Wood OSB, from English Oriented reinforcement plank (Oriented chipboard), it is a very versatile and high performance board whose main use is aimed at civil construction, where it has replaced the plywood mainly in Europe and the United States.
Thanks to their excellent properties, which include strength, stability and comparatively low price, they have become a reference not only in structural applications, but also in the world of decoration, where their striking and differentiated aspect plays in their favor.
Compared to other types of cards, it has been relatively short on the market. The first attempts to obtain such a plate were developed in the 1950s, without much success. It took until the 1980s for a Canadian company, Macmillan, the current version of the oriented reinforcement board was successfully developed.
What is an OSB board?
An OSB board consists of several layers of glued wood chips to which pressure is applied. The layers are not arranged in any way, as it may seem, but the directions in which the chips in each layer are oriented alternate to give the board more stability and resistance.
The objective is to imitate the composition of a plywood, plywood or plywood panel, where the plates alternate the grain direction.
What kind of wood is used?
Coniferous woods are used mainly, among which are pine and spruce. Sometimes, also species with leaves, like poplar or even eucalyptus.
How long are the particles?
For the OSB to be considered what it is and to have the properties it should be, chips of sufficient size must be used. If they were very small, the result would be similar to that of a card and, therefore, its benefits and uses would be more limited.
Approximately chips or particles should be between 5-20 mm wide, 60-100 mm long and their thickness should not exceed one millimeter.
OSBs have interesting features and advantages for various uses at really competitive prices. Although, on the other hand, they have disadvantages
Appearance. OSB boards offer a distinctly different appearance from other boards. This is easily distinguished by the size of the chips (larger than any other type of board) and rough texture.
This appearance may be inconvenient for use in decorative applications, but the opposite has happened. It has also become a popular material for decoration and not just for structural uses.
The color may vary depending on the wood used, the type of adhesive and the manufacturing process between light yellow and brown.
Dimensional stability. It has excellent stability, just slightly below that offered by plywood. Longitudinal: 0.03 – 0.02%. Overall: 0.04-0.03%. Thickness: 0.07-0.05%.
Excellent resistance and high load capacity. This characteristic is directly related to the geometry of the chips and the properties of the adhesives used.
Does not have nodes, gaps or other types of weaknesses such as plywood or solid wood. What these defects produce is that at certain points the plaque is weaker.
Thermal and acoustic insulation. It offers parameters similar to those naturally offered by solid wood.
Workability. It can be worked with the same tool and machined in the same way as other types of boards or wood: cut, drill, drill or nail.
Finishes, paints and / or varnishes can be sanded and applied, both water-based and solvent-based.
Fire resistance. Similar to solid wood. Its Euroclass fire reaction values standardized without the need for tests are standardized ranging from: D-s2, d0 to D-s2, d2 and Dfl-s1 to E; Efl
Moisture resistance. This is defined by the glues or adhesives used to manufacture the card. Phenolic adhesives offer the greatest resistance to moisture. In no case should the OSB board, not even the OSB / 3 and OSB / 4 types, be submerged or come into direct contact with water.
Durability against fungi and insects. They can be attacked by xylophagous fungi and also by some insects such as termites in certain particularly favorable environments. However, they are immune to insects in the larval cycle, such as woodworm.
Less environmental impact. Its manufacturing process can be considered more environmentally friendly or responsible than the manufacture of plywood. This puts less pressure on forest resources, that is, greater use is made of the tree.
Comparison with a plywood board
The following table compares a 12 mm thick OSB in spruce and phenolic wood glued with wild pine plywood:
|Density||650 kg / m3||500 kg / m3|
|Longitudinal flexural strength||52 N / mm2||50 N / mm2|
|Transverse flexural strength||18.5 N / mm2||15 N / mm2|
|Longitudinal elastic modulus||5600 N / mm2||8000 N / mm2|
|Transverse elastic modulus||2700 N / mm2||1200 N / mm2|
|Tensile strength||0.65 N / mm2||0.85 N / mm2|
Disadvantages and disadvantages of OSB
- Resistance limited to moisture, especially when compared to phenolic plywood. Edges also represent the weakest point in this respect.
- It is heavier than the plywood. In other words, for similar use and performance, it puts a little more weight on the structure.
- Difficulty in getting a really smooth finish. It is due to its rough surface.
In general, 4 categories are established depending on the requirement of their use (standard EN 300).
- OSB-1. For general use and indoor applications (including furniture) used in a dry environment.
- OSB-2. Structural for use in dry environment.
- OSB-3. Structural for use in a humid environment.
- OSB-4. High structural performance for use in a humid environment.
Types 3 and 4 are the most likely to be found in any lumber company.
However, we can also find other types of OSB boards (which will always be included in some of the previous classes) that are sold with some additional features or modifications.
Another type of classification is conditioned by type of glue used joining wood chips. Each type of queue can add properties to the card. The most used are: Phenol-Formaldehyde (PF), Urea-Formaldehyde-Melamine (MUF), Urea-Formol, Diisocyanate (PMDI) or mixtures of the above. Nowadays it is common to search for options or plaques without formaldehyde, as it is a potentially toxic component.
We could also classify them according to the type of mechanization with which they are sold:
- Straight edge or without machining.
- Leaning. This type of machining facilitates the joining of several plates, one after the other.
Measurements and thickness of OSB plates
The measures or dimensions are in this case much more standardized than in other types of panels. 250 × 125 and 250 × 62.5 centimeters are the most common measurements. As for thicknesses: 6, 10.18 and 22 millimeters.
This does not mean that they cannot be purchased in different sizes or even OSB when cut.
What is the density and / or weight of an OSB board?
There is no standard definition of the density that an OSB should have. It is also a variable that is directly related to the wood species used in its manufacture.
However, there is a recommendation for the use of slabs in construction with a density of approximately 650 kg /3. In general terms we can find OSB plates with densities between 600 and 680 kg / m3.
For example, a panel measuring 250 × 125 centimeters and 12 mm thick will weigh approximately 22 kg.
As we have already pointed out, there are different classes of OSB boards, each with different characteristics and, therefore, also with different prices.
In general terms, we are priced between € 4 and € 15 / m2. To be more specific:
- The 250 × 125 cm and 10 mm thick OSB / 3 costs € 16-19.
- The 250 × 125 cm and 18 mm thick OSB / 3 costs € 25-30.
Uses or applications
What are the OSB boards for? Well, the truth is that for a long time. This type of board surpassed the defined use during its conception and became one of the most versatile options.
These uses for what OSB was designed for are structural:
- Covers and / or ceilings. Both as a suitable support for a roof and as part of sandwich panels.
- Floors or floors. Floor support.
- Wall covering. In addition to standing out in this use for its mechanical properties, it should be noted that because it is made of wood, it has interesting characteristics such as thermal and acoustic insulation.
- Double wooden T beams or beam web.
- Construction of stands for fairs and exhibitions.
And they are also used to:
- Interior carpentry and furniture shelves.
- Decorative furniture. In this sense, the fact that they can be plastered, painted or varnished usually stands out.
- Industrial packaging. It has high mechanical resistance, is light and meets the NIMF-15 standard.
- Construction of caravans and trailers.
It is always advisable to allow the board to adapt to the environment where it will be placed. That is, store them for at least 2 days in their final location. This is due to the natural process of expansion / contraction of the wood in the face of changes in the degree of humidity.
External OSB sheets
Can they be used outdoors? The answer may seem ambiguous. They can be used outdoors, but covered (at least those of type OSB-3 and OSB-4), must not come into direct contact with water. Types 1 and 2 are for indoor use only.
The edges and / or edges are the weakest point on the board with respect to moisture. Ideally, after making the cuts, we seal the edges.
OSB panels for decoration
Something that caught my attention in recent years was the interest that OSB boards have aroused in the world of decoration.
This is a remarkable problem, since it is a table top with a rough and sloppy appearance, which was intended for structural and not decorative uses.
However, reality has put us in its place, we do not know whether because they like their appearance very much, because they were looking for something different or because this type of board was related to the world of recycling, something very fashionable, more than any other type.
The point is that we can find them not only in domestic environments, but also in offices, stores, etc. We will see them as part of furniture, wall covering, shelves, counters, tables …
Where can OSB board be purchased?
OSB boards can be easily purchased from any lumber company. It is a very common and common product, at least in North America and Europe.
What is not so common anymore is that all types of OSB are available from stock. OSB-3 and OSB-4 are the ones with the greatest possibilities you will find.