Forming screeds on a floor base is, as many believe, a simple matter. What they are very wrong about. Like any construction process, this requires certain knowledge and experience in carrying out this type of work. Therefore, in this article we will understand the question of how to make a floor screed with your own hands step by step.
Let's start with this question, because the screed performs several functions. Firstly, the layer of screed mortar is intermediate, that is, it is located between the base of the floor and the finishing coating. Further:
In some rooms, for example, in garages, screed is the finishing coating. This is where it is laid in one layer. But more often it is a two-layer coating:
Self-leveling floor screed Source tirichiamo.it
Before making floor screeds, you need to understand their varieties. And the separation is carried out whenever possible, the screeds are attached to the bottom layer. The latter is a reinforced concrete floor slab, wooden floors, and compacted soil. And more about the types:
Another classification based on a survey on how to fill a screed. There are also four positions:
And one more point that is included in the classification section. All screed mortars are divided into two types, which are based on two binding materials: cement and gypsum. There are other varieties, for example, bitumen or magnesium, but they are not used in residential construction.
Cement screeds have high strength, easily withstand the negative effects of water, and have a long service life. Cons - long drying process, during which they shrink.
Gypsum is not inferior to cement in strength and durability. When dry, they do not shrink, but they are afraid of water. But, as practice shows, both builders and home craftsmen give their preference to cement. They are easier to work with and have high strength, which is very important for floor structures.
So, having understood the concept of what a screed layer is, and also having examined its varieties, we move directly to the question of how to make a floor screed with your own hands. The whole process is divided into four main stages:
The complexity of the preparatory process depends on what kind of foundation needs to be prepared. For example, soil:
If the base is a reinforced concrete floor slab, then:
If the floor is wooden. This is a rare situation, because it is easier and cheaper to level wooden floors with plywood, chipboard or OSB. But if the need arises, then:
Sometimes there are situations when there is already an old screed on the floor. Experts advise that regardless of its quality condition, it is better to dismantle the old screed layer.
Before pouring the floor screed, the dowels are placed. For a garage, the use of beacons is not necessary, but for residential premises where finishing will be applied, this is a necessary step. The thing is that deviations of the floor plane from the horizon in the amount of 3 mm per 1 m of length are not noticeable within the same room. And this is the norm. But on the scale of a whole house, this can grow into several centimeters, which is no longer acceptable.
That is, if you are faced with the task of how to properly make a floor screed in a private house or apartment, then you need to fill it taking into account the evenness not only in each room separately, but taking into account the evenness of the entire area of the house. It is clear that if the floors in all rooms are leveled.
How to do it exactly right. This will require laser level, he is also a plane builder, which today has ceased to be a luxury. It is installed on a tripod so that the laser beam hits all or most of the rooms. At the required level, notes are made on the walls with a marker and marked with a laser. Then the device is brought into each room, where it is placed according to the already applied marks. A perimeter of rays is formed on the walls along which the screed will have to be poured. To avoid using the laser level later, the applied beams are used to mark lines on the walls, which are called basic lines.
Now, as for the lighthouses. There are a huge number of applications of this technology, the end result of which is always one hundred percent. In this article we will consider one of the simplest options.
To do this, you will have to purchase a PM-10 brand beacon profile, which is used for applying plaster, but is also successfully used for pouring screed. The lighthouse is made of galvanized steel and has a durable structure.
How to install beacons:
In fact, this method of placing beacons has several subtle points that affect the quality of the final result.
How necessary is a reinforced frame, because this structure inside the screed layer does not increase it bearing capacity. The main task of the frame is to increase the tensile strength of the screed. That is, so that it does not crack during operation. The only option when reinforcement is not required is if a fastening type is used to level the floor base.
In all other cases, the reinforced frame is a necessary element of the screed. Namely:
As for the reinforcing frame itself, it is a mesh made of wire or reinforcement. The latter are used in rooms where heavy loads will be applied to the floor. For example, in garages.
Today, nets are a huge assortment. For ties, products made from 2.5-6 mm wire, grade VR-1, are used. Grids can have square or rectangular shape with side dimensions of 50-200 mm.
Attention! The thicker the wire and smaller size cells, the greater the load the reinforced frame will withstand. It is recommended to choose meshes with notches on the wires.
And one more point regarding the location of the reinforcing frame. If the screed is thin (up to 5 cm), then the mesh product is laid so that it is in the middle of the screed layer in thickness. If the screed is thick, then the mesh is placed in the lower third of the layer.
As for laying the reinforcing frame, previously they used pieces of broken bricks or concrete, broken glass and other solid materials. Today, special plastic clamps are used for this. They are presented on the market in a huge range of sizes and shapes. So choosing the required type for the mounting height and wire diameter is not difficult.
Plastic stands for reinforcing frame Source dompodrobno.ru
And one moment. You cannot lay the reinforced frame on the floor and then attach heated floor pipes to it. We must do everything the other way around. That is, the pipes were laid on the floor, secured to it, then a reinforcing mesh was laid on top of the clamps. And only then the screed is poured.
The video shows an alternative way to raise the reinforced frame above the base floor:
This building material is often used today to form screeds. It is laid without constructing a reinforcing frame, because elements have already been added inside it, which provide strength, impact resistance, and cracking resistance. This is a regular screed mixture containing fibers from different materials. Eg:
steel fiber is pieces of wire with a diameter of 0.2-1.2 m and a length of up to 6 cm;
In the video, a specialist talks about what fiber-reinforced concrete is:
The next stage on the topic of how to make a floor screed with your own hands in a private house or apartment is mixing the screed mortar. Until recently, it was made from individual ingredients, which were also purchased separately. Today everything has been simplified, that is, you can purchase a ready-made dry mixture, dilute it with water to a homogeneous consistency and start pouring. The whole process is described on the packaging.
Self-preparation is sometimes also used if it is necessary to pour a thick concrete screed over the ground. For this, a classic mixture recipe is used, which includes:
Do not mix the solution with shovels. This is no longer modern, and the quality of such a solution may not meet the requirements. The best option– mixing in a concrete mixer with the addition of plasticizers, which increase the strength of the solution by 20-40% and frost resistance by 50%.
The video shows how to mix a floor screed solution with your own hands:
So, let's move on to the main question of the article - how to properly make a floor screed. This stage takes the least time when compared to preparation. The process itself is not that complicated, although there are subtleties:
The process must be continuous and start from the far corner, moving towards front door. If the screed is laid in two layers, the first one should give maximum evenness without gloss. It forms after applying the second layer.
If pouring is carried out on a heated floor heating system, then several nuances must be taken into account:
The video shows how to make a screed on a heated floor:
Briefly about how to properly make a dry screed:
Today this technology is often used, but instead of GVL, our domestic craftsmen give their preference to OSB boards, moisture-resistant plywood or chipboard, as well as thin asbestos-cement boards.
The video shows how to construct a dry screed from the Knauf company:
You know what you should know House master, who decided to make a floor screed with his own hands. The poured layer should last as long as the house itself. Or until the next renovation, at least. Because repairing screeds is not easy and very expensive. Therefore, perhaps it is worth shifting this simple process onto the shoulders of the masters.
One of the ways to prepare the surface for laying flooring materials is to level it with a screed. Now there are several technologies, using which you can create a full-fledged platform that meets the requirements. How to make a floor screed in an apartment in different ways? The answers to this question will be the topic of this article. As a result, you can choose the right technology, which seems better, and make a base for laying floor materials with your own hands. The attached video materials will certainly help you understand the order of work and the nuances of each method.
Until recently, screed was done only using liquid solutions such as concrete or cement-sand mixture. Now the list of materials used, as well as the technologies for their use, has expanded significantly. Depending on the tasks, today you can use the following methods for constructing a floor subfloor:
Each of these methods can be applied in an apartment, regardless of whether it is located in panel house or monolithic. However, each technology has its own advantages, and some methods have disadvantages. The screeding methods also differ in cost, which is determined by the prices of the materials used or components used to prepare the mixture. So it makes sense to study each method in detail in order to draw a conclusion about which one is better in a particular situation.
Materials for wet work when installing screeds are the most diverse, so it makes sense to classify them correctly. The following types of liquid mixtures are used to level the surface:
Each of these materials has its own operational features and priority areas of application, including when installing screeds in an apartment. To find out which one is better for properly pouring the subfloor in a particular situation, you need to consider their pros and cons.
This material is indispensable when pouring rough screeds, which are the basis for overlying floor structures. It is difficult to create clean concrete surfaces with your own hands without proper experience, since the material necessarily contains a large fraction, which prevents thorough leveling. For the initial formation of the base, concrete is best suited for the following reasons:
For finished surfaces, concrete is less preferable when compared with other materials. Here are its shortcomings:
These disadvantages of concrete became the reason that it was replaced by more practical materials, which we will consider further.
This is, in fact, the same concrete without crushed stone. Liquid cement-sand mixtures are used to construct inexpensive screeds of relatively small thickness. This material is somewhat more expensive than concrete, since the absence of a large fraction in the composition has to be compensated for by a higher cement content. Liquid cement-sand mortar for pouring the base of the floor is used infrequently, as it has almost the same disadvantages as concrete, while having much less strength.
Important! To prepare a cement-sand mixture, you need to use only washed or river sand. Sandy filler of quarry origin contains a lot of clay, which significantly reduces the strength of the screed and makes cracking and rapid destruction of the poured structure inevitable.
The cost of such materials, when compared with concrete (in terms of m2 of finished screed of a certain thickness), is much higher. Therefore, it is not advisable to use packaged mixtures for rough filling. For the construction of a base of small thickness (1.5-5 cm), such materials are better suited. The disadvantages of ready-made polymer-cement mixtures end at a higher price, followed by advantages, such as:
Thanks to these advantages, ready-made mixtures are much better for use in apartments, either panel or monolithic houses. It is convenient to use such solutions to fill the screed with your own hands on the balcony or in the bathroom under laying tiles. Although polymer-cement mixtures are increasingly used when pouring large areas when the leveling layer is small. To make sure that working with your own hands with such mixtures is not very difficult, watch this video below, which demonstrates the entire working process.
The idea of replacing concrete with a lighter filler was born a long time ago and was embodied in expanded clay concrete, where crushed stone was replaced with porous expanded clay granules. This material is used to create lightweight subfloors. Expanded clay concrete is not suitable for finishing screeds, since large granules do not make it possible to create a flat, smooth surface.
Relatively recently, they began to use an even lighter modification - polystyrene concrete. In this solution, the role of filler is played by foam granules, which come in different sizes. If you use a fraction of up to 5 mm, you can sufficiently level the surface with your own hands, for example, for laying tiles. The undoubted advantage of polystyrene concrete is that when pouring it, two goals are guaranteed to be achieved:
The cost of polystyrene concrete depends on the price of the filler. Large granules are cheaper, small granules are more expensive. Most inexpensive option, - expanded polystyrene crumbs obtained by grinding waste foam.
This technology has been used relatively recently, but has become widespread. The peculiarity of the material is the limited content of water, which is added to the mixture as much as is enough to wet the cement, in addition to which the composition includes sand as a filler and a plasticizer. The role of the latter is to make the material more plastic and enhance the ability of water to wet other components by reducing its surface tension. Sometimes fibrous substances are added to the composition, which significantly increase the strength of the subfloor.
The semi-dry, crumbly consistency of the mixture requires a slightly different approach to working with it yourself. Briefly described, the screed formation process looks like this. The prepared mixture is poured into the spaces between the beacons in a layer exceeding the required level, after which it is thoroughly compacted in any way. If necessary, add more and compact again. When the layer of already compacted material exceeds the level of the beacons, the excess is removed by the rule. Surface errors (depressions) are immediately corrected by adding the mixture and smoothing with a wide plaster float. You can watch this process in the following video.
There are many advantages to the method of installing a subfloor using semi-dry mixtures, the main ones are:
So today the dry mixture and the corresponding technology are one of best options in terms of price/quality ratio.
Important! When forming thick (8 cm or more) layers of screed with a semi-dry mixture, there should be several bedding/tamping cycles. That is, you should not pour everything in at once and try to compact it. The correct way to do this in such a situation is in layers.
This way of creating flat surface The floor base was developed by Knauf specialists. Now similar materials are produced by other manufacturers. This method is radically different from the established idea of screed design. The structure of such a floor base is two-layer: at the bottom there is a leveled cushion made of fine expanded clay, at the top there are gypsum fiber boards securely fastened together with glue and self-tapping screws.
To make your floor serve you a large number of years old, and looked perfectly level, before you start laying floor tiles, you should first do preparatory work and level the floor surface. Now let’s try to consider how to competently approach solving this problem. Let's learn how to screed a floor indoors together with the portal.
If you don’t know how to make a floor screed with your own hands, then you should watch the video below. Before we start talking about this process, we need to talk about what a floor screed is.
So, floor screed can be done using all kinds of materials and using various techniques. Exist the following types screed:
Concrete screed. This type screeds are one of the most common. This screed is used mainly for the initial leveling of the surface of the floor. If the surface has a large number of differences, then this method can be called the most suitable. The mixture fillers for this leveling method are usually sand and cement. But to complete this work you will need to spend a lot of time and effort.
Self-leveling screed It is performed mainly from already prepared mixtures. The leveling layer is approximately 3 cm thick. It is used at the end of the work to level out various differences in the floor surface. This method Suitable for almost all types of existing floor coverings.
Dry screed It is mainly produced if you need to level a floor that has very large uneven surfaces ranging from 4 to 11 cm in height. There are two options for making this type of screed.
A) Alignment by lags. Materials used are plywood, chipboard or various other types of sheet materials.
B) Leveling using gypsum fiber sheets. For this type of screeds are often used German materials KNAUF company. For the right choice material needed to level the floor, you need to know what the general condition of the floor surface is and what type of floor covering you will use when completing all the work.
In order to carry out complex repairs to your floor, in any case, you should screed its surface. Now let’s try to find out what functions this screed has.
To perform its functions to the maximum, the screed must meet all necessary requirements and standards. Namely:
The amount of work that, as a rule, must be done before laying the screed depends mainly on its type and on the condition of the floor surface. However, you will still need to do the following:
In this article we are talking about what a do-it-yourself floor screed should look like in an apartment. In addition to our tips, there is a video in this article that will also help you see this.
Correct execution of floor screed depends on compliance with all standards provided for this work. You should know what composition of the mixture should be used, as well as how to properly knead it and install it. The order of your further actions will depend on what type of screed you have chosen.
Carrying out work on laying concrete screed.
Leveling the floor using this method is very popular and quite common, despite the fact that this work is quite complex and time-consuming. First of all, it is necessary to make complete liberation from objects of the entire floor surface: remove furniture, various interior items, etc. from the room. Then they begin to remove the old covering from the floor, while painstakingly examining its base. The composition of a concrete screed usually includes the following components: sand, cement and other fillers. To complete this work you will need:
Most hardware stores sell already prepared mixtures of sand and cement for making concrete mortar. As a rule, all these elements are already present in them. But if you do not want to spend money, then it is quite possible to make this solution yourself, if you have all the necessary ingredients in the required proportions.
Basically, in order to make a screed, you should take three parts of sand to one part of cement. And plasticizers will help the mixture become more elastic, and it will not harden quickly enough, which will prevent chips and cracks from appearing on it. If you need to level the floor with large differences (more than 6 cm), then you should add fiber, which has reinforcing properties, to this mixture, or use a metal mesh for laying.
Pay attention to the article on the site: How to glaze a balcony with your own hands
Screeding the floor surface in a room using concrete mortar should be done in the following sequence:
You should also ensure that the room is completely protected from drafts and sun. Depending on what mixture was used to fill the floor, the first steps on it can only be taken after 4 days. Using a building level, you need to once again carefully check the floor surface to see if it is level, or if there are small irregularities somewhere that, immediately after detection, will need to be smoothed out with a special device. You must always remember that the time for complete hardening of a concrete screed is 25-30 days. Only after the end of the specified period can you begin laying the flooring or laying thermal insulation. An exceptional option in this case is laying ceramic tiles. This work can be carried out within 6 days after screeding.
Laying a self-leveling screed
This screed is used mainly to obtain a perfectly flat floor surface. In this case, we mean finishing installation linoleum, laminite, or any polymer coatings. The majority of construction stores sell a variety of self-leveling mixtures, the preparation of which is carried out at home according to the instructions attached to them. These works must be carried out in the following order. All debris and dirt should be removed from the entire floor surface. This work must be done with special care, since the small debris that may remain after cleaning may float to the surface of the poured layer.
According to the instructions, you need to start preparing the solution. When making it, to avoid the appearance of lumps, the mixture should be added to the liquid, but not vice versa. A mixer will help you mix the mixture thoroughly. The resulting solution should look like a creamy mass. It is saturated with oxygen and left for 10 minutes.
Filling is usually done starting from the farthest corner of the room to the corner of the door along its entire wall.
Thanks to the use of a metal brush and a needle-shaped roller, the solution is leveled and its thickness is leveled. Based on this, the floor surface dries quickly enough, unlike concrete. You can take your first steps on the floor after 9-10 hours. These terms may depend on the internal climate in the room and the thickness of the resulting layer. After pouring the floor, it must be protected from sun rays and draft, as well as water ingress on its surface.
If you try to follow all of the above recommendations, you will end up with a very hard surface that will not absorb any moisture in the future.
Dry screed
If you don’t know what a floor screed looks like with your own hands, then the instructions will help you see the whole process of work. To level the floor, you can use a dry screed. Dry screed is one of the latest technologies when carrying out these works. It has 2 layers:
The sheets are connected to each other with glue or self-tapping screws. And the resulting gaps are covered with putty. Next, they are polished. Such a screed will have excellent heat and sound insulation properties, and the floor surface will be more even.
Results
In this article, we tried to tell you how to properly screed a floor indoors. As we found out, this work can be done independently, despite all the difficulties of the process. We would like to give you one more small recommendation: Try to carry out all work processes in compliance with technology and use only high-quality materials that have passed the necessary certification.
From the author: Hi all! Have you ever seen what a bare concrete slab looks like in an apartment? The spectacle is not for the faint of heart, let me tell you. In general, I became interested in how to do a floor screed with your own hands in an apartment when I was planning to replace the linoleum in the kitchen with tiles. She washes well, and somehow it’s more fun to be with her. When I removed the old linoleum, I discovered that my floor was uneven to the point of tears. I decided to make a screed and then lay the tiles. I'll tell you how I did it.
So, the screed is a crucial moment of repair. It is necessary to obtain a smooth surface that will last a long time and will remove existing cracks and chips. Having done this, you can then lay linoleum, lay laminate or parquet, or tiling the floor.
Defects can be eliminated (floor leveling) using various building materials. It is important to consider that the method of carrying out the work depends on the choice made. The following types of screeds are distinguished:
The classic one, used in most cases, is concrete. It is used for initial stage eliminating irregularities. The mixture contains cement, sand and special fillers that provide elasticity. I would like to note that it is difficult to carry out such a screed on your own.
A dry screed is necessary if there are large differences in height (3–12 cm). Performed by various technologies, among which:
Self-leveling - made from ready-made mixtures. Most often used as a finishing surface (final layer), it effectively removes unevenness and height differences.
It is very important to remember the need to prepare the surface for leveling. This stage requires a responsible approach, since the quality of the entire work depends on it. For getting good result You will need to perform several steps:
The choice of type and method for eliminating deficiencies depends on financial capabilities. Features of the event preparatory work You can watch the video with your own hands:
High-quality apartment renovations, in particular screeding, are carried out using ready-made mixtures. Let's consider this point in more detail.
Concrete leveling is considered one of the most reliable methods for eliminating defects, and with its help you can pour a high-quality screed. After execution preparatory stage, installation begins directly. To do this you will need the following tools:
Using a building level, the surface to be treated with the composition is measured. At this stage, it will be possible to identify all the shortcomings that exist in the room - curvature, chips, cracks, height differences. Afterwards the surface is thoroughly cleaned.
It is important to note that sometimes there is a need for pre-installation waterproofing material(relevant private houses and apartments located on the first or ground floors). A reliable screed is performed using beacons, as they allow you to achieve a perfectly flat surface; and the best way to do the main work depends on the budget, so to save money they choose a concrete mixture.
The next stage is priming the surface. To do this, you need to prepare a solution from a dry mixture. It should be applied immediately because the primer hardens quickly. The rule allows you to easily and quickly level the layer. An important point: in one room, all work must be completed within 24 hours. Sometimes, to achieve better adhesion, mesh or reinforcement is used (lay before pouring the screed).
After pouring, the surface should be covered with ordinary film and para-insulating material (the use of wet rags is allowed). Leave the coating until the moisture from the composition has completely evaporated and the leveling material has hardened (this will take from 2 to 4 days, depending on the characteristics and properties of the mixture used). You can speed up the drying process by ventilating the room and doing work in sunny and hot weather.
After drying, you need to check the evenness using a building level. If the need arises, the bumps are cut off and rubbed down. The final stage is the application of the finishing layer, which is carried out no earlier than after 28 days. This period is necessary for the material used to dry completely. Also, until this moment, the installation of a “warm floor” cannot be carried out.
Can be used as a floor covering to speed up work ceramic tiles(and I’m a fan of it, as you understand), since it can be laid directly on the screed in 5-6 days. The screed suitable for leveling is selected depending on the characteristics of the room, so which one is best for the apartment is decided by its owner.
In general, work from start to finish may require a significant amount of time, but any person can carry it out independently, even without sufficient experience in matters of construction and finishing.
I hope it is now clearer in your head how to do this work with your own hands. If you still have questions, subscribe to our groups on social networks and improve your knowledge in repair and construction. See you again!
In order to properly make a floor screed based on cement mortars and concrete, the screed must correspond to the purpose of the room and have the necessary parameters for this.
The screed can become a solid foundation for the floor in any room of the house. Cement strainer is not afraid of moisture and is convenient to use as a base for flooring in wet areas, as well as outside the house - on the terraces, in the garage. The installation of heated floors in rooms is also not complete without a screed.
To install screeds, use a traditional cement-sand mortar of a grade not lower than M75. To prepare the solution, prepare a mixture of one part cement and three parts sand. The strength of the finished screed increases if the solution for laying the screed has a thick consistency.
Cement-sand mortar is easier to prepare and easier to lay in a screed than concrete. But the consumption of cement for constructing a screed of the required strength is greater than for concrete. That's why, A mortar screed is more expensive than a concrete screed.
Lime should not be added to the solution. Although lime increases the plasticity of the mortar, it reduces the strength of the screed.
Concrete of classes B10, B15, B20 is used for constructing screeds. Crushed stone and gravel are used as concrete filler. The size of the filler granules must be at least three times smaller than the thickness of the screed.
To prepare concrete for semi-dry screed, it is used significantly less water, than usual. A semi-dry screed has a higher compressive strength (up to 35 mPa) than screeds made from mortar and plastic concrete. In addition, it is less susceptible to shrinkage, which reduces the risk of cracks in the screed.
Semi-dry screed is suitable for installing heated floors. It is convenient to prepare concrete for semi-dry screed on a construction site in a special concrete mixer - mixocrete, which prepares the concrete and immediately supplies it with a pneumatic pump. flexible pipe to the installation site.
Cement mortars and concrete can be prepared at the construction site. It is recommended to include additives in their composition to increase plasticity, accelerate setting and reduce water permeability of the screed.
To obtain concrete of the required compressive strength class, It is recommended to use the following grades and quantities of cement:
During storage, cement loses its activity. The cement consumption indicated in the table is indicated for cement with a shelf life of no more than two months. The consumption of cement with a shelf life under normal conditions of more than 3 months is increased by 20%; more than 6 months - by 30-40%.
It is not recommended to use cement with a shelf life of more than 12 months.
When using old cement, the mixing time of the mixture is increased by 2-4 times. It is recommended to introduce additives that accelerate concrete hardening.
To prepare medium-strength concrete, use a mixture of 1 part (by volume) cement, 2.5 parts medium-sized sand and 4 parts aggregate - gravel or crushed stone.
The indicated ratio of mixture ingredients is approximate and depends on many factors. For example, the amount of sand in the mixture should be sufficient to fill all the spaces between the aggregate granules. For large granule sizes, the amount of sand is slightly increased, and for fine aggregate, on the contrary, it is reduced. Cement consumption is also adjusted depending on its brand, shelf life and required concrete strength (see table above).
The prepared cement mortar must have good plasticity and mobility. This solution is easier to level and compacts better. To increase plasticity, special additives are used - sulfite-yeast mash (SYB) in an amount of 0.15-0.25% by weight of cement; soap naft (M1) - 0.1-0.2% by weight of cement, and others. At home, craftsmen often add a small amount of grated laundry soap to a concrete mixer.
The mobility of the concrete mixture also depends on the ratio between sand and crushed stone. The best mobility is achieved with some optimal ratio, at which the thickness of the cement paste layer is maximum. When the sand content in the aggregate mixture exceeds this value, the concrete mixture becomes less mobile, which is explained by the increase in the surface area of the aggregate mixture.
To make the concrete mixture plastic, much more water is often added to concrete than necessary (40...70% by weight of cement). Concrete should not be made too liquid, adding a lot of water. A screed made from such concrete will take several months to dry and will have reduced strength and frost resistance. The risk of significant shrinkage and cracking of the screed increases.
Excess water that has not entered chemical reaction with cement, remains in the concrete in the form of water pores and capillaries or evaporates, leaving air pores. In both cases, the concrete will be weakened by the presence of pores and the more water, the more pores and thus the less strength and frost resistance of the concrete.
The best option, although more expensive, is to use ready-made dry mixtures for screeding. Such mixtures are commercially available at construction market. The mixture already includes the necessary additives.
Manufacturers can include microfiber in the mixture - fibers that serve as reinforcement. Microfiber screed is more resistant to shrinkage and cracking.
There are mixtures specifically designed for underfloor heating. This should be indicated on the packaging of the mixture.
There are quick-setting compounds. Floor tiles can be laid on a screed made from this mixture within 24 hours.
The packaging of the dry mixture should contain information about what screeds and installation conditions it is intended for, what compressive strength of the screed the use of the mixture will provide.
For residential premises, the compressive strength of the screed must be at least 12 mPa, for a garage - at least 20 mPa.
By design, screeds can be connected to the base on which they are laid, or laid on a separating layer, or floating.
Screeds connected to the base, are carried out if the base is also made of concrete. For example, a screed reinforced concrete slab ceilings or concrete floor preparation. To ensure adhesion of the screed to the base, the surface of the latter is specially prepared - dust-free and primed. The minimum thickness of the screed is 2.5 cm.
In screeds on the separating layer between concrete base(reinforced concrete slab or concrete preparation) and a layer is laid with a screed waterproofing film thickness of at least 0.2 mm. The edges of the film panels are laid with an overlap of at least 10 cm and sealed with adhesive tape. The edges of the film are wrapped on the walls.
The film separating layer prevents water leakage from freshly laid concrete. Dewatering of concrete reduces the strength of the screed. The screed concrete must be laid on a separating layer of film in all cases where water leakage from the concrete into the base of the screed is possible.
The minimum thickness of the screed on the separating layer is 3.5 cm.
Floating screed laid on a layer of insulation or sound insulation, for example, when installing or Minimum screed thickness 4.5 cm. subject to reinforcement. Floating screed with a thickness of more than 7-8 cm. it is allowed not to reinforce.
The screed is laid at a base and air temperature above +5 degrees C. The technology for laying screed does not change depending on whether cement-sand mortar or concrete, including semi-dry consistency, is used for laying.
The work is performed in the following sequence.
Prepare the base on which the screed will be laid. For a screed connected to the base, the surface of the base is cleaned of debris, dusted with a vacuum cleaner and primed.
To install a screed on a separating layer and a floating one, a layer of sound and heat insulation is laid, and a separating layer of waterproofing film is laid on top.
On walls and others vertical structures glue strips of polystyrene foam or edge tape made of polyurethane foam with a thickness of 1-2 cm. to create an expansion joint.
Guide rails - beacons - are laid on cakes of quickly setting cement mortar. Beacons are laid over the entire surface of the base in parallel rows with a pitch of approximately 1.5 m. and at a distance of 20 cm from the walls. They are used as beacons wooden slats or various metal profiles, pipes.
Special galvanized steel profiles for installing beacons are available for sale. Profiles are convenient because they do not need to be removed from the screed layer. But such profiles have little mechanical strength, increased flexibility and require careful alignment when installing on flats and accuracy when pouring concrete.
The upper surface of the beacons is leveled in one plane. If necessary, provide the required plane slope.
The solution prepared in a concrete mixer is supplied to the work site, and moving towards the door, it is evenly distributed between the beacons so that the thickness of the solution is slightly higher than the level of the beacons.
Using a grater, the solution is pre-distributed between the beacons and compacted. Finally, the solution is leveled with wooden or metal strip– as a rule, moving it along the beacons in a zigzag motion toward you. If shells remain behind the lath in the screed, they are filled with mortar and leveled again using the rule.
After the solution begins to harden and can support the weight of the worker, the beacons are removed from the screed. This is done in a timely manner, until the solution has completely set, and carefully so as not to damage the screed. If a semi-dry screed is laid, then the beacons can be removed within 3-4 hours.
The gaps in the screed left after removing the beacons are filled with mortar and smoothed with a grater, making circular movements.
Until the mortar has completely hardened, furrows are made in certain places on the screed, cutting through the mortar with a spatula to the required depth. After the solution has set, such grooves will have to be cut with a power tool with a diamond blade.
A wall expansion joint separates the screed from walls and other vertical structural elements buildings - columns, staircase supports, etc. The seam is necessary in order to eliminate the mutual transfer of stresses between the screed and the structures of the house. Stresses can arise as a result of thermal expansion of materials or their shrinkage, as well as as a result of deformations under the influence of loads.
In addition, the seam improves the sound insulation of rooms, making it difficult to transmit sounds from the walls to the floor structures and back.
To create a seam along the walls and other elements of the building, an elastic tape with a thickness of 1 cm. to the full height of the screed.
When placing heated floor pipes in a screed An expansion joint across the entire thickness of the screed is used to separate adjacent fields of underfloor heating pipes.
In addition to the expansion joint near the walls, cuts are made in the screed, which divide the screed into smaller rectangular sections. One side of the plot should be no more than 3-6 m. IN narrow corridors compensation cuts are made across the corridor, every 2-2.5 times the width of the corridor.
In addition, compensation cuts are made at the junction of different floor coverings, as well as at the boundary of changes in screed thickness, in door openings and in other openings at the boundary of different rooms of the house.
Compensation cuts are necessary to compensate for the shrinkage of the screed material during drying. Without them, cracking of the screed may occur. The cuts are made to a depth of 1/3 - 1/2 of the thickness of the screed. The width of the cuts depends on the thickness of the screed and the presence of heated floor pipes in the screed.
If the screed is reinforced with mesh, then the expansion cuts should be located above the joints of individual mesh sheets.
If the floor covering along the screed is tiles, then the compensation cut should coincide with the joint of the tiles.
Compensation cuts may remain empty if the flooring is parquet or laminate. The cuts are filled with waterproof silicone sealant if the floor covering is tile.
Must be reinforced thin ties thickness 4.5-5 cm on a separating film layer. Floating screeds, the base of which is a layer of insulation (sound insulation) or compacted soil, are reinforced with a screed thickness of 7-8 cm. and less.
If the screed has a thickness greater than that specified above, then the need for reinforcement is determined depending on the operational load. For example, a floor screed in a garage for passenger car or at open terrace on compacted soil it is recommended to reinforce with a screed thickness of up to 10 cm.
Screeds made from a ready-made dry mixture containing reinforcing microfiber fibers in many cases do not require additional reinforcement.
Typically, the screed is reinforced with a mesh of steel wire with a diameter of 3-4 mm. The mesh should have cells measuring 100x100 or 150x150 mm.
The steel mesh is laid on spacer pads so that it is approximately in the middle of the screed layer. The protective layer of concrete up to the mesh must be at least 2 cm. indoors, and at least 4 cm. when the concrete screed comes into contact with the ground.
On top of the mesh, as usual, beacons are placed on cakes of mortar and leveled.
When choosing the thickness of the screed, the strength of the base on which the screed is laid, the presence or absence of screed reinforcement and the operational load are taken into account. In addition, there are restrictions on minimum thickness different types of screeds (see sections of the article above).
In different rooms of the floor, the thickness of the screed, chosen for design reasons, may be different. For example, the thickness of the screed in rooms with warm floors should be such as to cover the heating tubes with a layer of at least 3 cm.
It is convenient in the house to have floors located in all rooms of the floor on the same level. Only in rooms where water can be spilled on the floor - in a bathroom, toilet, it is recommended to make the floor level lower by 1 cm. than in neighboring rooms.
To make the floors in the rooms at the same level, it is necessary to take into account that the floor covering that is laid on the screed in the rooms may have different thicknesses. For example, the thickness of the porcelain tile flooring in the kitchen differs from the thickness of the parquet flooring in the living room.
In order to determine the level of the screed surface in the room, first mark the level of finishing floor covering on the floor. To do this, choose a room where the total thickness of the screed and floor covering is greatest. The level of the finished floor in this room is taken as the level of the finished floor of the floor.
Then, the selected level of the finished floor of the floor is transferred to other rooms. The screed level in the room should be lower by the thickness of the floor covering.
In floor rooms, the thickness of the screed, selected for structural reasons, is adjusted to the specified level. If possible, adjust the level of the base of the screed, for example, change the thickness of the heat and sound insulation under the screed. Choose the most economical option.
To determine surface levels when installing screeds in a house, it is convenient to use laser device- level gauge, or hydraulic level - a transparent tube filled with water. Application of slats with bubble level will not provide the required accuracy.
Laying the screed indoors is done in one step, without interruptions. When planning work, take into account that the traditional solution must be laid within two hours after preparation. The shelf life for mortars prepared from ready-mixes is indicated on their packaging.
The solution is placed a few centimeters outside the doorway, and then the excess is cut off along the border of the expansion joint.
The surface of the screed is smoothed over with a trowel 8-10 hours after laying, until the concrete has completely set. The semi-dry concrete screed laid using a concrete pump is rubbed down after 3-4 hours. Smoothing eliminates minor roughness on the surface. There is no need to grout the screed if tiles will be laid on the screed.
The screed should remain damp for a week after installation. At this time, the screed should not lose moisture, otherwise the strength of the screed will decrease. To prevent the screed from drying out, it is covered with plastic wrap or sprayed with water daily.
After seven days, the film is removed, the room is ventilated and the screed is left to dry. After another three to four weeks, tiles can be laid on the screed. Moisture-sensitive floor coverings are laid on the screed after four to six weeks, when the moisture content of the screed is less than 3%.
On reinforced concrete floor A floating floor with a concrete screed is installed between floors. The floor is called floating because the screed does not have a rigid connection with the structure of the house.
The floating screed is separated from the walls and ceiling by a layer of elastic mineral wool. This floor design provides sound insulation between rooms of the house, and also allows the screed to move with changes in temperature and humidity.
If the floor is dry, with a humidity of no more than 3%, and the lower room is heated, then soundproofing slabs can be laid directly on the floor concrete. Otherwise, a vapor-waterproofing film is laid between the ceiling and the sound insulation slabs.
How to choose a material for sound insulation -
A layer of sound insulation made of mineral wool slabs is covered on top with a construction polyethylene film. The sheets of film are placed on the walls to a height of about 20 cm. The film strips are overlapped. Overlap amount 20 cm.
The film prevents the penetration of cement laitance from the freshly laid mortar into the sound insulation layer and into the edge strip.
A reinforcing mesh of steel wire with a diameter of 3 - 4 is laid on the film. mm. with cells measuring 100 x 100 mm. or 150 x 150 mm.
The floor screed can accommodate heating pipes to radiators, as well as pipes with electrical wiring. The pipes are laid on top of the reinforcing mesh and secured to it with plastic clamps.
It is recommended to wear corrugated covers on heating pipes and wires. plastic pipe. In the covers, heating pipes will be able to move freely when the temperature changes. In addition, corrugated pipes protect communications laid in the screed from mechanical damage during pouring cement mixture.
To level the cement mortar in the screed, beacons made of pipes or other profiles are placed on the reinforcing mesh. Beacon pipes are laid in increments of about 1.5 m. and level it horizontally using a level. The position of the beacons determines the thickness of the screed. Recommended screed thickness for residential premises is no more than 6 cm.
A cement mixture is placed in the space between adjacent beacons. Moving along the beacons rule or edged board distribute the mixture and level the surface.
Eight to ten hours after installation, the surface of the screed is smoothed (rubbed). Grouting can be omitted if ceramic or stone tiles will be laid on the screed.
After the cement mixture has hardened, the parts of the edge strip and construction film protruding from the screed are cut off.
Watch the video, which shows in detail how to mark the level and thickness of screed in rooms.
If pipes will be laid in the screed, then it is better to use a ready-made dry mixture specially designed for this purpose to prepare the solution. The finished mixture for heated floors contains additives that increase the elasticity of the solution.
If the mixture is prepared independently, then an emulsion is added to the solution to increase elasticity. For example, home craftsmen add PVA glue at the rate of 2 l. by 1 m 3 solution.
The screed should cover the underfloor heating pipes with a layer thickness of at least 4–5 cm. Thus, the total thickness (taking into account the diameter of the tubes is 1.6 cm) will be – 6–8 cm.
Caring for the heated floor screed for the first three weeks is carried out in the same way as usual. Before laying on the screed finishing coating, the screed must be thoroughly dried. To do this, 21 days after laying the screed, turn on the heating and increase the temperature by 5 every day. °C until it reaches the limit - 24 °C.
This temperature should be maintained for 14 days, and then reduced daily by 5 °C. Consequently, heating of the screed lasts another 23–24 days, which should be taken into account when scheduling finishing work.
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