What is expanded clay screed? Mortar with expanded clay: composition and proportions Expanded clay for the floor in the apartment.

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To give the floor a neat and beautiful appearance, you need to think about a quality screed. Experienced craftsmen They claim that screeding a floor with expanded clay literally works wonders. Let's try to understand the subtleties and nuances of technology in order to make this process a reality.

Expanded clay is considered popular among materials used for insulation. This is explained by its reasonable cost and excellent characteristics. The material is porous, light in weight, obtained by firing clay under the influence of high temperatures. As a rule, it is produced in the form of oval or round granules.

The manufacturing process takes place in the following way. Clay swells under the influence of temperature, the material is fired, and a sealed shell is formed. The product has good strength and is resistant to external influences.

The quality of expanded clay material fully depends on compliance with the technological manufacturing features.

The density of the material reaches 200 – 600 kg per cubic meter. The lower this indicator, the more pores the pebbles contain. This material has good thermal insulation qualities, but denser expanded clay has better strength.

The sizes of the resulting granules vary from 2 to 40 mm.

To the listed features of the material it is necessary to add naturalness and environmental safety. The material is chemically inert and does not react to aggressive environments.

Types of expanded clay backfill for screed

Based on the density indicator, the following types of material are divided:

expanded clay crushed stone – the diameter reaches 1 – 1.4 cm, for preparation concrete mixture used most often;
gravel - it is used when installing durable and lightweight floors. According to fractions, the material is divided into three groups: from 5 to 10 mm, from 1 to 2 cm, from 2 to 4 cm in diameter;
sand - this type of backfill is used when arranging a thin screed, the size of which is no more than five millimeters.

Fractions are selected taking into account the room in which the floor screed with expanded clay is planned, and what technology the work will be used.

Criterias of choice

If, when arranging a floor screed with expanded clay with your own hands, you use traditional methods that involve subsequent pouring with a concrete mixture, the fractions of the bulk material do not play a special role. Expanded clay of any size is suitable, even the smallest fractions.

By the way, expanded clay sand is excellent for leveling floors with big difference levels. This material is recommended for use in areas where the surfaces have significant damage, and when installing piece parquet boards.

It is fair to note that the opinion regarding the choice of expanded clay material with fractions of about 0.5 mm and minimum mass for the base is considered erroneous. The fact is that this type of filler is highly dense and better fills void areas, thus making the screed layers heavier.

When constructing a screed, professional craftsmen advise using expanded clay, the fractions of which range from 5 to 20 mm, taking the material in certain proportions. The recommendations are based on the fact that during the process of laying the expanded clay layer, grains of different sizes are perfectly combined with each other. This feature has a positive effect on the subsequent operation of the poured floor, which will not shrink or be deformed.

Advantages and disadvantages of expanded clay screed

To finally understand the floor screed with expanded clay, let's consider its pros and cons. As usual, first of all let’s talk about the advantages:

such a screed is considered the cheapest option for floor insulation;
ease of implementation - filled expanded clay granules are filled with concrete mortar;
long operational period, during which the formation of fungus and mold is excluded;
light weight, due to which the load on the floors is reduced.

Separately, it should be noted that the level can be displayed even in cases of large altitude differences. If the floor needs to be raised significantly, and the weight of the concrete mixture is unacceptably high, the most acceptable option is the use of expanded clay.

To make the picture as reliable as possible, you will have to mention the disadvantages of such a screed:

wet cement mud awaits you during work;
from the poured mass, the thickness of the floor will increase due to the installation of a heat-insulating layer;
The work process is quite labor-intensive.

As you can see, negative aspects cannot be considered critical; many do not even pay attention to them.

Methods and technology for screeding floors with expanded clay

The unusual characteristics of the filler allow it to be used different ways, based on the circumstances and purpose of the premises. Let's figure out how to properly make a floor screed with expanded clay.

Surface preparation

The preparatory work is important stage production. To begin with, the concrete surface is cleaned of residues. old screed, debris is removed, defective areas are repaired. If the subfloor is made of wood, rotted boards are replaced and the cracks are filled. The soil base is simply leveled - the mixture of expanded clay and sand will be backfilled directly onto the earthen surface.

In addition, the following activities are carried out in advance:

waterproofing layer - its necessity is dictated by the hydrophobic properties of the material. Insulating layers can be laid under the bottom of the screed or on its surface, but Lately lay down double layer, from each side;
thermal insulation – actual question for private houses, the first floors of which are located on the ground or above the basement;
soundproofing layer - if expanded clay is used, then other materials are not required in this regard;
placing beacons - only with their help will you get a flat surface;
damper tape - when installing a dry screed, it is fixed against the flooring so that it does not creak when walking. In other cases, it is laid across the entire thickness of the poured layer to compensate for expansion from the effects of humidity and temperature conditions.

Calculation of the amount of backfill

When installing a floor screed with expanded clay, it is necessary to preliminary calculations material needs.

When using the dry screed method, you should know how much expanded clay and other components are required. To do this, it is necessary to clarify a number of standard indicators:

thickness of the screed being poured;
room area;
placement options and sizes of materials.

To clarify the need for expanded clay, the approximate average thickness of the backfilled layer is determined.

To calculate the thickness of expanded clay concrete for a dry floor layer, it is necessary to multiply the height of the backfill by the area of the room. It should be noted that accurate calculations are difficult to make, so it is recommended to create a small reserve.

At wet method When arranging the screed, the height of the layer is first determined. Let's consider all the actions on specific example. The height of the screed is 10 cm, the area of the room is 16 m. The weight of one cubic meter of expanded clay is about 400 kg.

Knowing the parameters, we clarify the need for material in cubes.

Semi-dry

An expanded clay layer is poured onto the base, the level of which does not reach the beacons by one and a half to two centimeters. The layer is poured with cement laitance, the granules then set and are covered with a thin protective film, which does not allow moisture to penetrate the expanded clay.

All work stops, the surface dries for a day, during which time the water evaporates completely, leaving only hardened cement.

After this, a mortar mixture is prepared from cement material, sand and water. The solution is laid from the far wall, moving gradually towards the exit, stretching the mixture as a rule along the installed beacons.

The laid screed is given time to dry completely. As a rule, this will require at least twelve hours, which allows you to speed up all other work on arranging the floor.

Dry screed

This method is used most often. This is due to the fact that it does not require much time and effort to complete. The surface is leveled and laid waterproofing material– roofing felt, polyethylene, paper impregnated with a bitumen composition.

Expanded clay is poured dry, and sheets of gypsum fiber board, chipboard, and slabs of asbestos-cement material are laid on top. Installation work is carried out quickly, the amount of construction waste is minimal, the floor has good soundproofing and thermal qualities, and the finished flooring material can be laid immediately.

The disadvantages of this option are that you will have to pay a certain amount for materials. But the ease of installation allows you to do everything yourself, which will give a certain economic effect. Another drawback is the thickness, which is not very suitable for rooms with low ceilings.

Wet screed

This option involves installing a floor screed made of a mixture of expanded clay and sand concrete. In this case, the following components will be required:

cement material - one part;
sand - three parts;
expanded clay - four parts.

First, the expanded clay is filled with water and given time to get a little wet. After this, kneading is done and the screed is poured.

Note that you will have to perform calculations for other materials. To correctly calculate the need for raw materials for screed, you can use special calculators that are available on the Internet.

Often the floor surface has big differences, especially in recently completed properties. The steps between the floor slabs can reach a height of up to 10 cm. Leveling such floors with concrete mortar is ineffective for two reasons:

Unprofitable in economic terms - high consumption material
The screed turns out to be very massive and dooms the floor slabs to excessive load

To lighten the entire structure, low-density ingredients are added to the screed; quite often expanded clay plays their role. This material, depending on the size of the granules, has a thermal conductivity coefficient from 0.07 to 0.16 W/m. Knowing how to properly screed expanded clay, you can create a heated floor with good thermal insulation properties.

Experts recommend using expanded clay to level the floor when level differences exceed 5 cm. When using this material for screed, it should be taken into account that its granules have a low density and often float to the surface of the solution. It is difficult to determine experimentally what layer of expanded clay is poured onto the screed so that it evens out all the unevenness and does not crack. It is more rational to listen to the advice of specialists and make concrete in a layer of 2-3 cm. In this case, the technology for performing work on installing a flat floor is divided into stages:

Drawing a single horizon line throughout the apartment.
Light fraction flooring.
Installation of beacons.
Leveling fill.

Let's look at each operation in more detail.

A flat floor throughout the apartment without differences between rooms looks beautiful. It is better to install it in all rooms at once, and not separately - first one, then after a month or two, the next. To obtain the same floor level in the apartment, a zero horizon line is marked along all walls.

It is more convenient to mark using a water level. It will allow you to project a given mark onto all walls with an accuracy of 1 mm. Marking using this tool is carried out as follows:

Having retreated 1-1.5 m from the floor surface in any of the rooms, make a mark on the wall
The first communicating vessel with divisions is fixed near the drawn mark, moving along the walls, the second horizontal level is marked after 50-60 cm
Using the marks, the so-called “zero level” is drawn with a straight ruler.
Having retreated 7 mm from the highest point of the floor (2 mm for concrete + 5 for expanded clay), mark the mark of the finishing fill on the wall
The screed mark is projected onto all walls and a continuous line is drawn, which will serve as a guide for installing beacons

After breaking off the horizontal lines, they begin to prepare the surface. The floor is cleared of construction debris and dust, then sheets of waterproofing material are spread over the entire area, overlapping the walls to the marked horizontal. Polyethylene film can be used as protection against moisture. The joints between the canvases are overlapped with an overlap of at least 10 cm and taped with moisture-resistant construction tape. Expanded clay is laid on top of the film.

Light layer installation

The material that facilitates the screed is usually classified depending on the size and shape of the fractions into the following groups:

Crushed stone. Expanded clay grains of this type are 5-40 mm in size, predominantly angular in shape. They are obtained by crushing large pieces of baked foamed clay.
Expanded clay gravel. This material are round granules Brown. According to GOST, gravel is divided into fractions of sizes 5-10, 10-20 and 20-40 mm. Used as thermal insulation material, facilitating the construction of the screed.
Expanded clay sand. It is obtained by crushing baked clay granules into particles less than 5 mm in size. Sand is used to make light, thin screeds.

Expanded clay is installed into the screed in two ways - by pouring the dry fraction, followed by pouring “cement laitance” or laying out the solution. The granules have a low density and, if not fixed, they will float through upper layer and form irregularities on the surface of the screed. The most reliable fixation of expanded clay in a single mass occurs when mixing the solution.

To prepare the mixture, take 1 part of M-500 cement, 2 parts of construction sand and 7 parts of expanded clay gravel. The finished solution is laid out on the floor, making a layer 2.5-3 cm below the drawn horizon line and leveled using the rule. As soon as the expanded clay concrete reaches the initial hardness at which it can be walked on, the installation of beacons begins.

Securing the guides

To control the even layer of filling, construction beacons are used. They are placed at a distance less than the length of the rule, 10-15 cm from each other. The initial guide is mounted at a distance of 25-35 cm from the wall. To fix the beacons, self-tapping screws are used, which are screwed into expanded clay concrete. The use of screws allows you to smoothly adjust the height of the bar.

The screws are screwed in so that the top point of the beacon is at the same level as the marked horizon line. The screws are placed along the entire length of the plank with a distance of 35-55 cm. The even position of the guides relative to each other is controlled using a 2 m long building level.

An alternative option is to install cushions made of a cement-sand mixture under the beacons. With this method, the position of the slats is adjusted by recessing or pulling them out of the pillows. After fixing the beacons, all remnants of the solution located above the guides are carefully removed. Then they wait for the mixture to harden, check the reliability of the planks and proceed to pouring.

Leveling the surface

The final layer of concrete mixture (1 part M-500 cement to 4 parts construction sand) is poured between the beacons. When manually mixing the solution, first mix the dry fractions until smooth gray and then add water. When using a labor-saving concrete mixer, pour 1 part water, 1 cement, 4 parts sand into the container and wait until mixed into a homogeneous mass. Experts recommend adding plasticizers to the composition, for example, PVA glue. These substances increase the adhesion of the solution and prevent cracking of concrete.

A less labor-intensive, but more expensive method is to install a screed using ready-made dry mixtures. In addition to plasticizers, they contain special components that provide the screed with a long service life. Such mixtures should be diluted strictly following the manufacturers' recommendations.

The solution prepared using one or another method is laid out on expanded clay concrete and leveled using a rule that is carried out longitudinally to the beacons in close contact with their upper surface. In order for the concrete to lie evenly, it is distributed with small amplitude vibration movements transversely to the guides. When pits occur, using a trowel, the solution is taken from the leading edge and placed in the defective area.

To make the screed monolithic, experts recommend installing it in one day. If it is not possible to fill the floor in the entire apartment at once, it is leveled room by room, insulating it using a strip 3-4 mm thick, thereby providing a thermal expansion joint.

After 4-5 hours, the concrete will harden and the beacons can be removed, and the resulting voids can be filled with mortar. To prevent the screed from cracking, it is recommended to pour water from a watering can on it 1-2 times a day for a week.

Expanded clay makes concrete lighter and allows you to make a screed up to 15 cm thick. So if the floors are scary with changes, you shouldn’t trip over them. An effective remedy To eliminate such defects, use a two-layer screed with expanded clay, the installation of which gives the room a completely different look.

Updated: 09/01/2019

Of course, there are other technologies, but in some cases expanded clay is recommended:

the height difference of the base is more than 10 cm. If you place a traditional concrete screed on such a floor, its weight will create an impressive load on the load-bearing floors. Expanded clay is a lightweight filler that does not overload the structure;
the basis is reinforced concrete slabs. This is a cold material, which is especially felt on the first floor, and expanded clay insulates the floor;
the presence of additional communications and an electric heating system below the floor level;
limited renovation budget. Expanded clay screed is cheaper than concrete screed.

The raw material for the production of this material is a special clay, which foams under the influence of high temperatures. The result is light, round pebbles, porous inside. They are different sizes, depending on which it is customary to distinguish three main fractions: gravel, pebbles and crushed stone. From beneficial properties the following can be distinguished:

environmental friendliness;
durability;
strength;
thermal insulation;
sound insulation;
fire resistance;
chemical inertness;
resistance to moisture, heat, frost;
expanded clay does not rot, mold or mildew does not grow on it;
low price with excellent quality;
availability.

It follows from this that the use of expanded clay can not only save the most hopeless floors with holes or a slope of more than 10 cm, but at the same time insulate and soundproof them.

Preparatory work

There are several types of screed using expanded clay, but regardless of the one you choose, you should follow some general steps.

Cleaning and preparing the base

The base must be cleaned of dust and debris, and if possible, remove the old coating, if any. If there are gaps in the floor, they need to be sealed. Wrap the wires laid along the base with polyethylene and seal with tape at the joints.

Base waterproofing

The purpose of this action is to prevent leaks and damage to the screed. Nowadays, for waterproofing, you can use bitumen, purchase ready-made mixtures or roll materials, which are laid overlapping with a large margin, approximately 15 cm, and additionally secured with adhesive tape.

waterproofing

It is also possible to use film with a thickness of at least 100 microns, preferably in one piece for the entire room. Film or other insulating materials are applied to the wall with a height margin of 10 centimeters, and cut off after completion of the work.

Laying damper tape

It is attached along the walls, directly onto the moisture insulation. The purpose of the tape is to compensate for possible expansion of materials due to sudden changes in temperature, and in the case of a dry screed, the damper will prevent possible squeaks and other sounds arising from the coating touching the walls.

In order for the floor to be truly level, it is necessary to determine and maintain the screed level throughout the entire work process. For this purpose, so-called beacons are used.

With help laser level The plane of the future floor surface is projected onto the walls of the room, and marks are made at the intersection points, which are then connected by a horizontal line. Beacons need to be placed along them, taking into account the fact that for expanded clay dry screed a significant distance from the floor to the profiles should be taken.

Typically, slats or metal profiles. Pre-prepared wood or plywood dies are placed under them to match the level. When the rows of beacons are installed and verified, you need to fix them with a solution.

This porous aggregate differs in the size of the fractions, so it is best to mix several. Small ones will provide density, and medium ones will not allow the screed to gain weight.

It is important to know that the density of identical fractions may be different, and therefore there are 10 brands of filler. This property of the material should be taken into account when purchasing.

Denser expanded clay is heavier, but stronger. When all the preparatory work is completed, it is time to start leveling the floor. This can be done in different ways.

Expanded clay is poured onto the prepared base, leveled and compacted. It is necessary that the filler layer does not reach the top of the lighthouse by approximately 2.5 cm.

Then the evenness of the “pillow” is checked with a level and, if everything is good, the solution is carefully laid on the insulation. To avoid shifts and deformation of the base, you can put a mesh on top of the expanded clay, or fill it with cement laitance so that the granules set and the “cushion” itself does not sag over time.

Laitance is cement diluted with water to the consistency of thick cream. Expanded clay filled with such a mixture should be left for a day to harden. When the pillow is finally ready, you need to lay the solution on it using leveling movements, the layer of which will not be very thick, and therefore relatively light.

To prepare such a solution, the easiest way is to buy a ready-made mixture at a hardware store and dilute it according to the instructions. This will help avoid mistakes. If you have experience working with concrete and cement, you can prepare the solution yourself.

The floor made in this way will harden in a few days. After this time, the beacons should be removed and dents from them should be repaired, as well as possible irregularities should be sanded. The floor will gain full strength only after 4 weeks, and during this entire time it is covered with film to slow down the evaporation of moisture from the surface. You can do without film if you moisten the screed with water.

expanded clay

The main advantage of this alignment is the solidity of the screed. The solution will require expanded clay, sand and cement in a ratio of 3:2:1. Water will require approximately two-thirds of the total volume of remaining materials.

First, water is poured into the mixing container and expanded clay is poured in so that it has time to soak. Expanded clay is followed by sand, and only then cement. The mixture must be mixed until smooth construction mixer or a drill with an attachment.

The finished solution must be carefully laid out, leveling as a rule, along the beacons from the corner of the room towards the threshold. The distance of the expanded clay concrete to the top mark of the lighthouse remains about 2 cm, since a concrete screed will be laid on top of it. This can be done immediately, without waiting for the first layer to dry. The entire structure will take as long to dry as the previous one.

Expanded clay + self-leveling floors

A self-leveling floor, provided it has a suitable base, is the easiest way to get a beautiful, even and perfectly smooth surface. A liquid mixture based on various resins spreads over the surface and levels itself.

This type of floor hardens quite quickly, while being temperature resistant, chemically inert, and abrasion resistant. Expanded clay levels the floor and creates the very foundation that is necessary to obtain an even coating. It needs to be poured onto the prepared surface, compacted and leveled, focusing on the beacons. Then lay a film over the insulation and pour the solution onto it. Roll the liquid mass with a needle roller to get rid of air bubbles and let the floor dry.

This is perhaps the simplest and cheap way level the floors using expanded clay. Compared to previous ones, when all work had to be done quickly, in in this case you can interrupt as much as you like, make corrections, and you don’t have to wait for the screed to dry.

The floor is suitable for full use almost immediately. It is necessary to note one more advantage of the method. Finished design does not contain cement and sand at all, therefore it has the least weight. This alignment is perfect option for old houses with wooden floors, in which the weight of the screed is critical.

A layer of unfixed expanded clay makes it possible to lay telephone and electric wires, “warm floor” systems and any kind of communications. There are two more advantages to this method of floor leveling: better sound insulation and heat retention, and the only disadvantage is that the coating sheets are susceptible to moisture.

The execution steps are very simple. The dry expanded clay mixture is scattered on the floor, compacted and... You can not level the entire floor at once, but in fragments, since you will still have to walk on the backfill. As for the thickness, it is determined by the specific situation. Already 3-4 centimeters of filler allows you to create a fairly dense and stable coating, but you should not make it less thick.

Sheets of flooring material are laid on the compacted cushion. It can be gypsum fiber board, OSB, fibreboard, chipboard or just plywood. The sheets are placed relative to each other according to the principle brickwork, that is, the side of each sheet is in contact with the halves of the sides of the other two.

GVL sheets

The seams of the slabs are usually glued together, and a second layer is laid on top, attached to the first with self-tapping screws. The resulting coating should not reach the wall by about a centimeter; these gaps will be hidden later by baseboards. All joints of the resulting structure are puttied, and the finishing coating is laid on top of the finished floor.

So, leveling the floor with expanded clay can rightfully be considered an economically correct choice, which has a lot of advantages. The method also has alternatives, but it does not lose popularity, as it allows you to achieve your goal without many problems. Properly carried out work allows you to get a truly smooth and durable floor, which for a long time no repairs required.

Video - Leveling the floor with expanded clay

Expanded clay screed – perfect solution for leveling the floor, which does not require you to carefully preparatory work before laying on the base. Expanded clay is loved by builders for its unpretentiousness, ease of installation, low price. Simple screed with expanded clay will quickly help level the surface and create a floor with excellent sound-proofing and heat-insulating characteristics. has long been used in construction, the material cannot be replaced in the arrangement of thermal insulation of attics, as a filler for expanded clay concrete blocks, it is used in laying foundations and in many other areas of construction.

The quality of repairs in any room is determined primarily by how perfectly smooth the floors are. After all, this will give later and correct styling coverings. Serious errors and errors in screeding lead to problems with installation door designs and you will have to resort to all sorts of tricks in finishing. Therefore, it is better to do everything perfectly and correctly at once in order to avoid any questions and difficulties in the future.

How to achieve a smooth surface? Which floor screed should I choose if I additionally need to achieve good thermal insulation? The answer to this question will be filling the floor with expanded clay. The technology of this process is quite simple, so if you have basic skills, you can make such a screed yourself. What kind of material is expanded clay and why does it attract so much attention? Let's deal with this now.
What is expanded clay, its main pros and cons

Expanded clay is a free-flowing, lightweight and porous building material. It is based on clay rocks with an admixture of quartz. Expanded clay can have granules of different shapes and sizes. Expanded clay is useful for its thermal insulation properties, since it can significantly reduce heat loss in the room. Expanded clay meets almost all the requirements for modern insulation materials However, like any building material it has its advantages and disadvantages.

The main advantages of using expanded clay:

Due to the expanded clay layer, or rather its thickness, the internal area can be reduced;
Characterized by a large amount of crumbs and dust;
Can absorb moisture, so it is better to protect yourself from moisture penetration.

Technology of floor screed with expanded clay and its main features

Floor screed with expanded clay is considered one of the most simple ways leveling floors, however, has its own specifics and nuances, even when using ready-made mixtures. Depending on the surface of the base and what features of the room there are, three different technologies are distinguished:

Self-leveling floors with expanded clay filler;
Leveling followed by floor insulation (expanded clay and cement-sand mortar);
Dry expanded clay screed.

The whole process is simple, even non-professionals can do it, because here you do not need specific materials or tools. The most important thing is to monitor the thickness during screeding; it should be at least 30 mm. Expanded clay is used quite often for the purpose of thermal insulation, and due to its lightness, small loads on floor slabs are obtained.

As with any leveling, you first need to set the level; you can use a laser or hydraulic level. Markings are placed on the walls using lines, and the floor will be leveled along them in the future. After this, you can begin to repair defects on the floor surface, then begin installing the beacons.

Having aligned all the beacons, you can begin working directly with the expanded clay layer. The screed solution can be prepared in several ways. The entire preparation technology is the same, but working with expanded clay has differences, which will be mentioned below.

There is a semi-dry screed with expanded clay, an approach that solves two problems at once: insulation and raising the overall floor surface. A semi-dry screed with expanded clay provides a great advantage in terms of preparing the base - there is no need for thorough dust removal. You will need to remove the construction waste and the base is almost ready, all that remains is to dry it and make sure there is no moisture.

In what cases is screed with expanded clay used? The use of expanded clay screed is indicated in many cases. This is especially true when you need to significantly reduce weight concrete screed, because any ceilings have a certain margin of safety. Sometimes you just need to save on such a heavy material as cement, that is, the cost of consumables is reduced.

Strengthening the screed with expanded clay

Often an expanded clay layer is used when it is necessary to level the floor in all rooms to the same level. If the foundation has concrete or reinforced concrete slabs, or you have to deal with wooden coverings that can't bear the weight wet screed. In the case of installing electric or infrared heated floors, as well as placing communications in the lower ceiling, it would be appropriate to use a screed with expanded clay.

Installation option for dry screed with expanded clay in the video review:

Advantages and disadvantages of floor screed with expanded clay

Floor screed with expanded clay allows you to achieve additional insulation and fortifications. The thermal insulation properties of expanded clay are very attractive; a 6.5 cm layer of expanded clay filler is enough to replace a 4 cm of wood flooring or 190 cm of brickwork. It turns out that expanded clay is simply created for installation work for preparing heated floors.

All that remains is to choose the right and technologically competent use of the unique filler. Builders know that screeding with expanded clay is carried out in three various options. A small amount of expanded clay strengthens the screed, improves quality indicators, and is preferable to ordinary cement mortar. Now let’s look at what awaits us if we choose to install a floor screed with expanded clay.

The main advantages of screed with expanded clay:

The screed is resistant to temperature fluctuations and sudden changes;
Can be used in absolutely any room;
Any of the expanded clay fractions is not capable of rotting or flaming;
It becomes possible to level out any unevenness and defects;
Simplicity of installation work.

Reality and experience suggest that the advantages are good, but you also need to remember about the existing disadvantages that arise when the work is performed incorrectly:

The possibility of cracks appearing if any of the points in the technological process were performed incorrectly;
After a dry screed, the destructive effects of moisture on the sheet material can be felt.

During the production process, you can obtain expanded clay of different fractions, which will determine its purpose and features. Based on the size of the fractional size and the presence of elements with sharp corners, the following types of expanded clay are distinguished:

Expanded clay sand, each component particle of which is no more than 5 mm, is obtained by sifting after firing fine clay;
Gravel, which contains round and oval particles up to 40 mm in size;
Crushed stone containing angular particles with a diameter of up to 40 mm.

The choice of different fractions depends on the conditions in which the screed with expanded clay will be made, and sometimes also on the preferred type of flooring. If the weight needs to be minimized, then any fractions except sand are purchased. But if you plan to install piece parquet, then it’s clear that fine-grained expanded clay will be relevant.

The most the best option is to use expanded clay with particles of different sizes, because in this way you can prevent its shrinkage in the future. This screed will not deform, crack or disappear. Use reinforcing mesh; a mounted screed with expanded clay will be even more reliable.

Calculation of expanded clay for screed

To make a screed with expanded clay, you need to correctly calculate how much it will be needed for the work. In stores, expanded clay can be sold in liters or m³. Calculation is carried out according to standard scheme: to get a 1 cm layer of expanded clay, you need 0.01 m³ (or 10 l) per square meter of a given area. When purchasing, you should always take into account the deviation rate in the calculations, since in practice the situation may be different. For example, the surface in the room may have a slight slope, or when installing beacons, the profile may rise higher. All this leads to increased consumption of expanded clay.

Required materials and tools

In the process of screeding the floor with expanded clay, we will need following materials: waterproofing film, damper tape, expanded clay directly, gypsum fiber board floor elements, self-tapping screws, also for their installation you can’t do without glue, a professional set of guides and rules, adhesive tape, level, trowel, shovel, spatula, screwdriver, knife, cutting tools sheet materials.

As for the tape and film, they are used exactly the same as with a regular screed. When choosing an expanded clay composition, you should focus on ready-made mixtures, which are abundant in the modern construction market. The most popular and popular are Knauf and Kompevit. If you choose sheet materials, then the most practical are considered to be elements made of two layers based on gypsum fiber board, which can be ordinary and waterproof.

Expanded clay screed needs preparatory work. Waterproofing the surface will help prevent water from flowing down. Don't neglect initial stage waterproofing devices in preparatory activities. This task can be accomplished using thick polyethylene film, or hydrosol.

Apply the film with an overlap of about 40 cm and glue it with tape at the joints so that there is no ingress of dust or solutions. We advise you to use coating waterproofing, but in this case costs will increase.

Your floor screed with expanded clay will not crack; if you use a damper tape, which will separate all layers from the wall and structures, it is attached around the entire perimeter. Next, the premises are marked and prepared for the installation of beacons. They are placed in slides of cement mortar, with the first one being installed slightly away from the wall, and the subsequent ones parallel to the first one, their distance should not exceed the length of the rule. After installing the beacons, they are leveled using a level and left to dry.

Expanded clay screed - design options

Expanded clay screed is performed using several technologies:

The expanded clay layer is laid, compacted and leveled; its surface should not reach the level marked by the beacons. After this, the entire area is filled with cement “military”, which reliably fixes the expanded clay granules. After hardening, fill with cement-sand mortar.

In the second method, expanded clay is mixed with mortar. Spread the expanded clay mixture onto the surface and level it using the rule. For ease of application, the floor is divided into areas, which are processed one by one. If after leveling holes have formed, cement is added there.

You should start installing the screed with expanded clay from one of the walls and go to the doorway. By using proven expanded clay insulation, you can quickly and easily level floors, improve their characteristics, ensure their durability and trouble-free operation in the future.

Floor screed can be done using various materials. It all depends on the purpose, as well as the desired result. Under certain circumstances, a semi-dry floor screed can be installed under a “warm floor” or under any floor covering. Cases of installing a “sub-floor” on expanded clay, which is famous for its main advantages, are not uncommon. In addition, it is important to follow the technology itself so that there are no negative consequences.

Pros and cons of expanded clay

As for beacons, their number will, first of all, depend on the rule used and its length. With its length of one and a half meters, the above premises will require about five beacons over the entire area. The length of such beacons is selected over the entire width of the room - three meters.

The choice of expanded clay itself is focused on granules, or rather their fraction. To calculate everything correctly and independently, just open the calculation calculator, which can be found on the Internet. In this case, it would be a good idea to turn to familiar builders for help. They will tell you the exact amount of material that should be purchased. It is worth noting that the materials for underfloor heating screed do not differ in quantity.

Preparatory activities

The same preparation is performed for both conventional screeding and semi-dry screeding. That is, it makes no difference whether the floor screed is dry or semi-dry; it will be necessary for flooring flooring. It is very important here to level the foundations where the work will be carried out. All existing cracks and pits are eliminated, if possible, using cement mortar. Bulges may be knocked off. We must not forget about the waterproofing layer, which can be ordinary polyethylene film. How better material will be selected best qualities it will be able to manifest itself during operation.

After this, sand is poured in, acting as a cushion under the expanded clay. Usually its layer is 20-30 mm. The pillow must also be leveled using the rule. As for compacting sand, it will be sufficient to simply walk along the entire plane. In this case, the weight of a person is enough.

The choice of expanded clay is made depending on the fraction (fine, medium and large fraction). It is poured throughout the room, starting from the far corner. After filling the required layer, it should be leveled. Beacons are installed along the top of the expanded clay, serving as the basis for the subfloor level.

Profiles are used as beacons, which are mounted on the base using cement-sand mortar. Subsequently, the screed is poured, slightly overlapping the beacons, and they simply “hide” in the base of the subfloor.

Performing a semi-dry screed

When the expanded clay is poured, you can choose two options for further actions:

Not everyone knows how to make cement laitance. For this purpose, twice as much water is used as with the standard screed design. Depending on the result obtained, you should see whether it is necessary to add additional water or cement. In this form, after pouring the expanded clay, it is necessary to let the layer sit and dry for at least a day. Only after this can the semi-dry concrete floor screed be poured.

If the beacons are removable, then they are pulled out only after a few days. The resulting grooves are sealed with mortar, carefully compacted and sanded until a uniform layer is obtained.

Expanded clay with mortar

There is also an option for making a semi-dry screed, when the solution itself is mixed with expanded clay granules. This process takes much less time than in the previous case.

Expanded clay is poured into a container that is prepared in advance, which is filled with water. required quantity. Mixing is carried out using a mixer. The prepared dry mixture is poured into this, which must be thoroughly mixed until a homogeneous mass is obtained. You should be very careful with the amount of water. After all, it requires a small amount. Too much will lead to the manifestation of negative qualities.

There should be no lumps when stirring, and the granules themselves should become wet and acquire a gray tint. The mixture becomes slightly thick, with a consistency reminiscent of sour cream.

The finished solution is poured onto the prepared base to a thickness of 20-25 mm. But the thickness will depend on the evenness of the floor, as well as on the final result, which is necessary for laying the flooring. The reduction in time occurs because there is no need to wait a day for the first layer filled with cement laitance to dry and harden.

After the initial layer of the “pie”, the second and subsequent ones are performed until the “rough” floor is formed. During the work, we do not wait for the previous layers to dry. The finishing layer is not only carefully compacted, but also leveled.

Screeding a floor using a semi-dry method requires certain knowledge and experience in performing the work. Even small nuances will allow you to avoid possible problems in the future during operation. Some of them:

When placing wires on the floor, under the future screed, they should at least be wrapped in polyethylene and also attached to the base of the floor with tape.
To avoid cracks in the poured concrete solution, it is best to add a plasticizer to it. It will be enough only for the finishing layer of semi-dry screed.
Not only polyethylene film can serve as floor waterproofing, but also bitumen mastic, waterproofing, etc.
After pouring the screed, you should: The main activity is periodic wetting using a spray bottle.
The drying time of the screed is about a month. The longer it stands without external pressure, the more strength it can gain in the end. Much will depend on the flooring used.
Beacons can be metal slats or special profiles called “beacons”.

Compliance with the screed technology, no matter what it is, will allow you to obtain a flat surface of the subfloor, onto which you can immediately lay the flooring.

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