Laying plywood on a wooden floor: material selection, preparation, installation in stages. Plywood floor. Do-it-yourself plywood flooring video. Calculation, alignment, types How to properly lay plywood on a wooden floor

Plywood is a relatively budgetary, fairly durable and easy-to-work material, perfect for leveling a wooden floor. Mostly plywood is used to level small differences in the height of the base before the upcoming laying of the finish coating. If desired, even tiles can be laid on top of plywood.

It is not surprising that this sheet material gained such wide popularity both among professional builders and among private developers. By reading the information below, you will have a complete understanding of the selection of suitable plywood and the actual process of leveling a wooden floor using different methods.

Among the key strengths of plywood, the following points should be noted:

relatively big sizes sheets, which allows you to quickly level the floor with the minimum amount waste;
ease of installation;
high strength, reliability and durability;
the possibility of using even in rooms with a high level of humidity (meaning either special moisture-resistant plywood, or pre-treated material, more on that later);
lack of sharp unpleasant odors;
ease of processing.

Also among the important advantages of plywood is the fact that when it is used, there is an additional increase in the thermal insulation performance of the floor structure.

Most often, leveling a wooden floor with plywood is resorted to in the following cases:

if necessary, eliminate minor irregularities in the base;
when preparing the surface for the subsequent laying of the finishing coating;
when arranging a heat-insulating layer.

Choosing plywood for leveling a wooden floor

Plywood can be used both for arranging a subfloor and for installing a finished structure - it all depends on the quality of the material and features specific situation.

Plywood is classified into 5 grades. Grade E is the best - such material has absolutely no defects. It is not advisable to use expensive grade E plywood for leveling the floor. It is used mainly in Food Industry, furniture business, art craft, etc.

Information on other existing grades of the sheet material under consideration is given in the table.

Table. Plywood grades

Variety	Description
	As a rule, plywood of the first grade does not have external defects, although GOST allows the presence of microcracks and minor chips.
	In accordance with the approved regulatory requirements, the amount of traces of glue should be no more than 2% of the area of such plywood, small dents and scratches - up to 5%. Plywood of the second grade is optimally suited for leveling a wooden floor in terms of price and quality ratio.
	The material of the third grade will contain a relatively small amount of wormholes and knots.
	Worst option. The quality of veneer gluing is usually quite high, as well as the number of external defects. Such plywood belongs to the category technical materials and is used extremely rarely for leveling the floor, except in various temporary buildings and non-residential country houses.

To level a wooden floor, it is best to use plywood of 2-3 grades, made without the addition of phenols (marked as FC). Such sheet material will have a certain number of external defects, but in terms of quality and cost it is the best.

It is desirable that one side of the plywood be sanded. This can be understood either by visual inspection of the material, or by marking Ш1. If a finishing material will be laid on top of the plywood, the sheet leveling layer is laid with the unsanded side up to ensure better adhesion to it.

The optimal thickness of plywood for leveling the floor is 12-16 mm. If the floor of the room will be subjected to high loads, it is advisable to increase the thickness of the sheet covering.

It is best to buy certified material from a trusted manufacturer / distributor. In this case, the chances that the plywood has passed all the necessary technological stages of production increase significantly.

Additionally, veneered plywood can be included in a separate group. Such plywood is characterized by increased moisture resistance and is well suited for use in rooms with an increased level of humidity.

Prices per sheet of plywood

plywood sheet

Video - Types of plywood

About pretreatment of plywood

For use in residential premises, plywood of the FK, FSF brands and special grooved material are suitable. The first is characterized by less strength and moisture resistance, but is cheaper, the last two are more durable and resistant to moisture, but expensive.

If it is planned to level the wooden floor in a room with a high level of humidity and you do not want to overpay, buy FC brand plywood and prepare it accordingly for the upcoming operating conditions.

On average, the moisture content of plywood is kept at the level of 12-15%. To increase the moisture resistance of the material, polyvinyl acetate putty is used, which in its external qualities resembles PVA glue (polyvinyl acetate is its main component).

Buy the mentioned putty, prepare it for use according to the manufacturer's instructions and do the following:

take a sheet of plywood and start evenly covering it with putty;
apply 2 coats of putty reverse side sheet;
leave the plywood for 3-4 days in a room with room temperature and a normal level of humidity;
treat the dried sheet material with an antiseptic.

If you are not particularly limited in the budget, you can initially purchase moisture-resistant plywood.

To further increase the strength of plywood, it can be coated with a double layer of acrylic varnish on each side. Before applying a new layer of acrylic varnish, wait until the old one is completely dry.

Important! Apply paint coatings not allowed in rooms with high temperatures.

Most often, plywood for leveling the floor is sold in sheet format with dimensions of 1220x2440 and 1250x2500 cm. Experienced craftsmen recommend cutting such sheets (with an electric jigsaw or other suitable tool) into 4 squares with sides of about 600 mm. There are several advantages to such a solution:

Important! After sawing a sheet of plywood, make sure that there are no delaminations at the ends of the elements. Smooth out the identified defects. If you leave everything as it is, the finished design will be of extremely poor quality.

Before laying, let the plywood sheets lie down in the equipped room for several days. To avoid deformations, lay the elements on top of each other. Such actions will allow the sheets to get used to the conditions of the room. If you immediately lay out the floor, the sheets are deformed. Together with them, the finish coating will also deteriorate.

Useful advice! If possible, check with the seller in what conditions the plywood was stored in warehouses. If there is no difference between the temperature in the place of storage and the room being equipped, the acclimatization time will be 1-2 days, with a difference of up to 8 degrees, the sheets should be allowed to lie down for 3 days, if the temperature differences are more significant, the acclimatization period will drag on for a week.

In the future, methods for attaching plywood using self-tapping screws will be mentioned. It is impossible to use ordinary black fasteners for such work - low-power screwdrivers will not cope with screwing them, high-power ones will simply break them. To avoid such inconvenience, fix with special yellow wood screws.

Important! With any mounting option, plywood is laid in a run-up with the formation of T-shaped seams between sheets in adjacent rows.

Prices for putty for plywood

putty for plywood

Plywood fixing methods

There are several methods for attaching plywood to wooden floor:

with height differences up to 5-10 mm, plywood is attached directly to the base;
with differences of 10-80 mm - on logs or adjustable studs.

Attaching plywood to the base

The easiest option. The procedure is the following.

Note! The illustrations include third-party fasteners. We do not pay attention to them.

First step. The plywood sheets are allowed to acclimatize, after which they are marked into squares of approximately 60x60 cm (you can change the dimensions at your discretion, so that it is convenient), they are sawn with an electric jigsaw or other suitable tool along the marking lines and the resulting elements are laid out on the floor of the room, thereby determining the most optimal, correct and rational in terms of the amount of waste laying scheme.

Let the plywood acclimate

Second step. A visual assessment of the coating and seams is performed. Plywood is laid with dressing, so that the seams between the elements placed in adjacent rows do not intersect. Correct option stacking sheets is shown in the image. Detected inaccuracies are immediately eliminated. The gap between plywood sheets is up to 2-3 mm (most often they withstand a 0.5-1 mm gap), between plywood and adjacent walls - from 5-10 mm.

Third step. Sheets are numbered for greater ease of stacking in the future. At the same stage, if necessary, the surface is polished with a special tool or manually. sandpaper(long and laborious).

Fourth step. The coating is disassembled, the sheets are temporarily removed to the side. The base is cleaned of debris, dust and other contaminants.

Sheets are laid out on the surface in accordance with the previously selected scheme and compliance with the mentioned gaps. The flooring elements are attached to the wooden base with self-tapping screws.

The optimal length of the fasteners is 3.2 cm. Embed the self-tapping screws into the plywood by a couple of millimeters.

The optimal arrangement of fasteners is as follows: one for each corner of the sheet, one in the center of each side, one in the center of the sheet.

Useful advice! If the plywood is laid on top of a solid boardwalk, PVA glue for wood can be used to fix it in combination with self-tapping screws. In this case, firstly, better bonding of plywood to the base will be provided, and secondly, the risk of creaks when walking on the floor will further decrease.

Easy to apply glue notched trowel. Either the base or the plywood sheet is covered with a binder composition - as it is more convenient in a particular situation. For recommendations regarding the optimal thickness of the adhesive layer, check the instructions for the composition used. The order is as follows: first, the sheets are glued, then they are additionally fixed with self-tapping screws.

Also check the drying time of the adhesive in the instructions for the selected binder composition.

Prices for PVA glue for wood

pva glue for wood

Video - How to level the floor with plywood yourself

Video - How to level the floor with your own hands under the laminate, linoleum, flooring

High-quality coniferous or deciduous (except for poplar and linden, because they are not strong enough) boards of 2-3 grades 4 cm thick and 8-10 cm wide are well suited for arranging the log.

Linings of 10-15 cm wide, with a thickness of 2.5 cm and a length of about 20-25 cm are placed under the lags. The thickness of the linings may vary depending on the existing differences in the base. The linings are set strictly according to the level so that the logs, and with them the plywood laid above, do not deviate from the horizontal.

More modern method leveling the base involves installing a log on adjustable studs. Information regarding determining the operating level and setting the lag on adjustable feet cited in a publication dedicated to .

The design of adjustable logs

Logs for plywood are installed with a 40-50 cm step. Supports are attached across the room. A 2-3 cm gap is maintained between the ends of the log and the walls.

The procedure for installing the log with the subsequent laying of plywood flooring is given in the table.

Table. Leveling the floor with plywood along the logs

Stage of work	Description
	The leveled base is cleaned of all existing dirt and debris.
	Recommendations for determining the working level, according to which the surface will be leveled, are available at the link provided earlier.
	To level differences in heights, in this example, bosses are used - linings from pieces of timber, plywood, etc. In order to increase the accuracy of level control and the stability of the structure, place the bosses not only at the edges, but also in the center of each log. If the log length exceeds 2 m, install additional pads in 50 cm increments. By changing the height of the bosses, ensure that they are located in a single plane. You can make sure that there are no drops using a level or, even simpler, a rule - a straight rail with a length (specifically for this case) of at least 200 cm. The principle is as follows: lay the rule on the bosses and make sure that the tool lies evenly and without gaps on all linings . Useful advice! Lay a piece of linoleum or roofing material on top of the bosses. The material will take on the functions of a shock absorber and will allow you to more accurately adjust the level of attachment of the lag. Do not fix the bosses at this stage. The wooden floor is being leveled, so in the future, having laid the logs, you can pull them to the base using self-tapping screws or other suitable fasteners directly through the lining.
	Proceed to laying the lag on the bosses. Keep the step between the lags in accordance with the dimensions of the plywood sheet (in this example, 600 mm). Make sure that the lag is even with the help of a building level or a rule according to a familiar pattern. Eliminate the detected deviations by adding or removing the material of the corresponding bosses. For fastening the log to the wooden floor, as noted, it is convenient to use self-tapping screws. Screw 2 fasteners into each point.
	Without cross battens, plywood flooring will warp and fail very quickly. Reiki are made from the same material as the logs. In the center of each future cross-beam, lay the bosses on the base. Pull the rail to the base through the bosses with self-tapping screws - 2 for each pad. Use metal corners to fasten the cross-beams to the joists. The step between the slats is up to 50 cm.
	Having finished with the arrangement of the crate, proceed to the flooring of the sheet material. Each sheet must rest on at least 2 joists. To prevent squeaks from subsequent walking on the floor, lay sheets with gaps of up to 0.5 mm. Plywood is attached to the logs and intermediate rails using self-tapping screws. Maintain a 50-70 cm step between fasteners. Sink the heads of the self-tapping screws into the wood a little.

Video - Leveling the floor with plywood along the logs

Mounting plywood on adjustable studs

This option for leveling the floor with plywood is the simplest and fastest in its implementation: anchors are screwed into the base and plywood is put on them through pre-prepared holes. By screwing in / out of the anchors, the required floor level is set.

The system looks like this.

It was considered in detail in the corresponding publication of our site, be sure to check it out.

Video - Laying plywood on adjustable studs

As noted, the technology allows the use of plywood for leveling bases, the height of which does not exceed 80 mm. But what if the irregularities are more significant? Stop using plywood? Not necessary.

Recommendations regarding the obligatory preliminary elimination of height differences are given for the simple reason that the sheet material, under the influence of the loads exerted on it, will repeat the contours of irregularities, deform and fail.

To prevent this, do the following.

To get started, take a long level and find the places with the most pronounced elevation changes. In the discovered areas, in increments of about 20 cm, screw self-tapping screws into the floor. By tightening / unscrewing the screws, ensure that their hats are located at a single horizontal level.

Plywood will be laid on screwed screws. To prevent the sheets from bending, the void between them and the uneven base must be filled with something. A mixture prepared from a fraction of small sawdust and the same amount of PVA glue is perfect. Before laying plywood, cover the recesses with the specified composition. In addition, cover the side of the sheet with which it is laid on the base with a double layer of PVA glue. The specified mixture dries within a week.

To ensure the highest quality and even fit of plywood to the base, fix the sheets with self-tapping screws. Maintain a 50 cm stride. Correct scheme placement of fasteners is shown in the image.

Video - How to level a wooden floor with plywood

Dry prefabricated floor screed is most often made from plywood sheets. It is believed that this is an ideal base for any type of flooring, including linoleum, laminate, carpet and even ceramic tiles. A high-quality and durable plywood floor on logs requires attention to the nuances and compliance ground rules specified in SNiP.

Plywood is a multi-layer wood-sheet material, which is made by cross-gluing an odd number of layers of peeled veneer. For production, birch raw materials or coniferous species of technical grades are most often used, less often - oak, beech, linden and others.

Advantages of plywood:

high mechanical strength to any load;
relatively small weight;
low coefficient of thermal conductivity;
acceptable level of humidity (8–12%), which allows the use of some types of plywood in damp and unheated premises: kitchens, bathrooms, balconies, loggias, etc.;
application in combination with systems "warm floors" of water and infrared type.

The downside of sheet material is that adhesive compositions that are unsafe for human health are used for production. As a rule, products are assigned an emission class of at least E1.

Plywood products are classified according to the following criteria:

Scope of application.

The fields of application of sheet material are endless - from construction to electrical engineering. But for the formation of a prefabricated screed or a finished floor, it is recommended to use structural and building varieties.

Mark.

This parameter is determined by the type of adhesive used. Consider three basic types:

FSF (plywood glued with resin phenol-formaldehyde glue). The product is considered moisture resistant, it is used for finishing rooms with normal and high levels of humidity.
FC (plywood glued using urea-formaldehyde glue). Refers to products of medium moisture resistance, recommended for use in dry rooms.
FBA (plate on albumin - casein glue). Positioned as a material of limited moisture resistance.

Sort.

According to GOST 3916.1–96, the products differ in the number of permissible defects and flaws in wood, as well as the marriage made during processing. There are five levels of quality:

E - extra or elite. The product is made of oak, alder, birch and other species, has a perfectly even, smooth surface, there are no slightest defects. A slight deviation in the structure of wood of a random type is allowed.
I - pin and healthy light or dark knots are possible - no more than 3-5 pcs. for each square meter surfaces. Slots (except for closed cracks) and other types of marriage are excluded.
II - healthy, partially intergrown, non-united and falling knots with a diameter of up to 6 mm, wood inserts and open cracks up to 200 mm long and not more than 2 mm wide are allowed.
III - there are: a) wormholes and holes from fallen knots with a diameter of up to 6 mm in an amount of not more than 10 pcs. per 1 m² area; b) open cracks 300–600 mm long and up to 5 mm wide (provided they are sealed with fillers or sealants); c) dents and scallops.
IV - a surface with all sorts of defects: from intergrown and fallen knots without limiting the number to defects along the edges up to 5 mm deep.

For a subfloor on logs, as a rule, sheet material of 1–4 quality grades is used. Please note: plywood is usually double marked, such as 1/2 or 2/2. Corresponds to the grade of each side. That is, a class 1/3 product is characterized by the fact that one surface is assigned category 1, and the second - 3.

The nature of the processing.

Sanded and unsanded plywood.

Plywood boards are either sanded or unsanded. Marked:

Ш1 - processed only on one side.
Ш2 - polished on both sides.
NS - unpolished.

Laying the floor along the logs is carried out using plates of any kind. But common sense dictates that it is better to use products that have been sanded on at least one side. This will create the most even and smooth floor for the installation of linoleum, laminate, etc.

Dimensions.

Length plywood sheets can reach 6 m, width 3 m, and thickness starts from 3 mm. For draft and finishing work material used on horizontal bases:

1525x1525 - the most commonly used size for the floor by joists. The amount of waste is small, easy to transport.
1210x2440 - for leveling the bases in multi-storey buildings of standard series with elongated room shapes.
500x3000 - convenient in multi-storey or commercial new buildings, where the principle of studios or free planning is implemented.

The optimal thickness of plywood for the floor along the logs depends on the type of prefabricated screed and the level of load. If it is planned to install in two layers, then it is better to choose products with a cross section of 8–12 mm, and for single-layer installation - 8–22 mm.

Lags and fasteners

According to SNiP 3.04.01–87 (SP 71.13330.2017) “Insulating and finishing coatings”, chamber-drying wooden beams with a moisture content of 12–18% are used to form the floor along the logs, with a moisture content of 12–18%, without cracks, bark and traces of rot. In this case, the length of the joined supports should be at least 2 m, the thickness - from 40 mm, and the width - 80-100 mm.

Although many experts recommend purchasing slats with an aspect ratio of 1:1.5 and 1:2, in practice, logs of 50x40, 50x50, 50x70 and more are most often used. Moreover, the height of the supporting elements depends on various parameters: the load level, the section of the insulation used, the maximum floor height and even the personal preferences of the customer. There are no universal recommendations, components are selected in each case separately.

For the arrangement of the supporting frame in apartments and private houses, the most even, durable timber from inexpensive species is required: pine, spruce. If finances allow, then you can purchase products from larch, aspen, and alder that are resistant to moisture changes.

Do not forget that wooden structural elements are not highly bioresistant. Therefore, they must be treated with fungicidal and hydrophobic agents. This will significantly increase the life of the entire floor structure.

It would be useful to mention the lining elements under the logs. Building codes do not recommend the use of wooden wedges and bosses due to the fact that the material easily changes shape with changes in humidity. When mounting on a concrete or plank floor, mineral screed or point supports under a beam, it is better to lay hardboard strips.

In practice, many craftsmen prefer to lay pieces of OSB, chipboard, MDF or moisture-resistant plywood on the floor. The minimum size of the lining should be 10x10 cm or 10x15 cm, the interval between them should be at least 30 cm.

Laying the lag on glued plywood linings.

As an alternative, insensitive to moisture, you can use special anti-corrosion-coated support and fastening elements designed for adjustable floors.

Consider another important component of the floor structure - hardware. In addition to the lag, you will need fasteners for fixing them to the base, as well as for attaching plywood sheets to the frame. These can be anchors, nails, universal or self-tapping screws, metal corners, etc.

The range of fasteners is huge. For fixing pads or directly to the lag concrete base dowels are most often used - nails with a thread with a diameter of at least 6 mm or metal anchors of a mechanical type. The former are cheaper, but the latter provide a more reliable and durable fixation of the rails to the base.

An example of fixing a lag to the floor with corners.

Anchor fasteners for concrete and brick are made of high-quality alloys - brass, stainless steel. It consists of a spacer or working sleeve (changes dimensions when a connection is formed) and a non-spacer part - a rod. To mount the frame to the base, a hole is drilled in concrete with a diameter equal to the section of the sleeve or 0.5 mm less than it. When hammering or screwing in, the mounting post expands the sleeve inserted into the channel. And due to this, it is firmly fixed in concrete.

The dimensions of the hardware product depend on the dimensions of the supports. For mounting underlays made of chipboard, plywood, OSB, as well as wooden lag most often used products of category M 6 – M 12, that is, with a rod or wedge diameter of 6 to 12 mm. The length is selected based on the thickness of the lag and / or backings, taking into account the depth of penetration into concrete from 5 cm or more. The approximate interval between fasteners is 30–60 cm.

To rigidly attach linings or logs to a wooden subfloor, you can use wood screws with rare carvings or universal galvanized ones with a diameter of 4 mm or more. The distance between the hardware is at least 30 cm, the screwing depth is from 30 mm.
For attaching plywood to the logs, it is most convenient to use special self-tapping screws for GVL and chipboard or universal galvanized ones. The former differ from the standard ones in mixed screw threads and notches on the cone-shaped cap, which provide countersinking. The length of the hardware should be 2–2.5 times the thickness of the coating, the diameter should be from 3.5 mm or more.

For plywood on logs, it is not recommended to use black hardened wood screws. Practice shows that with seasonal changes in geometric dimensions, this type of hardware breaks under load, and the structure “loses” rigidity.

Ordinary nails with a cylindrical shaft and a sharp end can also be used. The efficiency and speed of work will increase several times if you use fasteners not in bulk, but in a cassette designed for nailer. The product is aimed at the base or the supporting frame often - at a distance of 15–25 cm.

Step-by-step instruction

For do-it-yourself installation of a prefabricated screed, you will need:

Plywood sheets of suitable thickness.
Legs are wooden.
Lining material for leveling the base.
Antiseptic primer.
Hardware.
Noise and / or thermal insulation with accessories.
Repair compositions for partial restoration of a damaged base.
Waterproofing.
Damper tape.
Silicone sealant or flexible wood putty.
Roulette, marking pencil, metal ruler or rail.
Drill / screwdriver or hammer / nail gun (nailer) with accessories.
Level laser or water.
Spatulas, brushes, rollers.
Cutting tool with accessories for wood and plywood ( a circular saw, jigsaw, etc.).
Grinder machine.

The technology of work on the installation of a prefabricated screed is partially presented in SNiP 3.04.01–87 (SP 71.13330.2017) “Insulating and finishing coatings”. In accordance with the recommendations of these standards, laying is carried out in 4 stages.

Training

Any repair begins with cleaning the base from debris, dirt and dust. It is advisable to remove oil, bituminous and similar stains, traces of soot and soot from the surface.

No professional will start work without partially repairing the damaged areas. Rotting, damaged elements of the wooden flooring must be replaced, and cracks and loose areas of the mineral base must be restored. To do this, you need to embroider the cracks, remove dust and fill with repair compounds. If possible, it is better to clean off fragile sections, and smooth out the formed pits with the help of cement-sand, bulk and other quick-drying mixtures.

If necessary, the floor is waterproofed. It is needed if:

need to protect the structure from residual moisture concrete base;
under the ceiling there is a cold basement;
the floor on the logs is arranged in the bathroom and the room located on the floor below should be protected from possible leaks.

To create a waterproofing, the entire available range of materials is used: films, membranes, rolled glued products, coating compositions, paints and the like.

In some cases soundproofing of the base is required. According to the rules, the acoustic layer is placed between the base floor and the screed. Therefore, noise-absorbing mats are laid under the logs. If soundproofing mineral wool (stone or glass) is used, then it must be laid in the openings between the lags, and they themselves support rails fixed using point acoustic spacers.

Laying lag on acoustic pads.

It is desirable at this stage to treat the timber, bosses and other wooden structural elements with antiseptic impregnations.

Formation of a power frame

The log frame can be formed in the form of longitudinal beams or as a single or double crate. Of course, the second option creates a more reliable support for plywood.

SNiP 3.04.01–87 (SP 71.13330.2017) recommends laying slats across the light flux, and in corridors and other premises with a certain direction of foot traffic - perpendicular to the movement. Of course, in the future, the frame will not be visible under the coating, but the essence of the advice is different. The developers of the building code determined that if the frame is formed across the most intensive movement of people, then the loads will be distributed over most of the supports. power frame, and not by 2–3 elements. Or worse, between them.

First of all, a zero mark is revealed, relative to which the supports are aligned. Further, beacons are mounted under the lag beam, or the required level is beaten off on the wall with a dye thread. But the most convenient way to build a reference line is a laser level with a plane builder.

If sound insulation is required, before installing the supporting frame, it is necessary to lay on the base acoustic material: plates, membranes, roll products.

Now you can proceed with the installation of the log in compliance with all the necessary clearances:

Between the extreme rail and the wall - at least 20 mm.
Between adjacent supports - from 30 cm, but not more than 50 cm. We remind you: the higher the load on the floor, the more often the logs should be.
Between the ends of one row - 0–0.5 cm.

For alignment, under the frame elements, gaskets made of chipboard, OSB, MDF, etc. are installed. After checking with a level, bosses or lining boards are attached to the base dowel - nails, self-tapping screws or anchors.

Plywood lining.

Legs on wooden lugs.

To drill holes for hardware in backing components, logs and plywood, you should purchase feather or special wood drills with a countersink.

On firmly fixed supports, many craftsmen recommend laying damper layers. Such a preventive measure will not allow the structure to start creaking in the future.

The penultimate step is fixing the log over the entire area of \u200b\u200bthe room using suitable hardware. Please note that in doorways a widened rail should be laid, which will protrude beyond the partition by 50–100 mm on each side.

For maximum leveling accuracy, you can use fasteners and support hardware designed for adjustable floors. In fact, these are powerful anchors that are installed in the floor slab. Adjusting nuts are screwed onto the main bolts, then a beam is placed and fixed with a lock nut. The excess anchor rod is cut off with a grinder or a metal saw.

If you plan to insulate the floor, then under the frame, in accordance with the manufacturer's recommendations, you need to lay a vapor barrier. But after installing the lag, a suitable thermal insulation material is laid in the formed “windows”: mineral wool, expanded clay, ecowool, linen or synthetic mats.

Laying plywood boards

The most controversial issue is the thickness and number of layers of plywood. There is no single correct opinion. It is clear that the higher the expected load on the floor (weight of furniture, intensity of foot traffic, etc.), the greater should be the thickness of the slabs and the smaller the distance between the lags. This will avoid the deflection of the structure and its damage.

What type of floor is best - single or multi-layer? There is no definite answer to this question. Each type has its own advantages and disadvantages. But the total thickness of the plywood flooring should remain constant - at least 18 mm.

Installation of plates begins with their preparation. They should be cut into the right dimensions, make cuts for communications or enclosing structures of complex shapes. Then a preliminary arrangement is carried out. The first row is laid out from the far corner along a solid wall.

Plywood sheets are adjusted if necessary, drilling points are marked for hardware with an indent from the edge of 2–3 cm and an interval between fasteners of 15–30 cm. An expansion joint of 0.4–1 cm should be maintained between the plates, as well as between the plates and walls.

After one row of plywood is drilled and the sawdust removed with a vacuum cleaner, the sheets are fixed with suitable fasteners. Start screwing the hardware experienced craftsmen recommend from the center of the plate, with a gradual advance diagonally to the edges, and then along the perimeter. This approach will straighten the plywood and avoid waves. Do not forget that the hardware must be "drowned" into the plywood by at least 0.2 centimeters.

The second and subsequent rows are laid in compliance with the rule of offset seams by at least 1/3 of the length. If the plywood is mounted in two layers, then the joints of the first layer should not coincide with the seams of the second.

Floor finishing

After laying, professional craftsmen recommend "walking" on the surface grinder with an abrasive nozzle from 80 to 120 units to eliminate the slightest difference between the sheets. After that, the flooring is cleaned of dust and sawdust, and the seams are filled with sealant or elastic putty for wood.

Not suitable for seams mounting foam, as it begins to sag and crumble over time.

A plywood floor can be mounted even without vast work experience, sophisticated equipment or building education. For clarity, we recommend that you familiarize yourself with the video from professionals.

Advice! If you need repairmen, there is a very convenient service for their selection. Just send in the form below detailed description work that needs to be done and offers with prices from construction teams and firms will come to your mail. You can see reviews of each of them and photos with examples of work. It's FREE and there's no obligation.

Many are trying to embellish their lives with a new renovation. To be completely satisfied, a person wants to use the highest quality and natural finishes for this purpose. For many years, it is precisely such materials as wood, stone, lime, gypsum, ceramics, and tiles that have not lost their popularity among consumers. Since many cannot afford expensive repairs, alternative replacements for natural products have to be found.

Finishing the floor and walls is the base that is the basis of any repair work. If these parts of the room are in an improper form, then no matter how hard you try, you will not achieve success in transforming your home. Therefore, it is necessary to start with these figurants.

Starting repairs, you want to do everything quickly and correctly in order to plunge into the aura of freshness, novelty and cleanliness as soon as possible. But everything is not so simple, because each surface requires mandatory preparation, cleaning of all kinds of flaws, deformations and protrusions. So, before you update the walls with any type of finish, their base requires careful alignment, and this is additional time and waste. The good thing is that it does not need to be reproduced from time to time, every repair. Made a solid foundation - got a 50% success rate and a durable design.

The floor has a high status in each room, namely its design and performance. Firstly, it must be warm, secondly, it must be of high quality, and thirdly, it must have a solid monolithic base under it. This required condition, because in a house where this surface is made anyhow, rodents, reptiles or microorganisms born by the processes of decay will definitely start up.

A plywood floor in its usual form is a practical and neat draft, which is most often a leveling base for other finishes. To the question: “Why this particular material?” - You can answer by lobbying for its strength, resistance to deformation and long service life. Many even use plywood flooring as their main flooring, as a well-done laying of sheets can create a picture that you don’t want to complement anything, and the sanded and varnished material looks so beautiful and noble. Laying plywood on a wooden floor is especially popular among owners of cottages, cottages and private houses. The reason for this was the inherent ability of the material for thermal insulation. Moreover, if after a while the owner wants to change the finish, such a floor can be quickly and easily dismantled or simply laid a new floor.

Plywood: what does it look like and what is it?

Plywood is a material consisting of peeled veneer with board sheets firmly glued together. The history of her name is rooted in distant France. It is from there that the word “plywood” is taken, which means “to impose” in translation. Typically, the number of veneers ranges from three to five pieces, and a special glue provides a strong connection between them. They produce such sheets for repair work, as well as for the manufacture of furniture. The quality of the material depends entirely on the properties of the adhesive that connects the layers of veneer to each other. Particular strength is provided by the method of adhesion of the plank elements that make up the sheet. So, if they create a perpendicular position of the fibers in adjacent rows, the guarantee that the shape of the product will be stable and strong will be beyond the norm.

There are several types of plywood:

Laminated.
Birch.
Combined.
Coniferous.

The first type of material is well applicable in the manufacture of durable bases. Such plywood is moisture resistant and independent of the influence of chemical processes and natural changes.

Birch is used exclusively in cases where you need to purchase a very reliable material with a planned heavy load on the surface being trimmed. Due to the multi-layer, plywood made from such wood is able to withstand any weight and not burst. This conditions the material as a carrier of excellent physical and mechanical properties. Birch products are widely used in the industrial production of transport and in construction organizations.

Coniferous plywood - the same unique material, as described above. It weighs a little and is used for wall decoration, construction of partitions and other types of repair work. Durable coniferous plywood is invulnerable to various fungi, mold and other microorganisms. Used for the manufacture of interior items, furniture and sales design ideas. Also, many builders like to use a coniferous look in roofing, as it is not subject to drying out and moisture.

Combined plywood - is a mixture of different types of wood. Very beautiful in appearance, it is also not expensive in price, which is why combined sheets of material are so popular in interior decoration and furniture manufacturing.

Also, the material under consideration is divided into sanded, sanded on both sides and not sanded plywood.

In addition to these types, there is a separate classification - by purpose:

Construction.
Furniture.
Formwork plywood.
Laminated.
Plywood for general use.
Bakelized.
Flexible.
Decorative.
Ship.
Aviation.

Choice of brand of plywood

Before you start laying material on a wooden floor, you need to understand the brands of plywood and decide which one will be the most the best option. This indicator is determined by the level of moisture resistance of plywood.

The FB and FSF brands are used exclusively for industrial purposes.
Marks FK and FSF play a significant role in construction. I would like to note that FC plywood is favorable to use for repairing children's rooms, as it is absolutely safe. In this material, the veneer is joined with a phenol-free adhesive. Moreover, plywood is resistant to mechanical damage and is produced in all manifestations of sanding.

Plywood brand FSF - waterproof and durable. These qualities remain unchanged even as a result of changing weather conditions and room climate. The minus of the FSF brand is that such a product reaches its final form by gluing the veneer with compounds with a high content of phenol-formaldehyde substances. It is because of this that plywood is not favorable in internal repair processes.

We mark the plywood elements in accordance with the dimensions of the room.

Advice: at this stage, it is important to make an allowance for damper joints (3 or 4 mm.), As well as 10 mm for wall joints. Such a solution will prevent changes in the material due to a change in the climate in the room, i.e. an increase or decrease in humidity, temperature. If you ignore the action, the plywood, due to the exactly measured parameter without allowance, may swell and deteriorate.

The next step is to check the integrity of the ends of the sheets - their delamination and divergence is unacceptable. In case of detection of defective products, they must be replaced or postponed as unnecessary use. Plywood boards are laid out on a wooden surface in the sequence in which the fastening will take place. It is important to place numbers on each element. On the contours, mark the floor in the sequence in which the sheets lie, while the joints between them should fall in the middle of the lag.

For work, logs made of plywood with a width of 30-40 mm are used. We distribute them according to the markings made and, using wood glue or self-tapping screws, fasten them to the floor. If in the course of work there are gaps between the floor and the lags, we lay the cut plywood in them, before lubricating them with glue on both sides. The same work must be done if the base surface has protrusions. To properly lay the lag in a horizontal layer, you need to use building level. If you do everything right, then the new surface will be perfectly flat.

Further actions depend on what type of finish you choose. If it will be a regular carpet, open the plywood floor with several layers of varnish. If laminate or parquet - an intermediate layer between the plywood and the finish is placed soundproof.

A well-made plywood base will last you a very long time. long time, and the material itself will serve as an addition to thermal insulation.

The easiest and least troublesome option is to lay plywood sheets directly on the old boards. Of course, you will bypass the process of leveling the floor, but if the base surface is perfect, this method can be used. The main condition of work is to ensure that the new coating is incapable of creaking under load. When laying plywood elements, you need to keep a small space between them so as not to cross the seams.

After the sheets are laid out in the correct order, check the resulting layer for uniformity. To do this, you need a building level.

Rules for laying plywood on a wooden old floor

During work, do not neglect the rules listed below, which are important in construction activities and set its rhythm.

The relevance of laying plywood on wooden base comes at the moment when old finish completely damaged, and the boards dried out or rotted. Who else but plywood can find a way to eliminate defects? Flooring from this material will cultivate the floor and save it from problems.
If the old boards sag while walking, they must be dismantled and the base prepared in the condition necessary for subsequent repair.
Plywood, as a material, does not like moisture, so try to avoid using it in such rooms. If this is unavoidable, treat the material with a special water-repellent solution and an antiseptic. It is important to remember that where there is high humidity or large temperature fluctuations, plywood is not recommended.

Advice: You can check the floor for moisture levels by laying polyethylene on it. Take one square meter of film and spread it on the surface to be tested. Leave the material for 3 days to “lie down with the floor”. If, over time, you notice that condensation has formed on the inside of the polyethylene, then such a base will be unfavorable for plywood finishing.

Before laying, the base floor must be in perfect condition, i.e. free from dirt, debris, dust.
The cleaned surface can be re-primed.
It is important to know that the size of fasteners should not be larger than the thickness of the plywood board.
After finishing the floor with plywood, using grinder treat its surface.

Features of laying laminate on plywood

In conclusion, I would like to consider some ways to finish the plywood coating as a base. Let's dwell on everyone's favorite laminate and finishing features with its use.

To begin with, we will prepare the necessary construction utensils in the form of materials and a set of tools. These will be:

Laminate.
Substrate.
Simple pencil.
Construction tape.
Square for marking parts.
Jigsaw.
A saw with fine teeth.
A piece of plastic for fitting the laminate.
Wedges for laying the starting row between the laminate and the wall.
Drill.
Dowels and screws.
Hammer.
Finishing equipment.

Advice: Before starting work, ensure that the laminate stays calmly in the room for 48 hours. This is necessary so that it “absorbs” the climate of the room and adapts, taking the desired shape.

Laminate involves two ways of laying:

diagonally across the room.
Parallel or perpendicular to the window.

The first method is technically difficult and requires building skills, abilities and competent measurement of parameters to be performed. One big plus is that the room in which the material is laid in this way looks aesthetically pleasing and interesting.

In the second case, the joints between the laminate elements will turn out to be invisible, and the coating consumption will be much less than with the first choice.

Getting Started with Plywood

The most important and exciting moment has come - laying the laminate on a new plywood floor with a plank base. Let's do the work in stages:

We set wedges along the perimeter of the walls for laying the first row of coating.
Applying construction stapler, fix the substrate on plywood.
Using a jigsaw or file, remove the edge panel of the laminate.
We lay the starting row so that the locking of the locking connection is located closer to the person.
When laying, sheets of material must not be screwed to the plywood base, since in the event of expansion or contraction of the boards, they may come into an improper shape. Therefore, the laminate is offset.
To obtain an indent between the side seams, the extreme panel of the next row is also cut, like the first.
Laminate tiles, padded with a plastic bar and a hammer, snap into place with a lock.
In the same way, we line the floor with the rest of the laminate sheets.
Upon completion of the surface coating, all wedges are removed and the work is fixed with skirting boards.

Laying tiles on plywood

Yes, your eyesight does not fail you: it is the tile, and it is the plywood. Although most of the masters do not accept such a combination, but with the right selection of materials, this is quite doable. Moreover, a floor screed is not needed, and this is a plus for time and effort. So, if you want to cultivate and transform flooring from plywood using tiles, you need to choose the material very responsibly. Recommended under finishing of this type, use plywood treated with a water-repellent liquid or buy sanded plywood (if base coat not ready yet). The thickness of the plywood sheet under the tiles should be at least 2 cm. By choosing such a material, you will ensure the strength and hardness of the future coating.

Stages of work:

Remove all debris from the base of the floor and wipe off the dust.
Seal all cracks, seams and joints with non-expanding sealant. You can also use a solution of cement and sand.
Cover the plywood floor with an antiseptic solution to avoid the formation of fungus, dampness and mold.
We carefully prepare the adhesive mass: the solution should not have lumps and debris.
Laying tiles can be started from the farthest corner or from the middle of the room.
We make a “dry” layout of the plates and determine the products that require cutting to fit the room.

Advice: Before gluing the material, make sure that it is laid out horizontally. You will need a one meter level.

When tiling the floor, you need to apply plastic corners for between tiles.
Using a spatula, apply glue first to the underside of the tile, then to the floor surface. Using a rubber mallet, gently tap the first piece to the plywood floor. Work the same way to the end.
After a few hours, after the tile is fully attached to the plywood base, grout the joints.

Installation of a parquet board on a plywood subfloor

Parquet is a coating that has not lost its relevance for decades. Moreover, it is one of the most popular floor coverings, as it has whole line Advantages: natural, beautiful, environmentally friendly and luxurious. Parquet will transform any room and make it truly elegant. It is rightly said among the people that beauty requires sacrifice. So our parquet is not so simple in installation technology. Since a plywood subfloor is a great option for those who do not want to bother with a concrete screed and wait until it dries, many are interested in the question of how to combine simple with complex, i.e. plywood with parquet board? Quite simply, opposites attract.

First you need to learn about the features of parquet laying:

Not only the construction of parquet flooring requires diligence and diligence, but the flooring itself is very whimsical and has certain conditions. One of them is to maintain the temperature and humidity level in the room. Since the parquet is made of wood, then, as a true natural material, it requires that all climatic indicators of the room be normal, otherwise any deviation threatens to swell or shrink the board.
If the air in the room is too dry and compressed, then the parquet may crack due to drying processes and changes in the structure of the coating.
In order for the new floor finish to take root, the following temperature indicators must be maintained in the room: heat from 18 to 25 degrees, humidity from 40 to 60%.
In the cold season, it is important to moderately humidify the air, using special means. This will prevent the harmful effects of heating pipes on the parquet.
Laying parquet implies an absolutely even base. That is why plywood is a great option.

Preliminary preparation

The parquet board is able to lie perfectly only on a flawless surface. To ensure this condition, you can use one of the options. This is: make a screed, install logs or make a subfloor. In our case, the last method is already ready, and we will lay the parquet on the plywood base.

parquet flooring

Let's start the main work step by step:

Prepare the base coat by cleaning it of debris.
Carefully sand the surface of the subfloor with a special tool.

Apply one layer of the finished adhesive mass and assemble the parquet.

Leave the finished coating to dry for one week.
After seven days, it is necessary to clean the surface of the finishing boards from industrial debris and dirt.
Using a drum-type grinder, level the surface.
The penultimate stage consists in puttying the new floor with an appropriate composition mixed with mortar and parquet flour.
Perform final sanding, after which the surface is primed and varnished.

Advice: Laying parquet is a complex process, so you'd better enlist the help of experts. When buying an artistic coating, the work becomes much more complicated, and it will be very difficult to cope with it with one pair of hands. Do not spare money and do not neglect the help of the master, because even the slightest mistake will cost the beauty of the entire parquet.

Conclusion

The article is a must-read for those who want to make a truly competent repair, because having golden hands (or at least "bronze"), with the help of instructions, you can achieve a lot, even put tiles or parquet on a wooden floor.

Modern technologies for interior decoration have also affected floor coverings. Residents give their preference to such of them as cork, parquet board, laminate. When using these materials, not the last place is occupied by the requirements for evenness of the base. In view of this, quite often one has to deal with the need to level the wooden floor. There are several ways to do this. One of them is leveling the floor with plywood. To properly perform these works, you need to know how and with what help plywood is attached to a wooden floor and what preparatory work should do.

Why plywood?

Plywood has the characteristics necessary for its use in construction and repair work. She has:

relatively small weight;
sufficient hardness of the surface of the material;
high quality grinding
resistance to water (in moisture-resistant varieties);
absence of unpleasant odors;
availability of installation technology.

Plywood is indispensable for leveling wooden floors.

In addition to an affordable price, it has the advantages that are necessary for such work. Namely:

due to the perpendicular arrangement of adjacent layers, plywood sheets have high strength in all directions;
production large sheets plywood allows for accelerated installation over large areas;
plywood sheets bend well without breaking;
plywood sheets are convenient for transportation and unpretentious in operation.

Preparatory stage of work

Naturally, laying plywood on a wooden floor must be done correctly and using the necessary tools. It is good that the master had experience with this inventory. For laying plywood you will need: a screwdriver; jigsaw; level; roulette; self-tapping screws with dowels.

Tools needed for work

Before leveling a wooden floor with plywood, it is recommended to check the subfloor for suitability for use. Replace old rotten boards and repair creaking ones. It will not be superfluous to check the evenness of the base. If the floor is uneven, then you need to determine the maximum surface difference. Small deviations can be smoothed out by laying a special substrate. Differences of more than one centimeter suggest laying the log exactly horizontally. They are set using the water level. The choice of plywood depends on the floor covering to be laid afterwards. If it is carpet or linoleum, thin sheets can be used. For parquet or laminate, it is necessary to choose plywood thicker than 10 mm.

Note. The thickness of the plywood laid under the laminate or parquet must be no less than the thickness of the floor covering.

Decide on the brand of plywood

Before starting work, you need to decide on the brand of the product. It is determined in accordance with the moisture resistance of the material. FB and FOF grades are used for industrial construction. For individual construction works plywood of the FK and FSF brands is intended.

In the production of FK plywood, glue without the use of phenols is used. Therefore, it is completely harmless and can be used in bedrooms and children's rooms. It is resistant to mechanical stress and is characterized by medium water resistance. It is produced both in polished form (Sh1 - polished on one side, S2 - on 2 sides), and in unpolished (NSh).

Before starting work, you need to decide on the brand of the product

Plywood brand FSF is characterized by increased water resistance, wear resistance and mechanical strength. These properties do not change even with changes in temperature and humidity. This is achieved through the use of phenol-formaldehyde adhesive resins. At the same time, these resins are quite toxic. Therefore, such plywood is not desirable for use in residential premises.

"Open" and fitting plywood

First of all, we carry out "cutting" plywood in accordance with the size of the room. In this case, it is necessary to take into account the size of the damper joints: 3-4 mm between the workpieces and a centimeter at the walls. If this is not done, changes in temperature and moisture will lead to "swelling" of the finished base. Upon completion of cutting, we check the ends of the blanks for delamination and defects. It is not advisable to use damaged sheets; they must be replaced.

After that, lay the plywood on the wooden floor in the order in which they will be attached. It is not recommended to make a joint of four corners. Plywood sheets are laid in the manner brickwork, with shift. Then you need to number all the sheets. Focusing on the joints between the sheets, mark the location of the lag and remove the blanks. The joints of plywood sheets should fall in the middle of the lag.

Installing a log on a wooden floor

Logs for leveling the floor are made of plywood 3-4 cm wide. We lay them according to the marks made. We fasten the logs to the floor with a special glue for wooden products or self-tapping screws. During installation, gaps may appear between the floor and the joists. In them we lay pieces of plywood suitable in thickness. Lubricate both sides with glue before laying.

Lags that serve as the basis

The same must be done if the base has differences in height. The horizontal location of the lag is determined using a level. The evenness of the future floor depends on the thoroughness of this process. After laying the log, a crate is made, its size should correspond to the size of the plywood. The space between the lags can be filled with a sealant.

Attaching plywood to a wooden floor

After the logs are installed, we fasten the plywood to the wooden floor according to the scheme. Before this, the blanks must be treated with an antiseptic. Fastening is carried out using self-tapping screws with plastic dowels. So that the plywood does not suffer from hammer blows, we drill a hole equal to the diameter of the dowel in the places where the screw is screwed. And then countersink a hole of a larger diameter. The cap of the self-tapping screw will hide in it.

The final treatment of plywood depends on the selected flooring. Under the carpet, the surface is covered with several layers of varnish. For laminate, the plywood base is carefully sanded and then coated with protective varnishes. Under the laminate or parquet, a special sound-absorbing substrate is laid on the base.

Using this plywood flooring technology, you can level almost any base. With careful work, the result is a solid and Smooth surface. After that, even linoleum, even parquet, can be laid on it. The flooring laid on such a base will last more than one year. In addition, the plywood layer serves as additional thermal insulation.

Plywood is one of the most versatile materials invented by mankind. Plywood is also widely used in construction: in terms of ease of working with it, strength, cheapness and environmental friendliness, plywood, perhaps, has no equal. Plywood is especially widely used in laying and repairing floors. But the high functionality of plywood also determines the variety of methods of working with it, so laying plywood on the floor with your own hands requires explanation for different cases of practice.

Chipboard or plywood?

Plywood is not the cheapest material for flooring and wall cladding. Chipboard is even cheaper. But let's leave alone for now phenol-formaldehyde resins - volatile carcinogens, on the basis of which chipboard is made.

Let's do the following experiment: put two pipe cuts on the floor and lay a sheet of plywood 12 mm thick on them. Let's get on it, let's go. What happened? Nothing. Bent over and straightened up. What about chipboard? Most likely, it cracked at a greater thickness. And it will definitely crack if you jump on it.

You can do two more experiments: hold plywood and chipboard trimmings in water and see how soon they swell and become limp. It is not necessary to knock on the edge with a hammer: everyone knows that chipboard is fragile. Therefore, the question: “chipboard or plywood?” definitely decided in favor of plywood.

What is plywood

There are many varieties of plywood. 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. The cheapest, about 170 rubles / sq.m with a thickness of 12 mm. 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 and with a comfortable temperature, it can be used as a substitute for FC.

What is contraindicated for plywood

Nothing is perfect, and plywood is made from a hygroscopic material - wood. Therefore, plywood cannot be used in damp rooms: long-term air humidity should not exceed 68%; short-term within 12 hours - 78%. When laying raw plywood, air humidity up to 60% is permissible.

The specified values are valid in a comfortable temperature range of 18-27 degrees Celsius. Outside these limits, the sensitivity of plywood, except for FC, to humidity increases: at 16 and 35 degrees and a humidity of 85%, plywood begins to delaminate after two months. Therefore, ordinary plywood for floors and walls should not be used in the kitchen, balcony, closet, hallway and bathroom.

How to improve plywood

Moisture resistance of plywood can be increased by impregnation with putty based on polyvinyl acetate (PVA); it looks like very liquid PVA glue and is cheap. Impregnate first on one side until spots appear on the opposite side, then on the other twice. Dry in a horizontal position. It will take a long time to dry - at least 3 days at room temperature. After drying, the sheets are treated with any antiseptic fungicide for wood.

The strength of the surface layer can be increased with acrylic varnish. It is applied in two layers; the second - after the complete drying of the first. If plywood for decorative purposes needs to be stained, paint before varnishing.

Acclimatization of plywood

Before describing how to lay plywood on the floor, it should be said about its acclimatization in the room. Plywood, like any wood material, requires acclimatization at the place of use. The term of acclimatization depends on the difference in temperature and humidity: if the conditions in the warehouse or in the store are the same as in the apartment, a day is enough; with a temperature difference of 2 to 8 degrees - three days; with more - a week. During acclimatization, the plywood is kept stacked in a horizontal position.

Subfloor Moisture Check

Before laying plywood on the floor, the base surface, and not only concrete, you need to check for moisture evaporation. To do this, 1 sq.m of the base surface is covered with a solid square piece polyethylene film, pressing it along the edges with slats with weights and lifting the center a little. Further depends on the time of appearance of condensate under the film:

The bubble fogged up from the inside during the day - the room is unsuitable for covering the floor with plywood.
Small drops appeared within 3 days - the base concrete floor must be covered with glassine or plastic film, put a construction mounting grid on it and make a screed. Wooden floor - disassemble; with such evaporation of moisture, the boards from the underside and the old logs are probably touched by rot. An option for 7-10 years is to lay plywood with an improved home method (see above) moisture resistance.
The condensate did not fall out on the 5th day: you can lay plywood in any way.

plywood base

Leveling the floor with plywood is a widespread building technique. It is used both for laying new floors and for express repairs to existing ones. For various combinations of base floors and top decorative coating different plywood laying technologies are used.

Concrete

Laying plywood on a concrete floor is possible both directly on the screed and on logs. The first method is used if the base floor is sufficiently even, and the finish coating is somewhat plastic; for example - under linoleum or cork floor. Marmoleum can be laid directly on the screed without a subfloor.

Important: remember that after the concrete has set, it must be dried for at least 40 days at room temperature.

On a flat dry screed

The room is thoroughly swept and vacuumed. The floor is treated with bituminous varnish or parquet mastic, diluted five times with solvent or kerosene (primerization). When working, windows are wide open, they work in a respirator-petal, and in the apartment completely, having unscrewed the plugs or turned off the machine on the floor panel, they remove the power supply: there is no need to explain what a spark is in air saturated with vapors of an organic solvent.

Plywood 8-18 mm is pre-cut into squares a quarter of a standard sheet (1250x1250 mm) or stripes. Lay apart, i.e. with a shift: there should not be four seams converging at one point. Sheets are cut with a jigsaw or a manual circular saw - this can be done in the next room an hour after priming. When cutting, it must be borne in mind that a gap of 20-30 mm should remain along the perimeter of the room.

Then the sheets of plywood are laid out on the floor, “dry”, adjusted and numbered without fastening. How to fix plywood to the base floor in this case? Under linoleum or cork, you can simply use glue such as bustilat or parquet mastic, without mounting slots - you get a floating subfloor. The ends of the sheets must also be glued.

Under ordinary oak or parquet similar in properties, plywood, along with gluing, is fixed with self-tapping screws 4-5x60 mm in dowels. In this case, sheets / strips must be laid out with mounting slots of 2-3 mm; For this, it is convenient to use halves of toothpicks:

Note: as a screwdriver insert for a drill, it is convenient to use the insert of a combination screwdriver (see figure above).

On concrete on logs

Under a laminate, inlaid parquet or parquet made of fine wood, plywood is laid on a concrete base on. The same is done if the stability of the temperature and humidity conditions in the room is in doubt. The device of the draft plywood floor on the logs is clear from the figure, we will give only the necessary explanations:

Boards for lags take unplaned 100 mm ("weaving").
Boards for lags can withstand at least a week in the room where they will be used, after which they are culled: those that are warped by an arc are put on the bosses, and those that have been driven by a screw are completely rejected.
Plywood is taken by FK or improved independently, with a thickness of at least 12 mm; better - 18-20.
The preparation of the base floor is done in the same way as in the previous case.
Lathing of logs is made in increments of 300-600 mm so that all edges of the plywood sheets fall on the logs.
Sections of the crate are filled with polyurethane foam or other hydro- and heat-insulating material, but not mineral wool- from it, microscopic needles will inevitably appear in the air, irritating the respiratory organs.
Plywood sheets are laid with a mounting gap of 2-3 mm and with a gap around the perimeter of the room of 20-30 mm.
Attach plywood to the joists with liquid nails glue and fix with nails; fastening with self-tapping screws in this case does not noticeably improve the quality of the subfloor, but it is more expensive.

Note: in Lately tongue-and-groove plywood with a thickness of 12-20 mm appeared on sale especially for subfloors. It is produced in the form of sheets from 300x300 mm and strips from 300x600 mm. For a floor made of valuable parquet, this is the preferred option: the cost of a subfloor in this case will still be an insignificant fraction of the total cost of materials, and the likelihood of moisture vapor leaking from under the bottom is reduced by an order of magnitude.

Repair of wooden floors with plywood

Plywood is an excellent material for repairing cracked wood floors that are cracked and creaky. In this case, plywood is laid on a wooden floor in whole sheets from the door so that the most walked surface is solid. Scraps are allowed along the edge and into places under furniture. The plinth is removed as carefully as possible and then it is put back.

Plywood is taken from 12 mm thick. Installation is done with the usual gap of 20-30 mm around the perimeter, but without mounting gaps between the sheets. Sheets are laid on bustilate, liquid nails or any other mounting adhesive; the ends are also glued.

Such a floor made of “self-improved” plywood, painted with any floor enamel, lasts 20 years or more in the bedroom. But it is impossible to repair damp, swollen floors with plywood, with traces of rot and mold, and in rooms with biting biting on the walls is impossible. It is necessary to remove the old floor, look for and eliminate the source of moisture, and only then lay a new one.

Warm floor on plywood

Under plywood, they are laid on a concrete screed on a mounting grid with waterproofing on the base floor. There is one caveat here: the edges of the waterproofing film must be brought under the plinth. If they are muffled with a screed, then the evaporation from heating can concentrate in one place and cause delamination from moisture.

When installing a subfloor under a warm one on the logs, such a problem does not arise, but it makes no sense to complicate and increase the cost of work: a warm floor dries the room well. So it's easier to leave a kind of vent around the perimeter for water vapor.

Plywood innovations

Plywood flooring is a branch of construction engineering that seems to be far from over. In the age of composites and nanotechnology, the good old plywood does not retreat and finds new uses for itself.

Adjustable floors

These floors are used as a base for wood inlays and other fine, exclusive work. Plywood flooring - double, made of high quality plywood. In the sheets of the lower layer there are threaded sockets for bolts. The bolts are shaped: above the thread there is a flat flare in the form of a press washer, and above it is a neck 3/4 of the thickness of the sheet for a hexagon or with a cross slot.

The top sheet with holes for the necks of the bolts is placed on the bolts screwed into the bottom sheet, and adjusted with an open-end wrench or a screwdriver. When using bakelized plywood, accuracy is achievable common surface quite mechanical.

Plywood parquet

But plywood parquet is an invention of craftsmen. In it, the forgotten skill was revived at a new level artistic sawing from plywood. The technology of plywood parquet is simple and accessible to anyone.