of price, strength and moisture resistance characteristics.
This material is used for the manufacture of base planes for roofing, external cladding and interior finishing of walls, installation of floors and ceilings, construction of disposable formwork and sandwich panels, creation of furniture, shelves, etc.
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Technical data
Characteristics of OSB3 boards for use under load in wet conditions.
The description of the main technical characteristics of OSB3 is as follows:
- density – 550-560 kg/cub.m;
- thermal conductivity – 0.131-0.14 W/m-K;
- moisture resistance – 15% (the material swells by this amount when kept in water for a day, but does not collapse);
- standard sheet size – 2440x1220 mm;
- plate thickness – from 6 to 22 mm;
- sheet weight (depending on thickness) – from 12.9 to 42.9 kg.
In addition, OSB3 is distinguished by high fire resistance and environmental friendliness. The slabs are assigned to emission class E1, according to the standards of which the formaldehyde content in a dry slab should not exceed 10 mg for every 100 g of building material.
- attics are hemmed with sheets with a thickness of 6 to 12 mm;
- the continuous base for the roofing is made of OSB 9-12 mm;
- wall cladding and partitions in residential and commercial buildings are made of 10- and 12-mm slabs;
- floors are mounted from OSB with a thickness of 12 to 22 mm.
Manufacturers note that OSB plywood has an almost unlimited service life if structures made from this material are designed and installed without errors. This characteristic indicates great prospects for OSB products.