Plywood wooden floor without joists. The procedure for leveling the floor with plywood. Aligning plywood with joists
Plywood is a relatively inexpensive, fairly durable and easy-to-process material, perfect for leveling a wooden floor. Plywood is mainly used to level out small differences in the height of the base before the upcoming laying of the finishing coating. If desired, you can even lay tiles on top of the plywood.
It is not surprising that this sheet material has gained such wide popularity both among professional builders and among private developers. After reading the information below, you will get a complete understanding of choosing the right plywood and the process of leveling a wooden floor using different methods.
Among the key strengths of plywood, the following points should be noted:
- relatively large sheet sizes, which allows you to level the floor as quickly as possible with a minimum amount of waste;
- ease of installation;
- high levels of strength, reliability and durability;
- Possibility of use even in rooms with high humidity levels (this means either special moisture resistant plywood, or material that has undergone pre-processing, more on this later);
- absence of strong unpleasant odors;
- ease of processing.
Also among the important advantages of plywood is the fact that when used, there is an additional increase in the thermal insulation performance of the floor structure.
Most often, leveling a wooden floor with plywood is used in the following cases:
- if necessary, eliminate minor unevenness of the base;
- when preparing the surface for subsequent laying of the finishing coating;
- when installing a thermal insulation layer.
Choosing plywood for leveling a wooden floor
Plywood can be used both for arranging a subfloor and for installing a finishing structure - it all depends on the quality of the material and the characteristics of a particular situation.
Plywood is classified into 5 grades. The best is grade E - such material has absolutely no defects. It is not advisable to use expensive grade E plywood to level the floor. It is used mainly in Food Industry, furniture making, arts and crafts, etc.
Information on other existing varieties of the sheet material in question is given in the table.
Table. Plywood varieties
| Variety | Description |
|---|---|
| As a rule, first-grade plywood has no external defects, although GOST allows for the presence of microcracks and minor chips. |
| In accordance with approved regulatory requirements, the number of traces of glue should be no more than 2% of the area of such plywood, small dents and scratches - up to 5%. Second grade plywood is optimal for leveling a wooden floor in terms of price and quality ratio. |
| Third grade material will contain a relatively small number of wormholes and knots. |
| Worst option. The quality of veneer sizing is usually quite high, as is the number of external defects. This plywood belongs to the category technical materials and for leveling the floor it is used extremely rarely, except in various temporary buildings and non-residential country houses. |
To level a wooden floor, it is most advisable to use plywood of 2-3 grades, made without the addition of phenols (labeled 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 advisable that one side of the plywood be sanded. This can be understood either by visual inspection of the material or by the marking Ш1. If finishing finishing material will be laid on top of plywood, to ensure better adhesion to it, the sheet leveling layer is laid with the unsanded side up.
The optimal thickness of plywood intended for leveling the floor is 12-16 mm. If the floor of the room will be exposed high loads, it is advisable to increase the thickness of the sheet covering.
It is best to buy certified material from a trusted manufacturer/seller. 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. This plywood is characterized by increased moisture resistance and is well suited for use in rooms with increased humidity levels.
Prices for plywood sheets
plywood sheet
Video - Types of plywood
About the preliminary preparation of plywood
Plywood of the FK, FSF brands and special tongue and groove material are suitable for use in residential premises. 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 you plan to level a wooden floor in a room with a high level of humidity and you do not want to overpay, buy FK plywood and prepare it accordingly for the upcoming operating conditions.
On average, the moisture content of plywood is kept at 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 putty mentioned, prepare it for use according to the manufacturer's instructions and do the following:
- take a sheet of plywood and start covering it evenly with putty;
- apply 2 layers of putty on the back side of the sheet;
- leave the plywood for 3-4 days in a room with room temperature and normal humidity levels;
- treat the dried sheet material with an antiseptic.
If you are not particularly limited in budget, you can initially purchase moisture-resistant plywood.
To further increase the strength of the plywood, it can be coated with a double layer of acrylic varnish on each side. Wait until the old one is completely dry before applying a new coat of acrylic varnish.
Important! Apply paint coatings in rooms with elevated temperature it is forbidden.
Most often, plywood for floor leveling is sold in sheet format with dimensions of 1220x2440 and 1250x2500 cm. Experienced craftsmen recommend cutting such sheets (with a jigsaw or other suitable tool) into 4 squares with sides of about 600 mm. Benefits such a decision some:
Important! After sawing a sheet of plywood, make sure there are no delaminations at the ends of the elements. Sand any identified defects. If you leave everything as it is, finished design will be of extremely low quality.
Before laying, allow the plywood sheets to sit in the room being furnished for several days. To avoid deformations, stack the elements on top of each other. Such actions will allow the sheets to get used to the room conditions. If you lay out the floor right away, the sheets will become deformed. Along with them, the finishing coating will also deteriorate.
Helpful advice! If possible, check with the seller about the conditions in which the plywood was stored in warehouses. If there is no difference between the temperature in the storage location 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 changes are more significant, the acclimatization period will last for a week.
In the future, methods of fastening plywood using self-tapping screws will be mentioned. You cannot use ordinary black fasteners for such work - low-power screwdrivers will not be able to screw them in, and high-power ones will simply break them. To avoid such inconveniences, fix them with special yellow wood screws.
Important! With any fastening option, the plywood is laid in a spaced pattern, forming T-shaped seams between the sheets in adjacent rows.
Prices for putty for plywood
putty for plywood
Plywood fastening methods
There are several methods for attaching plywood to wooden floor:
- with height differences of 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 simplest option. The procedure is as follows.
Note! The illustrations contain third-party fasteners. We don't 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 sizes at your discretion to make it convenient), cut with a 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 stacking scheme in relation to the amount of waste.
Let the plywood acclimate
Second step. A visual assessment of the coating and seams is carried out. The plywood is laid with bandaging, so that the seams between elements placed in adjacent rows do not intersect. The correct option for laying sheets is shown in the image. Any inaccuracies found are immediately corrected. The gap between plywood sheets is up to 2-3 mm (most often a 0.5-1 mm gap is maintained), between plywood and adjacent walls - from 5-10 mm.
Third step. The sheets are numbered to make them easier to stack in the future. At the same stage, if necessary, the surface is polished. special tool or manually with sandpaper (time-consuming and labor-intensive).
Fourth step. The covering is disassembled, the sheets are temporarily removed to the side. The base is cleaned of debris, dust and other contaminants.
The sheets are laid out on the surface in accordance with the previously selected pattern and compliance with the mentioned gaps. Flooring elements are attached to wooden base using self-tapping screws.
The optimal length of fasteners is 3.2 cm. Recess the screw caps 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.
Helpful advice! If plywood is laid on top of a solid plank flooring, you can use PVA wood glue to attach it in combination with self-tapping screws. In this case, firstly, better bonding of the plywood to the base will be ensured, and secondly, the risk of squeaks when walking on the floor will be further reduced.
It is convenient to use a notched trowel to apply the glue. Either the base or a sheet of plywood is covered with a binder composition - whichever is more convenient in a particular situation. Recommendations regarding optimal thickness Specify the glue layer in the instructions for the composition used. The order is as follows: first the sheets are glued, then additionally fixed with self-tapping screws.
Also check the instructions for the selected adhesive for the drying time of the glue.
Prices for PVA glue for wood
PVA glue for wood
Video - How to level a floor with plywood yourself
Video - How to level the floor with your own hands under laminate, linoleum, floor coverings
For arranging logs, high-quality coniferous or deciduous (except poplar and linden, as they are not strong enough) boards of 2-3 grades, 4 cm thick, 8-10 cm wide, are well suited.
Under the logs there are pads 10-15 cm wide, 2.5 cm thick and about 20-25 cm long. The thickness of the pads can 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 joists on adjustable studs. Information regarding determining the working level and installing joists on adjustable supports was provided in the publication dedicated to.
Adjustable jog design
The logs under the plywood are installed in 40-50 cm increments. The supports are mounted across the room. A 2-3 cm gap is maintained between the ends of the joists and the walls.
The procedure for installing joists followed by laying plywood flooring is given in the table.
Table. Leveling the floor with plywood along the joists
| Work stage | Description |
|---|---|
| The leveled base is cleared of all existing dirt and debris. | |
| Recommendations for determining the working level according to which the surface will be leveled are available at the previously provided link. | |
| To level out height differences, in this example, bosses are used - pads made 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 joist. 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 differences using a level or, even simpler, a rule - a straight strip 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 flat and without gaps on all the pads . Helpful advice! Place a piece of linoleum or roofing felt on top of the bosses. The material will take on the functions of a shock absorber and allow you to more accurately adjust the level of fastening of the logs. Do not fix the bosses at this stage. The wooden floor is leveled, so later, after laying the logs, you can tighten them to the base using self-tapping screws or other suitable fasteners directly through the pads. |
|
| Proceed with laying the joists on the bosses. Maintain the pitch between the lags in accordance with the dimensions of the plywood sheet (in the example under consideration - 600 mm). Make sure the joists are evenly positioned using building level or rules according to an already familiar scheme. Eliminate any deviations found by adding or removing material from the corresponding bosses. To attach the logs to a wooden floor, as noted, it is convenient to use self-tapping screws. Screw 2 fasteners into each point. |
|
| Without cross slats, plywood flooring will very quickly deform and fail. The slats are made from the same material as the joists. In the center of each future cross member, place bosses on the base. Attach the rail to the base through the bosses using self-tapping screws - 2 for each lining. To fasten the crossbars to the joists, use metal corners. The pitch between slats is up to 50 cm. |
|
| Having finished arranging the sheathing, proceed to laying the sheet material. Each sheet must be supported by at least 2 joists. To prevent squeaks from occurring when subsequently walking on the floor, lay the sheets with gaps of up to 0.5 mm. The plywood is attached to the joists and intermediate slats using self-tapping screws. Maintain a 50-70 cm spacing between fasteners. Recess the heads of the screws slightly into the wood. |
Video - Leveling the floor with plywood along the joists
Fastening plywood with 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/unscrewing the anchors, the required floor level is set.
The system looks like this:
Discussed in detail in the corresponding publication on our website, be sure to check it out.
Video - Laying plywood on adjustable studs
As noted, the technology allows the use of plywood to level bases whose height differences do not exceed 80 mm. But what if the irregularities are more significant? Stop using plywood? Not necessary.
Recommendations regarding the mandatory preliminary elimination of differences in height are given for the simple reason that the sheet material, under the influence of the loads placed on it, will follow the contours of the unevenness, become deformed and fail.
To prevent this from happening, do the following.
To begin, take a long level and find places with the most pronounced differences in height. In the identified areas, screw screws into the floor in increments of about 20 cm. By tightening/unscrewing the screws, ensure that their heads are located at the same horizontal level.
The plywood will be laid on screwed screws. To prevent the sheets from sagging, the void between them and the uneven base needs to be filled with something. A mixture prepared from a share of small sawdust and the same amount of PVA glue is perfect. Before laying plywood, coat the recesses with the specified composition. Additionally, cover the side of the sheet with which it is laid on the base with a double layer of PVA glue. The mixture dries within a week.
To ensure the highest quality and even fit of the plywood to the base, secure the sheets with self-tapping screws. Maintain a 50cm step. Correct scheme placement of fasteners is shown in the image.
Video - How to level a wooden floor with plywood
A major renovation of a residential premises is impossible without installing a floor covering. In most apartments the base is under flooring concrete serves. Finishing materials for the floor, such as laminate or linoleum, are recommended to be laid on a leveled, flat surface.
Leveling the floor with plywood without joists is one of the most practical, quick and inexpensive ways to organize a substrate for subsequent surface finishing.
Need to know
In order for the laid floor to be pleasing to the eye and to be smooth without differences or cracks, plywood must be laid on a well-leveled area.
Important! The unevenness of the concrete floor for laying plywood without joists should be no more than 1.5 cm.
Leveling a concrete floor with plywood without joists should be done on a clean, smooth surface no cracks, chips, potholes or changes. Otherwise, preliminary surface leveling is required:
- Leveling mass, most quick option, takes from 7 to 14 days.
- Performance concrete screed. Work is carried out after the coating has completely dried for at least 3 weeks.
The advantage of covering the floor with plywood is that it provides vapor permeability and the unhindered movement of air masses under the floor covering, which prevents the formation of mold.
The thickness of the material used can vary from 1.2÷1.6 cm. The choice depends on the load on the surface and the thickness of the facial floor covering. The greater the weight load, the thicker the sheets should be. The use of low-quality and too thin material very often leads to subsidence of the floor, followed by its disassembly and replacement of the substrate.
Important! The strength of plywood depends not only on the thickness, but also on the type of wood from which it was made.
Since another coating will be laid on the plywood, appearance has no sheets of great importance, it is allowed to use plywood of grades 2, 3, 4.
Techniques
The choice of technique depends on the quality of the concrete coating. Fastening plywood to a concrete base can be done in several ways:
- Using adhesive and anchors.
- No glue. Installing adjustable plywood using only anchors.
Preparatory work
I.Preparing the floor for plywood installation.
- Clean the surface from dirt and debris.
- Perform priming concrete base primer, for the manufacture of which you will need: glue, bitumen mastic, solvent or gasoline.
- Apply primer to the desired surface using a roller or brush and allow to dry.
Important! Laying plywood should only be done on a dry surface.
II.Perform preliminary fitting of plywood sheets. The thickness of the sheets used to cover the floor in one room should be the same.
- For better fit and laying of the substrate, purchased plywood blanks should be cut into several equal-sized squares using a special knife.
- Preliminarily lay out the cut sheets on the floor.
- Mark on sheets of plywood the places that will need to be cut for arches, corners or other elements located permanently on the floor surface.
Important! The sheets must not contain cracks or any other surface defects.
- When implementing pre-layout between the sheets leave a compensation distance for expansion/contraction equal to 5÷10 cm. And also there should be no joining of 4 corners in one place.
- Number the sequential sheets and record their current position on paper or using a photo. This scheme will be necessary for facial styling.
Performance
Installation using glue:
- Lubricate the primed surface with a 2mm layer of glue/mastic. Use a roller.
- Place sheets of plywood on a greased surface, smooth side up, and rough down.
- Using a hammer drill, additionally secure the glued sheets to the floor with anchors or self-tapping screws. The length of the fastening element must exceed the thickness of the material by three times.
- Sand the surface.
Installation on anchors only:
- Using a laying diagram and a marking pencil, mark the locations for installing anchors in the plywood.
- Use a drill to drill holes in the plywood and concrete.
- After removing the plywood, refine the holes with a hammer drill and install anchors with nuts in them.
- Using laser level and mark with a pencil special nozzle to the drill the level of lowering the anchors to the floor.
- Align the anchors to the same level and install round washers on top according to the mark.
- Install the plywood and install a second washer in each hole.
- Tighten the sheet to the anchors using a nut.
- Check the horizontal installation using a level, if there is a need to adjust problem areas.
- Carry out gradual laying of all slabs according to the attached diagram. The resulting gaps can be filled with pieces specially cut to size.
- After installation, cut off the parts of the anchors protruding from above.
- Having completed the installation of the first layer of plywood, proceed to install the second face layer. Lay the plywood sheets end-to-end, covering the cracks of the first layer towards each other and secure with nails or self-tapping screws.
- Perform grinding.
More details about the second method of leveling the floor with plywood without joists in the video:
Installing plywood as a backing will ensure high-quality, reliable and durable flooring installation. Carrying out work on your own using the first or second method does not require special skills in working with wood; all that is required is attentiveness, accuracy and lack of haste.
IN wooden house, bathhouses, multi-storey residential areas, a flat surface is required for laying floor coverings. If the base is a wooden floor, then plywood is laid on them. Alignment wood covering plywood is the topic of our conversation about Decoration Materials. In it we will share our experience of installing it on wooden floors.
Leveling a wooden floor under plywood
First you need to determine the condition of the wooden floors, whether there are large differences in height between the boards.
If the floors squeak, you need to pour graphite powder with talc into the cracks or drive wooden wedges into them.
If this does not help, then secure the defective boards with self-tapping screws or dowels with screws.
If you cannot level out significant differences in height with your own hands, then you need to dismantle the rotten structure, replacing the destroyed boards with freshly planed ones.
Do-it-yourself leveling of a wooden floor with plywood
First of all, we lay out the plywood sheets on wooden base in a checkerboard pattern for fitting and determining the guide lags. Let's draw these lines.
We already have an outline of the location of the horizontal bars.
Number the plywood sheets and the floor so as not to be confused during installation.
The logs represent square bars with a long side of 40-60 cm. Instead of bars, you can use boards or plywood sheets cut into strips.
Transverse strips are attached to the logs in approximately 40-50 cm increments. Metal corners make the connection of the longitudinal and transverse strips strong and reliable.
Using a level gauge, we level the lattice base. To ensure that the logs are at the same level, we place them under wooden spacers. And then using metal corners and self-tapping screws we attach the joists to the plank floor. You can also use dowels as lag fasteners, which are 3 times the thickness of the lag.
Between the lags we fill the free surface with sand or a homemade mixture consisting of sawdust and PVA glue.
We spread it in two layers and leave it for the leveling compound to harden.
If the logs are low or in the form of slats, then we use roofing felt or roofing felt. Only after this we begin to attach the plywood.
Installation of plywood on mini joists
Another method of leveling the floor with plywood in a wooden house is to use mini-lags.
This method is very accurate. It is carried out only by masters of their craft and engineers. The slightest inaccuracy in the calculations will make the design unreliable. Each element of the building is calculated separately using special instruments.
Mini-logs (slats) are laid lengthwise and crosswise in the form of a lattice. This method is used when there is a large slope of floors and significant differences in height - up to 8 cm. First, sheets of plywood are laid out for fitting to make markings. The thickness of the supports and the angle of inclination are calculated using formulas and programs.
Installation of plywood on the sheathing of point supports
The fourth way to lay plywood sheets is by lathing point supports. The blocks are cut from boards or plywood and laid in the form of a grid. The step between them is much smaller than with strip supports. This method is less accurate than using a lag.
Leveling a wooden covering with plywood under linoleum
Linoleum is a capricious coating; all roughness, unevenness and debris will be visible on it. Over time, due to its elasticity, it will take the shape of the base, enveloping the protrusions and recesses. Therefore, a perfectly flat surface is required for linoleum flooring.
Preparing the wooden covering. Best to spend wood floor scraping.
To protect yourself from dust, you need to wear a respirator and headphones to protect yourself from noise.
You need to work with a looping machine, starting from the corner of the room, moving like a snake to the other end of the room. The corners are processed manually.
Putty is needed to treat cracks and cracks in wooden floors.. When the mixture dries, you should repeat the scraping.
Collect dust after the process with a vacuum cleaner.
The wooden covering is treated with antiseptic agents. The top is varnished.
You can also scrape floors using a planer. But this is a more complex process. Floor scraping is carried out if the height differences are insignificant. In this case, plywood is not needed. It is also not needed when leveling a wooden floor with dry mixtures, which are applied to a sanded floor.
If the floors are located on a slope, plywood panels are required.
We take self-tapping screws and screw them into the wooden floor at a distance of 20-30 cm from each other. These are our beacons on which logs and plywood sheets will be placed. The screw heads must be at the same level.
We cut the plywood sheets into squares with a side of 60 cm. It is very important to check the sheets so that there are no cracks or chips.
We lay out plywood beams 3-4 cm wide. These are logs. They serve as support for plywood panels. If there is a gap between the joists and the floor, you can place a thin piece of plywood. Attach the joists to the floor using wood glue or self-tapping screws. Expanded clay can be poured between the joists. It will be a kind of insulation for the floors.
We begin the installation of plywood sheets. We lay out the plywood in a checkerboard pattern with an offset. We strengthen it with screws inserted into dowels. To ensure a neat finish, it would be a good idea to drill holes for the dowels before laying the plywood panels.
When laying plywood, the screws are simply screwed into the dowels. Plywood sheets are fixed to the joists. It is very important to step back 2 cm from the wall and leave between plywood panels gap. Then seal the seams with putty or mastic. When laying plywood, you need to remember that only three edges of plywood sheets can converge at one point, no more. After leveling the floor with plywood, you need to sand the floor and varnish it. You can lay a backing and linoleum on top.
Leveling wood flooring with plywood under laminate
Leveling a wooden floor with plywood under laminate is almost the same as under linoleum.
First you need to remove wooden skirting boards nail puller Tidy up the room, sweep, wash the floors. We make 2-3 holes in the floor in different places of the room to determine the height of the base of the screw. We make beacons in the form of self-tapping screws. The thicker the plywood, the greater the distance between them. The height of the log is 30-50 mm. We screw the plywood to the joists with self-tapping screws.
Experts often advise leveling a wooden floor with two sheets of plywood. The main thing is that the seams do not coincide, but are laid offset.
We told you how to level a wooden surface with plywood. Whether you call specialists or make the flooring yourself is up to you. The main thing is that you do it correctly and carefully.
Agree that the situation when floors need to be leveled, and “wet” processes are undesirable, is not uncommon. And it is not always possible and willing to build fashionable dry screeds with expanded clay, or the height of the ceiling does not allow it. What to do? There is an exit! Most often, such a floor is leveled with plywood or MDF, chipboard, or OSB boards. Each material has its own disadvantages and advantages, but in this article we will take a closer look at plywood, its properties and installation details, because unlike fiberboard and OSB boards, plywood is natural material, not recycled production waste. Everything, down to the last detail, so that you end up with a durable, moisture-resistant and truly even base.
Plywood may look like quite fragile and thin sheets, but in reality it is not. Plywood is one of the most popular building materials, which is made from several compressed sheets of treated natural wood. The wood fibers are located in different layers perpendicular to each other, which makes the final strength high.
Plywood is the fastest way to level floors so that you can even lay tiles on them. However, this finish has other advantages:
- Large sheet format, which is still convenient to transport.
- Easy installation that anyone can do.
- Reliability and strength of the finished base.
- Possibility of making plywood floors even in damp rooms.
- Complete absence of odors, only a barely noticeable aroma of wood - and this is without a topcoat.
- Ease of processing, cutting, coating protective agent and a minimum of construction waste.
- The rigidity of the sheets, which can also bend a little. Valuable quality!
Plywood also acts as insulation, which significantly reduces heat loss from the floor. In addition, plywood can also be used as either a rough or a finished floor, depending on its grade and sanding.
Basically, plywood floors are installed for three purposes:
- Level the floors with minor unevenness and prepare for subsequent laying of the finishing coating.
- Significantly improve the thermal insulation of the room.
- Provide additional waterproofing of the floor for laying laminate flooring.
The second point is especially relevant for those apartments and rooms that are located directly above the cold basement. But in rooms where there is a significant temperature difference (as in a seasonal dacha), it is impossible to level the floor with plywood. As well as where air humidity is high (for example, a swimming pool or sauna).
And now - all the technology step by step!
Stage 1. Assess the condition of the floor
If the error in the height of the floorboards is only 5 mm in different places, feel free to attach the plywood directly to the plank floor. If the height difference is more than 1 cm, but not higher than 8 cm, create point or strip supports in the form of a lathing. Speaking in simple language, adjustable joists. This is such a simple solution.
Stage 2. Select quality material
Construction requirements for plywood, which acts as an intermediate floor element, according to SNiPs are the same as for a rough floor screed.
In total, five types of plywood are produced today:
- Grade E is elite, it has no defects at all.
- First. This sheet has no external defects, although small chips and microcracks are allowed.
- The second one is more accessible. In such plywood you can find only up to 5% scratches and small dents, and only up to 2% traces of glue. For flooring, this type of plywood is most suitable, both in terms of cost and quality.
- The third grade already has knots on the surface, even if they have fallen out, and a small amount of wormholes.
- The lowest grade is fourth. This is where you will find the most flaws, although the veneer itself will be glued quite well. This is “technical” plywood; floors are rarely leveled with it, although this does happen. For example, this is not the worst option for budget construction solutions, such as a summer house or a temporary shed.
Here's what the process of laying grade 4 plywood looks like:
Also, so-called “tongue and groove plywood” has already appeared on sale. Its thickness ranges from 12 to 20 mm, and it is available in the form of 300x300 or 300x360 mm. It is more moisture resistant.
It is important to choose the right plywood material specifically for your floor. Pay close attention to the following points:
- The number of layers in one sheet, which is easier to measure in thickness. For the floor, it is better to take sheets of 12-16 mm, where the number of layers fluctuates around 9-11 per sheet.
- Surface quality, grade, and processing - whether there is grinding or not.
- Mark for water resistance of glue.
- Emission class. You don't need formaldehyde in your living space either.
The strength and quality of the subfloor, its resistance to loads and deflection, will depend on the thickness of the plywood sheet you choose. When choosing, consider what the final floor covering will be like. So, for carpet or linoleum you can lay the thinnest sheets, but for laminate or parquet - no thinner than 10 mm. In any case, the thickness of the plywood should not be less than parquet board or laminate. And it is correct to heat the screw head if the coating is very thin:
And now about the brands. For industrial construction, where there is a lot of traffic (and, therefore, a serious load on the floor), plywood is laid in the FB or FOF grades, but for private individual construction, a lighter option is suitable - FSF and FC. In the latter case, phenols are no longer used to produce sheets, but to create more strong foundation, as in FSF and FB plywood, they exist - so far it’s impossible without it.
FSF brand plywood is quite strong and wear-resistant, has an increased mechanical strength and water resistance. Such sheets do not change their properties even with serious changes in humidity and temperature, and all thanks to the small addition of phenol-formaldehyde resins. Which are non-toxic, but obviously not meant for bedrooms.
FC is plywood with extremely poor moisture resistance, but safe materials are used for its production. adhesive composition from carbamide resin. Lay this floor in a bedroom or children's room, where there is always an emphasis on environmentally friendly finishing. But FSB is already more suitable for corridors, kitchens and bathrooms due to its moisture resistance, but toxins are also present in it. You should not breathe with this floor at night, but it can be used for other rooms. You can see how unsafe such plywood is for health using the attached technical data. Find one of these values in them:
- E1 – per 100 g of dry wood mass there is up to 10 g of mole.
- E 2 – 100 g of dry mass already contains 30 g of resin.
Sanded plywood is well suited for further painting, laying laminate flooring or laying tiles. You can easily understand what kind of processing the sheets went through at the factory by looking at the markings:
- NSh – unsanded ordinary plywood.
- Ш1 – polished on one side only.
- Ш2 – polished on both sides.
One more thing. In each sheet of plywood, the layer thickness ranges from 1.7-1.9 mm. And the more such layers, the stronger the plywood sheet.
And finally, it is important what kind of wood the plywood is made from. Thus, coniferous wood is usually used only for flooring on balconies, loggias, roofs and basements. The thing is that even a small content of phenol-formaldehyde resin in its composition completely neutralizes everything valuable that is in spruce, pine, fir and cedar. Therefore, durable and safe birch plywood, which also has good thermal insulation properties, is more suitable for household work. Here's what it looks like:
Stage 3. Improving the quality of sheets
In total, plywood has 12-15% moisture content. You can increase the moisture resistance of plywood by impregnating it with putty based on polyvinyl acetate, which is somewhat similar to PVA glue. Do everything according to these instructions:
- Step 1. Take a sheet of plywood in your hands and saturate it on one side until stains begin to appear on the opposite side. Then - on the other, only twice.
- Step 2. Dry the plywood horizontally for at least three days, in a dry room at normal room temperature.
- Step 3. Once the sheets are dry, treat them with wood preservative.
Advice: if you need to level the floor with sheets that are not afraid of moisture, then pay attention to the Greenboard GB3 brand (12 mm). Insulation can also be laid between them.
And the strength can be increased using acrylic varnish. Apply it in two layers, and the second only after the first has dried.
Stage 4. Preparing the floors for leveling
Essentially, the entire process of leveling a floor with plywood looks like this:
Plywood is laid directly on the floor when the base can be called relatively flat and minor correction is required. But in all other cases, the floors need to be adjusted with joists, and only on them should plywood sheets be laid.
As for priming the base under plywood, experts urge you to use a primer instead - a special type of it, which differs in that it contains more solvent, and it penetrates deeper into the floor surface. This composition can be made at home: just take bitumen mastic for laying plywood, and dilute it with gasoline. The primer works much better for adhesion different materials, and covering the base with it is called priming in construction language.
Treat fresh floor joists with additional protection against fungus and insects. If you are concerned about environmental friendliness, then the German composition Leinos is suitable for you, where volatile compounds are only one gram per liter, and this is despite the European standard, which does not allow exceeding 30 grams per liter.
You can also level the floors with plywood on studs:
Even before leveling, be sure to check the condition of all communications under the floor and, if necessary, replace bad pipes. After all, after you lay down the plywood, you will not have access there. Also remove old rotten boards and replace them with new ones.
Stage 5. Format the sheets
Standard plywood sheets, as a rule, have dimensions of 125x125 cm. Here is an example of their installation:
However, many experienced craftsmen They consider it necessary to saw them into four more pieces to make squares with a side of 60 cm. Not only are these more convenient to work with, but they end up with much more damping joints at the joints, and this is important for compensating for moisture and thermal deformations. And the sheets themselves will be much stronger, because they are now less susceptible to deformation. But after cutting the plywood, it is important to pay attention to the ends of the workpieces - there should be no delamination in them. If there are any, then just change them; the floor will turn out to be of poor quality.
If you lay plywood in two layers, then divide the future thickness of the flooring by two:
Keep the plywood sheets for several days in the room where you will lay them. Just lay them on top of each other to avoid deformation; even better, place them on edge if the sheets themselves are not too thin. This is necessary for acclimatization of the sheets, but if you make a plywood floor right away, without such preparation, then the laminate laid on top will go in “waves”: the sheets will simply pick up moisture from the air, like everything that is in such a room, and this will happen natural expansion. The plywood base will swell and the laminate will begin to lift in places, breaking the fragile locks. Needless to say, the finishing coating itself will not last long under such circumstances either.
And it is also important how different the humidity and temperature were in the warehouse. So, if the difference is small or the conditions are the same, it is enough to leave the plywood in the room overnight; if the difference is from 2 to 8 degrees, it’s about three days, and if it’s larger, it’s a whole week.
Stage 6. Marking the scope of work
Here's how to correctly determine from which corner in the room to start laying plywood sheets. We just take a regular construction angle and apply: which of all four angles is closest to 90° (by the way, you will be surprised at the curvature found), and we start working from there. And it is desirable that this angle be the highest - find it. If you give preference to an angle that is greater than 90°, then an ever-increasing gap will begin to form between the wall and the sheets of plywood.
Another simple way to find out how much the angle of a room corresponds to 90° is to measure 3 cm on one side, 4 cm on the other, and draw the common hypotenuse of this resulting triangle. If it is 5 cm, then it is exactly 90°. Calculate required amount sheets of plywood are needed as follows: total floor area plus 10% for cutting.
Sometimes plywood on joists can make a squeaking sound when walking on the floor - this can also be solved. Just before laying it, pour a few drops of melted paraffin directly over the bars. But when professional installation The logs are glued with special construction tape:
Stage 7. Correctly attach the plywood to the base
Wood, of course, is a hygroscopic material. Therefore, the maximum air humidity in the room where the floor was leveled in this way should be only 68%. And if the plywood has not yet been processed before, then even up to 60%. At air humidity up to 85%, plywood will begin to delaminate within a month. This is what concerns the working conditions. And now about the technology itself.
Aligning plywood to the base
Plywood must be attached to a concrete or wooden base correctly. This method is called “envelope”: we drill in the corners, in the middle of each side, and in the very center. For a concrete floor, use a carbide drill - a regular one will immediately become dull.
Next, the sheets are removed, and concrete floor drill blind holes for dowels according to the marks from the previous ones. The dowels are driven into them, after which the plywood is put in place, and the self-tapping screws are driven in with a drill and a screwdriver with a special insert for the cross slot until the heads are sunk. Use self-tapping screws for fastening plywood with a length of 32, 41 or 55 mm; dowels are more suitable for SORMAT 6. Drill the hole at ¾ of the self-tapping screw. Although some builders do not complicate their lives with such subtleties, and drive the head of the screws into the plywood with strong blows of a hammer. As a result, the strength of the fastener is compromised.
Here's how to properly lay plywood with glue only:
- Step 1. Thoroughly clean the room from dust and dirt. This should be done not so much for hygienic reasons, but because even small debris may prevent the plywood from being laid flat.
- Step 2. Place an insulating layer: glassine, polyethylene or a regular backing under the laminate.
- Step 3. Now lay out the sheets of plywood without fastening - the way it will be mounted later. Select items to size, trim where necessary, and label all sheets to avoid confusion.
- Step 4. Remove the plywood and coat with drying oil if necessary. It is better in two layers, and special attention should be paid to the ends. Drying oil does not allow the plywood sheets to deform, but the seam between them remains sufficient to compensate for thermal expansion. It is important!
- Step 5. Once the sheets are dry, you can lay them down. When laying, make sure that all four corners do not meet together.
- Step 6. If you are laying thin linoleum and not laminate, then additionally fill plywood seams sealant. They will not be pressed, nor will they interfere with thermal expansion.
- Step 7. All that's left is the backing and fine coating– the floor is ready!
And to glue the plywood to subfloor, take Bustilat type glue or use regular parquet mastic. Do not leave any gaps - this is a kind of “floating plywood floor”. You can only glue the ends of the sheets. But under the parquet, plywood must be glued and secured with 5x60 mm self-tapping screws in dowels, and the sheets should be laid with mounting slots of 2-3 mm. For this purpose, it is better to use urea glue, which is essentially a solution of urea resin, which includes a hydrochloric and acid hardener, and a gypsum or starch filler.
Aligning plywood with joists
And now about the installation by lags. A plywood floor on joists is good because it is convenient to hide any communications under it, and even provide additional heat and sound insulation. You can arrange it without any problems, there is nothing complicated here:
- Step 1. We align the logs and attach them to the floor slabs. Use screws with anchor bolts or plastic dowels.
- Step 2. If the bars themselves have not been treated with anything before, now is the time. High-quality waterproofing will allow them to last much longer.
- Step 3. Pre-mark and drill holes for fastening in the plywood sheets. If you will “sink” the caps, drill the holes for them a little bigger size than needed.
- Step 4. Lay sheets of plywood across the joists. On adjacent sheets, screw screws only in a checkerboard pattern. Leave a gap of up to 3 mm between the sheets for thermal expansion. The edges of all sheets of plywood must lie exactly on the joists, and under no circumstances “hang” in the air.
- Step 5. Now you can lay linoleum or laminate.
But it is more convenient to attach the plywood not just to the joists, but to a sheathing of beams - 40x50 cm squares. Lay glassine on top of this structure, which will protect the floor well from condensation, and only then - sheets of plywood about 18 cm thick and cut into 60x60 cm squares. For a house with a complex floor structure, this is an irreplaceable option:
You can also level floors with plywood over old joists:
And even with insulation:
And here standard requirements to the width of the gaps between the sheets:
Although many experienced builders sure it's better large gaps between plywood sheets do not leave - small gaps of 1 mm filled with elastic glue or sealant are enough.
Stage 8. Sanding the finished plywood floor
Sanding plywood is necessary because this operation allows you to rid the base of burrs and cuts, as well as height differences that are hardly noticeable to the eye. Moreover, you can grind not only with a machine, but also with ordinary sandpaper. And after sanding, be sure to clean the plywood floor from any accumulated dust. It's simple:
Stage 9. Check the result obtained
Correctly laid plywood on the floor looks like this:
- The sheets do not touch the walls anywhere, and there are gaps between them themselves.
- The rule placed on the surface shows the exact horizontal line. Moreover, you need to check in several places, each time orienting the level in different directions. Maximum permissible value – 0,2%.
- Now you need to knock on the finished flooring wooden block. The sound should be the same over the entire area, solid. If somewhere you hear a dull sound, in these places the plywood has peeled off from the base, which is bad, because according to SNiPs, the adhesion area of the plywood to the floor must be at least 80%. And, even if under one of the sheets the voids under the plywood are more than 20%, this area will have to be re-glued.
Was the test successful? We congratulate you – your floors are perfectly leveled!
Sanding and sanding the boardwalk reduces the thickness and, accordingly, the strength and service life of the structure; puttying sharply increases the time required to complete the work. Therefore, leveling a wooden floor with plywood saves time and increases the strength of the base for the finishing coating. This option more expensive to use Chipboard/OSB, but by default provides a high turnaround time and stable spatial geometry of the subfloor.
Typically, the need for laying plywood arises for a property owner in several cases:
Before leveling a wooden floor with plywood, you need to take into account the following nuances:
- hydro, heat, vapor barrier must already be laid under the existing floor;
- one layer of plywood is used, so it is enough to choose a material with a thickness of 10 - 14 mm;
- Only white or yellow fully threaded self-tapping screws should be used for mounting to wood floors.
Advice! It is better not to use plywood as a finishing coating, since without gaps between the sheets it inevitably begins to creak. And sealing the seams with sealant reduces the aesthetic value of the coating and takes a lot of time and money.
Therefore, the technology for making a subfloor from plywood for finishing is discussed below. There is no particular difference between mounting on a tongue and groove board or on an edged board; the operations cosmetic repairs completely identical.
Leveling technology
To level the floor in a wooden house with sheet material, you need the following tool:
On a wooden floor, plywood with a thickness of 10 - 14 mm is screwed with screws 19 - 32 mm, respectively. For gaskets and improvised joists, you will need the same sheet material, which is split with an ax or chisel to ensure the required thickness.
It makes sense to remove the paint coating only if its adhesion to the base boards is low. In other cases, sweeping the floor is enough. However, sheet material will not be able to eliminate the existing creaking flooring, therefore, in defective areas, first replace or repair the floorboards and joists under them and recess the heads of the nails sticking out into the wood.
Marking and preparing gaskets
Unlike reinforced concrete floor The top point of the boardwalk is not always at the wall. Floorboards can bulge like a hump in the middle of the room, so making a horizontal level is a little more difficult here:
- first visually, and then by rule, all protruding above general level floor areas;
- then a laser level is installed closer to the center of the room, along the walls and in certain areas in the middle of the floor, identified at the preliminary marking stage;
- the distance from the floorboard to the beam of the plane builder is measured;
- the results are entered into a scale sketch of the room to determine the top point existing structure, which is marked with a cross on a marker or pencil lead.
Advice! Further marking for installation of leveling pads on a wooden floor is carried out only after cutting the plywood. Manufacturers produce sheet material in large-format slabs, which are prohibited from being laid entirely due to warping from internal stresses.
Cutting of sheet material
Plywood must be laid under an elastic floor covering (laminate, parquet) or facing material with low rigidity (carpet, linoleum), taking into account the requirements:
If the walls diverge in a trapezoid, it is better to choose a layout from the middle according to the following method:
After that, two options for further work are possible:
In the latter case, markings of slab joints are created on the boardwalk according to the selected laying pattern. Required thickness spacers and strips are adjusted by splitting the plywood and chipping away the veneer layers from it. Gaskets and strips should be secured separately from the slabs so that they do not move to the side when placing sheet material.
Important! You need to leave a gap of 2-3 mm between the sheets of plywood, and 3-5 mm at the wall, this will allow you to avoid warping and squeaking in the future.
Laying plywood
There are no particular difficulties when installing plywood slabs on a wooden floor; the technology does not require special skills or regular practice. It is enough to follow the given instructions to ensure a high service life of the subfloor made of this material.
Gluing
Since plywood is quite expensive material, the developer usually does without first gluing the slabs to the base. However, in difficult operating conditions (humid climate, underground pile grillage or kitchen cellar), you can play it safe. In this case, you should take into account the nuances:
Fastening with self-tapping screws
Plywood is wood-based construction material. Therefore, the danger of warping and other violations of the spatial geometry of structures constructed from it remains throughout the entire service life of the subfloor. In addition, in this case it is laid on a wooden floor, which doubles the likelihood of these defects.
Important! Unlike tongue and groove edged boards screws are screwed into sheet materials strictly perpendicular. It is better to drill a secret blind hole for the hardware head with a countersink, rather than with a drill of larger diameter, the sharpening angle of which does not coincide with the configuration of the screw.
Therefore, two power tools are usually used - a countersink is clamped into a corded drill, and self-tapping screws are screwed in with a screwdriver.
Sealing seams
If you plan to lay laminate, parquet or cork covering, expansion joints do not need to be sealed. Linoleum, carpet and PVC tiles will show all the joints of plywood sheets over time, so they are filled with a sealant (usually acrylic) that is highly elastic. Using ordinary putty Over time, squeaking may occur.
Thus, defects in finished or black wood floors can be eliminated with plywood. This flooring is suitable as a base for laying linoleum, carpet, cork, PVC tiles, laminate, parquet boards. Necessary tool usually fully present in the arsenal of a home craftsman.
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