We are coming to the end of our big topic on creating a high-quality, smooth and durable floor in an apartment. Today we are waiting for the last stage - laying plywood on the floor. After this, you can install any floor covering on the plywood, and here your imagination is completely up to you: linoleum, carpet, laminate, parquet board, piece parquet.
Laying plywood on the floor
Laying plywood on the floor is carried out in several successive stages, which we will now discuss.
Preparing plywood
We place the first sheet in the very flat angle, as always leaving a temperature gap of 3-5 mm between the wall and plywood. Then place the next sheet. We're not fastening anything yet! At the end of the row, you need to cut out an incomplete piece with a jigsaw (we measure everything first). In order for the joints to be staggered, in the next row of plywood we lay a whole sheet opposite the cut one. In this way we lay plywood over the entire floor area.
How to attach plywood?
We approach this process with special care. The plywood should be one piece with the subfloor. No gaps, otherwise everything will creak. Therefore, do not spare the screws, get ready to tighten about 2000 of them :).
Important!
Do not screw screws directly into the plywood! For each self-tapping screw, drill a hole with a diameter slightly smaller than the diameter of the self-tapping screw (countersink). Due to this you will receive:
- Tightly pulled plywood to the boards.
- Ideally flat plane. Plywood will not warp from many screws.
This is of course a rather labor-intensive process. But if you want a flat floor, don't be lazy! Pick up a drill, a screwdriver and go!
How to lay out plywood?
There are two ways.
- The first one is the simplest, for lazy people. Drill holes approximately by eye at the indicated pitch (10x15 cm). There is a big disadvantage here - some screws can get into the edge of the boards, or even won’t hold between them at all!
- The second way is correct. While the plywood is lying on the floor, we lift each side of each piece one by one and mark on the plywood the middle of each board lying under the plywood. Then, using a long ruler, we draw lines corresponding to the position of the boards under the plywood (in increments of 10 cm - our boards were just 10 cm wide). Next, we draw perpendicular lines with a step of 15 cm. We also make a series of screws on the edges of the plywood.
Important!
We do not drill on lying sheets of plywood in order to avoid drilling through the boards along with the plywood. In order not to confuse the sequence of sheets, we mark each sheet, where and which side it was lying on.
All plywood sheets should be coated with a primer. This will protect the plywood from possible moisture and increase the adhesion of the parquet glue (if the future parquet is supposed to be installed on glue). Prime the bottom of the plywood sheets before laying, and prime the top after the sheets are fastened with self-tapping screws.
Preparing a cork backing for plywood
The plywood is ready. Now we clean the surface of the subfloor - carefully sweep away all the debris. Then we roll out the prepared roll of cork backing on the floor:
Cork backing is essential! It evens out all the micro-irregularities of the boards and ensures that the plywood adheres tightly to them.
We place the cork neatly end to end. To prevent it from moving when laying the plywood, apply a thin strip of PVA glue under the edges of the cork along the joints and near the walls. Then we press down the edges of the cork (especially where it bristles) with the remains of the boards for 3-5 hours.
Fastening plywood to the floor
The cork is placed and the glue has dried. Now we lay down the plywood. It is better to do this together and carefully.
Important!
If you catch the cork with a corner of the plywood, displace it or break it, everything is lost!
First, we put the first sheet of plywood in place. When it is already lying flat on the cork backing, all the scary things are over. The sheet can be moved carefully, the cork will not move or tear, it is held in place by glue. Thus, we lay all the sheets of plywood according to the markings and fit them tightly together. If 1-2 mm gaps remain, this will not harm the parquet.
We have laid all the plywood, now we are fastening it with self-tapping screws. First we fasten all the corners, then everything else in any order. The most important thing is to screw the self-tapping screw so that the head is pressed into the plywood and is slightly below the plane of the sheet.
Important!
Do not allow caps to protrude. But don’t immerse too deeply - the sheets may drag!
This is what the laid plywood looks like:
Important!
Pay attention to the edges of the sheets - a line of screws along the edge is required!
Boxes of screws show how many were used. It took us about 2000 pieces for a room of 14 m².
We have laid the plywood, now all that remains is to sweep it and cover it with soil.
This completes the installation of plywood on the floor:
Well, dear readers!
You have made a good, high-quality foundation for your future floor!
All photos from the article
In this article we will figure out how to level a wooden floor with plywood. We will study all the main stages of this work - from visiting the store for materials to laying linoleum or laminate on top of plywood. So let's get started.
General points
First, let's decide in what cases it makes sense to take on the leveling of an old wooden floor.
Here are the boundary conditions:
- At least three-quarters of the floorboards and all joists are in acceptable condition (i.e. visible signs rotting, do not crumble under load).
- You are satisfied with the level of sound and heat insulation of the floor.
- The logs do not have significant deformations.
If any of these conditions are not met, our plans change.
We are faced with one of three operations:
- Re-laying floorboards (sometimes accompanied by replacing joists).
- Replacement with thick plywood along the joists.
- Complete dismantling of the wooden floor and pouring insulated screed over the concrete floor.
Please note: in the latter case, do not forget about the maximum permissible specific long-term load on the floor slabs.
It is standardized at 150 kg/m2, which corresponds to reinforced screed 5-6 centimeters thick.
Plywood selection
What kind of plywood should I lay on a wooden floor if all the above conditions are met?
First, let's list the characteristics by which it is classified.
Variety
Options range from elite grade to 3/4 grade (sellers usually do not separate them). In the latter case, there may be falling knots on the front surface in top layer veneer, traces of woodworm activity and other defects. Moreover, the price of a sheet, depending on the variety, can vary two or more times.
Since we need plywood as rough coating, the instructions are obvious: our choice is cheap, low-grade material.
Binder
This is indicated by the marking on the price tag:
| Marking | Description |
| BS | The veneer is glued with alcohol-soluble bakelite glue. The material is extremely durable and almost completely waterproof; however, the high cost and lack of widespread sale force one to pay attention to alternatives. |
| FBA | The binder is albumin and casein glues based on animal proteins. The material is impeccably environmentally friendly, but does not shine with water resistance. |
| FC | Urea glue is somewhat more water-resistant, but is absolutely harmless. |
| FSF | For gluing, exclusively waterproof and, alas, toxic phenol-formaldehyde resin was used. The material is not recommended for use in residential premises. |
What plywood should I use to level a wooden floor under linoleum or laminate? In this case optimal choice will be FC; its limited water resistance is leveled out by water-repellent impregnation.
Thickness
The thickness of plywood to lay on a wooden floor depends on the height differences between the floorboards and how much time you are willing to spend on repairs.
- Material with a thickness of 15-18 mm can even out differences of up to 5 mm per 30 cm of surface; at the same time, the thickness will not allow the flooring to sag under the weight of people or furniture. However, absolutely flat covering for obvious reasons it won't.
If for installation flooring you need a smooth and durable base, one of the fastest and simple ways- leveling the floor with plywood. Compared to screed, this method has many advantages: it does not require special skills and tools, repairs can be continued immediately after installation, and the price of plywood is cheaper. Depending on the thickness and impregnation used, the price per sheet of plywood varies from 300 to 1200 rubles.
Not every sheet material can be used on the floor.
- Plywood – best option. It consists of glued sheets of veneer, with each new sheet laid perpendicular to the grain of the previous one, which increases rigidity. Moisture resistance, durability and environmental friendliness depend on the binding material used (it can be distinguished by its markings).
- Most often, the FC brand is used for flooring. It is made on the basis of urea glue, and has lower moisture resistance and easily swells from moisture. Suitable for rooms with normal humidity, as it is safer for health.
- The FSF marking has increased moisture resistance, but is not very environmentally friendly; it is made on the basis of phenol-formaldehyde glue. It is better not to use it indoors due to phenol emissions.
- DSP - ideal for leveling wooden floors under tiles.
- OSB is a completely environmentally friendly material; theoretically, it can be used for leveling, but it is undesirable, because it bends more easily at the same thickness as plywood. In addition, OSB is usually slightly more expensive than plywood.
- Chipboard – has poor environmental friendliness and low strength.
- Fiberboard is not suitable for leveling, because it is too flexible a material and it will bend around all the irregularities.
- Before starting work, carefully clean the screed from dust and debris and coat it with a deep penetration primer.
- Apply glue with a notched trowel to the plywood or floor and lay it with offset joints. We also leave technological gaps of 2-5 mm between the sheets and near the wall.
- For additional fixation, we drill holes with a hammer drill, insert dowels and tighten them so that the screw heads do not stick out.
- Seal the gaps between the sheets gypsum plaster. If you plan to lay the laminate on plywood later, you can leave them as is, or seal them with sealant.
- When the plaster hardens, it is treated with a grout mesh and the seams are taped with reinforced tape.
- Uneven screeds can be corrected by filling them with fine sand. It is advisable to seal the cracks in the corners polyurethane foam(this is especially true in panel houses).
- When installing on a concrete floor, it is almost always important to use waterproofing, as concrete can release moisture even several years after pouring, and the wood will rot on the underside over time.
- If you wish, you cannot rigidly attach the joists to the floors or walls. It is advisable to install them on felt or rubber pads so that small vibration noises are damped. The joists should not touch the walls; step back 2-3 cm from them.
- Before installing the first log, you need to find zero level, relative to which all other lags will be aligned.
- The beams for the logs are leveled; for additional leveling, you can use wooden pads. The main thing is that the beam stands stable: in the future it will be bound by the sheathing and it will not budge.
- Additionally, for plywood, it is recommended to make intermediate logs so that the cell size is small and the sheets can be pulled well to the frame. To do this, tie the logs together with crossbars made from scraps, screwing them with steel corners. It is advisable to select the size of the cells in such a way that they are a multiple of the dimensions of the plywood, and the edge of the sheet always falls on the joist.
- If insulation and sound insulation are necessary, insulation is placed in the cells between the joists on the waterproofing - mineral wool. It must be cut exactly to the size of the cells so that the edges are not bent. It is closed from above vapor barrier membrane, which will remove moisture, but will not allow it to get inside. It is stapled to the joists.
- In any case, you need to leave a gap of at least 2 cm under the plywood so as not to interfere with floor ventilation. If after insulation and fastening of the vapor barrier there is no gap left, a 100*25 mm board is screwed onto the logs, which will serve as a counter-lattice.
- Important point - right choice self-tapping screws Regular black hardened screws will not do the job. Bad screwdrivers simply won’t screw them all the way, but good ones will break them. Therefore, you need to use special yellow wood screws with a powerful mounting hole.
- To prevent the floor from creaking in the future and to ensure that the plywood is better pressed against the joists, you need to pre-drill the scrolling area with a wood drill (with a sharp end).
- As in previous cases, the sheets are laid staggered to avoid cross-shaped joints (must be T-shaped).
To level the floor, you can buy grade 3-4 plywood; the presence of knots will not affect the final quality; they will be covered by the floor covering.
Laying tiles on plywood is not recommended as wood has a high coefficient of expansion and may fall off as the season changes.
Ways to level a floor with plywood
Depending on the requirements and initial data, plywood floors are laid in several ways.
Before starting work with any wooden materials, they must be left in the room where the renovation is taking place for at least two days.
Covering a wooden floor with plywood
This method has already been discussed in our article:.
One thick layer or two thin ones?
Plywood is composite material, that is, the layers in it are initially laid with fibers crosswise, due to which the sheet turns out to be quite rigid. Therefore, two layers of 10 mm each, instead of one 20 mm thick, will not provide additional rigidity to the sheets.
In terms of price, the result is also almost the same.
However, if you lay one layer of plywood on a curved floor, it will smooth out the unevenness, but height differences will remain at the joints. If you put an additional layer, the height differences will be smoothed out, and the edges of the second layer will already lie in the center of the sheets of the even first layer.
Therefore, it is better to use two thinner layers for leveling.
What to do if there are large depressions in the floor?
If large holes are found on the floor (which could have formed due to heavy load in this place), then it will not be possible to simply lay plywood here - it will follow the contour of the depression.
Gluing plywood to the floor
Laying plywood on a concrete floor allows you to hide minor irregularities in the screed and make it warmer.
To attach the sheets you will need glue and dowel screws. Tools: notched trowel, hammer drill, screwdriver or screwdriver.
The best glue is with the addition of pine resin (often it is not indicated in the composition, but its presence can be determined by the smell); this is, for example, Thomsit 200 or 400.
For better adhesion of glue to plywood and concrete, the floor is first primed.
The length of the dowels is selected so that they go 4-5 cm deep into the screed.
Adjustable plywood studs
Plywood on studs The next technology is the installation of an adjustable floor.
Laying plywood on the floor along the joists
In addition to leveling, laying plywood on joists allows you to additional insulation or soundproofing the floor. Compared to standard option When the logs are sheathed with tongue and groove boards, plywood allows you to speed up the process. With a standard lag pitch of 50-60 cm, plywood with a thickness of 15-22 mm will be sufficient.
It’s easy to check this yourself: put plastic wrap on it for a day. If perspiration forms under it, then waterproofing is required. The easiest way for such a floor is to make waterproofing from ordinary polyethylene film, gluing it together with tape with an overlap on the walls.
This approach allows us to prepare solid foundation for laying linoleum, vinyl tiles, carpet, parquet, and if the differences are less than 2 mm per meter, you can even
Plywood is an economical building material that is used as a base for further work or used to level the floor for future flooring (parquet, laminate, linoleum).
The advantages of using it for finishing room surfaces:
- strength;
- moisture resistance;
- heat resistance;
- high-quality sound insulation;
- environmental friendliness.
It is important to decide on the appropriate material before starting work. Depending on the technical characteristics And operational properties, there is a wide selection of this building material on the market.
Types of plywood:
- Moisture-resistant on urea resin (Urea). The advantage is the elasticity and strength of the material.
- Unsanded with casein glue (NS). Requires sanding before gluing.
- For the subfloor (Ш1). Feature – polished, on the one hand. The adhesive base is casein.
- Polished on both sides, based on casein (Ш2).
When choosing plywood, you need to pay attention to a number of important nuances, on which the properties of sheets and the possibility of their use directly depend. Moisture resistance, material of manufacture and formaldehyde content are the main evaluation criteria when choosing a building material.
The most suitable option for interior work moisture-resistant FC sheets.
Depending on wood defects and processing flaws, there are 4 types:
- 1st grade – a small number of defects or their complete absence is acceptable;
- Grade 2 – there may be scratches and dents, the area of which does not exceed 5% of the total area of the plywood sheet;
- 3rd grade - the presence of healthy, partially fused knots and the presence of wood inserts is acceptable;
- Grade 4 is a material where a large number of defects and flaws are allowed.
Considering the cost and quality the most suitable option is a construction material of 2 grades.
Cutting and fitting plywood
Determine quantity required material can be done by calculating the surface area of the floor. It is important to add about 10% to the reserve when calculating. The standard dimensions of sheets of this building material are usually 1.25 x 1.25 m. Working with such parameters is not always convenient. Accordingly, preliminary cutting will simplify the fitting and laying of building materials.
Please note that the best option is to cut into 4 squares. This will make it possible to get required quantity expansion joints, necessary for best styling warm floor.
The simplest tool for sawing is a hacksaw. But it may not always be effective and quick results. The ideal option would be to use a jigsaw or circular saw– they do not leave any chips or delaminations.
When the material is cut, it must be laid out on the surface for preliminary adjustment. IN in this case The use of glue or screws is excluded.
Please note that it is necessary to leave 8 - 10 mm seams between squares and 15 - 20 mm between building material and walls. By numbering the elements or drawing up a diagram of the area to be covered, you can significantly simplify the final work.
Methods for attaching plywood to the base
Fastening plywood to concrete floor can be done using dowels and glue. Today, there are several types of adhesives on the building materials market.
Its application features directly depend on their basis:
- on water based(safe for human health, but takes a very long time to dry);
- on a solvent (advantage: quick drying, disadvantage: caustic bad smell);
- based on two components (no pungent odor, dries in a short period of time).
The most preferred type of adhesive for plywood on a concrete floor is a two-component adhesive. Its use is possible even when gluing plywood to a partially dried screed.
Step-by-step guide to laying sheets
Laying plywood on a concrete floor is carried out in several stages. If you strictly follow the instructions, you will not have to involve specialists, which will significantly reduce costs. How to fix it to a concrete floor in several stages is described below.
Checking the moisture content of the concrete base
To avoid delamination of the plywood covering in the future, it is important to monitor the moisture content of the base. It should not exceed the permissible value, otherwise the plywood may delaminate in the future.
At home, humidity can be checked using plastic film. The film is laid out on the concrete and its edges are pressed down with a weight. After a week, check the condition of the film.
In the presence of condensed moisture, lay this material it is forbidden. Before this, with the help of appropriate compositions, it must be created additional protection from moisture.
Cleaning the base
Plywood floors should be installed on concrete floors only after stripping and priming. Using a grinder, sanding the base is not difficult.
Cracks and other defects must be eliminated using special mixtures, for example, cement-sand mortar. The base must be thoroughly cleaned of dust. Ideally, an industrial vacuum cleaner is used for this.
Under no circumstances should you use a broom with water for cleaning. Wetting the screed will harm the quality of the fastening of the plywood sheets.
Base primer
Before installing the sheets, it is necessary to prime the concrete base. For priming, it is better to use compounds recommended by the manufacturer of the selected building material.
- eliminates the smallest particles of dust;
- provides the base with maximum strength;
- ensures the strength and reliability of the connection of materials;
- prevents residual moisture.
Laying plywood
According to the numbering of the sheets or being guided by the drawn diagram of the surface, it is necessary to glue the sheets of building material.
The sequence of laying building materials on the floor is carried out in several stages:
- using a notched trowel concrete base covered with a layer of glue up to 2 mm. Please note that it is best to apply the glue in small sections so that you have time to lay out the plywood sheets before the adhesive begins to set;
- According to the previously drawn diagram, plywood is laid on the concrete. It is recommended to roll the sheet with a heavy roller;
- The sheets must be additionally secured using self-tapping screws with dowels around the perimeter and diagonally. It is recommended to fix the screws at a distance of 150 - 200 mm from each other; there should be a distance of at least 20 mm between the wall and the flooring. The diameter of the holes for the self-tapping screws should be of such a size that when screwed in, its head is recessed;
- To get rid of minor differences in the heights of adjacent sheets, eliminate burrs and other minor defects, process the laid sheets with a grinding machine or sandpaper.
Checking work
Any covering can be laid on a smooth, treated floor. But before this, it is important to check the work and eliminate all errors if found.
It can be done in three stages:
- there should be gaps between the elements, and it is also important to check the distance between the walls and the installation;
- the permissible discrepancy in surface height must be within 2 mm;
- It is important to check that there is no air space between the plywood and the concrete. To do this, you need to gently knock wooden block or with a hammer of the same material on the surface. The sound should not be dull.
Conclusion
Plywood sheets are a strong, durable material that is practically not subject to deformation. Sheets laid on frozen concrete screed, This perfect solution for private houses, apartments, where differences in floor levels are a real problem.
Environmental friendliness of the material, its strength, affordable cost, possibility self-installation will delight every potential buyer.
Plywood flooring is inexpensive and effective means for leveling and insulating the surface.
Plywood sheet is a reliable rough option in a residential area, and due to its reliability and resistance to deformation during mechanical loads, it is often used as an intermediate layer between floor tiles and a cement or metal frame.
Important! If layers of plywood are impregnated with a special adhesive composition, you can obtain a waterproof material for installation in rooms with high humidity.
Experts often use plywood as a base material. This is due to the fact that further exploitation and removal various types the floor covering will be light and not labor-intensive. I took it off and that's it.
It will allow you to level the old coating and prepare it for laying laminate, linoleum and other flooring materials.
Choosing a plywood sheet
First of all, you need to pay attention to the thickness of the product; if the fastening will be done on logs, then the thicker the sheet, the stronger the base will be. We choose plywood about 18 mm, maybe less, but not lower than 12 mm.
The master will need to have the following set of tools with him:
- Self-tapping screws required sizes, from long to short
- Screwdriver for screwing them in
- Electric jigsaw
- Roulette.
To lay plywood on a wooden floor you need:
- Make a correct and high-quality cut of the sheets, preferably measuring 60 by 60 cm, and lay them offset by 30 cm for each next row. All sheets that are susceptible to delamination after sawing with a jigsaw must be replaced with solid ones or glued with a special quick-drying construction adhesive. In this case, the flooring will have to be put aside a little until it dries completely.
- We pre-lay the plywood on the floor, numbering the sheets in advance. If everything fits together, there are no errors and no additional adjustment of the material, then we remove everything and begin to work on the wood flooring.
- Cleaning wooden boards from contamination, dust, condensation, check all cracks, remove deep crevices. We eliminate all kinds of deformations and creaking floorboards. We remove all unusable boards and fix loose ones with nails. After a thorough check, we go over the surface with a vacuum cleaner, removing any remaining debris and dirt.
- The prepared plywood squares are laid out on a wooden floor, taking into account expansion joints. The distance between the sheets should be no more than 10 mm, and between the plywood and the wall up to 20 mm.
Attention! Experts advise installing plywood on a wooden floor using adhesive composition, this will provide the coating with moisture resistance and reliability. Another option involves laying sheets with self-tapping screws, the distance between which should be at least 15 cm, along the edges and diagonally, and the distance from the edge should be 2 cm.
Warning! Experts do not recommend using plywood sheets for the bathroom or in unsinkable rooms; excessive humidity will quickly damage the products, cause an unpleasant odor, and deformation of the floors under various mechanical and physical loads.
Tips from experienced craftsmen for laying plywood on a wooden floor
- Before installation, plywood sheets must be stored in the same room where installation will take place. The coating will gain the necessary moisture and adapt to temperature conditions so as not to change later standard sizes. 24 hours will be enough.
- To check the humidity of the room, you need to put oilcloth on the wooden floor overnight; if it is dry in the morning, then you can lay plywood, and if condensation accumulates, then you should either replace the floor covering with a more durable and moisture-resistant one, or use a special adhesive sheet to install composition: water-dispersed PVA-based glue.
- If using plywood as the final flooring option, there is one thing to consider. When we lay plywood on a wooden floor, it is necessary to leave a slight gap between the sheets, which can ultimately distort appearance products.
- After laying plywood on a wooden floor is completed, it is important to check how firmly the coating is held. To do this, use a small block that should be tapped on the floor. If an empty, booming sound is heard, then this place is fixed with an additional long screw or the void is filled with adhesive.
Under laminate, linoleum or ceramic tiles . To do this, you need to use FC plywood, class 4/4, with a thickness of at least 12 mm.
Let's start work.
- Installation of a beacon. To do this, you need self-tapping screws that are screwed into the desired height over the entire surface. The beacons are fixed at the corners of a square with sides of 25 cm.
- If you have a screwdriver and a level, lay the logs. These are strips of plywood 25-35 mm wide. They are attached to the floor with construction glue or self-tapping screws, and the voids are removed with plywood blocks coated with glue.
- We are preparing plywood sheets for laying on a wooden floor. We cut it into squares 60 by 60 cm, the same as in the previous version of laying plywood on the base.
- Next, we lay out plywood squares around the perimeter so that the joints of the sheets end up on the bases of the logs.
- To avoid joining four seams at one point, we offset each sheet in the manner of brickwork.
- Now we adjust the plywood exactly to size, removing protrusions and other irregularities.
Attention! In order not to spend more material than you bought, you should accurately make preliminary measurements of the plywood sheets. To do this, we lay each of them on the logs and mark the joining place with a pencil.
- We are fastening the plywood to the joists with self-tapping screws, carefully sanding the ends.
Important! When laying linoleum on top, you can fix it with nails, nailing it directly to the plywood. To avoid the formation of cracks, when laying the covering, watch the joints of plywood and linoleum. This will not only provide a reliable and durable installation of the floor covering, but it will also look much more efficient.
