Plywood or OSB - which is better for the floor? Advantages and disadvantages of materials

Plywood is familiar to everyone. Until recently, a lot of very necessary and completely useless products were produced from material made from veneer. There were times when plywood was used in aircraft construction, and it was used to make fuselages and load-bearing planes of aircraft. This indicates that plywood is a very technologically advanced and quite durable material, which is why today it remains one of the most popular building materials, despite the emergence of more modern products.

The use of plywood in the aviation industry, shipbuilding, electrical engineering, construction and furniture production indicates the high manufacturability, strength and demand of this material.

Plywood or OSB: which is better?

Each of these materials has certain characteristics and has special requirements for the installation process. Of course, they are similar in many ways, and their purposes for use are the same, but each has its own advantages and disadvantages, which may limit the use of a particular material in a certain situation.

Both plywood and OSB are used to create a smooth subfloor, on top of which the main finishing coating is then installed. At the same time, depending on the conditions, the flooring can be installed either on top of old wooden floors or concrete screed , or on joists.

OSB boards

On a note! To install any of these products using joists, it is important to purchase fairly thick material, and the bars for joists must be at least 40 mm thick. In this case, fastening is done not with glue, but with self-tapping screws, which are screwed into the entire floor in increments of about 10-15 cm.

To understand in which case which material to use, and also to figure out what is better - plywood or OSB board, you should take a closer look at these types of products for rough finishing.

Plywood

Installation features

The two materials described are an excellent rough solution for the floor. It is recommended to make the right choice taking into account operational features.

When making repairs, the best option is to use a minimum of scraps, but only whole sheets.

The process of installing slabs Source drevplity.ru

The installation work of the two types of material is actually similar. A wooden surface is an excellent base for installing parquet, laminate and other types of coatings that are installed using the floating method.

Special types of OSB boards with grooved ends are produced for linoleum for the most convenient joining of the material.

In areas with high traffic, it is advisable to install solid sheets.

Room with OSB floor Source gallery.forum-grad.ru

Plywood - what kind of material is it?

Plywood as a material is familiar to everyone. It consists of sheets made of wood veneer, which are joined together and pressed using special adhesives. The result is a fairly strong and solid wooden slab. As a rule, veneer is glued in at least 3 layers, the thickness of the material, its strength and reliability, as well as its operational capabilities will depend on their quantity. In this case, all layers are laid in such a way that the wood fibers in each of them are perpendicular to those in the previous layer. Thanks to this, the material acquires a certain elasticity and becomes stronger.

Plywood sheets

Coniferous wood veneer is usually used as raw material. These are fir, spruce, pine, etc. However, there is plywood made on the basis of veneer from deciduous wood.

On a note! Plywood can also be used as a finishing material. Typically, for finishing floors or creating any partitions, a product made of Siberian cedar or birch is used. This plywood has a beautiful base surface color.

Natural resins (which increases the safety and environmental friendliness of the material) or synthetic adhesives can be used as adhesive components. The latter increase the resistance of plywood to moisture. By the way, even plywood based on synthetic resins, if it is made with high quality and without violating technology, does not pose a danger to human health.

The finished sheet of plywood has a smooth surface without bumps or knots, and is well sanded on at least one side. Although plywood of the lowest class may still have knots on the surface and be rough to the touch. This product is only suitable for very rough work.

The finished sheet of plywood has a smooth surface without bumps or knots

Which plywood is better to lay on the floor under laminate? What to look for when choosing? How to lay the material with your own hands? We will answer these questions in detail in a special article.

Plywood is often used to create formwork at various stages of construction of buildings and structures; it is used in furniture production; it is also suitable for leveling floors, arranging partitions, and screens.

Table. Classification of plywood sheets.

Plywood prices

plywood

Plywood grades: E (elite), I, II, III, IV

Of course, class 1 plywood is best suited for creating a finishing surface. Other types can be used if the finishing coating is laid. At the same time, if possible, you should not purchase class 4 - such floors will not last long, and the quality of work may not be the best.

On a note! Plywood can withstand a humidity of 78% for 12 hours, 68% for quite a long time. But untreated plywood can withstand a maximum of 60% humidity.

Plywood texture

Comparison

Let's now compare the two products according to separate criteria to understand what is better to buy - OSB or plywood.

Water resistance

OSB board can handle short exposures to water. However, if you place it in a room with high humidity, it will become deformed.

Although it contains a lot of phenol-formaldehyde resin, it swells strongly and unevenly. Plywood behaves completely differently, more stable.

If we talk about resistance to moisture, then OSB-4 is worse in this regard compared to FC and FSF.

Properly treated plywood is quite resistant to moisture

Environmental friendliness

Product manufacturers are always looking for a compromise between water resistance and environmental friendliness, since an increase in one criterion often negatively affects the second.

Formaldehyde emissions from FSF and OSB plywood used for flooring are approximately the same and are within class E2. If we talk about the FC brand, this figure will be higher there, since resins are not used in production.

Plywood is considered a more environmentally friendly material

Fire resistance

Plywood burns excellently, but OSB does not support combustion. Of course, if a fire occurs, this will not affect the safety of housing in any way, but it may well affect the rate of spread of the fire.

OSB does not burn - and this is its great advantage

Sheet sizes and shape

The material is placed on the joists or directly on the base when it is level. The standard size of OSB is 1220x2440 millimeters, and it is specially tailored to the pitch between the lags. The best step size is 0.3 millimeters for subfloors and 0.4 or 0.

Plywood in the 1220x2440 format is not so popular; you can usually see sizes of 1525x1525 millimeters. Using this product, you will need to shorten the step or trim the sheet, and this forces you to spend additional money.

OSB has an excellent geometric shape, with diagonals everything is normal. Some of the slabs are made with a tongue-and-groove connection on two or four sides, due to which the joining is better.

It is easier to work with OSB, because this material has a size and shape more suitable for the floor

Ease of use

Both products in question can be cut with a hacksaw without any problems; nails are used for fastening. The weight of these materials is approximately equal. Sheets of plywood measuring 1525x1525 have an advantage over OSB when moving into a home.

Both materials are easy to saw, which is convenient when working with them

Visual component

For a floor that is not yet finalized, this point is not of significant importance, with the exception of grade IV plywood, which cannot be used for soft floor coverings.

For the final floor, it is advisable to take OSB, which has no problems with the surface, and the texture is much more pleasant, especially if the product is treated with paint or varnish.

OSB has a beautiful, smooth surface, so it is best used for finished floors

Strength comparison

Taken as a whole, plywood of the same thickness bends slightly less compared to OSB. For the formation of gender, this characteristic is very relevant. Strength is derived from an assessment of bending along and across the long side of the product.

Buckling strength:

• OSB 3 - 16 to 22 MPa;
• FSF - 25-60 MPa.

Chip strength:

• OSB 3 - 0.34-0.13 N/sq. mm;
• FSF - 1.2-1.3 N/sq. mm.

If you compare materials of the same thickness, plywood bends less

Strength is also measured after the products are soaked. For OSB, the indicator is almost halved. As for plywood, it remains almost the same both when wet and after drying. Therefore, the choice of strength between plywood and OSB is obvious: plywood has higher strength. However, this information is relevant for FSF coniferous plywood - among other products, it best resists the effects of water, and it also has excellent strength data.

Comparison by weight

When you select suitable building materials, be sure to take into account such a criterion as mass. The feeling that a couple of extra pounds will not affect anything is deceptive. When carrying these very products, every extra gram is felt, not like a kilogram. Since the products we review may differ in size and thickness, it is more logical to compare based on density.

OSB is lighter than plywood, which is important when installing the material

In general, the density of sheet products is related to their thickness. The thinner the sheet, the higher the density, because it is necessary for the material to be durable. And they increase as density increases. Therefore, we will talk about average density. If you need specific data, it is better to go to the manufacturer’s website or study the characteristics in the store.

Average density:

• OSB 3 - 635-650 kg/m³;
• coniferous plywood - 670-680 kg/m³.

Consequently, a cubic meter of plywood is slightly heavier than OSB. In general, we can say that the differences in mass are not too significant. So it is impossible to draw a conclusion as to which is better in terms of mass. The difference is minimal.

The differences in the weight of materials are not too significant, but OSB still “wins” according to this criterion

Cost and manufacturability of processing

If we touch on the price side of the issue, then OSB wins in terms of cost. This is quite logical: wood chips are cheaper than veneer. If we compare waterproof versions of domestically produced OSB and plywood, the cost of OSB is 50% lower, so the difference is noticeable. If compared with imported OSB, the price tag will be similar to plywood.

Questions regarding which is better of these two products are raised precisely because they have approximately the same scope of use and manufacturability. They are cut either with a hand saw for wood or with an electric jigsaw. You can use serious equipment, but the one already mentioned will be sufficient.

The price of OSB is lower than plywood

If we talk about the need for processing for the final coating, this is not required for OSB. There are plywood options that are already sanded and have a smooth surface. However, such plywood costs more, but OSB is always supplied smooth. Therefore, OSB wins here.

If you compare products by how they hold fasteners, you also cannot definitely decide which one is better. This criterion directly coincides with them. Although, to place screws in plywood, it is advisable to first drill holes to make your work easier. And self-tapping screws sink into OSB perfectly. It is only enough that the screwdriver has good torque.

Both plywood and OSB are easy to fix using self-tapping screws

Let's summarize the results of our comparison in a table

Both materials have advantages and disadvantages: in some ways plywood wins, in others OSB wins

OSB (OSB) board - what is it?

OSB - oriented strand board and translates as “oriented strand board (board)”. This type of board is “younger” than plywood; it was developed precisely as its substitute at a time when it became difficult to find good plywood - it was a scarce material. During production, wood chips are used, which, thanks to resins and high pressure, are combined into a single structure.

Oriented Strand Board

In this sense, OSB is somewhat reminiscent of plywood, which also does not consist of a single piece of wood. The shavings used to create the boards have strictly defined dimensions: their length cannot be more than 1.8 cm, and their width varies from 0.6 to 4 cm. OSB board is very rigid and resistant to various factors. In general, the product can withstand loads of up to 100 kg/m³.

OSB boards

On a note! If the production technology of OSB boards was followed exactly, then the material is absolutely safe for humans. From an environmental point of view, these boards are much better than MDF, fiberboard, plywood and other similar materials.

Painting OSB floors

Expert opinion

Afanasyev E.V.

Chief editor of the pol-exp.com project Engineer.

OSB boards are a homogeneous material with a smooth surface and no defects in the form of voids or knots. In appearance they can sometimes resemble natural wood. The thickness of the material varies from 6 to 38 mm, and most often sheets of 2500x1250 mm are found on sale. The slabs are quite often used to create a level subfloor, as they are absolutely smooth to the touch and do not have various surface defects.

Prices for OSB/OSB boards

OSB plate

Types of OSB boards

There are several types, they differ from each other in technical indicators.

Table. Types of OSB boards.

OSB - texture

OSB boards are also divided into three types depending on certain characteristics. They are:

• laminated (usually used to construct formwork);
• varnished;
• tongue and groove (have special tenons for connections).

Of course, externally, OSB generally does not look as presentable as plywood, due to the shavings visible on the surface, and therefore is not used as a finishing coating. But it’s perfect for underlayment for floor finishing.

Differences by brand

FK grade plywood is used for the manufacture of containers and packaging, as well as in construction and furniture production.

Now, more about the brands of plywood sheets. They divide products according to the degree of their resistance to moisture.

1. Bakelized (bakelite) plywood (FB brand) has high performance. It is often called Finnish. It is impregnated with bakelite varnish and can be used in any climatic conditions, aggressive environments and sea water. It is preferred by builders of small ships. The unique properties of FB are evidenced by its use in the construction of formwork for pouring concrete (1pobetonu.ru). Floors made from this plywood have an almost unlimited service life, but its price is significantly higher than the cost of products from other brands.
2. BS is plywood, which is called aviation plywood. The veneer is impregnated with alcohol-soluble bakelite glue. The qualities of this plywood exceed those of BC, which is why it was widely used in shipbuilding and aircraft construction. It is distinguished by increased flexibility, strength, water resistance and resistance to fungi.
3. BV grade plywood is also glued with bakelite compounds, but they are soluble in water. Sheets of this brand have high strength characteristics, but are not able to withstand dampness.
4. FC – sheets, for gluing which urea adhesives are used. This plywood is familiar to almost everyone. Its moisture resistance characteristics leave much to be desired, but the building material is one of the most environmentally friendly. The resistance of FC to moisture can be improved by treating plywood with various impregnations.
5. FBA - veneer is glued with albumin-casein adhesives. This brand is also afraid of moisture, but plywood is an environmentally friendly product from which products can be made for storing food products.
6. FSF - waterproof plywood is made using phenol-formaldehyde resins. FSF is needed for flooring only on some external area, since this brand has a high level of formaldehyde release into the atmosphere.

OSB and plywood - advantages of materials

Plywood as a leveling material has the following advantages:

• she looks more beautiful;
• not prone to deformation;
• After a little wetting, it dries and easily returns to its standard shape;
• through cracks in the product cannot appear due to the special structure;
• the material is easy to process;
• The surface of the plywood is smooth;
• It is used for quite a long time without losing its characteristics.

Advantages of plywood for flooring

OSB board also has a number of advantages for which craftsmen value it:

• relatively inexpensive material;
• may have different sizes;
• resistant to moisture;
• durable;
• not prone to delamination.

Advantages of OSB boards

Briefly about the main thing

There is no clear answer to the question of which is better OSB or plywood.

OSB boards and plywood, if they are not moisture resistant, are recommended to be laid in any rooms where there is no humidity. In other cases, it is still worth giving preference to moisture-resistant plywood, since under the influence of moisture, it retains its strength.

In irregularly shaped rooms, it is advisable to use OSB - the boards are sold in different configurations. But plywood is easier to cut. When the room has non-standard corners, it is recommended to use this material.

The plywood is ideally attracted to the base of the floor, thanks to which its installation is carried out as tightly as possible. But, its installation is not recommended without the use of sound insulation.

What criteria are taken into account in comparison?

To determine which is better - plywood or OSB, they can be compared in terms of technical indicators. For example, let’s take two products 1 cm thick. The plywood will be made from coniferous veneer, and the OSB board will be class 3. Both of these options are relatively inexpensive, have a certain level of resistance to chemical attack and moisture, and are also environmentally friendly.

Oriented strand board OSB - 3 (OSP - 3)

Table. The relationship between the characteristics of plywood and OSB.

Plywood walls and floor

Marking

Due to the higher density of wood, birch veneer has higher quality characteristics than coniferous veneer.

Plywood is also marked according to the level of final surface treatment. The NS index characterizes a material with unpolished outer layers. Sheets with the Sh1 marking are produced with a single surface treated, and Sh2 indicates that the plywood has been sanded on both sides.

As an example, we can show what the standard marking of a plywood sheet looks like. After reading it, you will be able to choose the most suitable material for the floor. This alphanumeric set (plywood, birch, FSF, II/III, E2, NSh, 1220x1220x10, GOST 3916.1-96) says that the material is FSF grade plywood, the top layers of which are made of birch veneer grades II and III. According to the environmental class, the sheet belongs to E2, so it cannot be used indoors. Both surfaces were not sanded. The length and width of a 10 mm thick sheet is 1.22x1.22 m. The plywood is produced in accordance with the relevant GOST.

What is better to put on the floor - plywood or OSB?

Based on the table above, we can conclude that OSB still reacts more strongly to water and will deteriorate faster than plywood in a damp room. In such a room it is better to lay plywood sheets. The thermal conductivity of the materials is almost the same, but the strength is much higher for plywood. By the way, it is the latter that will cost more than an OSB board. And plywood is a more environmentally friendly material than OSB board.

OSB board is very difficult to cut and is very dusty - to cut a part of the required size, you may need several jigsaw blades, and it is extremely difficult to do this with a hand saw.

It is not easy to cut such slabs

OSB does not crack, and plywood does not deform, OSB does not delaminate, and plywood does not shrink. We can talk a lot about the pros and cons of materials, however, thanks to the information described above, the following conclusions can be drawn:

• OSB board can be installed in any room where there is no strong humidity. Where it is present, it is better to put plywood;
• Where the use of durable material is required, it is advisable to lay plywood. Although OSB has higher strength under mechanical pressure;
• in a shaped room it is easier to use OSB, since it comes in different sizes. However, plywood is easier to cut, and therefore, if the room has non-standard corners, it is advisable to use it;
• plywood is better attracted to the base, which will allow it to be laid as tightly as possible;
• In a children's room, from an environmentally friendly point of view, it is better to install a rough layer of plywood than OSB.

Using plywood to level the floor

Both plywood and OSB can serve as an excellent subfloor for a floor if you select them correctly in accordance with the operating conditions. When repairing, it is recommended to use a minimum of scraps - it is better to use whole sheets. In a place where traffic is maximum, a whole sheet must be mounted. Both plywood and OSB can be installed on either a wood floor or a concrete base. And also for logs, but depending on the thickness of the material used. During installation, glue or self-tapping screws can be used.

Practical recommendations

When arranging floors, such nuances are also taken into account.

• In rooms with high humidity it is better to use plywood. After pouring and drying, it restores its properties to a greater extent. OSB deteriorates faster.
• In rooms with an incorrect configuration, it is better to work with OSB. In addition to standard sizes, sheets are available in a variety of sizes.
• The plywood fits more tightly onto the base . Therefore, when installing on a concrete floor, you should take care of additional sound insulation.

Plywood floor installation

Let's look at how plywood is laid on a wooden floor.

Step 1. The subfloor is inspected. Rotten boards are replaced with new ones, old but strong ones are further strengthened. The evenness of the surface is checked using a rule.

Preparing the subfloor

Step 2. If bumps are found on the surface, they are trimmed off with a plane. To prevent chips and dust from getting into your eyes, wear safety glasses.

All irregularities are removed

Step 3. The base is cleared of construction debris, including sawdust or shavings. A vacuum cleaner is often used for this - it will clean the surface as quickly and efficiently as possible.

Floor cleaning

Step 4. The base boards are covered with fire and bioprotection agents. They will protect the material from fire and the occurrence of rotting points and mold.

Application of a protective composition

Step 5. Sheets of plywood are also impregnated with the same protective agent. The sheets are dried for 12 hours.

Processing of plywood sheets

Step 6. The rough base is covered with polyisol 5 mm thick. Sheets of polyisol are fastened together with tape. The layer will provide additional sound insulation.

Laying polyisol

Step 7. The floors begin to be covered with plywood. The first sheet is placed in the corner, the remaining sheets are close to it. There remains a gap between the plates as thick as a self-tapping screw.

Laying plywood sheets

Step 8. Near the upper corner of the outer sheet, a nail is hammered into which the fishing line is screwed.

Hammered nail with fishing line

Step 9. The fishing line is stretched to the opposite wall. Moreover, between the nail to which it will be attached and the wall parallel to it there should be the same distance as where the sheets of plywood were already laid.

Photos of the process

Advice! If you have a laser level, you don’t have to use fishing line.

Step 10. The next sheet is laid and aligned with the fishing line.

Laying the next sheet of plywood

Step 11. If necessary, plywood sheets are cut in accordance with the measurements taken.

Leaf trimming

Step 12. Sheets of plywood are attached to the rough base using self-tapping screws 45 mm long and 4.5 mm thick. The screws are screwed in in increments of 20-25 cm, with a 5 cm indent from the edge of the sheet. It is important to ensure that the heads of the screws are in the same plane as the plywood.

Self-tapping screws are tightened

This way the entire floor surface is covered. Next, you can apply the topcoat.

Video - Laying plywood

Where is the plywood made?

A lot can be learned about a material by the country of origin. Thus, in Russia, the produced volume of birch plywood exceeds coniferous plywood, the structure of demand on the market is: 70% birch, 30% coniferous.

European manufacturers also predominantly use birch veneer, which gives the sheets waterproof properties. Moreover, it is better to give preference to manufacturers from Finland or the Baltic states. They produce veneer that is more dense in structure; it is obtained from slow-growing birch trees. The initial raw material is cut into blank layers no more than 2 mm thick, so in the final product, with the same thickness of Russian and European plywood, the latter has more layers. Accordingly, it turns out to be stronger, has a rigid structure, and is less susceptible to warping and delamination. You can recognize European plywood by its color: it is light and has virtually no dark inclusions.

Installation on OSB floor

Let's consider installing OSB sheets on a concrete screed.

Step 1. The surface is carefully prepared. All cracks are sealed, construction debris and dust are removed.

Preparing the base

Step 2. The surface is treated with a primer to improve the adhesion of the adhesive composition to the base. The surface is dried for about 12 hours.

Applying primer

Step 3. The adhesive composition is applied using a notched trowel onto the rough base. A layer of glue is applied so that there is a small free gap of about 1 cm to the wall.

Applying glue

Step 4. The OSB sheet is laid on the surface treated with glue. The sheet is carefully pressed down, the evenness of the laying is checked using a level.

Sheet laying

Step 5. The next sheet is laid next to the previous one with a small gap - about 5 mm.

Gap between sheets

Step 6. If necessary, OSB sheets are cut according to measurements.

Trimming material

Step 7. All OSB boards are laid in the same way. All gaps remaining between them, as well as those remaining between the wall and the slabs, are sealed with silicone sealant.

Filling gaps with silicone sealant

Number of veneer layers

The second criterion is the number of veneer layers. It starts with three, and it is always odd. This is explained by the peculiarities of plywood production - to increase the mechanical strength of the sheet, the direction of the fibers of the veneer sheets during laying alternates, and the odd number allows you to maintain the same appearance on both sides. The exception is the four-layer one - in it the direction of the fibers of the two inner layers coincides, and the outer ones are laid perpendicular to the inner ones. In plywood factories, the required plywood thickness is achieved only by joining the required number of layers of veneer.

Environmental issue

Plywood is a natural product made from renewable materials. In many countries, authorities tend to plant more forests than cut them down. And due to the fact that plywood is one of the most environmentally friendly materials available to consumers, the authorities encourage its production.

Another argument regarding plywood. Increasing the number of things made from it reduces the CO2 content in the atmosphere. Due to the fact that fewer raw materials and energy resources are used in the production of plywood, the greenhouse effect can be reduced.