How to lay plywood on a wooden floor. Laying plywood on the floor. The nuances of laying plywood sheets

Many newcomers to construction sooner or later wonder how to lay plywood on the floor. This material is often used in cases where floors do not look perfect and require leveling.

Laying plywood on the floor helps prepare perfect coverage under finishing: laminate or parquet.

If you decide to replace flooring and have chosen laminate or parquet, you should definitely measure the floor level special device. In most cases, a scatter within a few centimeters is immediately detected. The most neglected cases– when the difference is already ten centimeters or more. Laying the floor with plywood will help correct this situation.

It is laid on a previously prepared base.

A concrete screed is perfect.

If you prefer it to other types of bases, remember that it completely hardens after a month and a half.

After this, work can be resumed. In most cases, a layer of waterproofing is laid on top of the concrete screed. And then they lay down the plywood. You should choose plywood with a high level of moisture resistance. Its thickness, as a rule, starts from 1.5 cm.

Rule: before laying plywood on the base, be sure to test it for moisture resistance.

How to measure the moisture content of a concrete base under plywood

To do this, use a polyethylene film 1 m wide. Spread it on the concrete. Press the edges. This can be done using improvised means. For example, bars. Leave the center free. Wait a few days.

After this, inspect the polyethylene. If its surface is not wet, therefore, the humidity is within normal limits.

But if condensation appears, you should wait some more time to concrete base finally dried out. Otherwise you will have to change the plywood.

Return to contents

Types of plywood used for flooring

Plywood varies in the number of compressed layers and types of glue, which affect the degree of moisture resistance.

If you decide to lay the floors in your home using this material, you should familiarize yourself with its types.

You might be interested in: How to make a floor screed

Plywood is a sheet covering that consists of several compressed layers.

But the number of these layers depends on several factors, more precisely, the purpose for which one or another type is required. For example, strength or increased load.

Plywood is divided into classes:

Their differences are in the degree of moisture resistance, topcoat and the type of glue used to hold the layers together.

If we talk about the first type of FC plywood, it can be characterized as high-quality coating. It is used for finishing residential premises. It has an average degree of moisture resistance. The adhesive is predominantly urea resin.

The second type of plywood - FSF - is more suitable for arranging the floors of rooms with high humidity. For example, bathrooms, kitchens or saunas. It has a suitable level of moisture resistance. This is achieved thanks to special staff glue, which includes phenol-formaldehyde.

If the first two types are used in residential buildings, then the third type is most often used in industry.

Return to contents

How is plywood processed?

Plywood varieties are distinguished by the degree of processing and the raw materials used.

You should also pay attention to such factors as material processing. Plywood can be made from different types raw materials. For example, birch or coniferous varieties wood Plywood from coniferous species made from veneer. It attracts buyers with its resistance to fungal attack and reduced level of rotting. This type is most often used for construction work related to roofing.

In the production of furniture or decoration interior spaces Birch plywood of the FK type is used. It is made from larch veneer. Birch plywood for finishing works external type should be FSF.

Return to contents

Classification of plywood by formaldehyde content

This factor is taken for every 100 g of dry sheet material.

For finishing residential premises, plywood of the first type is used - with minimal formaldehyde content.

Two types are produced:

You might be interested in: Filled floors – we create

The first option is calculated using the formula 10 mg of formaldehyde for every 100 g of dry sheet material.

The second type is a spread of 10 to 30 mg of formaldehyde for every 100 g of dry sheet material.

The first type of plywood, marked E1, is most often used for interior finishing work.

Return to contents

How to lay out plywood: features

Plywood is produced in leaf form. Standard size a sheet of plywood is 125x125 cm. But due to its considerable size, it makes work difficult.

First, the sheets need to be cut. This is best done in the form of squares. After this, it is laid out on the surface of the base. The sheets should be adjusted around the perimeter of the room, taking into account all the depressions and protrusions. When laying out the plywood, leave a small distance from the walls.

https://site/youtu.be/r1qtd4NaK04

Important! Make sure the edges plywood sheets did not touch the walls.

Gaps may form between some sheets of plywood. In this case, you need to watch the seams. Their width should not exceed 1 cm.

Tip: to make it easier to lay plywood sheets after measuring and cutting, you should apply the numbering on the back side with a pencil.

The sheets should be sawed carefully and slowly. Try to avoid delamination of the material. If defects do appear, the only conclusion follows: the material turned out to be very Bad quality. And it’s worth considering whether it’s worth using.

When making floors in residential and office premises A plywood base is often used. Laying plywood on joists to make a subfloor is a fairly reliable installation method. With this installation method, the advantages of plywood are more clearly demonstrated.

Laying plywood along the joists allows the subsequent production of the top layer of the floor of almost any type. This technology is applicable both when building a new house and when renovating a room. The method is very simple and can be done with your own hands.

Basic materials

The main materials are wooden joists and plywood. Typically, well-dried wood is used for logs. wooden beam. Recommended cross-sectional dimensions of timber:

width -70 mm;
height – 40 or 50 mm.

It is advisable to use a beam with a length of at least 2 m. The beam should not have deformations along its entire length. Before use, the timber must be kept for at least 10 days at room temperature, after which you need to check that there is no deformation due to drying.

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

1525x1525 mm;
1220x2440 mm.

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

Typically used for subfloors cheap plywood grade “NSh” (unsanded), and for parquet floors - grade “Sh1” (sanded on one side). The use of these grades of plywood is limited to a moisture content of no more than 60%. Where humidity is high or there is a high probability of floor flooding, it is recommended to use moisture-resistant plywood of the FK brand.

Step-by-step instructions: preparing the floor

Work begins with cleaning the floor from dirt, dust, household and construction waste, residues old coatings. To prevent the wooden elements from getting wet from below, a layer of roofing felt (roofing felt) or plastic 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 secured with construction tape. If the film thickness is small, you can make the flooring in 2-3 layers. This type of flooring serves as waterproofing.

Before installing the logs, check the level of the floor for horizontalness. Marking of timber installation sites is carried out and parallel lines the middle of future lags. Usually the timber is installed on pads. For them, plates made from pieces of boards 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 pads are attached to the floor with anchors on top of the waterproofing along the marked installation line of the joists. The level controls 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 felt or linoleum are added.

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

Installation of logs on the surface

The timber is laid according to the markings on the fixed pads. The logs are mounted parallel to the wall with windows, i.e. across the direction of entry into the room sunlight. The first lag is installed at a distance of 30-40 mm from the wall, and all subsequent ones - 40-50 cm from each other.

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

The logs are attached with screws to wooden pads, previously positioned and secured with anchors according to the markings. The heads of the screws should not protrude outward (it is advisable to have them recessed into the joist by 2-3 mm). The height of the logs must be strictly the same, so during installation the height is constantly monitored using beacons (if installed) or using a level. To increase the height, a roofing felt pad of the required thickness is placed under the joist.

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 lags, transverse bars (crossbars) are usually installed. Such bars are fastened across the beam in places where wooden pads are installed and are attached to them with screws.

For reliability, after installation the logs are all wooden elements coated with parquet or other similar glue. It is advisable to fill the volume between the joists with insulation and sound insulation. For this it is usually used mineral wool, expanded clay or expanded polystyrene (foam). Before backfilling, all communications are carried out (if necessary). It is also recommended to place a layer of parchment or bitumen paper on top of the lag.
Sometimes the timber is installed without the use of wooden supports. In this case, the lags are leveled by placing pieces of roofing felt. The joists are secured to the floor with anchors. The length of the anchor is selected 5-6 cm greater than the thickness of the bar.

Plywood laying process

For ease of laying plywood along joists large leaf it is advisable to cut into squares or rectangles of a size convenient for quality work. The main requirement is that the size must be chosen taking into account that the edge of the sheet when fastening should be located in the middle of the beam. It is recommended that after cutting the plywood, lay it out completely on the floor. The sheets should be secured staggered, i.e. Joining more than two corners of sheets at one point is undesirable.

The points of their attachment to the joists are determined on the plywood sheets and markings are made. In the marked places, it is advisable to drill a hole for a screw and drill (countersink) a hole with a diameter equal to the diameter of the screw head. When attaching plywood, this will allow the head to be recessed. 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 sheet of plywood is placed in a designated place and screwed to the joists and crossbars (if provided). Screws are selected with a length that is three times the thickness of the plywood. The joints of the sheets should be placed in the middle of the joists. 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.

Laying plywood is usually done in two layers.

When applying the second layer, you should avoid matching the joining seams in the layers.

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. In the second layer you can lay more thin sheets.

Tools and materials

When laying plywood, the following tools are required:

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

Consumables:

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

Plywood over joists is a fairly lengthy and labor-intensive process, but it allows you to make a reliable floor that will last. long years. Happy renovation!

Indoor floors are subject to the most stress, but a flawless surface is achieved by proper leveling during repairs, including by laying plywood on the floor. The material is suitable for inexpensive repairs, for installation under linoleum and carpet, under parquet boards, cork and warm floors, even with decorative purpose when it is laid out as a mosaic panel instead of parquet.

Properties and quality of plywood

Plywood is a universal building material based on natural wood, suitable for installation and repair of walls, floors, roofs.

It is indispensable for leveling floors and other purposes, but each installation case has its own technological differences. For example, laying plywood on a concrete floor requires maximum leveling of the screed, while laying plywood on an old floor with deformations is easier to do directly on the joists, provided there are high ceilings.

Laying is done in different ways:

on the logs that form a leveling sheathing on the floor;
on a fresh cement screed;
on concrete floors;
on top of the old plank floor.

Plywood sheets consist of layers of wood veneer, where the fibers are glued perpendicularly. The material was highly appreciated by builders, as it has its advantages:

environmental friendliness;
strength;
ease of cutting and installation;
cheapness;
reliability in operation;
wear resistance;
light weight and thickness;
moisture resistance - for more expensive varieties;
high density and hardness;
relative fire resistance;
sufficient wear resistance;
no toxic odors;
high availability of self-installation;
ease of transportation;
long service life.

When choosing plywood, you need to focus on its thickness - thin sheets are suitable for carpet and linoleum, and parquet and laminate are laid on plywood about 8-10 mm. However, plywood is contraindicated:

damp buildings with sharp temperature changes and air humidity above 75%;
those places where plywood is laid on joists, with machines and vibrating tools, quickly deform and become unusable;
rooms where communications can be laid under the false floor, which can lead to a water pipe break and flooding;
rooms where electrical wires are laid under the floor, which can become exposed and cause a fire.

Types of plywood

NSh - unsanded, contains casein glue, the cheapest from 170 rubles/sq.m, 12 mm thick, requires sanding before laying other building materials.
FC - based on non-toxic urea resin without phenols, harmless and durable, used in children's rooms and bedrooms, quite waterproof, similar in quality to BS aircraft plywood.
Ш1 - based on casein, suitable for subfloors, smooth on one side.
Sh2 - double sanded plywood for light loads in dry rooms.

Brands Sh1, Sh2, NSh and FK are suitable for individual construction, and FSF has increased water resistance, FB and FOF - only for industrial installation.

Preparation of improved quality plywood

1. If there is no need to quickly complete repairs, after purchasing in the cold season, it is better to dry the plywood - it is not known under what conditions it was stored in warehouses. It dries vertically for 2-3 weeks at room temperature, after which the plywood is treated with a wood antiseptic-fungicide and dried, ventilating the room.

2. The moisture resistance of plywood sheets is increased by impregnation with PVA-based putty, treated on both sides, and dried vertically. However, it is not advisable to install it on open balcony and loggias, in the pantry and toilet, in the kitchen and in the bathroom.

3. The strength of the outer layer of plywood is increased by treating it with acrylic varnish in 2 layers, and the second is applied after the primary paint has dried, then it is advisable to cover it with stain and varnish.

4. Plywood, like any wood, requires acclimatization in the place where it will be laid on the floor. The timing depends on the temperature difference and the general humidity in the room; even after a warm warehouse, it should get used to the apartment for 1-2 days horizontally.

Where to start laying plywood on the floor

Check the humidity of the floor in the room by covering a large area in the middle with a piece of plastic film, securing it with weights or slats and slightly lifting it in the center - a bubble will show condensation. If it appears within a day, the room is very humid, then additional measures are needed to dry it. Small drops over a concrete floor over 3 days are quite normal, but it needs to be covered with a waterproofing underlay; it is better to disassemble and dry a wooden floor. If no condensation has occurred within 5-7 days, the condition is ideal and the plywood can be laid without fear.

Attention: It is not recommended to restore old damp and moisture-deformed floors with traces of mold, mildew or rot, where there are rodent holes and other serious defects. It is better to remove the old floor, find a source of moisture and preserve it, dry and ventilate the room, bring the humidity back to normal and then do the flooring.

Surface and tool preparation

Floors for laying sheet plywood are prepared in stages:

preparing and cleaning the old surface;
waterproofing works;
preparing the base for installation;
alignment;
measuring the room and calculating the floor area;
preparing the necessary tools;
purchasing the plywood itself, additional materials and components;
cutting sheets, marking and numbering;
laying plywood;
grinding and additional processing.

Required tools and materials:

jigsaw for cutting sheets;
vacuum cleaner for cleaning the surface;
roller, primer;
water level;
roulette;
notched spatula;
countersink drill and screwdriver;
plastic dowels and screws;
finishing grinder.

To lay plywood as a substrate for decorative flooring, prepare an absolutely flat surface using a screed or self-leveling mixture so that the laminate, parquet bars, carpet and linoleum lay down as smoothly as possible. Such floors will be comfortable and warm. It is better to choose moisture-resistant plywood 12-15 mm. When laying plywood on a wooden floor, you may need glue, there are options:

solvent-based, requires fixation with self-tapping screws, it dries quickly, but requires ventilation;
on water based, also requires fastening the plywood with self-tapping screws, the glue is non-toxic, but takes a long time to dry;
a practical two-component composition, dries quickly and does not require fastening with screws or other methods.
Bustilate is also suitable, assembly adhesive, liquid Nails.

Cutting sheets and preparing the base

The cutting of plywood depends on the floor area in the room and the leveling joists; the dimensions of the damper joints are also taken into account. To do this, leave a gap of 3-4 mm between the workpieces and 1 cm at the wall to avoid swelling of the base due to temperature changes. When finishing cutting, check the ends of the workpieces to ensure that there are no defects or delamination of the plywood; a sheet with a defect is easiest to replace; they are suitable for cutting.

Preparing the base involves pouring a self-leveling liquid, and if the concrete floor is smooth and does not crumble, then it is simply vacuumed before laying and coated with a primer for adhesion. If necessary, a fresh screed is applied to an uneven old floor - up to 3 cm.

For convenience, cutting plywood can be marked into squares with sides of 50-60 cm - this makes it easier to prevent the occurrence of voids under the sheets and smooth out possible irregularities. Between the sheets, the seams are made at 0.8 cm, and at the walls - up to 1.5-2 cm. The plywood is well cut with a jigsaw, laid on the prepared floor surface and numbered, then removed until final installation.

Leveling a wooden floor with plywood

Installation is carried out in compliance with the rules for laying plywood on the floor, and it is better to have experience similar works or get advice from laying experts, but if you skillfully use the equipment, watch a video and understand the technology of laying plywood on the floor, it’s not difficult to do it yourself step by step.

1. If the floor is slightly uneven, the maximum difference in surfaces is determined; small deviations are filled with a special substrate or self-leveling mixture. A difference of more than 1 cm requires logs, which are set with a water level.

2. When laying sheets of plywood, try to place them so that there are no joints at 4 corners; it is better to mount them as brickwork, that is, with an offset. It is best to take FC plywood about 12-18 mm. The sheets are numbered and the blanks are removed so that during installation you do not get confused with the cutting, and it is better to place the joints of the plywood sheets in the middle of the joists.

3. Sometimes it is necessary to add greater strength to the floor - for heavy furniture or an aquarium, then the plywood is laid in 2 layers, additionally gluing, for example, PVA.

The logs are laid in compliance with the rules:

The boards are suitable for ordinary, unplaned, weaving, which will undergo acclimatization in the same room, after which the warped building material is rejected.
The sheathing of the logs is attached in increments of 300-600 mm.
The voids in the sheathing sections are filled with material for additional heat and sound insulation such as expanded clay.
For rough floors, you can take ready-made tongue-and-groove sheet plywood 12-20 mm - squares 300x300 mm and strips from 300x600 mm.
You can use self-tapping screws with a countersunk head.

Laying and fastening plywood on a wooden floor

Upon completion of the preliminary work, the plywood is attached to the floor using joists according to the cutting diagram. Fastening is done using glue, dowels and screws. It is important to ensure that the plywood is not deformed by hammering and working with tools. They drill holes with the same diameter as the dowels, countersink them - the head is hidden there, and then comes the final stage of processing.

Under carpet, laminate, parquet and linoleum we sand plywood and additionally need to be coated protective varnish, it is advisable to lay a substrate on the plywood base to absorb noise. If the work is carried out technologically and carefully, the surface will be smooth and aesthetic, and self-installation it will cost you much less.

The video of laying plywood on the floor clearly shows its versatility and the ease of installation with your own hands if you have the right tools.

Basic rules for laying plywood on a concrete floor

1. Floors must be clean and dry.

2. To increase waterproofing, a special substrate or dense polyethylene film, they cover the entire floor area with an overlap, the seams are fastened with ordinary tape.

3. A large whole sheet can be placed from the threshold, as there will be maximum load, and seams are undesirable.

4. We make sheets of plywood staggered, leaving a small gap.

5. Plywood is difficult to nail to concrete floor, so you can’t do without a hammer drill; you need to drill with a carbide drill.

6. Self-tapping screw heads are slightly larger than the diameter of the drill, so that it does not go through the plywood.

7. We insert plastic dowels into drilled holes, where the screws will go.

8. Sheets of plywood are secured in the center and along the perimeter.

9. Excessive length of the sheet is cut off with a jigsaw.

10. Upon completion of installation, check whether all screws are recessed enough so as not to damage the top floor covering - linoleum, carpet or cork.

1. Floor repairs begin after finishing any finishing of walls, ceilings and installation of carpentry.

2. Before starting installation, it is advisable to turn off the power to this room; the power tool is connected through an extension cord from another room.

3. It is important to monitor the level of humidity and avoid temperature changes - this will help avoid deformation of the wood.

4. Do not forget to pre-treat the plywood sheets with an antifungal preparation for wood if there is a risk of increased humidity.

5. When laying rough plywood under linoleum and carpet, keep in mind that these materials have a soft and thin structure, under them all irregularities are felt by the feet and are visible visually.

Plywood flooring is a very convenient subfloor for any living space. It is quite durable, does not deform, this floor will serve you for a long time and reliably. It, of course, can also be used as a final floor covering, because high-quality laid, carefully sanded and varnished plywood looks very noble. But still, plywood is more often used as a base for parquet board, laminate, linoleum. In cottages and private houses, laying plywood on wooden floors is especially popular. This is due to the fact that thanks to the plywood base, 20% more heat is retained in the room. In addition, if after some time you decide to replace the old floor covering, it can be removed without special effort. You won't need to do anything to the existing plywood base. You can simply lay a new coating on it.

Methods for laying plywood

Sheets of plywood are laid on cement base, logs or on a wooden floor.

When laying plywood on a cement base, it is important to either ensure that it is horizontal and even, or use adjusting posts. This is the most common way to lay plywood on a floor. As a rule, such floors can withstand pressure of up to 3 tons per square meter. meter.

The most labor-intensive and most expensive option for laying plywood is attaching it to joists. It is important to set the logs so that they top edges were in one horizontal plane. Next, a plywood floor is laid on them so that the joints of the sheets fall on the joists. Between the lags you can hide some engineering Communication, and also put a layer of sound insulation or insulation. It is important to know that when laying plywood on a floor with a single layer, its thickness should be at least 15 mm, and with a double layer - at least 9 mm in one layer.

The only disadvantage of laying on logs is that this method is not very suitable for rooms with low ceilings, since it takes up to 9 cm of height.

Laying plywood on a wooden floor: basic rules

Laying plywood on a wooden floor becomes especially important when the plank floors have dried out, become loose and become unusable. Plywood will allow you to carry out repairs in the most optimal way - quickly, inexpensively and reliably.

First of all, you should check whether the wooden floors are sagging along the joists (of course, if there are any). If they sag, you will have to completely dismantle the floor covering and repair the base of the wooden floor. If it's not a matter of lags, then the best way out from the position there will be plywood flooring on a wooden floor.
Remember that plywood is not recommended for use where there are too large temperature changes and high humidity. For bathrooms and unheated premises plywood is not suitable. To check whether your floor has high humidity, place a 1x1 meter sheet of polyethylene tightly on it and leave it for three days. If on inside polyethylene, condensation will not appear - the floor is suitable for further use.
Sheets of plywood are laid “dry” with an offset so that a maximum of three seams meet at one point. This is how individual sheets are adjusted to the size of the room, bypassing the protrusions and filling the niches. When carrying out this procedure, remember that between the scattered sheets you should leave a space of about 8-10 mm wide - these are the so-called damper seams. It is important to know: there must be a gap of 15-20 mm between the outer squares of plywood and the walls. Don't worry about it messing up general form, because later these indentations will be covered with baseboards.
In order to final assembly In order not to confuse the fitted sheets, it is worth numbering them and, based on the numbers, drawing up a small plan diagram of their location.
When choosing plywood, keep in mind that the thickness of the plywood sheet should be at least 12 mm, and even better - 15 mm. On perfectly flat surfaces, sheets with a thickness of 8-10 mm can be used. If you are planning, then plywood with a thickness of less than 15 mm will not suit you.
It is recommended to cut plywood sheets into squares with a side of 60 cm. This is how you will get optimal quantity damper seams. In addition, it is easier to detect delaminations that are not visible in whole sheets.
Before finally laying the plywood, you should very carefully clean the base from dust and debris. In addition, it is recommended to carry out priming - this is treating the floor with a special primer.
It is better to lay the plywood on glue, but it is quite possible to do without it. According to numerology, each sheet is placed in its place and fastened with self-tapping screws along the edges and diagonals in increments of 15-20 cm. Make an indent from the edges - 2 cm. It is imperative to recess the heads of the screws, countersinking the holes for the fasteners.
It is important to know that fasteners must be at least 3 times the length of the sheet thickness. For example, for a 12 mm sheet, 40 mm screws are suitable.
After installation, you must carefully

Plywood can be called one of the most universal materials that were invented by man. This raw material is widely used in construction industry. In terms of price-quality ratio, plywood has no competitors. Most often it is used for flooring and repairing floors. However, the high functionality of this material also determines big number methods of working with it, so you need to consider all the nuances in detail.

Types of plywood

IN construction stores for sale a large number of different types plywood. IN repair work The following types of raw materials are often used:

FC is a moisture-resistant material, glued with urea resin, without volatile and toxic compounds. It is strong and elastic, it can be compared to BS aircraft plywood.
NSh is an unpolished material glued with casein glue. This option is the most budget-friendly. Before installing a parquet board or other hard material you need to sand the sheets.
Ш1 is the main raw material for the subfloor. Sanding was carried out on one side. The adhesive composition is also casein
Ш2 - sanded on both sides, glued with casein glue. It can be used for very stressed areas in dry rooms. It acts as a substitute for the FK variety.

The ideal material has not yet been invented and plywood, for all its advantages, also has disadvantages. This material is made of wood, which is known to be a hygroscopic material. For this reason, plywood sheets are not used in damp rooms: prolonged contact with humid air above 68% causes damage to the material. At temperatures below 18 or above 27 degrees, the sensitivity of the material to humidity levels increases. In the range of less than 16 and above 35 degrees and a humidity level of 85%, plywood sheets will begin to peel in 40-60 days, with the exception of the FK grade. Regular plywood is not suitable for use in kitchens, balconies, pantries and bathrooms.

Is it possible to improve the characteristics of this material? A high level of resistance can be achieved by treating with polyvinyl acetate (PVA) putty. This is the most a budget option. The sheets are covered on one side until spots form on the opposite side. The procedure is repeated several times, after which you need to dry it, leaving it horizontally. Drying takes a long time - at least three days at room temperature. When this composition dries, you need to treat the material with an antiseptic-fungicide. Higher strength can be achieved using acrylic varnish. It is applied in two layers, with the second only after the first has finished drying.

Before we talk about how it happens laying plywood on the floor, it is worth noting her adaptation to the room. Plywood, as a natural raw material, needs time to get used to the conditions of use. The acclimatization period depends on fluctuations in temperature and humidity levels:

if the conditions at the place of purchase are similar to those at home, then one day is enough
if the temperature difference is from 2 to 8 degrees, it will take three days
and if the difference is more than degrees, you need to leave the material alone for a week.

Laying plywood over a wood floor is great solution, if the old plank floors have dried out or squeaking has appeared. Using plywood you can short time, at the lowest cost and high level reliability to replace the old coating. First of all, you need to make sure whether there is a deflection in wooden floors by lags. If there is a deflection, you will need to completely disassemble the floor covering and repair or replace it. If the logs are in good condition, then plywood is laid directly on the old base.

How to check if the humidity level in a room is normal? It is necessary to put 1x1 meter polyethylene on the floor and leave it for three days. If after this time the inner surface polyethylene does not form condensation, which means you can begin installing plywood. It is laid “dry” with such an offset that no more than three seams meet at one point. The material is adjusted to the dimensions of the room, but do not forget that you must leave a gap of 8-10 mm between the sheets. In addition, you need to leave a gap of 15-20 mm from the outer squares of plywood to the wall. These gaps will not be visible; they will be covered by baseboards. It is very convenient to work with numbered sheets, relying on a simple layout diagram. When choosing a material, remember that plywood from 12 to 18 mm is suitable for the floor. Only in the case of a perfectly flat base can you take 10 mm sheets. If the finishing material is solid board, then plywood must be laid at least 15 mm.

For greater convenience, experts recommend cutting the plywood into squares with a side of 60 cm. Thus, you will get optimal number damper seams. Plywood sheets are placed only on a clean, level base, free of dust and debris. For greater reliability, the base is treated with a special primer.

Installation of plywood directly on a concrete base is carried out using a special adhesive composition. How to choose glue? When purchasing, pay attention to the following factors:

If children or allergy sufferers will live in the house, water-based glue is preferable. It is odorless and simply diluted with water. It is also suitable as a primer. When using this glue, dowel nails are required. However, this glue takes a very long time to dry.
There are solvent-based adhesives. When choosing such glue, remember that concrete screed additional coating with primer solution is required. The drying period for this glue is 3-5 days. You will also need dowel nails here. The glue has a strong unpleasant odor
two-component adhesive composition dries within a day. Its main advantage is that it does not need additional fastening. If construction works need to be carried out as quickly as possible, then this glue - best option, because it, together with an epoxy primer, can be applied to a damp screed.

Before laying plywood sheets, they need to be cut into squares of 60x60 cm or 75x75 cm. This procedure helps to create multiple seams, which in the future will lead to adjustment of vibrations temperature regime, as well as humidity levels. When installing squares on a concrete base, you need to ensure that all 4 seams do not converge in one corner, but are shifted.

Sequence of work:

Using a notched trowel, place a 2 mm layer of adhesive on a clean base.
Place numbered squares on top. Iron them with a roller to get rid of excess air.
To securely fix the squares, you should use self-tapping screws with plastic dowels, which should be three times longer than the thickness of the sheets. The screw head must be hidden
To obtain a smooth surface, you need to carefully sand the plywood after installation.

After all this work, the concrete floor will be fully prepared for laying any finishing material.

Laying plywood on a wooden floor

Plywood is attached to wooden base two ways:

screws directly onto the base
mounted on installed logs.

How to lay plywood on the floor? At the core the right choice lies a preliminary assessment of the situation and study of the surface. If there are no depressions, then the sheets can be attached immediately. Using plywood you will level the floors.

Installation on joists is carried out mainly in cases where the floor is severely curved or has significant defects. The flooring is successfully carried out both on nails and on self-tapping screws. In both cases, a high-quality coating is obtained. In this work it is preferable to use whole sheets of plywood.

Main installation rules:

checking the stability of the base before installation. If a deflection is detected, the damaged area must be replaced
Do not lay plywood in rooms with high humidity or sudden temperature changes
numbered and adjusted sheets will greatly facilitate the installation process
the optimal sheet thickness is 1.5 cm
Before fastening the plywood, you need to thoroughly clean the surface and prime it
fastening elements must exceed the thickness of the material at least three times, for example, for sheets of 1.2 cm, you need to take screws 4 cm in length
The final step is sanding.

During all work, do not forget that when correct execution all work, the result will please you for a long time.