How To Lay Plywood Sheets On A Concrete Floor Under A Laminate Flooring

2023 Author: Philip Bishop | [email protected]. Last modified: 2023-05-24 22:24

• Features of plywood
• Choosing the right plywood
• Pros and cons of alignment
• Preparatory activities
• Cut plywood
• Plywood fixation
• Surface grinding

More and more often, it is the laminate that is chosen as the flooring. This is due to the large number of its positive features, which is manifested not only in the material itself, but also during the installation process. But the laminate requires a well-prepared base. For this, there are a large number of options, among which it can be noted, laying plywood on a concrete floor under a laminate. The main thing is to choose the right plywood, for which there are appropriate recommendations.

Features of plywood

Plywood is selected according to several criteria, including acceptable material cost and optimal qualities. About the latter, we need to talk in more detail and highlight the most basic of them:

1. A wide range of plywood applications due to its strength characteristics. It is perfect not only for this area, but also for industrial facilities and office premises.

   

2. Excellent thermal insulation qualities.
3. Long operational period of the material.
4. There are no foreign odors in the room after plywood is laid on the concrete floor under the laminate.
5. It can be used when installing various types of underfloor heating systems in the room (water, electric).
6. Convenience and practicality due to the significant size of plywood sheets.
7. Ease of installation.
8. Rigidity and high wear resistance.
9. Resistant to various synthetic products that can be used during cleaning.
10. Resistance to external influences (pressure loads).

But these are only the main features of the plywood sheet. In the process of laying on a concrete floor, it can be of various types and varieties, which is specified upon purchase. As for the grade of sheets of material, it will be determined depending on the level of water resistance of its connection. Pay attention to the type of plywood that will be used for laying on a concrete floor. In addition, the plywood surface can be pre-sanded or not, have different sheet thicknesses, as well as dimensional characteristics.

A single plywood sheet can be used in various circumstances. This suggests that you should think in advance about the conditions where it will be used. The material itself may contain different amounts of formaldehyde content, which will indicate the level of environmental safety.

Choosing the right plywood

When visiting a hardware store and buying plywood sheets, the birch option will be considered optimal. It is perfect for 2nd grade laminate flooring. With an average moisture resistance, plywood on a concrete floor is marked with FN, which indicates its purpose for individual construction.

When it comes to plywood sanded on one side, it is designated as Ш1. Also, when choosing, its safety looks from the point of view of ecology, emission class. Usually, in the latter case, E1 will be acceptable, when there will be no more than 10 grams of formaldehyde per 100 grams of material. In this case, the sheet thickness should not be less than 12 mm.

Residential premises require the purchase of plywood of the FC and FSF brands. It is best to choose the first option, since, despite the lower moisture resistance, such sheets have increased environmental friendliness and lower cost compared to the FSF class.

Pros and cons of alignment

Leveling the floor with plywood for the subsequent laying of the laminate is a universal method. This indicates the presence of a sufficient number of positive aspects, including:

1. The strength of the material itself, as well as the level of moisture resistance, makes it possible to slightly increase the operational period of not only the leveling layer, but also the floor covering.

   

2. Work to create a flat surface is carried out in a short time and without unnecessary effort.
3. The result is a really flat base that can be used for any type of flooring, including laminate on a concrete floor.
4. Excellent heat and sound insulation properties.
5. Reasonable material cost, as well as low costs for installing plywood on a concrete floor.

As for the disadvantages of such material, first of all it is worth noting the reduction in the distance from the ceiling to the floor. Some rooms do not accept this alignment option and have to be abandoned.

Preparatory activities

To begin with, you should take care of the plywood itself after the purchase. It will not be superfluous to dry the material a little, especially if the purchase was made in the winter season. Everything should be done for about 15-20 days at room temperature.

After all, no one knows in what conditions it was before the purchase. After that, the plywood sheets are treated with various antiseptics.

The outer layer can be made more durable. To do this, it is covered with acrylic varnish, which is enough and two layers. It will not be superfluous to cover with a stain at the end.

The level of moisture resistance is also increased before laying on a concrete floor under the laminate by using a putty, which impregnates the sheets. It is best to choose a putty based on PVA.

There are also certain requirements for the base of the concrete floor from the laminate side. The most important of them is perfect evenness. Even before laying plywood, the existing surface should be carefully analyzed. If there are minor protrusions, they can be hidden by filling with self-leveling mixtures. In all other cases, you will have to fill with concrete solution. Attention should also be paid to the level of humidity, which will differ depending on the particular room and its purpose.

Indeed, in the bathroom or in the kitchen there will always be high humidity compared to the bedroom or nursery.

To measure humidity, special devices can be used - a barometer, a hygrometer, etc. There is also a more popular method - a polyethylene film is laid on the existing concrete floor. She must stay there for three days. At the same time, the edges of the film should be very well pressed. The normal humidity level is characterized by the absence of condensation from the inside of our film. Otherwise, measures should be taken to reduce the moisture characteristics of the concrete base. Otherwise, in the future, there is a high probability of the appearance of mold and fungi of various types on the plywood sheets. With the latter, an antiseptic with which plywood is processed will help to cope and fight.

Cut plywood

Initially, plywood sheets are cut into squares, which are then distributed over the entire surface. This is done in order to fit each of the sheets to the entire area of the room. We also pay attention to the ledges and niches in the room.

A damping joint of 8-10 mm must remain between the sheets on the concrete floor. It's kind of a gap. There should also be a gap to the extreme sheets from the walls, but slightly more - 15-20 mm.

None of the sheets should be in contact with each other or with the walls in the room. In this case, not all four seams should converge in one place; displacement should be made during laying, as with brickwork.

When all the sheets on the base of the concrete floor are distributed, it will not be superfluous to draw up their scheme and number each of them. So it will be much easier in the future to install and fix them on the concrete floor. When cutting, it is best to adhere to dimensional standards: 1250 * 1250 mm. But working with them will be problematic. Experience and skill are required here. In the initial study of leveling a concrete floor under a laminate, it is best to cut a sheet of plywood into 4 elements with a size of 600 * 600 mm. In addition, it will be possible to easily arrange the required number of damper joints in the so-called "backing" of plywood under the laminate on the concrete floor. Smaller squares will be less affected by deformation and external mechanical stress than squares - "standards".

When cutting purchased plywood sheets, everything should be done with high quality. There should be no torn cuts or bundles. If they did appear, but everything was done according to the rules, then most likely low-quality plywood was purchased. We'll have to look for the best options for flooring on a concrete floor under a laminate.

Plywood fixation

Often the same question arises before leveling the base under the laminate, related to how to attach plywood to the concrete floor. Laying sheets should be done exclusively on a dry and clean surface. In addition, it is necessary to increase the level of waterproofing. Here you can choose a special backing, which you can buy in the store, or use a regular polyethylene film of the appropriate thickness. The film should be laid with an overlap, connecting the seams with tape.

It is rational to lay large sheets of plywood directly at the entrance to the room due to the presence of a greater load. Next, the already measured and prepared sheets are distributed. Only now can you think about how to put plywood on a concrete floor.

In work, it will not be possible to do without a perforator, with the help of which sheets of plywood will be nailed to the concrete floor under the laminate. This uses a carbide drill. To prevent the screw caps from falling through the plywood, you should choose their diameter larger than the drill diameter. Self-tapping screws are placed in plastic dowels, which are placed in the drilled holes. Fastening should be carried out not only along the edges of the prepared sheets, but also in their central part. The self-tapping screws used in the work should have a length three times longer, at least than the plywood sheet. So, if the plywood sheet is 16 mm thick, then the self-tapping screw used is 50 mm in length. Exactly the same parameters are provided for the plug-in dowels.

If, even in this case, after fastening, an extra length of plywood sheets is found, it can be cut off with a jigsaw. When all the sequential actions are completed, the quality of the embedding of the self-tapping heads is checked. This is necessary so that the laid laminate is not damaged during operation. Another very important tip after laying plywood on a concrete floor under a laminate is to tap each sheet. To do this, you can use a wooden hammer or a prepared block. The sound should be extremely homogeneous, as everything else indicates the material is peeling from the concrete base. Such sheets should be replaced immediately before the laminate flooring, so as not to repair it later.

There is one subtlety when laying plywood as a substrate for laminate flooring - the use of glue, which is applied to the substrate before spreading over the entire plane of the sheets. It is necessary to fill the available space in the presence of uneven concrete floors.

Surface grinding

In any case, it is problematic to immediately get a perfectly flat surface from the sheets. To come to it, sanding should be done after laying. A special grinding machine is used here. Usually, a coarse sandpaper is installed in it.

When the work is completed, there should be no burrs that appeared earlier during the sawing of plywood sheets. The process of sanding plywood will in some cases even eliminate minor level differences between adjacent sheets.

Subsequently, it remains only to check the work for quality. For this purpose, the evenness of the laid sheets on the area in the room is checked. Using a 2 meter long rail, the height difference is checked. If it does not exceed 2 mm, then we can say with confidence that the work was not done in vain.

It remains to further lay the laminate on the thus prepared base, without fear of the consequences. Well-executed work and the sequence of all actions will lead to a long operational period of the whole "pie". In addition, the laminate itself can be matched to absolutely any interior in the room.

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