The minimum thickness of the floor screed. Dry floor screed. Calculation of the thickness of the floor screed

In the process of laying or repairing the floor, the screed is the main point, as the upper floor covering is laid on a perfectly flat plane. For a good quality screed, you need to calculate everything correctly:

• Choose the desired thickness.
• A kind of screed.
• Composition of the solution.

First of all, the maximum and minimum thickness of the floor screed should be determined: the stability and durability of the coating depend directly on these characteristics. A very thin layer will not be able to provide the reliability that you are targeting, and with thick it is very likely that the load on the overlap is high.

Conditions affecting the thickness of the screed

The minimum thickness of the floor screed is formed in each case personally, depending on:

• How to do the styling.
• What materials are used for the screed.
• Under what coverage (linoleum, laminate, etc.) the base is prepared.

Because the screed can be formed as a heat and sound insulation layer made of solid or loose materials, and on a concreted coating.

The thickness of the screed also depends on the evenness of the base, respectively, the worse it is, the thicker the layer of the composition should be, since almost all surfaces require a completely flat surface.

Diagnosing uneven sex

In order to calculate the thickness of the floor screed, it is very important to take into account the specificity of your base directly: the difference in heights and the presence of depressions. It is not enough just to see and understand whether the floor is flat or not. If, when considering, it seems to be smooth, then at check by a building level or a bar all can change. You need to walk the device on the floor, and you can notice the existence of holes between the building level and the base. If minor gaps are found, the floor will need to be leveled using a screed.

Basically, the thickness of the screed in the living quarters where the old coating is replaced with the new one varies from 3 to 5 cm. Some mistakenly believe that the thicker the ground, the better. However, this is not so, do not forget that the purpose of the screed is leveling, and not increasing the height of the flooring.

In addition, if the coupler is carried out as a normal filling of the surface with a thick layer, the surface will not become even, and it will dry out for a very long time, thereby creating great inconvenience.

Minimum thickness

When calculating the thickness of the screed, several factors should be taken into account:

• On what basis it is formed.
• What kind of mixture is used for it.

When pouring the composition onto concrete slabs, the minimum thickness of the floor screed should be 20 mm.

When laying the solution on heat or sound insulation from loose or solid materials, the layer must not be less than 40 mm, and also a reinforcement with a metal net is required. These same rules must be adhered to when pouring mortar onto the waterproofing layer in the bathroom and in the kitchen.

In accordance with SNIP, the thickness of the screed for overlapping pipelines should differ from the diameter of the pipes by 10-15 mm in the larger direction.

Of course, the thinner the layer of the screed, the more economical the repair will be, but do not forget that "the miser pays twice", so some factors should be taken into account:

• A thin layer forms a rapid evaporation of moisture, which can provoke cracks in the screed.
• A thin layer of screed may not "mesh" with the base;
• Possible damage to the integrity of the screed when things fall.

Max thickness

The maximum thickness of the screed for each case is determined separately. Basically, this indicator is indicated on the box or in the memo to the solution. The maximum height for all solutions is different, it varies from 20 to 80 mm. Experts recommend to use for leveling the impressive level drops "rough screed", because it perfectly copes with the task and much more profitable than the dry floor screed.

If we talk about the maximum thickness, then there are their principles of what thickness is used for different coatings:

• When laying on a flat concrete surface 20 mm is enough.
• When laying on the insulation - 45-50 mm.
• On the cold pipeline - 10 mm.
• On the hot - 20 mm.

When laying out a large volume, it is required to leave a cushioning layer at 20 mm along the edges, which is required to expand the material while warming. Fill this layer with a construction foam or a special tape.

The maximum thickness for a dry mix does not exceed 80 mm. This is explained by the fact that this material practically does not evaporate moisture.

The usual composition of cement and sand can be laid by any layer, however professionals are advised not to make it above 150 mm, the exception is the priming.

Classification

In terms of thickness, there are three types of screed:

• Slim draft version. When choosing this kind, self-leveling solutions are used, which make it possible to form a thickness of up to 20 mm.
• Screed height up to 70 mm. To create it, reinforcement is used from the iron mesh or rods of the reinforcement.
• The maximum thickness is up to 150 mm. Formed by laying a monolith with an internal iron frame.

Mixture composition

The minimum thickness of the floor screed, as well as the limit, directly depend on the composition of the mixture and the problems with the substrate.

When detecting thresholds of less than 20 mm and slight unevenness, it is recommended to use self-leveling compounds, which eventually give an even and thin layer. They independently spread themselves over the surface without human help. After the solution has dried, you can immediately begin to lay out the top cover. The composition of the solution includes:

• Cement or gypsum.
• Fine sand.
• Plasticizers for quality improvement.
• Paste.
• Pigments.

In nonessential disadvantages, the minimum and maximum thickness of the floor screed in the apartment is determined by the manufacturer of the composition.

In addition to the above, there are still some recommendations on the height of the screed:

• If the screed is formed on top of the insulating layer, it is required to leave a gap of about 40 mm between the wall and the cavity. Later it will be filled with an insulating filler. Professionals recommend the screeds from the monolith to be fenced off from the walls by a waterproofing foil.
• For laying on slabs the thickness should be 10 mm.

Cement-sand screed

This compound is used to compensate for irregularities in excess of 20 mm. Since the sand-cement mixture contains plasticizers in the composition, experts say that the thickness of the cement screed for the floor should be at least 30 mm. With a smaller thickness, cracks will appear with time.

Screed at high differences

There are cases when monolithic plates are laid very poorly, resulting in the formation of strong level differences of more than 60 mm. In this case, it is recommended that the screed be made from a mortar of a mixture of concrete and coarse sand. The thickness of the concrete floor screed can be up to 100-150 mm. In the most neglected cases, when the slope and thresholds reach enormous values of 150-170 mm, it is absolutely necessary to make the bottom layer of claydite concrete, in another case the cost and weight of the screed will be simply very high.

Dry floor

In the presence of significant defects, a dry floor screed is often used to accelerate the process, which includes substances that do not require long drying. Screed includes a layer of backfilled raw materials, for example, expanded clay, and over it is covered with sheet material (plywood, particle board and others). If necessary, you can conduct hydro, heat or noise insulation. The thickness of this coating is from 35 to 60 mm.

Water warm floor

When the question arises as to what the thickness of the screed should be, then you should first clarify some points. The fact is that in the device of a warm water floor, the screed performs two functions simultaneously. First of all, this is, of course, the basis for the final coating, the second is the accumulation and distribution of heat. In addition, the layer also provides a protective function, namely:

• Protects the pipes from damage.
• The upper layer of the floor from overheating.
• On the lower layers, sound and heat insulation are formed.

Therefore, to understand what the thickness of the screed for the warm floor should be required for anyone who repairs.

In order to perform a warm floor screed, inertial solutions are produced that can hold and retain heat for a long time. The remaining solutions are not suitable for this, because they "eat" heat. In addition, in the device of a warm floor often there are temperature differences, which adversely affects the screeds of cement and sand.

The best solution for the warm floor at the moment is the floor, for the reason that it is very plastic and dries quickly.

So, what thickness should be the floor screed in the device of warm cover? In this case, a high screed will "eat" heat, in addition, adjust the temperature regime will not be easy. But on the other hand, the coating will be warmed for a long time, which means it is more to keep the heat.

Too thin a screed is also not a good option. In this case, overheating may occur, and heat will be distributed in places, where pipes are laid.

In an apartment, the screed should not be thicker than 100 mm and thinner than 70 mm, above the pipes a layer of mortar - 20-50 mm. In some cases, the design is slightly "hanging": in the middle of the base and flooring, thermal and noise insulation is carried out, in this case it is better to create a layer of at least 35 mm.

Another important parameter that determines the thickness of the screed for a warm water floor is the material of the heating element. Above the pipes of the water floor it is necessary to lay a solution 30 mm thick.

What can lead to improper installation of the screed?

If the laying technology is not complied with, the operating properties of the screed are reduced. It is very important to observe the slope of the level of coverage, if the coefficient is exceeded by 0.2%, the finish coating will not be in accordance with the rules.

In the ground, which is poorly aligned, crevices can form between the canvas of the top coating. And about such reviews, when unqualified repairmen simply scatter cement on the floor and fill it with water, you do not even want to talk. Reports of such cases can be easily found at specialized forums. Screed, laid with irregularities, quickly begins to crumble, and will never become a reliable basis for any top coating.

This alignment must be broken with a puncher, taken out of the apartment and mounted again. The work of non-professional masters guarantees extra expenses and time loss. It is much better to do the work on your own with the observance of all the details and moments, but most importantly, adhere to the recommended thickness of the screed.

As you can see, it is not difficult to calculate the parameters. However, depending on the type of screed, you need to consider all the nuances that you now know about.