2023 Author: Philip Bishop | [email protected]. Last modified: 2023-05-24 22:24
- Advantages of a semi-dry screed
- Thickness selection
- Solution preparation
- Working in the winter
- Drying time
There are several options for performing a cement-sand screed. The most popular of the available is the filling of a semi-dry screed. This is a more versatile way to build a "rough" floor. No knowledge is required when performing installation, but some features are worth exploring.
Advantages of a semi-dry screed
To begin with, you should dwell on the positive qualities of a semi-dry screed, including:
- Cheap materials to purchase, which give a very high quality and at the same time an even semi-dry screed.
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Additional leveling of the sub-floor surface is not required, but you can immediately proceed to the flooring of any selected floor covering.
Features of a semi-dry screed - The turnaround time is reduced due to the use of dry mixes, which are usually prepared outside the installation site. The solution is supplied by the pump used in the work.
- The process of supplying the solution to the place of the future floor should not be interrupted. But this quality helps the solution to lie evenly over the entire surface, practically without flaws.
- A small amount of water used, which removes the possibility of flow of the ready-made solution to the floors located below. Shrinkage also practically does not occur if the technology of work is followed.
- Excellent heat, noise and sound insulation qualities.
- Abrasion resistance, which is achieved through the use and addition of fiberglass.
There are, of course, disadvantages that are usually encountered in the case when the stages of the work are violated, the solution for the floor screed is not mixed in proportions, the filling is not performed according to the technology.
Thickness selection
Pouring a semi-dry screed provides for the selection of a suitable thickness of the finished "cake". It is worth thinking about its minimum parameters, as well as maximum ones, in order to subsequently correctly calculate the required amount of material.
The thickness of the poured floor will depend on the base itself, where the mortar is laid. The smoother it is, the less mix will be required to work. Despite the fact that a semi-dry floor screed already gives an insignificant load on the floor, the weight must be taken into account when determining the thickness. At the same time, the screed itself must withstand certain loads (constant walking, the presence of large-sized furniture, household appliances, etc.).
A layer of hydro and thermal insulation, communication pipes, underlying layers can be located under the screed. Their presence or absence will also have their say in the question of how thick to fill the floor. Particular attention should be paid to the warm floor, regardless of the specific option: water or electric. All these elements must be covered with a semi-dry screed. In addition, the floor covering must be placed on a specific version of the "rough" floor.
There is a huge nuance of a semi-dry screed in that there is no overlap adhesion, and the base itself is a polyethylene film that acts as a waterproofing layer. For this reason, the semi-dry screed must be made with a minimum thickness of 40 mm. If expanded clay acts as a base or, for example, foam plastic, then generally 50 mm.
The warm floor makes its own adjustments, as it must be completely covered with a screed. In this case, a semi-dry floor screed should cover all its elements by at least 35 mm. When installing an electric floor with heating, in addition to a thickness of 40-50 mm, there must be a layer of underlayment - heat-reflecting. It will not be superfluous to use a plasticizer as an additive, which helps to minimize the appearance of cracks and chips on the surface.
In any work, you should be guided by special regulations, which include building codes and regulations 2.03.13-88. Directly in paragraph 5, the minimum requirements for the screed are indicated.
If a semi-dry screed is performed in several rooms at once, then its thickness may differ depending on the floor covering used.
In this case, it would be better to perform a multilevel screed.
When it comes to a semi-dry version of the subfloor and its maximum thickness, then it is not limited by anything. Average indicators are 5-12 cm.
But it is worth noting that it depends on how much the semi-dry floor screed dries. The thicker it is, the longer you will have to wait before laying the floor covering. Any finishing work must not be carried out on a wet screed. Otherwise, one should prepare for negative consequences.
Solution preparation
Before installation, it is important to prepare the solution for work. It consists of special building mixtures, which have already been added with special ingredients to improve quality. The solution can be prepared independently by mixing cement, sand, water with each other, do not forget about the reinforcing agent. As the latter, fiber is most often used, which gives the finished solution excellent qualities of plasticity and strength.
The solution should be homogeneous, without lumps. This will eventually fill a really flat floor. All large lumps are broken if possible. Only after that the floor is filled with a semi-dry screed.
The entire area of the room is filled evenly, without interruption. Leveling mortar is performed using a rule. Subsequently, it remains only to grout the surface and leave it for a certain time to dry.
Working in the winter
When renovation work begins in the winter, many people think about the temperature at which the floors can be poured. Here it is worth considering the moment that sand begins to freeze into lumps at sub-zero temperatures below -10 degrees. This makes it almost impossible to mix a complete solution. If you just need to fill the screed in winter, then there are two options:
- Wait until the air temperature rises to -2 degrees.
- Arrange a heated room for mixing the solution. True, this option is more suitable for private households.
The increase in the cost of the material will cause the purchase of antifreeze additives. But in the end, this will not allow the solution to freeze, it will be possible to perform installation.
In certain ready-made dry building mixtures, this additive is already available. It remains only to prepare the solution.
In winter, you can fill in a semi-dry screed with the help of another folk remedy - add a few drops of detergent to the water. This will facilitate the delivery of mortar to high-rise floors in an apartment building. It will not be superfluous to insulate the hoses themselves with various options that will be more profitable.
At what temperature can a semi-dry screed be made indoors? In this case, the minimum temperature should not fall below +5 degrees. Otherwise, the poured solution will not be able to fully dry before further work with it. This suggests that you can still fill the floors in winter.
Drying time
Semi-dry screed using German technology dries instantly, within a few days. Then the flooring can be laid. But it is worth noting that each specific finished flooring requires a certain time until it dries completely.
The period under the tiles increases due to the fact that special glue for installation will be used. Leaving the subfloor damp will prevent the adhesive from grabbing and causing the ceramic tiles to flake off. Average drying rates are 14 days.
But much will depend on the thickness of the subfloor. It is important to know how long the screed must dry before laying the laminate. The floor covering should not be exposed to excessive moisture, but should remain dry at all times.
With a screed thickness of 60-70 mm, it will take about three weeks to completely dry the screed, and you will have to wait four weeks for a 10 cm coating to dry. It should be noted that almost any coating in a semi-dry way can be walked on after 12 hours after installation, carry out finishing activities indoors. At the same time, you cannot put pressure on him from the outside.
If the deadlines are not running out, then it is better to leave the "rough" floor for a longer period, so that all excess moisture comes out. Then you get not only even, but also a very high quality, durable coating, ready for any kind of flooring.
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