During renovations, it is often necessary to replace the floor. In this case, select suitable covering is not difficult. Before laying the top layer, it is necessary to level the base, since the service life of any flooring. Laminate and board, for example, have locking connections and when laid on a bumpy surface, cracks form.
In this case, the most favorable option for leveling the base would be plywood. And here, not very experienced repairmen are faced with the question of how to strengthen the plywood onto the base, and with what tools to do this. Before leveling the main floor, you need to assess in advance the condition of the surface and the degree of deformation of its “relief”. Sometimes the subfloor per 1 m² has differences of about 2 mm. Then you can achieve perfect evenness using putty made from wet sawdust mixed with PVA, or by covering the base acrylic sealant. Old boards are renewed with a plane and laid back. All loose parts are simply nailed or secured with screws. But in order to smooth out significant unevenness, you will need to lay sheet material. Here again, information on how to attach plywood to the floor before finishing is useful.
Working conditions
Before you start repair process, you should prepare all the tools that will be required for the job. This list includes:
- perforator;
- hammer;
- notched spatula;
- electric jigsaw;
- roulette;
- drill;
- screwdriver;
- spirit level
To secure the plywood to the base, glue and dowels are used. The adhesive can be solvent based, water based or two-component. What is the difference between these means? In short:
- the water base slows down the drying of the glue and can delay the repair for several days;
- glue, which is based on a solvent, dries very quickly, but has a pungent specific odor;
- two-component adhesive is used most often, especially if communications are laid in the concrete and the screed has not yet dried.
To lay plywood on the floor, you simply need a good screed.
This is where it begins labor process. It doesn’t matter what method (wet or dry) the screed is made, but it must be done with high quality and in perfect horizontal position. To keep the floors in original form, kept dry and warm, the following conditions are necessary:
- screed completed according to all rules;
- waterproofing;
- compliance with technological standards when installing thermal insulation;
- the presence of moisture in the base is not more than 1%.
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Mounting Selection
For the base under a parquet floor, it is best to choose material of grade FK 4/4 and higher. A thickness of 1 cm or 1.2 cm is suitable. It is these plywood sheets that have sufficient strength and the necessary flexibility. And this plays an important role, since laminated plywood bears quite a serious load when arranging furniture and when residents walk around. When choosing a material thicker than 1.2 cm financial resources will be wasted, since its properties are equivalent, but the cost is more expensive. If we take into account the price-quality ratio, then 2nd grade plywood is suitable. When marking on plywood sheets it is indicated what type they belong to – polished or unpolished:
- Ш1 ─ grinding 1 side;
- Ш2 ─ grinding of 2 sides;
- NS ─ without grinding.
Sanded plywood is marked with the free formaldehyde content:
- E1 ─ 100 g of dry plywood mass contains less than 10 ml of formaldehyde;
- E2 ─ 100 g contains 10-30 ml of formaldehyde.
To make the floor perfectly flat, you need to choose a 2nd grade plywood sheet, marked with the marks Ш1, ФК and Е1, the thickness of which is 10-12 mm.
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Cutting and fitting
Plywood consists of several layers, so high humidity does not in the best possible way affects it and soon you can expect delamination. Before you start laying, you need to determine the humidity concrete structure. To do this, during repairs, the worn out top covering is removed, and during construction the ceiling is cleared. Then a large piece of polyethylene is laid out on concrete slabs and pressed tightly along the edges, leaving the central part free. After 7 days, the film is examined. If no condensation is found on it, then you can safely lay the substrate. If drops of liquid appear on the polyethylene during testing, then the floors must be additionally covered with waterproofing.
When everything is ready to lay plywood, the room is measured and the sheets are cut according to the measurement results. In this case, you need to ensure that the seams between the sheets of plywood are 1 cm, and near the walls they are 1.5-2 cm. The plywood covering should not be allowed to touch the walls. This gap is left in case the coating parameters increase due to heat or humidity. If there is no free space, the floors may simply swell. In addition, the small format of plywood panels has greater stability and strength.
After cutting, check the ends of the workpieces. If they delaminate, they are rejected and new ones are prepared. Then the plywood sheets are laid out on the floor and adjusted to the base. It is very important that 4 sheets do not join in one place. To do this, all blanks need to be laid out using the method brickwork, that is, with a shift.
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Surface primer
Having adjusted the plywood, the sheets of blanks are numbered and a schematic representation of the layout is sketched out. Then the parts are removed and the base is leveled. To do this, remove the remaining solution, paint and construction waste. After this, dust is removed. It is better to do this with a special vacuum cleaner, but a simple broom will do. Do not carry out wet cleaning, as the water will deteriorate wooden parts designs.
Now the coating needs to be primed. A primer is required for this. It is prepared from an adhesive composition, diluted with a special solvent. The purpose of the primer is to:
- Increase the strength of the bonding surface. This is achieved by the primer penetrating into the pores of the concrete base and gluing microscopic dust particles. All this increases the adhesion of plywood, glue and any dissimilar materials.
- The primer holds it together concrete surface and protects against the formation of cement dust.
If the room is large, then it is done in sections. In this case, the primer should be applied in parts. Base for plywood covering small rooms primed entirely. In both cases, the primer is applied before laying the plywood sheets.
Plywood is one of the commonly used finishing materials, which is used, among other things, to sheathe the surfaces of walls, ceilings, and floors. This material is characterized by low thermal conductivity, resistance to deformation, low cost, and can also have varying degrees of moisture resistance and high decorative properties, depending on the variety. How to properly lay plywood on wooden floor, and what materials need to be used - read on.
The modern flooring market offers wide range finishing materials. As a rule, all flooring for living rooms requires a perfectly level base. For example, laminate cork covering, parquet, etc. must be laid on a pre-leveled wooden floor. A level base for the finishing floor covering can be created using sheets of plywood.
When choosing the size and type of plywood for mounting the base for finishing coating gender, the following parameters should be taken into account:
- Humidity level. FK plywood is suitable for kitchens, bathrooms and bathrooms. For the remaining rooms, plywood is used that does not emit toxic FBA resins.
- What is the thickness of the plywood sheets. The plywood sheet must have a thickness that is equal to the thickness of the final covering, i.e. from 10 mm.
- Economical finishing material. To level the floor level, you can use ordinary unsanded plywood.
It should be noted that the undoubted advantages of leveling the floor with sheets of plywood include the low cost of this method, due to the relatively low cost of plywood. In addition, a wide range of standard sizes and assortment of plywood allows you to choose exactly the type of material that is needed for a given room, taking into account temperature and humidity conditions. Plywood for floor leveling is one of the most practical, inexpensive and easy to use materials.
Laying plywood on a wooden floor: work procedure
Before the final installation of a row of floor coverings, the floor must be leveled. You can successfully use plywood for this. In general, the steps of laying down plywood before laying down the final covering are not difficult. The plank base is leveled by cutting down a layer of boards.
The correct placement of plywood sheets should be in a checkerboard pattern, i.e. Simultaneous joining of no more than 3 seams is allowed.
Plywood sheets should be laid observing technological gaps. Thus, the gap between the laid plywood sheets should be 2-3 mm, and between the walls and the plywood - at least 1 cm. To ventilate the wooden floor in each of the rooms where plywood needs to be laid, it is necessary to cut a hole measuring 5x5 cm in the plywood covering, which it is subsequently preserved in the final coating and decorated with an insert.
To screw plywood sheets:
- Self-tapping screws are used;
- Place the screws at a distance of 15-20 mm from the edge of the sheet;
- Fastening occurs in increments of 25 to 30 cm.
Installation of plywood using self-tapping screws is carried out so that the heads of the screws are recessed into the surface of the sheet. The number of screws is approximately 5-6 pcs. per 1 m 2. It is also necessary to fasten screws diagonally to each sheet. Leveling the floor using plywood, according to various sources, can be carried out with differences in floor level of no more than 6 cm. In general, to create flat surface sex, use various types plywood, up to 18 mm thick.
How to lay plywood on a wooden floor: algorithm of actions
Home renovations often involve replacing old flooring. It is often not necessary to tear down the wood of the floors, but you can replace and refinish the flooring with plywood. You can lay plywood on an old plank floor if its level differs within 6 cm in a simple way.
First you need to remove the old paintwork from the floor.
Next, the baseboards are torn off and all their attachment points are chipped. The height of the door is adjusted taking into account the designed floor level. To level out differences in the floor, it is necessary to screw screws into the boards according to the size of the plywood sheet in a checkerboard pattern. specified depth. As a result, the heads of the screws must be at the same height, which is set by the laser level. Therefore, you should choose in advance which screws will be used to carry out the work - these are self-tapping screws various lengths, but having the same slot for a screwdriver. Self-tapping screws are screwed strictly vertically into the boards in increments of 0.25-0.3 m.
- The floor surface is wetted with water.
- Polyurethane foam is applied along the perimeter at the wall-floor joints on the boards.
- Also, in a checkerboard pattern with increments of 10-15 cm, the foam is applied in islands on the boards according to the size of the plywood sheet. The height of the foam island should approximately correspond to the height of the nearest screwed-in screw. In this way, a base cushion is created for laying plywood.
- A sheet of plywood must be placed on the screws and foam. This laying method allows you to get a perfectly flat plywood floor.
- Technological gaps between the walls and the plywood sheet should be within 10-15 mm, and between the plywood sheets - 4.4 mm.
It should be noted that, as a rule, this technology for laying plywood sheets allows you to obtain a perfectly flat and durable floor. In some cases, to relieve stress in a sheet of plywood, before laying the sheets, they should be cut into 4 equal parts each.
Is it necessary to underlay plywood on a wooden floor?
The qualitative characteristics of plywood sheets directly depend on the type and components used in the production of this finishing material (type of wood, synthetic resins, etc.). It is these factors that determine which plywood flooring will be used to create a high-quality coating.
The materials that can be placed under plywood on a plank floor should be “breathable” materials that have the following properties:
- Provide ventilation of the plank floor;
- Do not experience temperature and humidity deformations;
- Create a level base for laying plywood.
As a rule, in general, for laying plywood on a plank floor, no special underlay is required, since the plywood flooring levels the floor and itself serves as the base for the final floor covering. When laying plywood sheets using mastic, the following technological clearances should be observed – 1-2 cm between the wall and the plywood sheets. To compensate for temperature and humidity deformations, the gap between the glued plywood sheets should be 1.8-3.1 mm.
Tips: which glue to choose for plywood on a wooden floor
There are cases when the surface of the floor boards is quite flat. In this case, you can glue the plywood sheets to the ceiling using polyvinyl acetate mastic.
The flow of work is as follows:
- The mastic should be applied in a thick layer using a notched trowel (teeth size 1.1-3 mm).
- For better adhesion of plywood sheets to the floor covering, the back side of the plywood sheet should be treated with a thin layer of epoxy adhesive, and then covered with a layer of coarse sand or other crushed natural material, having a grain size of 1.8-2.8 mm.
- Polyvinyl acetate mastic should be applied only after the epoxy adhesive has completely dried and hardened.
Thus, with the help of plywood sheets, you can solve a number of problems that arise during the operation of plank flooring (repair or replacement of the floor). It should be added that laying plywood sheets in a certain way also allows you to compensate for significant differences in floor levels, for example, an old plank floor (up to 6 cm).
Underlay for plywood on a wooden floor (video)
In conclusion, we note that the use of plywood involves fastening sheets in various ways, including the use of adhesive materials. However, when working with plywood materials, do not forget about the necessary technological gaps that ensure further correct operation of the entire resulting multi-layer floor covering.
Floorboards are durable, environmentally friendly, and abrasion resistant. However, after several decades, the boards begin to creak, dry out or rot from high humidity indoors. If you lay linoleum or carpet on an unprepared plank floor, or lay laminate or parquet, the surface will not be perfectly flat. All defects of the rough base will be visible through the final finishing coating, and in the case lock systems Installation will be impossible if uneven.
To make the floor high-quality and durable, under flooring you need to lay the underlayment. For this purpose, sheets of plywood are suitable, which will hide all the unevenness and imperfections of the wooden floor.
Peculiarities
To choose plywood for leveling the floor, you need to understand the features and classification of the material on the market. Plywood varies in grade, thickness, moisture resistance and material of manufacture.
The main characteristics will help you choose the right sheets.
There are 4 types of plywood that can be distinguished visually:
- The fourth grade has defects on the surface, rough, there are holes from knots, since the lowest quality raw materials are used for production.
- The third grade is of better quality than the previous one and there is less defect on the surface.
- The second grade has minor cracks and is smooth.
- The highest quality and most expensive first grade is well polished, all sides are without defects.
When choosing a variety, they are guided by price and quality. For the construction of a subfloor, plywood of the second and third grades is suitable. According to the processing method, they are distinguished:
- Unsanded plywood.
- Sanded (one or both sides).
For installation on the floor, take one-sided sanded material, laying the smooth side on top.
Plywood sheet is made from hardwood and coniferous species wood (usually pine and birch). Wood veneer is bonded together using natural and synthetic resins. Top layer can be treated with a varnished water-repellent composition.
Based on resistance to moisture in residential premises, the following brands are distinguished:
In bedrooms and others living rooms with low humidity, FK and FBA brands are laid, made on the basis of urea and albumin casein glue. They are environmentally friendly and have average resistance to moisture.
The FSF brand is installed in the hallway and in the kitchen, where greater moisture resistance is required.
The thickness of the canvas is determined by the number of layers of veneer. Their odd number is laid perpendicular to the previous one, creating a strong building material. For laying the subfloor, use plywood with a thickness of 10 mm and above.
Plywood lends itself well to fastening with self-tapping screws and does not crumble or crack.
An analogue of plywood in the construction market is OSB - oriented strand board. Such materials have similar properties, but differ only in production. For plywood, the raw material is wood veneer, and for OSB, wood chips are processed with natural resins.
OSB is divided into different categories:
- The first one is suitable for minimal load and dryness.
- The second is produced for low-traffic residential premises.
- The third is characterized by high moisture resistance and strength.
- The fourth is used in the construction of walls.
- Lacquered or laminated – coated protective layer varnish or laminate.
- Tongue-and-groove - has a connecting groove at the joints.
The best solution for the subfloor there will be OSB 3, tongue-and-groove and easy to install. Such sheets are produced with a thickness from 0.5 cm to 4 cm.
Pros and cons
When it is difficult to decide which substrate is better: plywood or chipboard, you need to consider the advantages and disadvantages of each material. Plywood covering has the following advantages:
- Withstands heavy loads.
- Light weight.
- It is flexible, has high bending and deformation strength.
- There is no foreign chemical smell.
- High leveling abilities.
- Easy to process and saw.
- Easy to use.
- Smooth beautiful outer surface.
- Retains heat in the room.
Advantages of using oriented strand boards:
- Affordable.
- They don't delaminate.
- Surface without defects.
- Various sizes.
- The panels are lightweight.
- Resistant to harmful insects.
But all wood materials have general disadvantage – great influence there is moisture on them. Humidity will quickly destroy wood raw materials, so it is better to lay moisture-resistant types of coatings. Reverse negative side moisture resistant panels– environmental friendliness. They emit formaldehyde, which is harmful to health, but it is this that helps fight moisture.
Both leveling materials have high degree fire from open fire, therefore, before laying the material, you need to take care of increasing the fire-retardant properties.
If you lay the flooring on joists, you lose up to 10 cm in the height of the room. This is not always acceptable in certain situations. To lay the sheets, it is necessary to make a clear calculation so that there is no waste and unnecessary rework. It is recommended to fasten these materials using self-tapping screws with an average pitch of 20 cm.
Such sheets tolerate fasteners well and are tightly attached.
The price differences between plywood and OSB of the same brand are not the most significant, but OSB is cheaper. In suitable and unpretentious conditions it is possible to lay OSB boards, but plywood is suitable for a durable, wear-resistant coating.
Materials and tools
Plywood and OSB are similar in laying technology. To cover the floor with wood sheets, use the same installation tools. The materials for fastening are also the same. In order to quickly and efficiently lay plywood sheets on a sub-plank floor, you need to stock up on basic construction equipment. In this work you will need:
- Level for measuring the evenness of the floor.
- Screwdriver or screwdrivers for screwing screws.
- Drill for drilling holes for dowels.
- Tape measure for measuring the required length.
- A jigsaw or hacksaw for sawing sheets of plywood to the required dimensions.
- Sanding attachment on a drill or grinding machine for sanding joints between sheets.
- Roller or paint brush for applying primer.
- A broom or vacuum cleaner for removing debris.
- Spatula for applying glue.
- Hammer for nailing.
To increase the moisture-resistant and fire-retardant properties of the material, it is advisable to use special antipyretic compounds and primers.
It is better to lay plywood or OSB on water-dispersed adhesive bustilate or PVA. These brands are suitable for gluing wood surfaces. They are safe for health, odorless and dry within 24 hours. The glue is easily applied with a spatula or brush (depending on consistency).
You can fasten plywood sheets with screws and nails. If laying materials is carried out in an apartment, it is preferable to use self-tapping screws with dowels, since working with a drill and screwdriver is easier and quieter than using a hammer and nails.
Preparatory work
Before installing plywood on a wooden floor, basic preparatory work. First, the original rough timber base is assessed. Visually assess the condition of the floorboards, the presence of poorly fitted and creaky floorboards.
Check the building level for differences and surface unevenness.
Then the baseboards are dismantled. All loose boards must be additionally secured with nails or screws to the lower beam. Floorboards affected by fungus are replaced or cleaned, impregnated with an antifungal compound. Deformed and damaged boards need to be replaced. The protrusions on the surface are trimmed with a plane and sanded. Gaps and cracks are filled with sealant or glue.
After repairs, remove debris, sawdust and dust using a broom or vacuum cleaner. Unfinished plank floor is treated antiseptic. Rolled material can be laid under the plywood floor as noise insulation and insulation.
Penoplex or isolon of small thickness is suitable for the substrate. Connect the strips of the substrate to each other with construction tape.
The plywood is fastened after drying to avoid deformation. To do this, the material is brought into the room and left for 2-4 days. The optimal solution to protect against moisture and fire, both sides of the panel will be treated with a primer or acrylic varnish. The technology for laying wood sheets requires a distance of 1-1.5 cm from the wall between sheets of up to 0.5 cm.
This must be taken into account when cutting and laying plywood blanks on the floor.
To relieve stress from the material during operation and ease of installation, the sheet is cut into 4 parts using a jigsaw. All parts are first placed and adjusted, a layout diagram is drawn and the workpieces are numbered. Sheets should be laid offset to reduce the number of joints and avoid crossing.
If you follow all the rules when laying plywood, it will serve as a high-quality, durable base for any floor covering. Finishing decorative material can be remade, and plywood base will remain the same.
Alignment methods
The leveling method depends on the levelness of the subfloor. Differences in height of more than 1.5 cm require plywood to be laid over joists. Minor irregularities are covered with plywood directly onto the wooden floor.
Boards with differences of less than 1 cm are leveled with supports in the right places. Thin squares, blocks of wood or plywood are used as support.
Laying plywood on the floor can be done with or without a backing. The lining roll is rolled out over the entire surface and secured with tape. Plywood material is spread on top in accordance with the diagram, the evenness is checked and secured with self-tapping screws. In this case, sheets with a thickness of 1 cm or more are needed.
Without the use of cushioning material it is applied glue method fastenings Small area The premises are covered with 2-3 mm of glue, starting from the corner. A sheet of plywood blank is placed on top and pressed tightly. Additionally, you can screw in several screws for better fixation. This method is used to install the remaining part of the room.
Laying birch plywood does not require special skills and can be done with your own hands.
When a sheet of plywood does not lie flat, bends, or there are slight differences in height with other pieces, supports are used. The support points are placed in poorly fitting places and are fixed through and through with self-tapping screws.
If on wooden base If the fiberboard is lying, then dismantling is carried out if the material is old, warped from moisture, crumbles and flakes at the edges. It is not recommended to lay fiberboard on the floor, since the sheets deteriorate from moisture and have poor leveling properties due to their small thickness.
To level out significant differences in height, logs are used. As logs, boards of the required length with a section of 3-5 cm by 7-10 cm or coniferous plywood slats of the same size are used. The location of the joists depends on the thickness of the plywood and the load during operation. Small thickness requires a smaller distance between the logs, starting from 40 cm. You should not use sheets less than 1.5 cm in height. The installation of the joists is designed in accordance with the layout of the plywood in the room, so that the joints are laid in the middle of the beam.
The horizontal position of the logs is measured with a water or laser level. The evenness of the entire floor depends on the accuracy of installation. The logs are attached with glue and screwed in place. Between them, bars are placed perpendicularly, obtaining a reliable sheathing on which plywood blanks are laid.
Plywood is more rigid than wood covering, because a sheet of plywood covers an area that cannot be covered by a single floorboard.
Because of this, the strength of the floor and resistance to squeaks and knocks increases.
From this article you will learn how to lay plywood on a wooden floor, as well as the pros and cons of such a repair.
The following types of plywood are most often used in construction:
- FC is a moisture-resistant plywood based on urea resin, which is non-volatile and non-toxic. It has strength and elasticity comparable to BS aircraft plywood.
- NS – unpolished with casein glue. Before gluing parquet or other hard flooring onto it, it requires sanding.
- Ш1 is the main material used for the subfloor. Sanded on one side. Adhesive base– also casein.
- Ш2 – polished on both sides, on casein. For lightly loaded parts in dry rooms with comfortable temperature can be used as a substitute for FC.
Main advantages and disadvantages
Inner plywood sheets are made from cheap material, with a large number knots and defects that do not reduce the strength of the material. External sheets, depending on the type of plywood, are made of pine or birch. The sizes of plywood sheets reach 2.5 meters in length and 1.5 meters in width. Finished plywood floors are 5-10 times cheaper than laminate floors or solid board. Such floors can be painted in the color you like and varnished. Or use it as a base for applying 3D cast floors.
Plywood floors over wood floors are less attractive than solid wood, parquet or laminate flooring. But their installation costs tens of times less. Not all types of plywood have high moisture resistance and are used for finishing floors Finish coating plywood cannot be leveled by milling, like parquet or solid boards.
Using plywood for the subfloor ties the joists together single design. Batten connects the logs only along the installation, with each board secured separately. Therefore, plank floors are more susceptible to squeaks and knocks than plywood floors.
Plank floors are not suitable for laying laminate or parquet, unlike plywood floors, which level the surface.
Using plywood in floor construction
Laying plywood on a wood floor places the same requirements on the subfloor as it does on a plank floor. Rigid fixed base - wooden logs fixed in the walls, a concrete slab or steel structure ceilings When constructing a floor with wooden load-bearing elements(lagami), them upper part becomes the basis for laying plywood. Therefore, lay the logs using building level and a two-meter ruler with which to measure the difference in heights. Attach plywood to such ceilings with wood screws, the length of which exceeds the thickness of the plywood by 3-5 cm.
Flatness concrete slab for laying plywood is 2 mm by two meters. If the height differences are greater, fill the screed along the beacons or use a self-leveling coating. This will avoid areas of loose fit, leading to squeaks and knocks. To secure the plywood, use anchor dowels of length equal to the thickness of the plywood plus 5-7 cm.
To lay plywood on a steel load-bearing floor structure, two installation options are used - directly on the structure and laying on logs pre-attached to the structure. When installing this way, use for joists wooden blocks, the width and thickness of which are 50 mm. The second installation method is preferable, because it is easier to attach bars without plywood to load-bearing structure using countersunk bolts. And fasten the plywood with wood screws.
When creating a subfloor from plywood, the permissible gaps between the sheets are 5 mm. If the gaps are larger, it is necessary to adjust the sheet to fit required dimensions. When laying laminated plywood for floor coverings, gaps wider than 0.5 mm are unacceptable. This type of coating cannot be puttyed or cleaned. sandpaper. This will damage the protective and decorative lamination layers. When laying a finished plywood floor for painting, do not allow gaps wider than 1 mm. From the cracks larger size The putty falls out after two to three months.
Laying plywood on an old wooden floor levels the surface, connects strong and weak areas, thereby increasing the overall strength of the floor. Repair the floor before installing plywood. Replace damaged floorboards, subfloors and joists, repair insulation and waterproofing of the floor. Additionally, attach the subfloor to the joists, and the covering to subfloor. By knowing how to properly install plywood on a wood floor, you will strengthen its structure and be able to avoid repairs in the next two to three years.
Fastening plywood sheets
To fasten plywood, use wood screws; they are sold in hardware stores and construction stores. Drill through the plywood with a drill whose diameter is equal to diameter self-tapping screw, and drill a hole in the floor boards of half the diameter. Then drill the plywood with a drill with a diameter of 10-12 mm to a depth of 1-1.5 mm. The self-tapping screw will easily screw into the floor boards, and the head will go a fraction of a millimeter below the surface of the plywood. Screw sheets up to 15 mm thick, used as a finished floor in technical rooms, without drilling holes.
If you lay plywood on concrete screed, then during operation the plywood sheets will bear the brunt of the blow. Microcracks form on the wood, but they do not affect the quality of the floor.
The wood building material from which the subfloor is made is in good contact with any external finishing. This has a beneficial effect on the condition of the floor for many years. The surface remains smooth, without cracks or bends.
Another advantage of using plywood is ease of installation. This material is easy to cut into pieces and quickly installed. One person will be able to carry out all the work with minimal experience and the most common construction tools at hand.
Plywood has low thermal conductivity, which reduces heat losses indoors. And if you take sheets of the highest grade and fine grinding, then you can use them for final finishing.
Where not to use
Despite all the advantages, plywood sheets are not recommended for use in rooms with high humidity. This is their minus. Plywood is not installed in bathhouses, swimming pools, showers, or bathrooms. Of course, there are moisture-resistant laminated varieties, but their price is high, so not everyone will want to use them over a large area.
It is not recommended to cover the floor with plywood in rooms with strong temperature changes, for example unheated dachas. Excessive heat after freezing may cause the sheets to warp.
What kind of plywood to lay
Before laying plywood on the floor, you need to familiarize yourself with its characteristics:
- The brand for residential premises must be FC. This is the safest option, although its moisture resistance is not very high. Laminated products are also used, but they are more expensive;
- For safety reasons, choose E1 or E0.5 class;
- Inexpensive grades 3 and 4 are suitable for subfloors; for finishing floors, you need to take a higher grade. The designation of grades 2/2, 2/3, 1/2 and the like is often found. This is how the grade of veneer is indicated from different sides;
- the humidity of the sheets should be no more than 15%, the lower it is, the better;
- plywood used for the subfloor must have a thickness of at least 12 mm; for finishing, a value of 10 mm is allowed. Laying in two layers is possible. In workshops, workshops, public spaces with high traffic, the thickness can reach 2.5 cm;
- For subfloors, unsanded plywood, designated NSh, is suitable. It can also be polished on one side - Ш1.
Laminated plywood with a mesh texture is used primarily for transport floors. It is suitable for finishing on the terraces, in country houses, outbuildings.
The dimensions of the sheets are chosen in accordance with your own needs; they are not of fundamental importance for installation. It must be taken into account that the larger the leaf, the greater its mass. The process of transportation and manipulation during installation becomes more complicated. To avoid tension in the material under load, large sheets are sometimes cut. When gluing to a screed, it is convenient to work with squares of 75 x 75 or 60 x 60 cm. Elongated strips are suitable for joists. IN large rooms they may not be cut.
Domestic manufacturers offer plywood good quality, which is quite suitable for the floor. The same applies to Western European brands. Regarding Chinese goods, then you need to be careful when choosing, because there are products that do not meet the standards. For example, the declared thickness may be greater than the actual thickness.
Subfloor laying options
Plywood is easy to lay on a flat concrete screed in an apartment. Sheets 12 mm thick are glued to the surface, having first checked its horizontalness. The height differences should be no more than 2 mm, otherwise you need to fill it for leveling and wait until it dries completely.
Pay attention! For any installation, gaps of 2.5–3 mm must be left at the joints of sheets, and 1–1.5 cm away from the walls. This will avoid deformation due to changes in temperature and humidity, and there will be no creaking or sagging.
Plywood sheets are laid with a slight offset so that there is no clear joining of the four corners. This installation increases the strength of the floor covering.
The most common installation method is by wooden joists. It can replace the screed. The surface is perfectly smooth and can be used for any finishing. The logs can be adjustable. How to perform such installation will be discussed below.
When there is a difference in height on a wooden floor, fastenings in the form of studs or screws are used, which allows you to level the surface without the use of joists. This interesting way installation, in which fasteners (screws, self-tapping screws, studs) are drilled over the entire area at the same distance from each other. The height of their heads should be at the same level. You can check this using a laser or a regular level. The hardware must be screwed in evenly. Foam is squeezed out between the fasteners and a thick plywood sheet is laid on top.
Installation on joists
If you need to insulate the floor, level it or raise it, then use logs. Installing a plywood floor on joists with your own hands is more labor-intensive.
It is recommended to take plywood with a thickness of 12 mm or more. You can use two layers of 9 mm sheets or take sheets different thicknesses, but so that in one layer they are all the same. The top layer can be laid out from thinner sheets. Total thickness plywood covering can reach 25 mm. The second layer is laid so that the joints do not coincide with the first.
Beams with a cross section of 70 x 50 are used as logs. Beams and plywood sheets must be kept at room temperature for several days before they are mounted. Moreover, the plywood should be in a horizontal position so that there are no bends.
The logs are screwed anchor bolts To concrete base or with strong wood screws (if, for example, the installation is on an old wooden floor). The first log goes at a distance of 30 cm from the wall, then subsequent logs are laid in increments of 50 cm, strictly parallel to each other.
Pay attention! To screw plywood sheets to the joists, use only high-quality yellow wood screws.
The screws must be completely screwed in and not break. Their length must be at least three times the thickness of the plywood sheet.
The tools used are a circular saw, laser level, meter and screwdriver. It would be a good idea to impregnate all wood materials with fire protection.
The walls do not always go straight, so the first sheet must be leveled using a level and a square. Next, measure the sheets and cut them circular saw and spread on the surface. The layout should be staggered so that more than two corners meet at one point. And we should not forget about deformation gaps.
Self-tapping screws can be fastened quickly if you drill countersink holes in advance. It is convenient to use a screwdriver with a countersink. The distance between the screws is 20–30 cm. In this case, there must be at least 8 fasteners on one sheet.
After the floor is laid, everything is secured, the remaining joints are sealed with special mastic.
Leveling with plywood sheets
In old houses there are floors with worn out wooden planks. If the wood is not rotten, then it should not be removed. It is enough to remove old paint, remove debris, level the floor with plywood sheets on top. Such multi-layer flooring will be an excellent thermal insulator. As finishing you can use laminate, linoleum, parquet boards.
Laying plywood on a wooden floor is carried out in the same way as on a screed, leaving expansion joints(gaps). Secure the sheets with self-tapping screws, twisting them so that the cap is recessed. Then they smooth everything out with a sander, filling the cracks and recesses with putty. If installation is to be done parquet board, then cover the substrate.
Plywood should not be laid under a wooden plank floor. Natural wood is quite massive; materials from it are laid directly on the logs.
Finish floor
There is controversy surrounding whether plywood can be used to finish a floor. Many people say that such floors look unpresentable, but there are good examples of pure plywood coverings.
Pay attention! If you need to lay out the finished floor with plywood, then choose high grades with polished front surface.
Square or rectangular panels are used for finishing. If you plan to lay out some special pattern, then first make a sketch. The most common layout option is in a checkerboard or herringbone pattern. It is very reminiscent of wooden parquet.
The base on which the plywood slabs will be laid must be perfectly flat, regardless of whether it is a concrete screed or wood material. The surface is primed, which ensures good adhesion. Next, mark the plywood sheets and cut out the slabs of the required size. Each slab is numbered, as in a sketch or diagram, so that you know exactly where to lay it. This is especially important for a complex pattern, but if all the slabs same size and forms, there is no need for numbering.
Advice! To make the joints look better, the ends of the plywood are chamfered. You can also use T-shaped plastic inserts at the joints.
First, the slabs are laid out on the floor, then finally glued. To add color, the plywood is treated with stain and covered with several layers of matte varnish. You can use an opaque paint to hide uneven spots and stains if they appear after applying the stain. One of the design options is to seal the joints with putty and paint with enamel paint, which will protect against moisture and hide imperfections.
