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Semi-dry and wet floor screed test. Screed in the apartment. Dry or wet? During operation of the screed, it is prohibited

The feasibility of installing a screed in an apartment is determined by the condition of the foundation, the planned finishing of the floors and additional tasks determined by the apartment renovation project. For example, in a new building you cannot do without finishing or screeding. However, the choice of screed option in an apartment depends on a host of other factors.

About the screed in the apartment

According to SNiP2.03.13-88, which is called “Floors”, clause 5.1: screeds in an apartment are used if necessary:

• Level the base of the floor;
• Close utility lines;
• Evenly distribute the load over the layer of heat-sound-insulating materials;
• For normal heat distribution (for heated floors).

As you can see, all the regulatory reasons for making a screed in an apartment renovation may be present; all that remains is to choose one of three options for screeding in an apartment. Namely:

• Wet screed;
• Semi-dry screeds;
• Dry screeds.

Note: Self-leveling floors can be classified as leveling screeds, but in this article I will NOT talk about self-leveling floors.

Wet screed

Wet screed is usually called a screed based on cement and sand, the solution of which contains a large amount of water. For apartments, a solution called a cement-sand mixture is used, which belongs to the concrete strength class B 22.5, the concrete trademark is M300.

3 options for screeding in the apartment: wet screed

In conditions apartment renovation Such a solution can be easily obtained by mixing a ready-made sand mixture of grade M150 or M300 with water. On square meter screeds 10 mm thick will require 22 kilograms of mixture.

An important characteristic of a wet mixture is its mobility. It is determined by the methods of settling the cone or immersing the cone in the solution. For concrete mixture The cone sediment test method is used. For screeding, the slump of the concrete cone should be 20-30 mm. For a cement-sand mixture, the immersion of the cone should not exceed 4-5 cm.

A distinctive feature of their wet screeds. Wet screed thicker than 20 mm must be reinforced metal mesh with square cells 100 mm.

More often, it is performed on a layer of sound-heat insulation. This option is called a floating screed. The floating screed is isolated not only from the base, but also from the walls of the room.

An alternative to an isolated screed is a connected screed. The solution of this screed enters chemical reaction with base. To avoid drawing water out of the solution, the base must be coated with a strengthening (NOT deep penetration) primer.

A wet screed takes 21-28 days to dry. The wet screed should be moistened with water for the first three days, and covered with polyethylene for the first week.

Semi-dry screed

A semi-dry screed is a screed based on a solution with a reduced water content. Reduction achieved required water adding special plasticizers and additives to the mixture.

3 options for screed in an apartment: semi-dry screed

It is quite difficult to prepare such a solution at home. For its production, special machine installations are used.

In addition, working with semi-dry screed requires serious skills and it is almost impossible to make a semi-dry screed with your own hands without training.

The minimum thickness of a semi-dry screed on a rigid base is 40 mm; when laying a semi-dry screed on a layer of sound-heat insulation (expanded clay, polystyrene foam, expanded polystyrene, extruded heated floor slabs), the minimum thickness of a semi-dry screed cannot be less than 50 mm. The maximum thickness of semi-dry screed is 120 mm.

It is important to note that semi-dry screed belongs to the class of NOT bound. That is, even when laid on a rigid base, the semi-dry screed must be separated from the base by a layer of polyethylene, and from the walls by a layer of damper.

Another argument against making a semi-dry screed “with your own hands”. Immediately after installation, the semi-dry screed must be sanded with special expensive machines.

Dry screed

For the installation of dry (prefabricated) screed, solutions and mixtures are not used. A dry screed is assembled from a layer of special bedding, reminiscent of fine-grained expanded clay, and two (three) layers of gypsum fiber boards (GVLV GOST 51829-2001) 10 mm thick, laid at intervals.

In this article we will tell you how to properly make a wet (concrete, cement) screed for a subfloor with your own hands. Subfloors with wet screed can be laid on floor slabs or on the ground.
Wet screed can be made of 4 types:
o Knitted. The simplest option. The screed is laid directly on the base (slab). Waterproofing and finishing flooring can be laid on the screed.
o On waterproofing. A waterproofing layer is laid on the slab, and a screed is placed on it.
o On thermal insulation. As a rule, such screeds are used on soil foundations. First, sand is laid on the ground and compacted, then comes insulation, waterproofing and screed (necessarily reinforced, since it lies on the insulation). If thermal insulation is laid on a slab, then sand bedding is not needed.
o With self-leveling coating. Self-leveling coating The subfloor is poured onto a hardened screed to create a perfectly flat and smooth base for laying sensitive coatings (for example, linoleum).
The process of preparing and pouring a wet subfloor screed with your own hands:
1. Preparing the base. If it is a stove, it is cleaned of dust and debris. If it is soil, remove all vegetation, compact the underlying base (expanded clay, crushed stone, gravel) to the required height, then compact sand cushion 10 cm high. If you are going to make a knitted screed, then the slab needs to be primed (pour a thin layer of primer and smooth it over the entire surface with a roller or brush; the primer dries for 3-5 hours).
2. Thermal insulation. Insulation can be laid on the slab if desired, but on sand preparation on the ground – it is obligatory. In any case, the insulation must be rigid.
3. Waterproofing. Waterproofing layer it is not needed only for a knitted screed (instead, a damper edge tape is laid along the perimeter of the walls). In all other cases, waterproofing is laid (with a 10-15 cm overlap on the walls). If the waterproofing is rolled, then it is laid overlapping with an overlap of 10-15 cm.
4. Reinforcement. Mandatory screed reinforcement is required when creating a subfloor on the ground. In other cases - optional. Reinforced mesh need to be installed at a distance of 1-2 cm from the base.
5. Installation of “beacons”. Lighthouses are metal profiles(for example, T-shaped), along which the screed is aligned. Therefore, they need to be aligned horizontally. The easiest way is to install beacons on a solution (the solution should be the same as that which will be used for the screed). Mix the solution and lay it in heaps along the future profile line. Place the profile on the solution and level it with water or laser level. The height of the level of the beacons should be 3-5 cm. The beacons must first be placed along the walls with a distance of 20 cm from the walls. The step (distance) between the beacons should be 1-1.5 m (the main thing is that the step should be less than the length of the rule that you will use align the screed). Align the beacons both along and across between adjacent profiles. The solution under the beacons must harden so that the subfloor screed can be leveled using them.
6. Preparing the screed. The screed can be made from ordinary cement-sand mortar(1 bucket of cement for 3 buckets of sand; as a result, the solution should not be liquid or thick), but it is better to include tile adhesive in a portion of cement (if you have extra packaging). The glue increases the grip (adhesion) and strength of the screed. Also, the market is already filled with special solutions for wet screed subfloors. If you bought a special solution for screed, strictly follow the proportions indicated by the manufacturer on the packaging. In any case, preparing the solution begins by pouring water into the vessel, and then only everything else. Also, the prepared solution should be used as quickly as possible.
7. Filling and leveling the screed. This stage It is better to do the work together: one fills and levels the screed, the second prepares the next portion of the solution at this time. You need to align the screed with the beacons towards you, moving the rule (or rod) left and right. Filling the screed begins from the far corner of the room, moving towards the exit. After each leveling of a new portion of the screed, the solution must be pierced with wire in several places (during mixing, it may form air gaps, which will come out when punctured). After completing the work, a day later you can stick out the beacons, treat the cracks with a primer and seal them with the same solution composition.
8. Finish self-leveling self-leveling layer. The self-leveling layer is applied under sensitive coatings (for example, linoleum). But before pouring it, the screed must completely harden (this takes 1 month).

Do not ventilate or create drafts in the room under any circumstances during the entire curing period of the screed. In short, do nothing for a whole month. Many people make a huge mistake by trying to reduce the drying time of the screed. The point is that the screed should not dry out, but harden. And this is a smooth process. If it is accelerated, microcracks may appear on the surface of the screed.
Some will say that microcracks are not scary at all. Just the opposite. The screed dries from below, not from above. Therefore, if microcracks appear, they come from the very bottom. To prevent cracks from appearing, you need to literally check the surface of the screed every day for dryness. If it is very dry, moisten the surface with a wet roller.
If microcracks do appear, immediately cover them with solution and moisten the entire surface with a damp roller.
It is advisable to screed the floor in one room in 1 day. If you have unused solution left, it will not work next time, because it will set quite strongly, and it cannot be diluted with water.

Every adult, even without special construction education, understands that in order to lay any covering on the floor in a room, you must first level its base, which is why you need a floor screed. What is a floor screed? This is a construction procedure of forming on the floor flat surface . Today there are a huge number of varieties of screeds. When renovating apartments, office and industrial premises, both wet and dry floor screed are often used. The screed solution, called wet, is used quite often and is prepared from sand, cement and water. Additional fillers can also be used. This is the simplest and most inexpensive way to level floors.

The main tasks of a wet screed:

• Smooth surface;
• strengthening the sexual foundation;
• additional sound insulation, thermal insulation of the room;
• hiding the structural elements of a heated floor.

Types of wet screed

According to the specifics of preparing the type of floor surface and making the final layer, wet screeds are divided into four types, which are presented below.

You can also make self-leveling floors by using a thinner mixture that can spread onto the floor without physical intervention. But it’s not worth using only self-leveling floors without creating a key screed.

Preparing the subfloor

Preparing the floor for a wet screed involves rough renovation work, which include:

• dismantling the old screed;
• clearing debris from slabs;
• base primer.

Note: The primer must be allowed to dry for five hours!

If the base is soil, then it is first cleared of vegetation, then a layer of sand (at least 10 cm) is poured. When using expanded clay for this purpose, sand is also poured on top of it. The formed layer is carefully compacted. For better shrinkage, the embankment can be slightly moistened with water. With the use of expanded clay, a wet floor screed is much simpler and cheaper, since a minimal amount of solution will be used. If repair work is carried out in the bathroom or toilet, then the water pipes are laid at the same time.

Thermal insulation

As thermal insulation material expanded clay is used, polystyrene foam boards. But the insulation must be sufficiently rigid. Expanded clay has worse thermal insulation and sound insulation characteristics, but is more reliable and has a longer service life. When performing a wet screed on the ground, insulation must be carried out, and on slabs in some cases (for example, if there is a basement below).

Waterproofing

Roofing material, a thick film, can be used as a material for waterproofing. Strips of material should overlap by up to 15 cm and overlap by 10 cm on the walls facing water pipes, which must be coated with sealant above the planned level of filling the solution. Waterproofing must be carried out in bathrooms, as well as in other rooms that are connected, for example, to the basement.

Reinforcement

When screeding on the ground, it is recommended to reinforce it with reinforcement. For this, a steel mesh welded from reinforcement can be used. You can also simply add a special fibrous metal (plastic) material - fibrin - to the cement mortar.

Installation of additional equipment

If it is planned to lay wiring, install a heated floor system, repair and construction work is also carried out at this stage, with mandatory consideration of all technological specifics.

Stages of performing a wet screed

Wet screed is performed in several stages, which are given below.

Placement of beacons

To ensure that the wet floor screed is completely level, during its implementation a beacon system is used, which is formed on the floor from profile slats. To install the beacon strip, it is recommended to use a solution designed for screeding.

• Pre-to the base of the floor parallel to the wall Screws are screwed in along a line at a distance of 20 cm; their heads must be at the same level (you can check this using a special building level), but below 10 mm of the planned screed level (depending on the height of the slats used).
• It is worth maintaining a distance of up to 80 cm between the screws; this is no longer recommended, as the slats installed on them may bend.
• The next line with screws is placed every 1.5 meters from the previous line. Here you need to take into account the length of the rule planned to be used for alignment cement mortar. The rule should lie on two parallel slats.
• Next, the mortar is applied to the screws and the slats are mounted. During the installation process, it is necessary to check the evenness of the resulting plane using a level. After installing all the slats, you need to let the solution dry.

The use of beacons is used even in small areas. There should be at least two of them so that the solution can be leveled.

Solution used

After complete preparation for the wet floor screed, it is necessary to prepare the mixture. As a mortar for floor screed, you can already use ready-made mixtures, specially designed for leveling floor surfaces. Currently on the market building materials They are available in a fairly wide range and may differ from each other in some characteristics. To prepare them for use, you must strictly follow the manufacturer's instructions.

Proportion of standard solution: 1 part - cement, 3 parts - sand. For improvement strength characteristics You can additionally add adhesive mass into the solution, which is used for tiling work.

The finished mixture should not:

• spread too much;
• be dry.

It is recommended to order concrete in a ready-made state. It is made of much better quality. Besides, it’s much more profitable. Concrete is usually used for such work in private country cottages, as well as the premises of the first floors of buildings. Thick-layer wet concrete screed on the upper floors is used only in certain cases.

Pouring the floor

Important! To obtain high-quality screed, the area of ​​the room must be filled at once, since the cement solution tends to harden within an hour, after which it will be impossible to adjust it.

Grinding

If concrete was used as a liquid screed, then after it hardens, the surface is polished with special grinding equipment (a grinder with a special attachment can be used). This event will help remove noticeable irregularities and prepare the floor surface for laying any type of flooring.

The traditional method of leveling foundations for future floor coverings. The technology of its device is quite simple, and the price is one of the lowest among all types of screeds. On a perfectly flat base obtained after installing a wet screed, you can lay polymer floors or floor coverings (tiles, laminate, linoleum, etc.).

Application features and types of wet screed

To make a choice - wet or dry screed, you need to know the features and area where the wet screed is used.

The scope of application of wet floor screeds is very wide, compared to dry screeds, which can only be used in rooms where there is no risk of exposure to moisture. Wet screed can be used both in production and at home. This can be a self-leveling screed, which also belongs to the “wet” category, a traditional cement-sand screed or concrete screed with fillers.

With the help of wet screeds, modern heated floors are installed when pipes or cables are laid under the screed layer.

Wet screeds can be single-layer or multi-layer. Single-layer screeds are convenient to use to eliminate defects in floors. But with significant differences in height, for rough leveling, it is better to use cement-sand mortar. After installing the first layer, you can apply it finishing layer from a self-leveling mixture.

The main advantage of wet screed is its relatively low cost due to the low cost of materials. This screed is durable, fire-resistant and moisture-resistant, it has a small thickness. There are, of course, disadvantages of wet screed. In particular, such a screed takes a long time to harden and dry; it has poor heat and sound insulation. Also, a disadvantage can be considered the high labor intensity of wet screed.

Wet screed technology

To install a wet screed, you can use a traditional cement-sand mortar, which is prepared immediately before starting work by mixing the components. Ready-made mixtures for screeds greatly simplify the procedure for preparing the solution. If concrete floors are installed in industrial premises designed to withstand very heavy loads, a filler of gravel, expanded clay, screenings, etc. is added to the solution. The solution is distributed over the base area using a rule.

The thickness of the wet screed ranges from 10 to 80 mm. If the layer needs to be thicker, for example, to raise the floor level, then expanded clay is poured under the screed or expanded polystyrene is laid. In addition, these materials have heat and sound insulation properties.

The drying time of a wet screed is from 3 to 36 hours. It all depends on the composition of the solution and the thickness of the layer. But you can walk on the surface no earlier than in a week. Semi-dry floor screed hardens more quickly, which is installed with a minimum amount of water in the solution.

In order to give the wet screed greater strength and durability, you can use reinforcement - reinforcing mesh or fiberglass. In the second case, the duration technological process The cost of laying a wet screed is significantly reduced, since fiber can be added directly to the solution, while installing the reinforcing mesh will take a lot of time.

Material consumption and price of wet screed

The consumption of materials, which affects the price of a wet screed, is determined depending on the characteristics of the technology and the quality of the base. IN classic version To make a wet screed 6 cm thick, you will need an average of 15 kg of cement per 1 m2. The company’s specialists, after inspecting the premises, will be able to accurately calculate the cost of the wet screed. In any case, in the foreground is quality corresponding to the price.

Wet screed can be made of 4 types:

• Knitted.
• The simplest option. The screed is laid directly on the base (slab). Waterproofing and finishing flooring can be laid on the screed. On waterproofing.
• A waterproofing layer is laid on the slab, and a screed is placed on it. On thermal insulation.
• As a rule, such screeds are used on soil foundations. First, sand is laid on the ground and compacted, then comes insulation, waterproofing and screed (necessarily reinforced, since it lies on the insulation). If thermal insulation is laid on a slab, then sand bedding is not needed. With self-leveling coating.

The self-leveling subfloor coating is poured onto a hardened screed to create a perfectly flat and smooth base for laying sensitive coatings (for example, linoleum).

Installation of wet screed subfloor

1. The process of preparing and pouring a wet subfloor screed with your own hands: If it is a stove, it is cleaned of dust and debris. If it is soil, remove all vegetation, compact the underlying base (expanded clay, crushed stone, gravel) to the required height, then compact a sand cushion 10 cm high. If you are going to make a knitted screed, then the slab needs to be primed (pour a thin layer of primer and level it over the entire surface with a roller or brush; the primer dries for 3-5 hours).
2. Thermal insulation.
3. Insulation can be laid on the slab if desired, but on sand preparation on the ground – it is obligatory. In any case, the insulation must be rigid.
4. Waterproofing.
5. A waterproofing layer is not needed only for a knitted screed (instead, a damper edge tape is laid along the perimeter of the walls). In all other cases, waterproofing is laid (with a 10-15 cm overlap on the walls). If the waterproofing is rolled, then it is laid overlapping with an overlap of 10-15 cm. Reinforcement. Mandatory screed reinforcement is required when creating a subfloor on the ground. In other cases - optional. The reinforced mesh should be installed at a distance of 1-2 cm from the base.
6. Installation of "beacons". The screed can be made from ordinary cement-sand mortar (1 bucket of cement for 3 buckets of sand; as a result, the solution should not be liquid or thick), but it is better to include tile adhesive in a portion of cement (if you have extra packaging). The glue increases the grip (adhesion) and strength of the screed. Also, the market is already filled with special solutions for wet screed subfloors. If you bought a special solution for screed, strictly follow the proportions indicated by the manufacturer on the packaging. In any case, preparing the solution begins by pouring water into the vessel, and then only everything else. Also, the prepared solution should be used as quickly as possible.
7. Filling and leveling the screed. This stage of work is best done by two people: one fills and levels the screed, while the second prepares the next portion of the solution. You need to align the screed with the beacons towards you, moving the rule (or rod) left and right. Filling the screed begins from the far corner of the room, moving towards the exit. After each leveling of a new portion of the screed, the solution must be pierced with wire in several places (when stirring, air layers may form in it, which will come out when pierced). After completing the work, a day later you can stick out the beacons, treat the cracks with a primer and seal them with the same solution composition.
8. Finish self-leveling self-leveling layer. The self-leveling layer is applied under sensitive coatings (for example, linoleum). But before pouring it, the screed must completely harden (this takes 1 month).

Do not ventilate or create drafts in the room under any circumstances during the entire curing period of the screed. In short, do nothing for a whole month. Many people make a huge mistake by trying to reduce the drying time of the screed. The point is just that The screed should not dry out, but harden. And this is a smooth process. If it is accelerated, microcracks may appear on the surface of the screed.

Some will say that microcracks are not scary at all. Just the opposite. The screed dries from below, not from above. Therefore, if microcracks appear, they come from the very bottom. To prevent cracks from appearing, you need to literally check the surface of the screed every day for dryness. If it is very dry, moisten the surface with a wet roller.

If microcracks do appear, immediately cover them with solution and moisten the entire surface with a damp roller.

It is advisable to screed the floor in one room in 1 day. If you have unused solution left, it will not work next time, because it will set quite strongly, and it cannot be diluted with water.