How to repair cracks in the floor screed? Floor screed cracks - what to do? Review + Video

How to repair cracks in the floor screed? Floor screed cracks - what to do? Review + Video How to repair cracks in the floor screed. If you do not follow the rules for pouring concrete screed on the surface, many defects may appear. Repair of the screed will make it possible to prevent further damage to the integrity of the rough base.

In the article we will consider how to repair cracks in the floor screed, as well as what are the main types of defects, effective ways to eliminate them, as well as recommendations on how to lay concrete mortar.

Reasons for the appearance of defects in the form of cracks

Interestingly, that the cement mixture has low plasticity, adhesion and a fairly high coefficient of linear expansion.

Why can the floor screed start to crack? In fact, there are a lot of prerequisites for flaws to appear on the rough base. As practice has shown, cracks, potholes and dents can appear even if a professional grout has been filled. With what it can be connected? It is worth noting in advance that in most cases defects may appear after the installation of the cement screed has been completed. When laying gypsum and semi-dry mixtures, cracking of the coating is much less common.

Dimples and peaks in the rough finish may appear after the beacons are dismantled.

The reason for the appearance of flaws will lie in the physical and mechanical properties of the material used. The cement mixture has a low level of plasticity, adhesion and a high coefficient of linear expansion. For this reason, even if very little time passes between the installation and dismantling of the beacons, this will inevitably lead to the fact that small cracks and holes will appear.

What are the main reasons for the appearance of defects on the screed surface?

  • How to repair cracks in the floor screed? Floor screed cracks - what to do? Review + Video A solution has been mixed incorrectly in which the concentration of water is too high.
  • Rapid (forced) drying of the coating.

  • Uneven drying of the screed along the entire perimeter.
  • Absence of a membrane base under the finished solution (polyethylene).
  • The presence of large temperature differences and drafts that interfere with normal drying.
  • Direct adhesion of the cement mixture to communications and the wall.
  • Use of a fine mixture that is simply not suitable for grouting.

  • Non-observance or absence of the prescribed distances for the expansion joint.

The reasons for the formation of flaws, namely the fact that the floor screed of the sub-base is cracking, can be very different, and will not be limited to the list presented. In addition, the quality of the concrete pavement can be affected by:

  1. Incorrect installation of waterproofing and thermal insulation.
  2. Poor cement-based mixture.
  3. Solution dissimilar in preparation.

  4. Lack of the required tools for pouring and leveling concrete.
  5. Non-observance of the proportions when preparing the working composition.

Let's take a look at what is best to do during the renovation process for the floor.

Recommendations for floor repair

Repairing a floor screed is an extremely important undertaking, which requires strict compliance with all established rules for the restoration of an old and freshly poured screed.

To carry out repairs to the base without having any problems, before performing the whole procedure, you should pay attention to the following nuances:

  1. To start you should find out exactly what is the reason for the appearance of all the flaws.

  2. Check if there are expansion joints on this covering.
  3. You should also find out how the cement mixture was poured, on which base the mortar was laid (concrete or wooden).
  4. If there are no expansion joints on the floor, care must be taken to install them first before repairing gaps or cracks.
  5. To determine if there is local concrete delamination, it is advisable to take a rubber mallet and tap the coating with it.

Please note, that if you ignore all the recommendations listed above, then after a couple of months, dents, potholes and "coiled" concrete will appear on the base again .

.. You can learn more about how to eliminate flaws in a cement screed from the video tutorial.

The main types of defects

During the repair work in the apartment, most of the masters personally encountered such a problem as violation of the integrity of the screed. Considering that when pouring a concrete mixture, it is practically impossible to achieve uniform drying of the solution, the risk of flaws increases several times.

How to carry out repair work in this case?

First, you should decide on what type of deformation is in your case.

The method for eliminating defects will largely depend on the degree of damage to the concrete floor:

  • Microscopic cracks up to 1.5 cm in size. They may appear with uneven drying of the coating. If there are only a few cracks on the surface, then ordinary tile adhesive can be used to cover them.

  • Large cracks, the size of which is from 1.5 to 2 cm. This type of damage most often appears against the background of the absence of expansion joints, as well as due to the strong impact of the mechanical type. When renovating apartments, it is not recommended to use caustic compounds, and for this reason, it is most often recommended to use cement mortar or glue to eliminate cracks.
  • "Coiled" concrete.

    The concrete floor can be mobile due to the air cavities that are located under the floor. If it becomes necessary to close up the swollen areas, then the detached concrete should be cleaned off, and the detected potholes should be filled with cement mortar.

  • Local irregularities with a height of up to 0.5 cm. The bulges should simply be removed with a grinder, and small dents should be filled with tile glue or M500 / M300 cement mortar.

  • Potholes and holes larger than 1.5 cm. It is extremely difficult to repair a lot of damage that is located locally. For this reason, in this case, it should be done, as experts recommend - pour a new screed with a small thickness, that is, the layer should be up to 4 cm.

Pay attention, that repairs in apartments are a problem for most craftsmen.

What to do to prevent the floor screed from cracking? When placing concrete mix, it is extremely difficult to prevent drafts, but it is precisely because of them that uneven drying of the base often occurs. To perform high-quality restoration of the floor in an apartment or house, you should use solutions and adhesives that have excellent adhesion characteristics.

Expansion joints

Here it should be understood that repair work for the screed on the floor should begin in order to eliminate the causes that caused the problem. If cracks appear on the coating, and you think that the reason lies in the fact that there are no expansion joints, then you should definitely make them.

So, in order to make expansion joints, you will need:

  1. How to repair cracks in the floor screed? Floor screed cracks - what to do? Review + Video Make indentations in the base, which is made of concrete, approximately 5 meters apart.

  2. Next, install a strobe into the resulting crack to expand the gap to 2 cm.
  3. Then prime the cracks and fill with an adhesive that does not have shrinkage.
  4. As soon as the glue hardens, remove the excess with regular sandpaper.

Watch the video below for how to make expansion joints. During the repair work, experts advise to ventilate the rooms being repaired well, since non-shrinking compositions are ways to contain harmful volatile substances.

Can the crack widen

The cement mixture itself is highly flawed. In this case, it is extremely important to find out not only the cause of their appearance, but also the dynamics of the increase in cracks in the screed on the floor. In particular, this practice affects precisely apartments in which the interfloor floors do not have sufficient rigidity. How to understand if there is a tendency for cracks to increase on the base?

When checking the coating to see if there is a possibility of further deformation, the following should be done:

  1. Stick on the crack of a strip of paper.
  2. Do not touch the covered area for about a month.

  3. If, after a specified period of time, the paper breaks, it can be argued that there is a tendency for the crack size to increase.

What to do in such a case? Most often, such problems appear when doing self-repair of an apartment. Because of which? This may also be due to non-observance of the rules for mixing and laying concrete mortar, which will inevitably lead to the fact that the material will deteriorate. To rectify the situation, it is advisable to seek help from specialists. Naturally, the cost of subfloor restoration can be quite high.

But in this case, you can be sure that the work has been done efficiently.

Eliminating small defects

To repair cracks in a concrete screed with your own hands, you will need the following:

  1. Use an angle grinder with a diamond disc and make the crevice slightly wider.
  2. Remove loose concrete at the edge of the crevice.
  3. Prime the resulting crack.
  4. Fill the crevices with tile adhesive.

Performing repair work in an apartment is fraught with certain difficulties, which are worth saying a few words. If the concrete surface begins to crack, and it is located in the sanitary unit, then it is no longer possible to repair the defects with the help of a conventional tile adhesive. After a couple of months, it will already begin to flake off due to the high level of humidity inside the room. If the microclimate in the room is specific, then a mixture that has water-repellent properties should be used to cover up the flaws. We suggest watching the video below in order to know how to repair a screed in a sanitary unit.

Elimination of large-sized cracks

Repair work for the old screed, which has large cracks, will not differ much in technique from the previous version. And yet, in such a case, a mixture made of epoxy and cement will be used to seal the cracks. With the help of tile glue, large defects should be repaired - this is what home craftsmen think. In fact, this cannot be done due to the low adhesion of the adhesive solution. What to do if your concrete screed is cracked?

  1. First, you need to grind the crevice.

  2. It is desirable that the cracks have straight edges on both sides.
  3. The formed dust should be removed with a vacuum cleaner so that the adhesive mixture obtains a high level of adhesion to the concrete.
  4. After that, several large and deep enough cuts should be made across the crack so that the load on the seams is reduced.
  5. Next, the prepared areas should be primed with a special primer solution.
  6. At the final stage of the repair work, a mixture should be applied, which is prepared on the basis of epoxy resin.

In more detail, repair work in the apartment for the restoration of the screed will be shown in the video.

Strengthening the base

Strengthening a weak screed is a way of preventive repair.Performing certain not very complicated manipulations can save you from removing the screed from the base, and will also protect it from destruction and postpone the need for urgent repairs. To strengthen the screed, use a puncher to drill holes 2 cm in diameter to the capital base. The distance between the holes should be 1/4 meter.

The best option is when the top is twice as wide in diameter as the hole itself. After all the holes have been drilled, they should be cleaned.

When the preparatory work is completed, arm yourself with scraps from the reinforcement, which have a diameter of 1.2 cm. The reinforcement rods should be degreased and made shorter in length so that it is equal to the depth of the holes.

In addition, when strengthening, you cannot do without a special epoxy mixture for concrete called "Rizopox 3500". It can be used for various repairs that will be associated with the destruction of the screed. The diluted mixture should be mixed with quartz sand, and then poured into the holes that formed in the floor. After filling the holes, you need to insert pieces of reinforcement into them, and then cover everything with liquid, including the upper part of the hole.

The end result of the work will be the strengthening of the screed due to its strengthening with metal reinforcement.

This method can be used not only to strengthen the weakened screed, but also as a preventive measure during the installation of a new screed. Reinforcement during installation will help prevent potholes and cracks and also make the floor resistant to wear and tear.

Tips from professionals

Strengthening the screed can also be done with the help of special compounds that penetrate into the depth and improve the properties of concrete. They will help to extend the life of the screed, the need to dismantle the coating in the future will simply disappear. Before applying such products, thoroughly sand the surface.

Small repairs to cement-based screed will be justified if no more than 1/3 of the area is damaged. If a large area has been deformed, the old screed should be replaced. Repairing a cracked and broken screed is a fairly simple undertaking with proper approach and preparation. You can do it yourself, but it should be done on time in order to avoid unpleasant consequences. The main thing is that you can correctly determine the cause of the destruction and take appropriate measures.


What to do if the floor screed starts to crack? First, you need to determine the nature and extent of damage, as well as the reasons for their occurrence. Depending on the size of defects, to eliminate them, you can use a tile adhesive, mixtures prepared on the basis of epoxy resin or cement mortar, the cost of which is quite acceptable.

( 1 grade, average 5 of 5 )


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