Screed floor in the bathroom: wet, dry and semi-dry. Filling technology

Screed and floor waterproofing in the bathroom
  • Varieties
    • Wet
    • Dry
    • Semi-dry
  • Substrate preparation
  • Mix preparation
  • Mounting of thermal and moisture insulation
  • Installation of beacons
  • Filling technology
  • Hardening of the top layer

Any major maintenance of the room begins with the preparation of floors for finishing. Many who have just bought an apartment face the fact that the floors in it look not the best way. Concrete slabs are uneven, there are numerous potholes and hillocks, in some places even pieces of reinforcement can stick out of them. That is why it is so important to perform a quality floor screed in the bathroom - applying an intermediate floor covering between the base and the finish finish.

The device of a coupler in a bathroom

Screed allows:

  • to hide irregularities,
  • provide additional heat and sound insulation,
  • creates the necessary degree of technological bias of floors,
  • evenly distributes the load on the base,
  • makes it possible to hide some communications,
  • makes it possible to raise the floor level to the desired level.

It is difficult to make a floor screed in the bathroom, but we will try to help you, after reading our article, you can conduct these works without attracting professionals. But first, we want to draw your attention to the fact that it is necessary to calculate the height of the floor in the bathroom, taking into account that it should be several centimeters lower than in other rooms.

If there is a flood in the bathroom, the water will not immediately flood the other premises of the apartment and you will have more time to eliminate the consequences.

Quality screed in the bathroom


The main components of the screed are water, sand, cement and crushed stone. If you want to level significant differences in the height of the floor or if the floor is not strong enough and it needs to be strengthened, the mixture is added with expanded clay or perlite.

Screed can be:

  • wet,
  • dry,
  • semi-dry.


Wet screed is considered an ideal option for rooms with high humidity. When using a wet screed, remember that its thickness should be at least 3 centimeters. Therefore, if you have ceilings in the bathroom and are already low, it is not recommended to use it.

The waterproofing layer can be executed both on top of a wet screed( in this case we are talking about a so-called knitted screed) and under it. In addition, an additional heat-insulating layer can also be laid under the screed. If you plan to use a decorative coating in the bathroom, which is sensitive to the slightest height differences, a floor is applied over the screed or instead of it, a special coating that makes the floors perfectly smooth and even.

Wet floor screed in the bathroom


If you use a dry screed in the bathroom, you need to be careful, since it is likely that over time, such a coupler will crack under the influence of moisture. Therefore in the bathroom this kind of screed is rarely done. In addition, it will cost an order of magnitude more expensive than other types of screeds, as the consumption of building materials will increase.

When performing a dry floor screed, first lay a layer of expanded clay or rubble, then evenly distribute the dry mixture, and the top is laid moisture resistant sheets of gypsum board.

Among the advantages of this type of screed is the fact that it does not require any special labor costs, and from it there will be less dirt in the apartment. In addition, there is no need to lay any additional coating on top of the dry screed, except for the decorative coating itself.

Dry tie in the bathroom


In the manufacture of a semi-dry screed, light aggregates are added to the solution, which reduces the load on the floor, reducing the coating weight, and also dries considerably faster than the wet screed.

This screed will cost more than wet, and also requires special skills and the use of additional equipment. So, at first you need to knead the screed mixture by mixing the water with the necessary ingredients in the right proportion, and then, after drying, the screed needs to be wiped to get rid of possible irregularities and bumps.

Semi-dry tie in the bathroom

There is another qualification of screeds, which is based on which layers separate the screed from the base.

  • If the coupler is executed immediately directly on the base, then it is a question of the so-called bonded screed.
  • If a separating layer is used between the screed and the substrate: a polyethylene film or other waterproofing material, then such a screed is called a separating layer.
  • If additional noise or thermal insulation is required in the room, an additional noise or heat insulating layer is laid between the screed and the hydrosolating layer. In this case, it is a so-called floating screed.
Floating floor screed in bathroom

Substrate preparation

Before laying any of the above types of screed, it is necessary to prepare a foundation for it. If previously a screed has already been made in the bathroom, its old layer must be completely removed.

Screed is a monolithic layer that must be spread evenly over the surface. Otherwise, it will quickly crack and cause you a lot of trouble. After removing the old screed, carefully sweep the floors and cover with cement mortar all cracks in the base, if any. Some builders recommend additionally priming the base before making the screed.

Then you need to install and wiring the communication pipes. As we have already mentioned, all communications are hidden under the screed, and heat and waterproofing is already bypassed.

Extremely important stage of the preparatory work is the installation of waterproofing. Experienced masters advise to use in the bath bitumen mastic and various roll waterproofing materials. This waterproofing will help to protect not only the floor, but also the walls of the walls, as it also grips the walls to a height of 15-20 cm from the floor.

Floor waterproofing in the bathroom

Preparing the

mixture Regardless of which screed you use, first you need the to calculate the average consumption of the mixture per square meter of area, and also determine the thickness of the screed in different areas.


  1. To do this, use the level to find the lowest and highest points on the floor.
  2. To the highest point, add the minimum height of the screed, which is acceptable in this room and calculate the thickness of the screed at the lowest point.
  3. Find the average value and multiply it by the amount of the mixture consumption per 1 sq. Km.square meters.

If the height difference in different areas is large enough for you, you must buy the mixture with a margin. In the rest, follow the instructions on the package with the mixture.

Here is an example: , for example, you use a cement mix for screed, having a consumption of 13-15 kg per 1 sq. M.m at a thickness of 1 cm.

If the bathroom area is 15 square meters.m, and the average thickness of the screed - 5 cm, then you will need to multiply the average consumption of the mixture 14 kg / m2 * 5 cm * 15 m2.Thus, in the end, you will need only about 1050 kg of the mixture. This is 42 standard bags weighing 25 kg.

Such calculations are convenient when using a ready mix for floor screed. If you plan to use a cement-sand screed, then you need to start from the fact that 1 part of cement is usually used 3 parts of sand.

Average cement consumption for a cement-sand screed of a floor of 1 cm per 1 m2 - 5 kg, and sand - 15 kg.

Dismantling of the old concrete screed
Bags with floor screed
Lightweight floor screed

If you plan to perform cement screed, then it is better to take concrete ready. In any case, the amount of consumption of cement mixture or concrete per square meter of area should be specified from the seller or the manufacturer.

In some cases, builders also add special additives to the mixture that minimize the amount of water needed to prepare the mixture. The mixture remains plastic and is conveniently applied. Plasticizers for concrete screeds are used when laying the system of a warm floor in the bathroom.

Screed on the floor heating system in the bathroom

Installation of heat and moisture insulation

Moisture insulation in a room with high humidity is always needed. There are coating, plastering, cast, roll and backfill varieties of moisture-insulating materials.

Floor insulation is necessary in houses with a cold base. Typically, these are private houses, as well as apartments that are located on the ground floors of buildings.

The need for a thermal insulation layer is eliminated if you plan to install a "warm floor" system in your apartment. For the insulation of the floor can be used a layer of expanded clay, polystyrene, polystyrene concrete, cork, glass wool or mineral wool.

Hydro and heat insulation of the floor in the bathroom

Installation of beacons

To install the floor screed as precisely as possible, install special beacons - guides from the T-profile or wooden bars. All lighthouses should be on the same level - where the height of the screed above the floor will end. Lighthouses can both be left in the screed, and can be removed after the screed has been completed. If you plan to leave the beacons inside the screed, they must be treated with an anti-corrosion or water-repellent agent so that in time they do not rot and because of them cracks did not form.

Installation of lighthouses under the screed in the bathroom

Stages of work:

  • First measure about 20-25 cm from the wall. There will be the first lighthouse. The rest is located about 40 cm away from it.
  • In the place where the beacon is planned to be located, at a distance from each other point a few hillocks of cement. On them the beacon will hold.
  • Arrange the beacons throughout the entire area of ​​the room and allow the cement mortar to harden. Only then proceed directly to the screed.

Filling technology

It is recommended to fill the screed at the same time throughout the entire area of ​​the room.

The solution for the water-based screed freezes after 1-1.5 hours. Therefore, it is necessary to work with it at a fast pace.

Filling is carried out by strips, between installed beacons. If you do not plan to leave the beacons in the fill, then the bands between them you fill through one. After the solution has dried, the beacons need to be removed and the distance between the strips filled with the remaining solution.

Filling the floor with a cement-sand screed

Here are some tips for filling the floor:

  • The filling should be started from the farthest corner from the entrance door.
  • The solution is poured slightly above the beacon level, then it is compacted and leveled using a special tool - the rule. The rule is placed on the lighthouses, close to the wall, and, constantly moving from side to side, gradually move forward. Surplus solutions are used to fill the next strip.
  • Wet and semi-dry screeds will need to be additionally wiped after pouring, so that the surface is perfectly even. This can be done both manually, making circular movements with the tool, and using a special machine for grouting floors. The surface of the screed must be slightly moistened with a spray gun.
  • After grouting, it is necessary to check once again the level of how evenly you have distributed the screed, whether there is nowhere any misalignment. If everything is smooth, the covering is covered with a polyethylene film for two weeks, periodically checking its condition and maintaining the proper level of humidity.
  • Some experts advise in the process of pouring the floor pierce the mixture with a thin metal rod. This is done in order to avoid the formation of voids with air in the screed, which can subsequently lead to cracks.
  • It takes up to 28 days to completely dry the screed.

Now available for sale are mixtures for the so-called self-leveling floor. Working with them is really easier - you do not need to install beacons or grind screed.


  1. The mixture is spread over the surface in an even layer, beginning at the far corner of the room.
  2. After the mixture covers the surface of the floor, it must be evenly spread with a squeegee or spatula and pierced with a special needle roller to prevent the occurrence of air bubbles in the solution.

Such mixtures are really more convenient than classic ones, but they will cost you much more. In addition, in large areas the self-leveling floor is not very convenient to use - otherwise, it is necessary to delimit the space into several sectors and fill them in stages.

Self-leveling floor in the bathroom

Hardening of the top layer

Some of the so-called topping is used to impart strength to the floors, a special mixture that is applied over the screed to harden it. This mixture may have a quartz or metal filler, or contain corundum.

The topping is distributed evenly over the surface and rubbed directly into the screed. After it is processed with a special mixture.

The use of topping to harden the screed is justified if you do not plan to cover the screed with any additional decorative coating. If you plan to lay tiles, laminate or other materials in the bathroom, there is no need to use additives.

Laying tiles on the screed