Laying laminate on the concrete floor itself

Before laying the laminate on a concrete floor, you should take care that the surface of the substrate prepared for it was as flat as possible and does not have clearly visible defects. Most experts believe that high-quality preparation of the concrete base is the main condition for the reliability and durability of the flooring.

Note! One of the features of laminate coating is that, under the influence of loads, it begins to lose its shape and repeats all the flaws of the base. In the event that these irregularities reach a critical value, the laminate board begins to deform (it bends under the load), which usually leads to the breakdown of its locks.

For a more detailed acquaintance with the technique of preparing concrete foundations, it is necessary to consider the most general requirements for all types of flooring without exception.

General requirements for the grounds are as follows:

1. First of all, the surface of the concrete base must be completely clean. If there are grains of sand or other debris under the laminate, any movement on it will be accompanied by an unpleasant crunch. That is why during the preparatory work it is desirable to vacuum both the base itself and the plates mounted on it.
2. For the materials of the type we are considering, differences are considered safe, not exceeding two millimeters in height for every 2 meters of the length of the section.
3. Evenly distributed over the base surface, the slope should be no more than 4 mm for every 2 meters of the flooring length.
4. In order to avoid undesirable swelling of the laminate plates, the base must have normal humidity within the premises to be arranged.

How to lay

Concrete base is called any coating, which includes the cement component. These include:

• self-leveling ties;
• cement-sand screeds;
• plain concrete;
• reinforced concrete slabs used as floor slabs.

Consider each of the previously described requirements in relation to all known types of bases.

On a conventional concrete base, height differences will be observed regardless of the quality of its manufacture; so you have to align them anyway. The leveling of the surface of fine-grained concrete is usually done using so-called self-leveling mixtures. For leveling processing of concretes prepared on the basis of large fractions and characterized by increased "roughness", it would be more reasonable to use a classic screed.

Reinforced concrete floor slabs in turn have characteristic irregularities and differences in height (especially in the joints), which also forces the use of a cement-sand screed for their leveling.

When using a previously prepared screed, it is necessary to carefully inspect its surface for the presence of differences that are unacceptable for laying laminate. In that case, if they do not fit into the specified range, laying the laminate on the concrete floor with their own hands should not be done immediately. The surface is first primed, and then poured self-leveling mixture. The relatively even surface of the screed can be simply primed before laying the laminate on the concrete floor.

For floors treated with self-leveling mixtures, the “fit” conditions for the given requirements will of course be much simpler. In the event that unacceptable differences in height are found on such floors, you should treat them with the same composition one more time, after which you can proceed to the primer surface.

Note! If the surface of the self-leveling screed meets all standards, then you can do without repairing it; at the same time, it is not necessary to prime it before laying the substrate.

Styling Features

As noted earlier, the permissible uniformly distributed over the surface slope of the concrete base should not exceed four millimeters for every 2 meters of the length of the room. With a larger value of this indicator, the floor surface must be leveled (regardless of what it is made of).

It should not be overlooked that the final drying of the screed will take about 7–10 days. As for self-leveling compounds, some of their varieties (quick-drying mixture, for example) “seize” in just a few hours. For ordinary mixtures, this period is, as a rule, no more than 3-5 days and is determined by the thickness of the cast layer.

It should be noted that a weighty argument in favor of choosing a quick-drying mixture is that in the passage room you cannot afford to wait for the complete drying of the composition for several days. If the repair is made in a room that does not have passage and time, as they say, “tolerates”, then it will be possible to use an ordinary mixture to eliminate irregularities.

And now we will consider a number of requirements imposed directly on the surface of the screed (self-leveling mixture), as well as ways to eliminate the existing shortcomings.

Before you lay the laminate on a concrete floor you will need to make sure that the surface of the screed is sufficiently rigid; and check it for compliance with this requirement will be quite easy. In the event that while walking along the composition which has just “seized” there are no traces left on the surface, there will most likely not be any problems with the operation of the coating. But if at the same time, sand remains in places of contact with the foot, then the strength of the upper layer of the screed obviously does not meet the required standards. The laminate laid on such a base will, in time, begin to crunch and creak, and the substrate entering into its composition will wear out faster than usual. In order to avoid all these troubles, you will need to treat its surface with a special primer applied twice with a break of about 12 hours (after the first layer of primer dries out). At this stage of the preparation of the screed, you should get a concrete surface that is well impregnated with the primer material. Immediately, we note that sometimes the desired result can be obtained after a single priming.

Further, the most important condition for obtaining a high-quality surface layer of the screed is the absence of even the smallest cracks on it. Their presence leads to the fact that the base (after a certain time) can lose its solidity. To eliminate cracks of various dimensions, you will have to take the following steps:

• cracks up to 1 cm wide are carefully cleaned and then filled with a special repair solution;
• after it dries, they are primed with a deep penetration compound (ceresite CT 17, for example, or its equivalent). In the case when after carrying out these operations the floor surface partially loses its strength - it will need to be primed completely;
• to make a repair mix yourself, you should take one part of the cement and add four parts of sand to it. Then mix all this thoroughly, adding to the resulting mixture one part of tile glue (of the same ceresite, for example).

With a fairly flat floor surface, you can begin laying the substrate within a day or two after repairing the surface. If there are small irregularities and dips in some places, they should be eliminated with the help of a self-leveling mixture or a special solution made from glue, cement and sand.

If there are not enough fragments (large-sized pieces) rigidly fixed in the concrete, you will have to fix the surface in addition to the alignment by arranging the screed about 3 cm thick. If necessary, you can reinforce it using a fine-grained mesh.

The strengthening fastener is applied with the obligatory installation of beacons. The mixture is made of cement and sand with the addition of a special plasticizer. Reinforcement of such a tie is made with the help of a metal mesh, connected from a wire with a thickness of 2-3 mm (with a mesh size of 100 × 100 mm). About a day later, you can use the rule to cut off the sags and irregularities present on the surface of the screed. On hot days, its surface should be moistened periodically, which eliminates the possibility of drying and re-cracking.

After a few days (approximately 3-4 days), the screed is finally treated with a primer already familiar to us, after which it dries, the substrate is laid on the surface.

The surface of the screed must be completely dry, for which it must be allowed to stand at least five to seven days. For self-leveling screed, this indicator is of the order of several hours.

Note! The prepared surface should be perfectly clean, for which it is desirable to vacuum.

Sometimes for the purpose of additional warming the floor, the concrete base is advised to be covered with plywood sheets and only after that the substrate and laminate should be laid. But this technique is not always applicable in practice, since there are not so many benefits for warming it, but the room size in height is reduced by a good 2–3 centimeters.

Video

You can watch a video on laying laminate flooring on a concrete floor below: