How to put plywood on old joists. Thickness of plywood on a wooden floor: laying the underlay, how to lay it without glue, flooring in the house, how to lay the covering

When conducting repair work wooden floor apartment owners and country houses Often the old base is covered with sheets of plywood.

Such repairs are quite economical, simple and do not require special skills.

Let's take a closer look at the options for repairing a wooden floor, what type sheet material for this, choose and how to lay plywood on wooden floor.

Material properties

Thick plywood can last for many years

Plywood is a fairly versatile material.

Due to the ease of processing, cutting and installation, sheets can be used to lay quite durable flooring in a short time.

With all this, the material is economical, practical and has other advantages:

non-toxic, does not emit unpleasant odors;
has low weight but high strength;
does not break when bent, elastic;
easy to transport;
has a beautiful front surface;
the dimensions of the sheet make the work of laying a new covering less time-consuming;
budget;
a huge selection of materials in any hardware store.

When choosing plywood as a future floor covering, it is important to buy the right and suitable material and not make a mistake in its physical properties. This type of material also has its disadvantages.

Like any wood-based coating, plywood does not like high humidity, requires getting used to the operating conditions before installation, and is capricious in storage.

Plywood does not crack when drying

The sheet is made by gluing together several layers of wood under pressure. Depending on the number of layers, as well as the adhesive and impregnation substances, the properties of the resulting material vary.

What plywood of any grade has in common is increased anisotropy or uniform distribution properties physical activity know the volume of the slab. At the same time, the material does not crack when drying out and is not prone to deformation.

It is these qualities that make plywood an indispensable material for floor repairs. All manufactured materials are divided by grade, surface quality and moisture resistance.

Marking values on sheets

Marking	Designation	Characteristic
Variety	E, I, II, III, IV	Indicates the structure of the sheet gluing, the quality of the front and back layers
Moisture resistance	FSF	It has an increased level of water resistance, strength and wear resistance. Not for use in residential areas, releases toxins.
	FC	Does not have high stability to moisture, but will remain intact when exposed to water for 24 hours.
	FKM	Increased water resistance
	FBA	Suitable for children's rooms, living rooms, bedrooms. One hundred percent environmentally friendly product. Will not withstand prolonged high humidity.
Surface quality	NSh, Sh1, Sh2	not polished; polished on one side; polished on both sides.
Environmental friendliness (formaldehyde level)	E1, E2, E3	E1 - no more than 10 mg, E2 - from 10 to 30 mg

Any other numbers and designations indicate that the product is rejected and does not comply with GOST.

Suitable material

Which plywood to lay on the floor depends on many factors:

lay sheets on top of the old coating;
laid on joists;
used as finishing or as a leveling base under decorative material.

For the floor, choose birch sheets, which are stronger than other species

It is important to understand which plywood is best to use for various types works For floors on joists, as well as for the base under roll material, it is better to choose birch sheets, they are harder.

To save money, it is appropriate to use grade 3 or 4 unsanded material as a leveling base.

Under hard decorative covering: laminate, parquet, plywood can be used coniferous species. For grouting joints, putty is selected to match the color of the selected material: birch or pine needles.

To level the base, use sheets with a thickness of 1 to 1.5 cm.

Before purchasing, draw a plan for laying and cutting plywood to optimally select sheet sizes and reduce the amount of waste.

Preparation and laying on old boards

Before laying plywood on the floor, the material should be allowed to rest in the room at room temperature and humidity no more than 55% for several days.

The sheets are always laid in a run-up pattern: that is, with the seams offset by at least 1/3 of the side.

There should be a gap of 10 mm between the wall and the plywood layer: plywood is a living material, therefore, in order not to spoil the decorative coating, you need to give it the opportunity to breathe.

The material can be glued to old floor boards

If you decide to lay the slabs on the boards of the old covering, then they should be carefully secured. It is necessary to screw the boards to the joists so as to get rid of creaks and deflections.

The slab should be screwed to the floor with self-tapping screws, securing it around the perimeter and diagonally in increments of 15 - 20 cm.

Installation begins from the wall opposite to front door. During the entire process, be careful to ensure that the sheets do not form waves. The seams should be sealed with acrylic-based putty.

If the plywood will be processed as decorative covering, then it is better to lay high-grade sanded material, rubbing the seams with wood-colored putty, which must be sanded after drying.

Laying plywood on joists

When laid on joists, you can at the same time insulate and waterproof the floor

If it is possible to remove the old wooden covering, then it is better to do this and lay the sheets over the joists. At the same time, you can check the strength of the coating structure and, if necessary, strengthen it.

It is also possible to carry out additional measures to improve hydro- and thermal insulation, which is important for the floors of the 1st floor. When laying sheets on beams, you should calculate the distance between the logs so that one sheet falls on at least 3 guides. For all the details of the process, watch this useful video:

To add additional rigidity, you can mount the sheathing by making jumpers made of beams between the lags. Carefully secure the sheets with self-tapping screws to the joists.

When laying, the sheet should not bend under the weight of a person, otherwise during operation the putty from the seams will begin to collapse, which will cause deformation of the top decorative coating.

Advantages of plywood covering

Plywood flooring is considered by most experts to be a good alternative concrete covering for the floor.

This option eliminates the hard work of installing a leveling screed; installation will not take much time, and the plywood will serve as additional insulation.

In addition, it is a warm and pleasant material to use.

Unlike plank flooring, installation of plywood is economical in terms of money, time and does not require special skills.

The disadvantages include the need additional processing sheets or stacking decorative material. Be careful when purchasing, remember that not all plywood is suitable for flooring in residential premises due to its environmental friendliness.

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

The content of the article:

Laying plywood on the floor is simple process, however, 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.

Main types of plywood for flooring

Wood-laminated board (chipboard) - construction 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. An odd number of layers must be selected - minimum 3, maximum unlimited. 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). The 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 higher than normal - bathrooms, kitchens, bathrooms.
FSF (super moisture resistant). The veneer layers are glued together with poisonous phenol-formaldehyde resin glue. The material has high strength, wear resistance, resistance to mechanical damage. This plywood is used mainly for exterior work. It is prohibited to use in baths and saunas.
FBA (environmentally friendly). The veneer layers are glued with albumin casein glue. The use of such plywood is limited only to dry rooms, as it is susceptible to moisture.
FB (moisture resistant). Impregnated with bakelite varnish. The scope of application is wide. Plywood does not deteriorate even in conditions of high humidity.
BS. Plywood produced using bakelite glue on alcohol based. The material has increased flexibility, strength, is not affected by mold, and is resistant to moisture.
BV. The veneer sheets are joined with water-soluble bakelite glue. Plywood is strong and flexible, but not moisture resistant.

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

When buying flooring material, you need to choose it correctly:

Premium grade (marked E). The material has no external flaws. Used as finishing coating, including for the floor.
First grade. There may be knots on the surface, but they do not exceed 10% of total area sheet, the length of the cracks is no more than 2 cm. This plywood is also used for finishing the floor.
Second grade. There are chips, knots, burrs, and cracks on the surface. The length of cracks can reach 20 cm. The total volume of defects does not exceed 40%.
Third grade. The gluing of the layers is high quality. Wormholes with a diameter of no more than 6 mm are allowed. The number of defects on the sheet is no more than 9. Plywood is used for leveling and 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 fused knots on the surface. For use on subfloors only.

Another division of plywood is produced according to the type of wood - coniferous and birch. Coniferous is made from spruce or pine, some inner layers may be veneer hardwood trees. This plywood is resistant to rot and fungal infections, thanks to the resin contained in coniferous wood. Birch is used for internal and finishing works, made from birch veneer. It is significantly more expensive than coniferous wood and is less often used in construction.

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

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 installation of parquet, linoleum and laminate.

Important! Do not purchase third-grade plywood for flooring. Optimal combination prices and quality for flooring with second grade birch plywood.

Criteria for choosing plywood for the floor

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

When going to the store, pay attention to the following points:

Glue. It is used to connect veneer sheets together. Urea and formaldehyde are hazardous to health. They slowly evaporate. Inhaling them can cause severe poisoning. Albumocasein and bakelite adhesives are safe for human health.
Prices. If the price of a plywood sheet is suspiciously low, it is most likely a low-quality product from China. It has poor performance characteristics, “ruffy” upper layer and poor edge processing.
Marking. Shows the resistance of the material to moisture and what impregnations the wood is treated with.

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

Advantages and disadvantages of plywood for flooring

Wood-laminated boards have 4 positive qualities:

Strength/wear resistance. The original purpose of plywood is to strengthen weak points on wooden floor. The veneer layers are glued perpendicular to each other, resulting in a durable surface. The thicker the plywood for the floor, the stronger it is.
Low price. Plywood is made from veneer, whole pieces of wood are not used, and there is little waste during production. Therefore, the cost of the material is low.
Versatility. Plywood, especially not large thickness, easily takes rounded shapes. Using natural wood this is impossible. Using plywood you can create rounded structures, while finished surface will never crack.
Easy to install. 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 the appearance of knots and burrs. Such manipulations are impossible with wood.

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 the right size and thickness, but 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. She for a long time resists moisture, but is expensive. Therefore, it is irrational to use it for anything other than shipbuilding.

Technology for installing plywood on the floor

Plywood is laid on both concrete and wooden bases, according to the principle of brick bonding with offset, in order to avoid connecting the corners of four slabs at one point. Standard size the sheet is too large to lay it entirely, so it needs to be cut into four parts, obtaining small squares of 60 x 60 cm. In addition to basic ease of use, it is possible to increase the number of damping joints, which are necessary to compensate for deformations when the floor is exposed to heat and moisture .

Preparatory work before laying plywood

To lay the plywood you will need a few tools. This includes a screwdriver and self-tapping screws for attaching the material to the base, a level for checking evenness, a tape measure for marking and cutting, and a jigsaw for high-quality cutting.

Another important point- the surface on which marking and cutting will take place. It should be perfectly smooth and stable. Work with 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 working on the rough base. This material is sensitive to the quality of the base, so you will definitely need a level for work. With its help, you need to check the base on which the plywood will be laid for evenness. If the slope is more than 1 cm per meter, you will have to resort to leveling.

If the floor is wooden and you do not plan to remove it, laying joists will be the solution. If plywood is to be laid on concrete, then you will have to work hard to level it “like an egg.” Before laying plywood, the room must be swept and vacuumed as thoroughly as possible.

Further steps if the base is wooden:

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

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

The work is done like this:

Clear concrete slab from debris and dust.
Knock down any protruding bumps and fill in areas cement mortar.
“Pound” the sinks with cement mortar. Let the floor dry and prime it deep penetration on concrete to enhance adhesion between the subfloor and the future cement screed.
Mark the floor into approximately equal squares. Use beacons for this. Fix them to the plaster mortar and set them at the desired level.
Close the dry cement mixture water according to instructions. Use a drill with a mixer attachment for mixing.
Place the solution in a square located in the far corner of the room, level it with a rule and bring it smooth with a trowel.
When the solution has set, remove the beacon closest to the wall and fill a new square with the solution.
Repeat the steps until the entire floor area is covered with a new screed.
Wait 28 days for new surface will not gain working strength and will not dry completely.

Trying and cutting plywood sheets for the floor

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

Measure the area of the room.
When cutting, take into account the presence of damper gaps of 3-4 mm between sheets of material and one centimeter near the walls. If this is ignored, temperature changes and moisture ingress will lead to “swelling” of the base.
Try on the plywood - lay it down without fastening the way it will be laid in the final version. Lay the sheets with vertical joints shifted according to the bricklaying method. The joints between them should be in the middle of the joist.
After trying on, number the material.

Important! Be sure to check for defects; if the sheets are peeling, replace them.

Floating fixation of plywood to the base

There are two options for installing wood-laminated slabs on concrete - floating directly on the base and on joists.

Installation technology:

Dust the leveled base.
Place the cut and numbered plywood in a stack in the order of the sheets.
Apply glue to the back side of the sheet (the glue should contain pine resin).
Place glue-coated plywood in the far right (or left) corner and press it to the floor.
Using a hammer drill, drill holes in each corner of the glued board (the length of the dowel).
Insert a dowel into the hole and hammer it in.
Repeat the same with the remaining sheets.
Seal the joints between the sheets with wood putty and cover them with mounting tape on top.

Fastening plywood to joists

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

We attach the log system in the following sequence:

Make markings on the floor for installing joists.
Attach them along these markings using special wood glue and self-tapping screws. If there are gaps between the floor and the joists, fill them with pieces of plywood of suitable thickness, having previously coated both sides with glue.
Make the sheathing. The dimensions of each cell must match the dimensions of the plywood sheets.
Fill in free places insulation between the rough and finished floors.

It’s easy to lay plywood floors on joists yourself. The material is marked so that in the middle of each joist there is a junction of two parts or the middle of the sheet. Self-tapping screws are used for fixation, 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 a floor with plywood. Always use a level when working. Use it to level the rough base and install joists. Plywood - comfortable material for further finishing; in addition, it provides good additional thermal insulation and dampens some of the noise.

Both in new buildings and in houses put into operation several decades ago, residents are faced with the task of leveling the floor to change the floor covering, be it linoleum, parquet or parquet board, laminate or other. But modern market offers such a wide range that it is sometimes difficult to give preference to one or another building material.

The purpose of this article is to dispel all doubts and help make a balanced, reasonable choice before starting repairs in own home or apartment.

Features: pros and cons

Of the variety of materials suitable for these purposes, the choice comes down to four of them:

plywood;

When choosing flooring for leveling the floor, you need to take into account the characteristics of each.

Fiberboard– a material made from compressed wood fibers, pre-treated with steam. Synthetic resins or paraffin are used as binders. The production technology does not allow making fiberboard of large thickness, and the raw materials used (most often wood processing waste) do not allow achieving satisfactory strength. Of the entire list, slabs of this kind are the most fragile. Moreover, if the rough surface has significant, and even more so local, hard protrusions, for example, an influx of concrete or a fragment of reinforcement protruding from the screed, this type the material may be damaged even at the marking stage.

DSP– slabs made of fine and medium fraction shavings bound with cement. In addition, a number of chemical additives to reduce negative influence shavings on cement. At the same time, CBPBs have a higher density, and therefore more weight for the same area. They are quite fragile to fracture, although somewhat stronger than fiberboard, they are more resistant to moisture and heat, and are much less susceptible to mold.

OSB– a slab made of large chips, bonded with phenolic-based resins. It is important to remember that in enterprises with incomplete quality control, production technology may be violated, and then the release of phenols may exceed permissible standards.
Plywood– the most environmentally friendly from this list. Technically, it consists of several layers of birch (less often coniferous) veneer glued together. Has a relatively low specific gravity, and is superior in strength to all other materials on this list.

For a number of reasons, plywood is much more convenient to use for repairs:

Save time. In addition to the usual formats of 1.5x1.5 meters, sizes 2.5x1.25 meters and 3x1.5 meters are also produced - you can cover a large area in one time.
Saves effort. Even a leaf big size Can be carried by one person.
Elasticity. Adjacent layers of veneer are oriented perpendicularly, which ensures strength in all directions. This quality will provide higher wear resistance both during installation and during operation of the floor.

Elasticity. If there are some local unevenness of the subfloor in this place, the sheet will be crushed without much loss, and this area will remain flush with the rest. Thanks to its elasticity, the material will not crumble or crack either during installation or during operation.
Environmental friendliness. In most cases, natural resins or natural-based adhesives are used, which increases environmental and consumer safety.
Porosity. Due to its natural origin, this provides ventilation, which will prevent rotting of the lower surface of the finished floor.

Given brief characteristics it is quite enough to make an unambiguous conclusion: a plywood floor is better than a floor made of OSB board, DSP or fiberboard in a number of properties.

Which one to choose?

To perform rough work there is no need to choose premium grades. Moreover, the third grade is also suitable for repairs (according to current standards, there is also a fourth grade, but it is almost never found on the market) - for the intended purposes, this choice is optimal. Small irregularities and roughness need to be cleaned with sandpaper or cut off with a knife.

Of course, if there are obvious geometric violations, “twisted” or, as builders also say, “behaved,” as well as sheets with obviously not right angles, such options are not applicable.

When purchasing, it is also important to check whether there was any damage during storage - for chips, breaks, damp areas, traces of rodents, insects or mold.

Many repairmen determine the quality of a sheet literally by smell - undamaged material has a noble woody smell with barely noticeable notes of glue.

You can often hear from sellers the designation of classification according to international standard ISO (and sometimes according to their own quality system, up to the “F-1 grade TBS grade”), so you need to clarify the grade according to Russian GOST, or, by looking at the packaging, the grade of the product must be noted.

Perhaps some of the material will go to waste, so it is better to purchase with a small margin, about 5-10%.

As for thickness, builders are guided by simple rule– the thicker the better. Indeed, a thicker substrate can hide larger defects. At the same time, you should not overdo it; 8 mm is considered the minimum, recommended – from 14 to 22 mm. In any case, the underlay should not be thinner than the final floor covering.

It is preferable to use sheets of large sizes, but if transporting or laying them is difficult, smaller sizes can be used.

Some stores may offer cutting into ones that are more convenient for transportation.

What to process?

In order not to reduce the quality in the future, it is enough to carry out simple pre-treatment.

This stage consists of several simple operations.

Drying. Before starting repairs, the plywood must be brought into a dry, warm room and left for at least a week (ideally, two to three weeks). This will relieve it of excess moisture that it may have absorbed during transportation and storage. Such long term drying is due to its structure - moisture that penetrates into the deeper layers evaporates much more slowly than from the surface layers.

Biosecurity. To avoid the proliferation of destructive microflora, you can soak at least the outer layers with antiseptic solutions. This will relieve residents from the moldy smell of dampness if water leaks from above or condensation accumulates from the concrete.
Ventilation. After antiseptic treatment, wait at least 24 hours. Of course, while maintaining minimal gaps.
Add moisture resistance can be applied in one or two layers of acrylic-based varnish.

Preparatory stage

At least two days before the start of work, the plywood must be brought into the room where the repairs will be carried out. The workpieces must be laid horizontally, allowed to rest, and excess stress in the structure caused by storage in a vertical position must be removed.

The floor must be prepared: remove the old baseboard, remove all debris and dust, knock down uneven concrete and cut off protruding parts of the reinforcement, soak it with an antiseptic solution.

If the flooring is made without joists, the surface of the concrete must be leveled, if possible, with a cement-sand mortar, then a primer must be applied and allowed to dry. Cement-sand mortar sets for several days, all this time being allocated in environment excess moisture, so it’s better to start preparing in advance.

If the differences in height when checking the level are large, it is necessary to screed or lay joists to compensate for the unevenness.

If laying is carried out over old boards, inspect their condition. Rotten or crumbling areas must be replaced, creaking or wobbly areas must be secured. On wooden base You also need to apply a primer, antiseptic and dry.

At the next stage, you need to lay out the sheets in the way they will subsequently be secured. Compensation gaps should be provided: between elements 3-4 mm, from the wall 8-10 mm, this will avoid swelling if the temperature or humidity conditions change.

During the cutting process, it is necessary to coat the ends of the sheets with glue to avoid their cracking in the future.

Mark the workpieces, and indicate the orientation of the workpieces in one direction either with the inscription itself or with an arrow. For example, indicate a row with a letter, a number with a number, that is, A1 is the first element in the first row. This will avoid confusion in the future. For convenience, you can sketch out a laying diagram on paper.

It is worth avoiding cases when they converge at one point corners of four neighboring fragments. In other words, lay out the workpieces “staggered”, as in brickwork.

Materials and tools

For installation you will need the following tool:

Electric jigsaw. It is unlikely that it will be possible to cover the floor with solid sheets, and perhaps when the angle formed by the floor and the wall is not perfectly level, it may be necessary figure cutting. In addition, you will need to bypass the riser pipes at their exit points. For these purposes a circular saw It is much less suitable, since it allows only straight cuts.
Building level. A level of at least 2 meters in length is preferable, since a shorter tool will not allow you to notice unevenness over long distances.
Tape measure and pencil. After preliminary unfolding, make the necessary markings and markings before starting cutting.

Construction knife.
A screwdriver with a bit that matches the fastener being used.
Vacuum cleaner or broom.
Personal protective equipment: strong gloves, glasses, knee pads, if necessary - headphones (earplugs).

From additional materials:

Self-tapping screws (self-tapping screws) - if laying on joists or an old wooden floor. Fasteners are selected using a simple formula - the thickness of the element being fixed is multiplied by three. For example, if the sheet is 20 mm, then the length of the screw is at least 60 mm. In this case, the screw should not be longer than the combined thickness of the flooring and the wooden base.
Dowels corresponding to self-tapping screws - if installation is carried out on concrete or screed.
Wood glue (usually regular PVA is used) or “liquid nails”.
Sealant (polyizol).

Installation methods

Depending on the condition of the room being repaired, apply different methods installation of the rough base:

on top of a concrete floor (or screed);
on top of an old wooden floor;
on the logs.

Based on this, one or another fastening technology is used.

On the old floor

The technology for laying plywood on old floor boards is quite simple. In your own house or apartment, it is quite possible to do this work with your own hands. After all preparatory activities you need to lay out and cut out the backing. It is important to avoid overlapping laying, preferring butt laying, so as not to add unevenness. Secure the joints of the seal with wide tape and trim off the excess.

Then start laying out according to a pre-drawn plan, observing the markings. Start from the corner, gradually expanding the “spot” in both directions.

The elements are screwed on with self-tapping screws, retreating from the edge at least 2 cm, and with a step between the fastening points of no more than 20 cm, recessing the cap.

How to lay on joists?

For the logs, a timber made of coniferous wood with a cross-section of at least 50x50 mm is selected. Preference should be given to dried timber without visible violations of geometry (not twisted into a screw and without bends along the longitudinal axis), without chips or other mechanical damage.

To isolate wooden elements from dampness below, before laying them it is advisable to pre-lay them with insulation (polyizol), securing the seams with adhesive tape.

It would be correct to start laying the logs from the highest point selected using a level. It is important to keep the pitch of laying the timber uniform, 50 – 60 cm, no more.

Innovative technologies for decorating rooms today have also affected floor coverings. The most commonly used materials for this are laminate, cork, and parquet boards. Such coatings require a perfectly flat surface, so technology that considers the question of how to properly lay plywood on a wooden floor has never been more relevant.

Plywood as a leveling material wooden floors has many beneficial advantages.

Advantages of the material:

Low cost of purchasing material.
Thanks to the peculiarities of the manufacturing technology, during which plywood layers are laid perpendicular to each other during gluing, the material receives a high level of strength.
Plywood sheets can have a large format, due to this you can significantly facilitate and speed up the process of covering large areas.
Due to its excellent flexibility, the material can bend without being damaged.
Does not create problems with storage and transportation.
Ease of use.

Features of material laying

The installation procedure becomes especially relevant when the plank floor dries out, becomes loose and becomes unsuitable for further use. Using plywood you will save not only money costs, but also your efforts.

Features of working with plywood:

Before laying plywood on a wooden floor, check that it does not sag where the joists are placed. If this happens, you must do complete disassembly coverings and repair the base of the wooden floor. If there are no problems with the joists, then you can proceed to laying the plywood directly onto the wooden base.
Plywood should not be laid in rooms where there is a sudden change in temperature or where there is a high level of humidity. Unheated rooms and bathrooms are not suitable for laying this material.

Note! In order to find out how high the humidity level of your floor is, you need to tightly lay a polyethylene sheet with parameters of 100x100 cm on its surface and leave it in this position for at least three days. After this period, look at the inside of the polyethylene, if you do not find condensation there, the floor is suitable for laying plywood.

The plywood is laid in such a way that the sheets move slightly. As a result, at least three seams should converge at one point. Be prepared for the fact that you will have to adjust some sheets to the parameters of your room. Such nuances may be caused by the presence of niches or protrusions in the room. It is necessary to leave gaps between the plywood sheets, as well as in the area near the wall. Subsequently, these distances will be covered with skirting boards or sealed.
To make your work easier and not get confused with the placement of sheets after cutting them, you should number the plywood and draw up a plan for its installation.
The most convenient size a square with sides of 0.6 m is considered. Using plywood of this format, you can provide yourself required amount damper joints and at the same time identify delaminations that are invisible on solid plywood sheets.

Before you begin laying plywood, you need to prepare the floor surface, remove traces of dirt and dust, and apply a layer of primer.
Sheets of plywood are laid on an adhesive composition. Otherwise, you will have to secure the material with self-tapping screws, not only along the edges, but also along the diagonals in increments of 20 cm. You need to retreat a couple of centimeters from the edges. The screw caps must be well recessed.
The length of the fasteners must be at least three times greater than the thickness of the plywood sheets. For example, with a sheet thickness of 1.2 cm, you will need to take screws 4 cm long.
After laying is completed, the surface must be sanded using a parquet sanding machine and sandpaper with large grains.

If you want to learn more about how to lay plywood on a wooden floor, the video review below describes all the nuances of this procedure.

Cutting plywood and installing joists

Plywood is cut to fit the sheets to the room parameters. As for damper joints, the gap between the sheets should be at least 4 mm and one centimeter at the walls. If you ignore this nuance, subsequently, when temperature changes occur in the room, the floor surface will begin to deform and swell.

After cutting the material, check the end parts. In places where cuts are made, delamination and other defects usually occur.

Note! If the plywood sheet is damaged, it is better not to use it.

All sheets cut according to the size of the room must be placed on the floor in the order of their further fastening. You should not achieve a joint at the four corners; it is better to take the technology of placing bricks as a basis. In places where the joint of plywood sheets is formed, there should be a joist.

The logs themselves should have a thickness of 3-4 cm; they are secured using an adhesive composition intended for wood. You can also use self-tapping screws. During the installation of joists, gaps may form between them and the floor, which must be closed with pieces of plywood of appropriate thickness. To do this, the sheet is smeared on both sides with an adhesive composition and placed in the required place.

This is also the procedure if you get inaccuracies in height. Be sure to control the horizontal placement of the logs using a building level, because this will determine how level your floor will be. It is worth placing sealing material in the space that is formed between the joists.

Before fixing the plywood to the joists, it would not hurt to treat all sheets with an antiseptic.

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

Plywood is widely used in construction industry. It can be used to create partitions, cladding walls and ceilings in wooden house, formwork is built from it and floors are often leveled with it before laying coverings that require the 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. Due to this, the strength of the material increases.

For installation in warm and dry rooms, e.g. residential buildings, plywood is a material that fits perfectly. It’s easy and quick to work with, which is what attracts many builders and novice craftsmen to use it. If necessary, sheets that have lost their strength and reliability can be easily replaced with new ones.

On a note! Plywood makes an excellent option for a dry screed; you won’t have to wait 30 days for it to dry (unlike a regular cement screed) - you can begin laying the topcoat almost immediately after installing the plywood. Using this material will save not only time, but also money during renovation of the premises.

Advantages of plywood on the floor

Plywood is so often used as a leveling material for wooden floors 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 repairs gender;
makes it easy to make floors even, copes with both the curvature of the base and 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;
do-it-yourself installation without the involvement of craftsmen;
easy to process;
is environmentally friendly pure material , smells nice of wood.

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

On a note! Sometimes plywood is used to create very beautiful options floor finishing.

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

What types of plywood are there?

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

Also, plywood varies depending on its purpose. The following types are distinguished:

industrial;
for package;
furniture;
structural;
construction

Sheets of material can be made from various types of wood. So, they distinguish:

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

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

On a note! The size range of plywood sheets is quite large. 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 albumin casein glue. Such plywood is afraid of water, but is absolutely safe for human health, as it is environmentally friendly.
	The plywood is impregnated with carbamide glue. It does not have increased moisture resistance and therefore can only be used for making furniture and for indoor work. Exposure to outdoor precipitation or high level it will not tolerate humidity.
	Also called aviation. It is made using bakelite alcohol-soluble glue. It was previously used in shipbuilding, the creation of aircraft and other aircraft. Has increased strength and resistance to impacts external factors, 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 open-air structures.
	The layers of material are impregnated with bakelite-based varnish. This plywood can be used in quite aggressive environments. If necessary, the material can long time withstand exposure to moisture.
	Plywood with high fire resistance. Otherwise, this material is unremarkable.
	The layers of this plywood are impregnated with formaldehyde glue. It turns out durable material, which is not afraid of moisture. It also practically does not burn, which is important for the construction industry.

Prices for plywood for flooring

plywood for floor

Which plywood to choose

Among such a variety of types of plywood, how can you choose the one that is suitable for a subfloor and will cost reasonable money? To do this, it is important to evaluate the operating conditions of the material. For example, in an ordinary room, plywood without any special properties can be used to level a subfloor of wood. 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 purpose well. 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 designated by the abbreviation FBA. This is the most environmentally friendly type of material.

Advice! You should not buy plywood made with phenolic glue for your apartment or house. It may be too toxic. Although, it is worth admitting, its level of moisture resistance is excellent.

The dimensions of the sheets are also important, especially their thickness. To make wooden floors smooth, it is enough to use sheets 10-15 mm thick. Although some experts claim 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’s easier to evaluate the actual costs and see which option will be more profitable from a budget point of view. 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 requires compliance with installation certain rules. If they are neglected, 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: installation 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 unsightly gaps between individual boards or has lost its appearance. The sheets are placed with small gaps - up to 3-5 mm between them. A distance of 15-20 mm should be maintained to the wall. The sheets are attached using self-tapping screws or glue. Glue consumption is about 1.2-1.5 kg/m2. Installation of the sheet should be carried out by screwing in self-tapping screws around the perimeter, and then diagonally.

Plywood can also be used to cover a slightly crooked floor. In this case, the material is partially laid on the base itself, as well as on small bars that will act as a kind of lags. The bars can have different cross-sections depending on the curvature of the floor. Sometimes even scraps of boards are used.

Less often, when the subfloor has completely become unusable, a new base is created from plywood installed on joists or supports. In this case, the old base is completely dismantled, and then logs are installed, onto 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 support underneath them.

Required tools and materials

To install plywood sheets on a wooden base, you may need the following tools:

screwdriver;
drill;
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 to use, since they are the easiest to work with.

Preparing for work

Before laying sheets of plywood, a series of preparatory work. It includes:

assessing the condition of the wooden base and repairing it if necessary– replacing dried out floorboards or floor screed. Floors should not “walk”, sag, or creak;
checking and measuring humidity levels in room;

On a note! You can find out the humidity this way: a piece of polyethylene measuring approximately 1x1 m is placed on the floor and secured to the base. After 3 days have passed, the film is lifted and its condition is assessed. If condensation has accumulated on it, then the humidity in the room is high and only moisture-resistant plywood can be laid.

removing all debris from the rough base. If it remains, the plywood will not lie flat. The floors can be swept and vacuumed, and washed if necessary;
The plywood itself must also be cleaned of sawdust and dust;
recommended process the old one wooden surface 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 a building level, after which the protruding parts can be filed down. The floor should be as level as possible.

Step 2. Holes are drilled in the floorboards where the joists run and screws are screwed into them. This procedure will make the floors stronger. Screws are screwed into each board at approximately a distance of 50 cm from each other.

Step 3. The rough base is covered with a thin backing. Its individual strips are fastened together using tape. The strips are laid with an overlap of 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. The 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 can be taped after installation. The base is ready for laying the finishing coating and installing skirting boards that will hide all the gaps near the walls.

Video - An unusual way of laying plywood on a wooden floor

Video - Installation of 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 the work. This is important to do before installation. finishing coating. Using a long, even strip, the evenness of the material is checked - the gaps between it and the floor level should not be more than 2 mm according to SNiP 3.04.01-87. Next you need to use building level and evaluate horizontality. The permissible slope cannot be more than 0.2% according to the same document.

SNiP 3.04.01-87. Insulating and finishing coatings. Downloadable file (click the link to open the PDF 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 areas of possible delamination of materials. Where the sound upon impact will be dull, there is problem area. The sound when tapping the entire plywood floor should be the same if the sheets were laid correctly and were not damaged during installation.

It's not called plywood for nothing universal material. It was also suitable 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.