What kind of plywood to lay on a wooden floor. How to lay plywood with self-tapping screws? OSB is divided into different categories

Laying plywood on the floor, material selection criteria, varieties, advantages and disadvantages, installation technology.

The content of the article:

Laying plywood on the floor is a simple process, but you need to know how to properly cut the material, how to fit the finished sheets and how to use them to level the surface. An equally important issue is the quality of plywood. To choose it correctly, you will need to understand the varieties and find out where each of them is used.

The main types of plywood for the floor

Wood-laminated board (chipboard) is a building material consisting of several layers of veneer glued together. Each layer is laid perpendicular to the fibers of the previous one, which increases the strength of the material. Be sure to select an odd number of layers - at least 3, the maximum is not limited. The thickness of plywood is selected depending on where it will be laid, the expected load and the required strength.

The generally accepted division of plywood according to moisture resistance:

• FC (moisture resistant). Veneer layers are glued with a urea compound. The production technology allows the use of such plywood in residential premises, except for those where the humidity is above the norm - bathrooms, kitchens, bathrooms.
• FSF (super moisture resistant). The layers of veneer are glued together with poisonous glue - phenol-formaldehyde resin. The material has high strength, wear resistance, resistance to mechanical damage. Such plywood is used mainly for outdoor work. It is forbidden to use in baths and saunas.
• FBA (environmentally friendly). Veneer layers are glued with casein albumin glue. The use of such plywood is limited only to dry rooms, as it is susceptible to moisture.
• FB (moisture resistant). It is impregnated with Bakelite varnish. The scope of application is wide. Plywood does not deteriorate even in conditions of high humidity.
• BS. Plywood made with alcohol-based Bakelite glue. The material has increased flexibility, strength, is not affected by mold, and is resistant to moisture.
• BV. The veneer sheets are bonded with a water-soluble bakelite adhesive. Plywood is strong and flexible, but not moisture resistant.

There are 5 varieties of plywood for the floor. Each of them has its own characteristics - a regulated number of cracks, knots and other defects (GOST 3916.1-96).

When buying material for the floor, you need to choose it correctly:

• Top grade (marking E). The material has no external flaws. It is used as a finishing coating, including for the floor.
• First grade. Knots may be encountered on the surface, but they do not exceed 10% of the total sheet area, the length of the cracks is no more than 2 cm. Such plywood is also used for finishing the floor.
• Second grade. On the surface there are chipped, knots, burrs, cracks. The length of cracks can reach 20 cm. The total amount of defects does not exceed 40%.
• Third grade. Gluing of layers - high-quality. Wormholes with a diameter of no more than 6 mm are acceptable. The number of defects on a sheet is no more than 9. Plywood is used for leveling, creating a rough base for finishing the floor.
• Fourth, lowest, grade. The gluing of the layers is of high quality, the diameter of the wormholes can reach 4.5 cm, the edge is uneven, there are many intergrown knots on the surface. Used for subfloor only.

Another division of plywood is produced according to the type of wood - coniferous and birch. Softwood is made from spruce or pine, some inner layers can be hardwood veneer. Such plywood is resistant to decay and fungal infections, thanks to the resin contained in softwood. Birch is used for interior and finishing works, it is made from birch veneer. It costs significantly more than coniferous and is less often used in construction.

Plywood can be laminated, sanded on both sides (Sh2), on one side (Sh1) and unsanded (NSh). It is divided into two classes according to the content of formaldehyde (milligrams per 100 grams of dry weight) - marking E1 and E2. In class E1, the level of the harmful substance is 10 mg per 100 g, in class E2 10 - 30 mg per 100 g of dry leaf weight. Plywood marked E1 is preferable for indoor use.

Thus, the best option for a finished floor is birch plywood FBA-2E1SH1 with a thickness of 12-16 mm. It is safe for humans, affordable and perfect for further laying of parquet, linoleum and laminate.

Important! Do not purchase third grade plywood for the floor. The best combination of price and quality for flooring with birch plywood of the second grade.

Criteria for choosing plywood for the floor

Affordable price, decent quality and environmental friendliness are the main characteristics of building materials that we always pay attention to. In order to finally decide on the question of which plywood to choose for the floor, you need to correctly assess your desires and capabilities.

When shopping, pay attention to the following points:

• Glue. It is used to join sheets of veneer together. Carbamide and formaldehyde are hazardous to health. They slowly evaporate. If inhaled, they can cause severe poisoning. Albumocasein and bakelite adhesives are safe for human health.
• Rates. If the price of a plywood sheet is suspiciously low, it is most likely a low-quality product from China. It has poor performance, a "ruffy" top layer and poor edge finishing.
• Marking. Shows the resistance of the material to moisture and what impregnations the wood has been treated with.

Plywood itself must be selected depending on the finish flooring. For carpet and linoleum, you need to use thin sheets, and for parquet or laminate thicker -> 10 cm. For a high-quality rough base, give preference to the FBA brand of the third grade with one sanded side.

Advantages and disadvantages of plywood flooring

Wood-laminated boards have 4 positive qualities:

1. Strength/wear resistance. The original purpose of plywood is to reinforce weak spots in a wood floor. The layers of veneer are glued perpendicular to each other, resulting in a durable surface. The thicker the plywood for the floor, the stronger it is.
2. low price. Plywood is made from veneer, whole pieces of wood are not used, there is little waste during production. Therefore, the material cost is low.
3. Versatility. Plywood, especially of small thickness, easily takes rounded shapes. This is not possible with natural wood. Using plywood, you can create rounded structures, while the finished surface will never crack.
4. Ease of installation. Plywood is easy to work with. It is easily cut with a jigsaw or a small hacksaw. Sawing can be carried out in any direction without fear of knots and burrs. With a tree, such manipulations are impossible.

Plywood has only 2 drawbacks - standard dimensions (length, width and thickness of sheets) and fear of moisture. The dimensions of the sheets are 1.525 x 1.525 m, the thickness varies. You can contact the manufacturer directly and order the material of the desired size and thickness, only it will cost 50 percent more.

The fear of moisture is due to plywood production technologies: water can get between the layers and seep deep into the sheet, destroying the adhesive joint. Bakelized plywood is used for the manufacture of yachts. It resists moisture for a long time, but it is expensive. Therefore, it is irrational to use it for something other than shipbuilding.

Technology for mounting plywood on the floor

Plywood is laid on both a concrete and a wooden base, according to the principle of brick bonding with an offset, in order to avoid connecting the corners of four plates at one point. The standard size of the sheet is too large to lay it entirely, so it must be cut into four parts, getting small squares 60 x 60 cm. and moisture.

Preparatory work before laying plywood

You will need a few tools to install plywood. This is a screwdriver and self-tapping screws for attaching the material to the base, a level for controlling evenness, a tape measure for marking and cutting, a jigsaw for high-quality sawing.

Another important point is the surface on which marking and cutting will take place. It must be perfectly flat and stable. Working with an electric jigsaw requires precision movements. If the cutting table is unstable, you will not be able to cut the plywood correctly.

Leveling the floor with plywood begins with work on the rough base. This material is sensitive to the quality of the base, so a level is required for work. With it, you need to check the base on which the plywood will be laid for evenness. With a slope of more than 1 cm per meter, you will have to resort to leveling.

If the floor is wooden and it is not planned to remove it, laying the log will be the way out. If plywood is to be laid on concrete, then you will have to do a good job of leveling it “like a testicle”. The room must be swept and vacuumed thoroughly before laying the plywood.

Further actions if the base is wooden:

1. Check the floor for strength, identify old rotted floorboards and replace them with new ones.
2. Walk on the floor with the level. If the difference is up to 1 cm per meter, when laying plywood, use a system of linings (small pieces of plywood that can be used to achieve the desired height) under the sheets. If the difference is significant, it is best to remove the old coating completely and pour a self-leveling concrete screed. True, it will take more than a month to wait until it is completely dry and gains working strength.
3. The second option for leveling a wooden base before laying plywood is the lag system. It can also be used on a flat base, if in the future it is planned to lay a wooden floor, laminate, carpet, linoleum.

Laying plywood on concrete is almost always associated with a complex of works to level the base. The rough slab, on which the floor is then laid, always has a rough surface, dotted with bumps and shells. Before installing plywood, all these defects must be eliminated.

The work is done like this:

1. Clean the concrete slab of debris and dust.
2. Knock down protruding irregularities, seal the places with cement mortar.
3. “Clog” the sinks with cement mortar. Let the floor dry, treat with a deep penetration primer on concrete to enhance adhesion between the subfloor and the future cement screed.
4. Mark the floor into approximately equal squares. Use beacons for this. Fix them to the gypsum mortar and set at the desired level.
5. Mix the dry cement mixture with water according to the instructions. Use a drill with a mixer attachment to knead.
6. Lay out the solution in a square that is located in the far corner of the room, level it with a rule and bring it to smoothness with a trowel.
7. When the solution sets, remove the beacon extreme to the wall and fill the new square with the solution.
8. Repeat the steps until the entire floor area is covered with a new screed.
9. Wait 28 days until the new surface has gained working strength and is completely dry.

Fitting and cutting sheets of plywood for the floor

This stage also refers to the preparatory work and consists of several mandatory steps:

• Measure the area of ​​the room.
• When cutting, consider the presence of damper gaps of 3-4 mm between sheets of material and one centimeter near the walls. If this is ignored, then temperature changes and moisture ingress will lead to “swelling” of the base.
• Try on plywood - lay it without fastening as it will be laid in the final version. Lay sheets with a shift of vertical seams according to the brickwork method. The joints between them should fall in the middle of the log.
• After fitting, number the material.

Important! Be sure to check for defects, if the sheets delaminate, then replace them.

Floating fixation of plywood on the base

There are two options for mounting wood-laminated boards on concrete - floating directly on the base and along the logs.

Mounting technology:

• Dedust the leveled base.
• Fold the cut and numbered plywood in a stack in order of sheets.
• Glue the back side of the sheet with glue (pine resin should be part of the glue).
• Lay the plywood smeared with glue in the right (or left) far corner and press it to the floor.
• Drill holes with a puncher in each corner of the glued plate (for the length of the dowel).
• Insert a dowel into the hole and hammer it in.
• Repeat the same with the rest of the sheets.
• Seal the joints between the sheets with wood putty, glue them on top with mounting tape.

Fastening plywood to the logs

This is the easiest way to level the base. Plywood 0.5-1 cm thick can be used as a log, or you need to purchase a beam with a square section of 2 x 2 cm.

We fix the lag system in the following sequence:

1. Make markings on the floor to install the lag.
2. Attach them to this markup using special wood glue and self-tapping screws. If there are gaps between the floor and the joists, fill them with pieces of plywood that are suitable in thickness, having previously lubricated both sides with glue.
3. Make a crate. The dimensions of each cell must match the dimensions of the plywood sheets.
4. Fill the empty spaces between the rough and finish floor with insulation.

Do-it-yourself plywood floors are easy to lay on the logs. The material is marked out so that in the middle of each lag there is a junction of two parts or the middle of the sheet. Self-tapping screws are used for fixing, so you will need either a screwdriver or a drill that can work at low speeds.

Watch a video about installing plywood on the floor:

Now you know everything about how to level the floor with plywood. Always use a level when working. Use it to level the rough base and install the logs. Plywood is a convenient material for further finishing, in addition, it provides good additional thermal insulation and dampens part of the noise.

Plywood is more rigid than wood flooring because the plywood sheet covers an area that a single floorboard cannot.

Because of this, the strength of the floor and the resistance to squeaks and knocks increase.

From the article you will learn how to lay plywood on a wooden floor, as well as the pros and cons of such a repair.

In construction, plywood of the following grades is most often used:

• FC - moisture resistant plywood on urea resin, non-volatile and non-toxic. It has strength and elasticity comparable to BS aviation plywood.
• NSh - unpolished on casein glue. Before gluing parquet or other hard flooring onto it, it requires sanding.
• Ш1 - the main material going to the subfloor. Sanded on one side. The glue base is also casein.
• Ш2 - polished on both sides, on casein. For lightly loaded parts in dry rooms with a comfortable temperature, it can be used as a substitute for FC.

Main advantages and disadvantages

Internal plywood sheets are made of cheap material, with a large number of knots and defects that do not reduce the strength of the material. The outer sheets, depending on the type of plywood, are made of pine or birch. The dimensions of plywood sheets reach 2.5 meters in length and 1.5 meters in width. Finished plywood floors cost 5-10 times cheaper than laminate or solid board floors. Such floors can be painted in the color you like and varnished. Or use as a base for applying cast 3D floors.

Plywood flooring on a wooden floor is less attractive than solid wood, parquet or laminate flooring. But their installation is ten times cheaper. Not all types of plywood have high moisture resistance and are used for finishing floors. A finished plywood flooring cannot be leveled by milling like parquet or solid board.

The use of plywood for the subfloor connects the logs into a single structure. The floorboard connects the logs only along the laying, while each board is fixed separately. Therefore, plank floors are more prone to squeaks and knocks than plywood.

Plank floors are not well suited for laying laminate or parquet, unlike plywood, which level the surface.

The use of plywood in the construction of the floor

Laying plywood on a wood floor has the same subfloor requirements as a wood floor. Rigid fixed base - wooden logs fixed in the walls, a concrete slab or a steel ceiling structure. When building a floor with wooden load-bearing elements (logs), their upper part becomes the basis for laying plywood. Therefore, lay the logs using the building level and a two-meter ruler, with which you measure the height difference. Attach plywood to such ceilings with wood screws, the length of which exceeds the thickness of the plywood by 3-5 cm.

The evenness of the concrete slab for laying plywood is 2 mm per two meters. If the height differences are stronger, pour the screed over the beacons or use a self-leveling coating. This will avoid areas of loose fit, leading to the appearance of squeaks and knocks. To fix the plywood, use anchor dowels long, equal to the thickness of the plywood plus 5-7 cm.

For laying plywood on a steel load-bearing floor structure, two mounting options are used - directly on the structure and laying on logs previously attached to the structure. With this installation for the log, use wooden bars, the width and thickness of which is 50 mm. The second method of installation is preferable, because the bars without plywood are easier to attach to the supporting structure using countersunk bolts. And fasten the plywood with wood screws.

When creating a subfloor from plywood, the allowable gaps between the sheets are 5 mm. If the gaps are larger, it is necessary to adjust the sheet to the required dimensions. When laying laminated plywood for flooring, gaps with a width of more than 0.5 mm are not allowed. Such a coating cannot be puttied and cleaned with sandpaper. This will damage the protective and decorative lamination layers. When laying a finished plywood floor for painting, do not allow gaps wider than 1 mm. From larger cracks, the putty falls out after two to three months.

Laying plywood on an old wooden floor levels the surface, bonds strong and weak areas together, thereby increasing the overall strength of the floor. Repair the floor before laying plywood. Replace damaged roofing boards, subfloor and logs, repair floor insulation and waterproofing. In addition, attach the subfloor to the joists, and the covering to the subfloor. By knowing how to properly lay plywood on a wood floor, you will strengthen its structure and avoid repairs in the next two to three years.

Fixing plywood sheets

To fasten plywood, use wood screws, they are sold in hardware and hardware stores. Drill the plywood with a drill, the diameter of which is equal to the diameter of the self-tapping screw, and drill a hole half the diameter in the floor boards. Then drill the plywood with a drill with a diameter of 10-12 mm to a depth of 1-1.5 mm. The self-tapping screw will easily screw into the floor boards, and the hat will go a fraction of a millimeter below the plywood surface. Sheets up to 15 mm thick, used as a finished floor in technical rooms, twist without drilling holes.

In the manufacture of floors in residential and office premises, a plywood base is often used. Laying plywood on logs for the manufacture of a subfloor is a fairly reliable installation method. With this method of laying, the advantages of plywood are more pronounced.

Laying plywood on the logs allows the subsequent production of the top layer of the floor of almost any kind. This technology is applicable both in the construction of a new house and in the repair of a room. The method is very simple and can be done by hand.

Basic materials

The main materials are wooden logs and plywood. Usually, a well-dried wooden beam is used for the log. Recommended beam dimensions in section:

• width -70 mm;
• height - 40 or 50 mm.

It is advisable to use a bar with a length of at least 2 m. The bar should not have deformations along its entire length. Before use, the beam must be kept at least 10 days at room temperature, after which it is necessary to check the absence of deformation due to drying.

Plywood is used in the form of sheets. Standard sizes:

• 1525x1525 mm;
• 1220x2440 mm.

The thickness of the sheet must be at least 12 mm. With a two-layer coating, a plywood sheet with a thickness of 9 mm can be used. Sheets should be smooth, without damage. Residual deformation of sheets in any plane is not allowed.

Usually, cheap plywood of the “NSh” brand (unsanded) is used for the subfloor, and “Sh1” brand (sanded on one side) is used for parquet floors. The use of these plywood grades is limited by moisture content not exceeding 60%. Where the humidity is high or there is a high probability of floor flooding, it is recommended to use moisture-resistant plywood of the FC brand.

Step by step instructions: floor preparation

Work begins with cleaning the floor from dirt, dust, household and construction debris, and remnants of previous coatings. To exclude moistening of wooden elements from below, a layer of roofing material (roofing felt) or polyethylene film is laid on the floor surface. The film is applied to the entire surface with an overlap of 15-20 cm. The joints of the film are fastened with construction tape. If the film thickness is small, it is possible to produce flooring in 2-3 layers. Such flooring serves as a waterproofing.

Before installing the lag level, the horizontalness of the floor is checked. The marking of the installation sites of the beam is carried out and parallel lines are drawn in the middle of future lags. Usually the beam is installed on linings. For them, plates from pieces of board or plywood are used. The recommended size of each such lining is: width - 100 mm, length - 200-250 mm, thickness - at least 25 mm. Wooden linings with the help of anchors are attached to the floor over the waterproofing along the marked lag installation line. The level is controlled so that the height of the floor along the lining is the same over the entire surface. If it is necessary to adjust the height, pieces of roofing material or linoleum are added.

To prevent the formation of mold in the future, all wooden parts and logs are treated with an antiseptic. For the convenience of installing the floor, beacons are sometimes used. As beacons, you can use screws (self-tapping screws), which correspond to the height of the lag in terms of the height of the cap. Such beacons, screwed evenly over the floor surface, during the installation of the beam will help control their height and their pressing force or the need for additional gaskets.

Mounting the lag on the surface

The timber is laid according to the markings on the fixed linings. Logs are mounted parallel to the wall with windows, i.e. across the direction of sunlight entering the room. The first log is installed at a distance of 30-40 mm from the wall, and all subsequent ones - 40-50 cm apart.

When specifying the distance between the lags, it must be remembered that the gap between the last beam and the back wall should also be no more than 40 mm. The distance between the lags should be the same. Logs should be fixed parallel to each other strictly at the same height (along the surface). All logs are selected with the same section size, except for the log located at the front door. It is advisable to install this timber from a wider bar (at least 50 mm).

With screws, the logs are attached to wooden linings, previously set up and fixed with anchors according to the markings. The heads of the screws should not protrude (preferably their recess in the log by 2-3 mm). The height of the lag must be strictly the same, therefore, during installation, the height is constantly monitored by beacons (if installed) or using a level. To increase the height, a roofing material of the required thickness is placed under the log.

The beacon allows you to determine the force with which the screw is screwed in, so the height of the log is adjusted.
To strengthen the log, the installation of transverse bars (crossbars) is usually carried out. Such bars are fastened across the bar at the places of installation of wooden linings and fastened to them with screws.

For reliability, after installing the log, all wooden elements are coated with parquet or other similar glue. It is advisable to fill the volume between the lags with a heater and a sound insulator. For this, mineral wool, expanded clay or expanded polystyrene (polystyrene) is usually used. Before backfilling, all communications are carried out (if necessary). It is also recommended to apply a layer of parchment or bituminous paper over the lag.
Sometimes the installation of the timber is made without the use of wooden linings. In this case, the alignment of the lag is carried out by placing pieces of roofing material. The lag is fixed to the floor with anchors. The length of the anchor is chosen 5-6 cm more than the thickness of the bar.

plywood laying process

For the convenience of laying plywood along the logs, it is advisable to cut a large sheet into squares or rectangles with a size convenient for high-quality work. The main requirement is that the size must be chosen taking into account that the edge of the sheet during fastening should be located in the middle of the beam. It is recommended that after cutting the plywood, it is fully laid out on the floor. Sheets should be fixed apart, i.e. at one point, joining more than two corners of the sheets is undesirable.

On sheets of plywood, the points of their attachment to the logs are determined and marking is carried out. In the marked places, it is advisable to drill a hole for the screw and drill (countersink) the hole with a diameter equal to the diameter of the screw head. When attaching plywood, this will allow you to drown the hat. The distance between the holes for the screw is selected within 20-30 cm, but taking into account that the number of fasteners on one sheet must be at least 8.

The prepared plywood sheet is placed in the place determined for it and screwed to the logs and crossbars (if provided). The screws are chosen to be three times the thickness of the plywood. Sheet joints should be placed in the middle of the lag. The gap between the sheets is left within 2-3 mm. After laying the entire layer, the gap is sealed with mastic using a spatula.

Plywood is usually laid in two layers.

When applying the second layer, the overlapping of the butt joints in the layers should be avoided.

The total thickness of plywood in both layers is selected within 24-25 mm. In each layer, the thickness of the plywood sheets should be the same, but it may differ in different layers. Thinner sheets can be laid in the second layer.

Tools and materials

When laying plywood, the following tools are needed:

• electric drill;
• Bulgarian;
• screwdriver;
• jigsaw;
• hacksaw or saw for wood;
• a hammer;
• roulette;
• meter ruler.

Expendable materials:

• nails - 50, 70 mm;
• screws (self-tapping screws) - 35, 50, 75 mm;
• anchor bolts with a diameter of 10 mm;
• roofing material or polyethylene film;
• construction tape;
• mastic is elastic;
• parquet glue;
• antiseptic;
• parchment or bituminous paper.

Plywood on logs is a rather long and laborious process, but it allows you to make a reliable floor that will last for many years. Happy repair!

• Date: 20-09-2015
• Views: 727
• Comments:
• Rating: 43

New technologies for decorating rooms also affect flooring. In most cases, cork, laminate and parquet are used. You should be aware that such materials can only be laid on a flat surface. That is why quite often people are faced with the need to level the floor base made of wood.

For the house, it is better to choose plywood of the FC brand, it is less toxic and well protected from moisture.

There are several methods on how to do this. One of them is the alignment of the floor base with plywood. In order to properly carry out all the work, you will need to know how and with what you can fix plywood to a wooden floor. In addition, you need to know what kind of surface preparation work you need to do.

Advantages

The principle of leveling a wooden floor with plywood on adjustable logs.

It makes sense to use plywood for floor leveling, because it has the following advantages:

1. Low cost.
2. Neighboring layers are perpendicular, so plywood sheets will have good strength in all directions.
3. Plywood sheets are produced in large sizes, which makes it possible to perform accelerated installation in large areas.
4. Plywood sheets can bend well, and they will not break.
5. Plywood sheets are quite easy to transport.
6. Such sheets are unpretentious in use.

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Nuances when laying

Laying plywood on a wooden floor is especially important when the plank floors dry out, loosen and become unusable. Plywood allows you to make repairs in an optimal way - with minimal cash and labor costs.

When sheets on a wooden floor, it is important to know the following nuances:

1. First of all, you will need to check whether the wooden floors sag along the logs. If there are deflections, then it is necessary to completely disassemble the floor covering and repair the base of the wooden floor. If the problem is not in the lags, then it is best to lay plywood on a wooden base.
2. It should be remembered that plywood should not be used where there are large temperature differences and high humidity. Plywood sheets are not suitable for bathrooms and unheated rooms. To check if there is high humidity near the floor, you need to tightly put a sheet of polyethylene measuring 1x1 m and leave for 3 days. If there is no condensation on the inside of the polyethylene sheet, then plywood can be laid on the floor.
3. The plywood is laid dry with an offset so that at least 3 seams converge at one point. Separate sheets are adjusted to the size of the room, while you need to bypass the ledges and fill in the niches. In the process of carrying out such a procedure, it must be remembered that a gap of about 9-10 mm must be left between the scattered plywood. In the future, these gaps will be covered. There should also be gaps between the walls and plywood, which in the future are covered with skirting boards.
4. In order not to confuse the fitted sheets during the final assembly, you need to number them and draw up a plan.
5. Plywood sheets are best cut into 60 cm squares. In this way, a suitable number of damper joints can be obtained. In this case, it will be easier to find delaminations that may not be noticed in solid sheets.
6. Before final laying of plywood, it is recommended to thoroughly clean the base from dust and other contaminants. You can also perform priming, which consists in treating the floor surface with a primer.
7. Plywood must be installed with glue. If glue is not to be used, each sheet must be fixed with self-tapping screws along the edges and diagonals. The fastening pitch should be 18-20 cm. The indentation from the edges should be 2 cm. The screw heads are recessed.
8. Fasteners must exceed the thickness of the sheets along the length of at least 3 times. For example, 40 mm self-tapping screws are suitable for 12 mm sheets.
9. After laying, the base must be carefully sanded. This can be done with parquet sanders and sandpaper with large grains.

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Preparation work

Installation of plywood on a wooden floor must be done correctly and using the necessary tools. The master must have experience with all the tools to be used.

For laying plywood, the following elements are needed:

1. Screwdriver.
2. Electric jigsaw.
3. Building level.
4. Roulette.
5. Self-tapping screws.
6. Dowels.
7. Glue for wood.
8. Plywood sheets.
9. Sealant.

Before leveling a wooden floor with plywood, you need to check the base for suitability for use. In addition, you need to replace old boards and repair creaking elements. It is recommended to check the evenness of the base using the building level.

If the floor surface is not too flat, then it is worth determining the maximum difference in the base. If you need to smooth out small irregularities, you should use a floor underlay. If there are differences of more than 1 cm, you will need to lay the log horizontally. They can be set using the water level.

The choice of plywood sheets will depend on the flooring that is planned to be laid. If you plan to lay carpet or linoleum, it is recommended to purchase sheets of small thickness. If laminate or parquet boards will be laid, plywood 10 mm thick or more must be purchased.

The thickness of plywood sheets that are laid under a laminate or parquet board must be no less than the thickness of the floor covering.

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Plywood brand

Before laying, it is important to choose the right brand of plywood sheets. It can be determined according to the moisture resistance of the material. For industrial construction, the FB and FOF brands are used. For individual construction work, plywood of the FSF and FK brands is intended.

FC brand plywood can be used in children's rooms or bedrooms because it uses a phenol-free glue in the manufacturing process, as a result of which the plywood is harmless to human health. It has an average level of moisture resistance and is resistant to mechanical stress.

Plywood brand FSF has an increased level of moisture resistance, wear resistance and mechanical strength. These properties will not change with changes in temperature and humidity. This is achieved thanks to special resins, but this makes such plywood toxic. Such material is not recommended for use in living rooms.

A wooden floor, like any other base, eventually loses some of its operational properties. Wood is a living material, and gradually it begins to change - it deforms somewhat, the floorboards are no longer so even. But plywood will help to correct the situation (and this may be necessary when laying a laminate or other material demanding evenness of the base). How to lay plywood on a wooden floor?

Plywood is widely used in the construction industry. It can be used to create partitions, wall and ceiling cladding in a wooden house, formwork is built from it, and floors are often leveled with it before laying coatings that require evenness of the base.

This material is a layered "pie" created from wood veneer. To create it, an odd number of veneer sheets (from 3 pieces) are glued together, which are connected in such a way that the wood fibers in different layers are perpendicular to each other. This increases the strength of the material.

For laying in warm and dry rooms, such as residential buildings, plywood is the ideal material. Working with it is easy and fast, which attracts many builders and novice craftsmen to its use. If necessary, sheets that have lost their strength and reliability can be easily replaced with new ones.

On a note! From plywood, an excellent version of a dry screed is obtained, which (unlike ordinary cement) does not have to wait 30 days to dry - you can start laying the finish coat almost immediately after installing the plywood. Using this material will save not only time, but also money during the repair of the premises.

Benefits of plywood flooring

Plywood as a leveling material for wooden floors is so often used for good reason. It has a lot of advantages:

• has a low price, and therefore with its help you can perform a budget, but high-quality repair of the floor;
• makes it easy to level floors copes with the curvature of the base, and with small surface defects;
• is an additional insulating material, thereby reducing heat loss in the room;
• can also be used as a finishing option for flooring;
• put in by hand without the involvement of masters;
• easy to handle;
• is an environmentally friendly material, pleasantly smells like a tree.

Plywood itself is a fairly stable material, practically does not deform under the right operating conditions, which means it allows you to create a reliable and durable subfloor that will last for decades. And to work with it, a small set of tools that are in almost every home is enough.

On a note! Sometimes very beautiful options for finishing the floor are created from plywood.

The disadvantage of plywood is its fear of water. Ordinary material does not like a high level of humidity, which means it cannot fit in a bathroom or bathroom. For these purposes, it is better to purchase moisture-resistant plywood.

What are the types of plywood

Plywood is divided into several types depending on its characteristics. For example, according to the presence and number of defects, the material can be divided into 4 groups.

Table. Types of plywood.

Variety	a brief description of
	The best grade of material. Sheets of such plywood do not have defects, they are even, smooth, there are no knots and cracks on them. Although a certain number of small cracks are allowed, they will practically not play a big role in the quality and appearance of the material, since they are not noticeable to the eye.
	Such plywood may have up to 5% defective area of ​​the entire sheet. Defects can be small dents, glue residues (no more than 2-3%).
	Such sheets have knots and wormholes, but in moderation.
	The worst kind of plywood. It can only be used to create formwork, as it has too many external flaws. However, the sizing of sheets, as a rule, is still of high quality.

Also, plywood varies depending on the purpose. There are the following types:

• industrial;
• for packing;
• furniture;
• structural;
• construction.

Sheets of material can be made from various woods. So, allocate:

• birch plywood;
• coniferous (made from cedar, larch, pine, fir, etc.).

Coniferous is cheaper than birch. In its manufacture, varieties of deciduous trees can sometimes be used, however, only in the inner layers.

On a note! The size range of plywood sheets is quite large. The parameters vary from 1525x1525 to 3050x1525 mm.

Table. Types of plywood depending on its properties.

Abbreviation (designation)	Characteristic
	The impregnation in these plywood sheets is represented by albumin-casein glue. Such plywood is afraid of water, but it is absolutely safe for human health, as it is environmentally friendly.
	Plywood is impregnated with carbide glue. It does not have increased moisture resistance and therefore can only be used for the manufacture of furniture and for indoor work. It will not tolerate exposure to precipitation outside or high levels of humidity.
	Also called aviation. Manufactured using bakelite alcohol-soluble adhesive. Previously used in shipbuilding, the creation of aircraft and other aircraft. Possesses the increased durability, resistance to influences of external factors, is not afraid of water and microorganisms.
	Bakelite-based glue is used to create this plywood. It is water-soluble, and therefore the sheets are not used to create any structures in the open.
	Layers of material are impregnated with bakelite-based varnish. This plywood can be used in a fairly aggressive environment. If necessary, the material can withstand moisture for a long time.
	Plywood with high fire resistance. Otherwise, this material is unremarkable.
	The layers of this plywood are impregnated with formaldehyde glue. It turns out a durable material that is not afraid of moisture. It also practically does not burn, which is important for the construction industry.

floor plywood prices

floor plywood

Which plywood to choose

How among such a variety of plywood types to choose one that is suitable for the subfloor and will cost moderate money? To do this, it is important to assess the operating conditions of the material. For example, in an ordinary room, plywood without any special properties can be used to level a rough wooden floor. This may be a material belonging to grade III or IV, because a finishing coating will be laid on top of it and defects will still not be visible.

Next, you should think about choosing the type of plywood. In a residential building, ordinary FC plywood will serve its time perfectly. Moreover, it will even cope with the level of humidity that can be observed in the bathroom or kitchen. And in the nursery, you can lay sheets marked with the abbreviation FBA. This is the most environmentally friendly type of material.

Advice! You should not buy plywood made using phenolic glue for an apartment or house. It may be too toxic. Although, it is worth recognizing, the level of moisture resistance is at its best.

The dimensions of the sheets are also important, in particular their thickness. To make wooden floors even, it is enough to use sheets 10-15 mm thick. Although some experts argue that only sheets more than 18 mm thick can withstand the load. And to achieve optimal strength, plywood can be laid in two layers. Here it is easier to evaluate the actual costs and see which option will be more profitable in terms of budget. For ease of transportation, you need to pay attention to the length and width.

The nuances of laying plywood sheets

Plywood is a simple material, but, nevertheless, it requires compliance with certain rules when laying. If they are neglected, then it will not be possible to achieve the desired effect, or such a foundation will quickly become unusable.

How to lay plywood on the floor: laying methods

The process of laying plywood will directly depend on the condition of the subfloor, as well as on additional work. For example, sheets can be laid directly on a wooden base if it has not yet become unusable and is still strong, although it has ugly gaps between individual boards or has lost its appearance. Sheets are placed in compliance with small gaps - up to 3-5 mm between them. A distance of 15-20 mm must be maintained to the wall. Sheets are attached with self-tapping screws or glue. The consumption of glue is about 1.2-1.5 kg/m 2 . The installation of the sheet should be carried out by screwing the screws around the perimeter, and then diagonally.

Plywood can be closed and a somewhat curved floor. In this case, the material is partially laid on the base itself, as well as on small bars, which will act as a kind of lag. The bars can have a different section depending on the curvature of the floor. Sometimes even cutting boards are used.

Less often, when the subfloor has completely become unusable, a new base is created from plywood installed on logs or supports. In this case, the old base is completely dismantled, and then the logs are installed, on which fresh sheets are attached. They are laid in such a way that the edges of the sheets do not sag - on the contrary, they must have a support under them.

Necessary tools and materials

The following tools may be required to install plywood sheets on a wooden base:

• screwdriver;
• drill;
• a hammer;
• screwdriver;
• level;
• electric jigsaw.

The materials used are self-tapping screws, usually 30-50 mm long, nails or glue. The first ones are preferable, since they are the easiest to work with.

Preparation for work

Before laying plywood sheets, a number of preparatory work should be carried out. It includes:

• assessment of the condition of the wooden base and its repair, if necessary- replacement of cracked floorboards or floor screed. Floors should not “walk”, bend, creak;
• checking and measuring the humidity level in room;

On a note! You can find out the humidity like this: a piece of polyethylene about 1x1 m in size is laid on the floor, fixed on the base. After 3 days have passed, the film rises, its condition is assessed. If condensation has accumulated on it, then the humidity in the room is increased and plywood can only be laid moisture resistant.

• removal of all debris from the rough base. If it remains, then the plywood will not lie flat. Floors can be swept and vacuumed, if necessary - washed;
• plywood itself must also be cleaned of sawdust and dust;
• recommended treat the old wooden surface with a primer mixture.

Laying plywood on an old wooden floor

Step 1. If necessary, the rough foundation is repaired. The evenness of the floor is checked using the building level, after which the protruding parts can be filed. The floor should be as level as possible.

Step 2 Holes are drilled in the floorboards in places where the lag lies and screws are screwed in. This procedure will make the floors stronger. Self-tapping screws are screwed into each board at a distance of approximately 50 cm from each other.

Step 3 The draft base is covered with a thin substrate. Its individual strips are fastened together with adhesive tape. The strips are overlapped by about 10-15 cm.

Step 4 The first sheets of plywood are laid so that there is a small gap of 2-3 mm between them, and the gap to the walls is about 10-15 mm.

Step 5 Sheets of plywood are screwed to the boards with self-tapping screws in increments of about 20 cm.

Step 6 Plywood in the next row is laid with joints shifted by 1/3 of the sheet. If necessary, the sheets are sawn in accordance with the measurements taken.

Step 7 The joints of individual plywood sheets after installation can be glued with adhesive tape. The base is ready for laying the top coat and installing skirting boards that will hide all the gaps near the walls.

Video - An unusual way to lay plywood on a wooden floor

Video - Mounting plywood on a wooden base

Checking the quality of plywood floor installation

Immediately after the installation of plywood sheets has been completed, it is recommended to check the quality of work. This is important to do before laying the final coating. With the help of a long even rail, the evenness of the laying of the material is checked - the gaps between it and the floor level should not be more than 2 mm in accordance with SNiP 3.04.01-87. Next, you need to use the building level and evaluate the horizontal position. The allowable slope cannot be more than 0.2% according to the same document.

SNiP 3.04.01-87. Insulating and finishing coatings. Download file (click on the link to open the PDF file in a new window).

The base, covered with plywood, is tapped with a hammer at the end of the work. The procedure is necessary to identify the places of possible delamination of materials. Where the sound on impact will be deaf, there is a problematic place. The sound when tapping the entire plywood floor should be the same if the sheets were laid correctly and not damaged during installation.

Plywood is not in vain called a universal material. It also works well for leveling floors. And if the installation of the sheets was carried out correctly, then the master provided himself with high-quality and reliable flat floors for many years.