There are many reasons why a floor screed should be done indoors. This process is quite complex and requires special skills, especially in cases when the screed is performed over large areas. But in relatively small rooms, such as an apartment or a private house, you can handle all the work with your own hands.
It is enough to follow the technology exactly, having previously studied the detailed recommendations for beginners.
Features of the
The main purpose of the screed is to make the concrete base under the floor covering as even as possible. This is done for both aesthetic and practical reasons: furniture will not stagger on a flat surface, and decorative floors will last much longer and will not deform.
The screed is required in the following cases:
- On earthen ground in a private house, garage and other premises;
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For parquet, laminate, linoleum and other modern coatings, according to the laying technology, requiring an absolutely flat base layer surface;
- When it is necessary to make waterproofing or thermal insulation of the floor in the room, including when installing a system of warm water or electric floors.
The features of the laying technology and the choice of materials depend on many factors. It is necessary to take into account such characteristics of the premises as the condition of the old coating, the height of the ceilings, the floor and the presence of the basement. Based on these data, the required screed thickness is calculated and the necessary materials are selected.
Time-tested budget options - cement-sand or concrete mixtures, are laid on the ground in a private house and garage. They can also be used in an apartment on the ground floor.
For apartments on the second floor and above, it is better to fill the floor with more expensive, but light, self-leveling mixtures or dry screeds.
Three types of screeds are distinguished according to the method of laying:
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Dry or prefabricated screed … This is a structure made of durable building boards of plasterboard or plywood, covered with a waterproofing compound. The thickness of the slabs is 15-30 mm. Laying is done on a layer of dry polystyrene or expanded clay with sheets overlapping each other so that the joints are completely closed. The prefabricated method is the simplest and does not require drying before finishing. Possible only in rooms with low humidity. In cases where the coating is not even enough, it is poured with a liquid self-leveling mixture.
- Semi-dry screed is a concrete or cement-sand mixture with a minimum amount of water. The device of such a floor requires considerable experience and many special devices, so this method is mainly used by professionals.
Depending on the method of installation, the screed can be made either single-layer or multi-layer. A multi-layer screed is made from a rough concrete and a smooth finish layer. The roughing layer is used to correct large floor defects and to give the necessary rigidity to the structure. Its thickness should be at least 2 cm. The finishing layer, the thickness of which is from 3 to 15 mm, is needed so that the surface becomes perfectly flat and smooth.
There are also three screed methods according to the nature of the adhesion to the base:
- Tied or continuous screed. In this case, there is a direct adhesion of the material to the base coat. It is important to ensure good adhesion and uniformity of the screed.
This method can only be used on a dry base not lower than the second floor of the building.
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Screed on a separating layer … Such a layer can be waterproofing materials, in rare cases oiled paper. The base and screed layers are obtained independent of each other. According to the laying technology, the minimum layer is 30 mm, reinforcement may be required.
- Floating screed is carried out on materials intended for heat, hydro and sound insulation with allowances for walls of about 15 cm. Thus, the concrete layer and the floor itself are not connected to the base. The minimum layer thickness is 5 cm, reinforcement is required. It is laid on the first floors of residential and utility rooms on a concrete and soil base.
Floor coverings characteristics
The choice of decorative floor coverings on the modern market is quite wide and is limited only by the owner's imagination and the operational characteristics of the room. Under any of the coatings, the floor screed must be done correctly. And since the requirements for materials and evenness are different for them, it is necessary to carefully approach the choice of a leveling compound.
So, for laying parquet, laminate and bulk polymer floors, you need a perfectly smooth and horizontally flat surface. For the device of such a screed, self-leveling liquid mixtures are used. At the same time, for a polymer self-leveling floor self-leveling mixture should be based on the same polymers.
For laying linoleum, carpet or tiles in the bathroom, a flat concrete or cement-sand screed will be enough.
In new buildings, a floor screed may not be needed, but, unfortunately, this does not always happen. Well, if the apartment was bought with a rough finish, then you can make a minimal screed and proceed with further repairs. It is worse when the apartment is turnkey, and the quality of the finished coating leaves much to be desired. Then it must be redone, completely dismantling the low-quality layer.
In a private house, to save money, you can make a concrete or cement-sand screed. On earthen soil, it is imperative to make a concrete base on a multi-layer cushion of gravel, crushed stone, expanded clay and waterproofing materials. Lightweight mixtures may be needed only on the second and third floors.
The device of floors can be carried out on almost any surface, you just need to choose the right composition. The exception is wooden flooring. On such surfaces, the finished coating can quickly deform and crack, and the tree itself underneath it can rot. Of course, there are special blends, but they can be quite expensive. Therefore, if there is a possibility of dismantling to the concrete base or to the ground, then it is better to do just that.
If it is not possible to remove the wooden floor, then it must be very carefully prepared. To do this, it is necessary to replace all rotten and damaged elements, cycle the surface of the tree and cover with a special primer.
It is recommended to use a gypsum-based screed, but it is not suitable for rooms with high humidity.
Where to begin?
To complete the work in a short time, the premises, materials and tools are prepared. All communications are being laid, such as electrical wiring, water supply, sewerage and heating, and the entire room is being repaired. There are also requirements for the microclimate of the room: air temperature - within 5-25 ° С, humidity - 60%, without sudden changes. The absence of drafts is important and direct sunlight is not allowed.
The most difficult is the preparation of the subgrade. First of all, you need to remove the top layer of soil, the thickness of which can reach 40 cm. In cases where the distance from the soil to the screed leveling mark is more than 35-40 cm, a layer of sand of the required thickness is poured. After that, the entire surface is carefully compacted using a special vibration machine or a heavy log 1 meter long. A surface is considered sufficiently tamped if no shoe marks remain on it.
To calculate the materials that will be needed for screed on a concrete base, the highest point of the floor is determined. This is the mark required for the finished coating to be smooth. It is usually located in one of the corners or near one of the walls. It is defined as follows:
- From the threshold of the room vertically along the wall, you need to measure 1 meter and make a note with a pencil. Using a building or laser level on the wall, draw a straight horizontal line;
- Using a tape measure, measure from the drawn line to the floor for every 10-15 cm. The point, the distance to which will be the smallest, is the highest point of the floor;
- Mark the obtained measurements on the rail as much as the floor will rise;
- Using the same rail, mark the highest point of the floor around the entire perimeter of the walls and draw a reference line along them. Clean the wall from plaster 0.2-0.3 cm above the marks made.
Also, to calculate the height of the screed, you need to take into account that at the joints of different rooms after laying the flooring, there should be no floor level drops. The exceptions are the bathroom and toilet, where the level must be lower to avoid leakage in the event of unforeseen failures of water supply and sewerage pipes, and some design solutions. In this case, the thickness of the coatings is taken into account, and the difference is compensated for by the levels of the screed.
Materials (edit)
Depending on the characteristics of the room and the chosen floor covering, one or several possible variants of compositions for floor screed can be selected, to which additional materials may be needed:
- Concrete screed: cement grade M400 is used, with heavy loads on the floor - M500. Depending on the fillers, there are several recipes for preparing the mixture. The most common is 3 parts of sand to 1 part of cement, 2 liters of water are added to 10 kg of the resulting mixture. With the use of large inclusions, such as crushed stone, expanded clay or gravel - 1 part of cement, 4 parts of coarse filler, 2 parts of sand, 0.4 parts of water. For strength, polypropylene fiber is added to such mixtures at the rate of 50 g per 100 kg of the mixture. For plasticity, plasticizers are used, the required amount of which is indicated in the instructions.
The minimum layer of such a screed is 4-5 cm; it is recommended to lay a reinforcing mesh or reinforcement structure. Drying speed - about one month.
- Cement-sand screed: 1 part cement, 4 parts perlite, 2 parts sand, 13 parts water. The preparation of the mixture is done in several stages, the order of which must be followed exactly. You may also need to change the amount of water to achieve the desired consistency. Plasticizers can be added. A layer of such a floor is made from 2 cm, reinforcement is recommended only with a layer of 4 cm or more. Dries up within 3-7 days.
- Self-leveling mixtures sold ready-made and diluted with the required amount of water specified in the instructions. There are mixtures based on cement, gypsum or a combination of both, as well as using polymers. It is forbidden to use a gypsum-based screed in rooms with high humidity, since if the gypsum gets wet it acquires the consistency of a sticky dough. The thickness of the mixtures can be from 0.3 to 30 cm, which is indicated in the manufacturer's instructions, but given their high cost, it is advisable to make a layer of up to 3 cm. In this case, the thickness of the rough layer is 5-25 mm, and 1-2 is enough for the finishing surface. mm. Drying time - from 10 hours to 3 days, depending on the composition.
- Dry screed - These are large sheets of drywall or plywood, which are laid on a layer of bulk materials such as polystyrene or expanded clay. Further work on such a screed can be started immediately after its installation.
When working with any kind of screed, a primer and putty will be required. For concrete and cement-sand screeds, a universal primer or concrete contact is suitable. Suitable types of primers for self-leveling floors are indicated on the mix packaging.
The putty must be selected on a resin or adhesive base.
You will also need polyurethane foam to fill large gaps near the heating pipes. For laying the reinforcing layer, the easiest way is to use a special fine-mesh wire or plastic mesh. For floors with increased stress, a welded steel mesh or reinforcement structure is required, which is welded on site. To fix the reinforcing structure, you need to prepare special supports, which can be made of plastic, wire or metal. For 1 sq. m you need from 3 to 5 units of such clamps.
In cases where it is necessary to lay a layer of waterproofing materials, the choice is limited by the condition of the base and the chosen method of screed. In terms of composition, there are 4 types of waterproofing:
- Polymeric;
- Bituminous;
- Bituminous polymer;
- Mineral.
There are also differences in the way the material is laid:
- Roll or film. This is the most demanded method of waterproofing using polyethylene film or roofing material. Modern types of polymeric multilayer membranes are also distinguished by heat-insulating qualities. Such materials are used for laying on earthen ground and on the first floors of apartment buildings. Self-leveling mixtures and cement-sand screed less than 2 cm thick are not used for this type of waterproofing due to poor adhesion and the risk of surface deformation;
- Liquid. These are special formulations that differ in different degrees of viscosity and have water-repellent properties;
- Mastics and powder. The latter are friable compositions based on plasticizers and various binders, which are diluted with water according to the instructions immediately before use.
In some cases, materials with a heat-insulating effect are laid on top of the waterproofing layer. This is a mandatory procedure when installing a screed on the ground and for structures of underfloor heating systems. You can choose from the usual bulk materials such as perlite, expanded clay, crushed stone or coarse sand. Some people prefer heaters in the form of plates, which can be made of mineral wool, polyurethane foam or extruded expanded polystyrene - penoplex.
Tools
The list of necessary tools depends on the chosen method of screed device and some other factors:
- Sander … It will be needed for processing the concrete base before work. If the area of the room is small, a metal brush can be used instead at this stage. And it is imperative to grind the concrete screed with a grinder after it has completely solidified.
- Industrial or powerful household a vacuum cleaner.
- Lighthouses. It is possible to use a T-shaped aluminum profile, round or rectangular steel pipes up to 70 mm in diameter, wooden battens, dowel-nails. It should be borne in mind that pipes and slats are dismantled from a partially frozen solution. If the screed is made with self-leveling mixtures, beacons may not be needed, or special bench mark beacons are used.
- Building level … A bubble building level is required without fail, the recommended length is from 2 m. For greater convenience, you can additionally use a laser level, with its help it is much easier to install beacons.
- Roulette. The minimum length is 8 meters.
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Spatulas, trowel
- Rule and construction mixer or drill with mixer attachment. The latter is needed for mixing the components of mixtures. For a concrete screed, it will be more convenient to use a concrete mixer.
- Rollers and brushes for applying primer and waterproofing compounds.
- Needle roller, paint shoes, squeegee and reference beacons for working with the leveler.
- Construction gloves, respirator, goggles. For the protection of skin, respiratory tract and eyes.
- Capacities for mixing.
How to calculate the expense?
For bulk mixtures, the average consumption values for a coarse leveling agent are 2-5 kg per 1 sq. m premises with a layer thickness of 1 mm. For the finishing leveler - 1.5-1.7 kg per 1 sq. m per 1 mm layer. All that remains to be done is to count the quantity.
Example: the consumption of a coarse leveling agent of 5 kg is multiplied by a layer thickness of 3 mm, and then multiplied by the area of the room in square meters. It turns out the following: 5x3x10 = 150
In total, you will need 150 kg of self-leveling mixture for a room with an area of 10 sq. m. Taking into account the fact that the package contains 25 kg of dry mix, this is 6 bags of leveler. Calculations for the finishing layer are done in the same way.
For a classic concrete screed for 1 sq. m and a layer thickness of 5 cm will need 22.5 kg of cement, sand 47.5 buckets with a volume of 10 liters, water 10 liters. For screed using large inclusions in the form of crushed stone per 1 sq. m and the thickness of the layer will need 8.5-9.2 kg of cement, 40.7-46.1 kg of crushed stone, 22.8-26 kg of sand.
These calculations are approximate, you need to make accurate calculations yourself based on the recommendations of the manufacturers of building materials.
Important nuances
If the difference in height in the room exceeds 4 cm, then it is necessary to select a starting leveling device for the subfloor layer. Cement-sand and concrete composition is always laid along the lighthouses. In rooms with high humidity, such as a bathroom, toilet, kitchen, they work with cement-based solutions. In living rooms, it is possible to use a screed using plaster.
When installing a multi-layer screed, you need to choose such solutions that have a lower weight. It will be better to opt for compositions using expanded clay or polystyrene concrete.
If the differences in the level of the floor surface are small, it is better to fill in self-leveling mixtures. They can be based on cement, gypsum, sand, with additives for plasticity and shortening or increasing the drying time. Polymeric self-leveling floors based on polyurethane, epoxy resin or methyl methacrylate, despite their high cost, have a large number of advantages.
Due to their thin filling layer, they are perfect for apartments with low ceilings. The finished surface has good waterproofing properties and special strength, is not subject to temperature extremes, deformations, and aggressive environments.
For the final leveling of the surface, self-leveling self-leveling mixtures are usually used. Such a composition can be made as an independent decorative coating by using pigments to create a colored background or pattern. By adding mineral chips or other inclusions to a standard cement mortar and then sanding after the mortar has set, a surface similar to natural stone can be achieved.
If the area of the room is too large and the work will take more than one day in time, the surface is divided into several sections using closed beacons or partitions.
Preparatory work
The preparation of the room when installing a screed on the ground begins with laying a cushion of heat and waterproofing. You can choose the materials at your discretion, but there are some general recommendations. Layers can be swapped, different fillers can be used, or the thickness can be changed.
A layer of gravel or crushed stone 5-15 cm thick is poured onto the surface prepared in advance. The next layer is 10-15 cm of sand, which can be moistened, and a 10-15 cm layer of crushed stone or expanded clay. Each layer is carefully compacted using a vibrator or a heavy log. Crushed stone must be selected with a fraction of 40-50 mm.
It is recommended to sprinkle layers of crushed stone or expanded clay with crushed stone or sand. The last layer is well leveled and check the absence of sharp corners on the rubble. If sharp stones remain, the waterproofing material may tear. For better adhesion, it is recommended to spill the top coat with liquid cement and wait until it dries.
For waterproofing on the ground, roll materials or film with a density of 200 microns or more can be used. The material must be laid on the base with an overlap on top of each other, the edges must be raised above the level of the future screed by 15 cm and attached with tape to the walls. Attach a damper tape at the level of the screed with a small margin of height. It compensates for the contraction and expansion of the screed, thereby preventing deformation of the walls and floor due to changes in temperature and humidity.
A reinforcing layer is laid on top of the waterproofing. Fine-mesh welded steel mesh, which has the required rigidity, is best suited. A steel mesh is installed at a height of 1/3 of the thickness of the screed using special pads-chairs. If a reinforcement structure is used, concrete after pouring will need to be compacted with special vibration equipment.
A room that is too large can be divided into square or rectangular pieces, also called maps. One card needs to be filled in one day and its size depends only on the productivity of the workers.
The map is fenced off with formwork made of wet wood or laminated plywood with a height at the level of the screed; after the cement has set, the formwork must be removed.
To prepare the screed room, work begins with dismantling the old coating. Linoleum and wooden floor boards are torn off quite easily, but the tiles will have to be beaten off with a puncher. Skirting boards and doors, along with the slopes, must also be removed.
Under the dismantled layer, there may be both floor slabs, which greatly simplifies the task, and an old screed. In the second case, the concrete must be carefully inspected. If it crumbles or there are a large number of defects in the form of cracks and chips, the entire layer should be beaten off with a perforator. If the old screed is in good condition, only light thin-layer mixtures can be poured onto it.
After cleaning debris, you need to clean the surface with a grinder or brush. Remove crumbling concrete, glue residues, mixtures and stains. Vacuum and degrease the floors with soapy water or solvent. Small cracks, chips, potholes and joints between the floor and the walls should be expanded up to 5 mm, primed and covered with a thin layer of putty based on resin or adhesive. To correct large defects, it is more advisable to use a cement-sand mortar or a self-leveling mixture.
The next step is to treat the surface with a primer using a roller or paint brush. Any universal primer or concrete contact is suitable for a concrete or cement-sand screed; for self-leveling self-leveling floors, you need to use a special polymer primer. With a multi-layer screed, priming of the surface is mandatory before each layer. The average surface drying time is two hours. If necessary, you can apply a second coat of primer after the first coat is completely dry.
With the help of polyurethane foam, it is necessary to seal up all the holes through which the screed mixture can flow into another room or to the neighbors below. Most often, such places are located near heating pipes.
You need to wait until the foam is completely dry, cut off the protruding excess and only after that proceed to the rest of the work.
A layer of waterproofing is laid on the prepared surface. This must be done in the following cases:
- If there are large gaps at the joints of the floor and walls;
- In the bathroom and in the kitchen;
- On the first floor of the house;
- When arranging underfloor heating systems.
For these four cases, it is best to use roll or film materials. They need to be laid overlapping each other, bringing the edges of the material to the walls with a margin of up to 15 cm and attaching with tape. In some cases, you can use liquid waterproofing, which is applied strictly in accordance with the manufacturer's instructions. It is recommended to attach a damper tape over the waterproofing layer to the walls, the protruding part of which is cut off after the end of the work.
At this stage, a system of warm water or electric floors is installed. Thermal insulation in the form of plates must be laid under them to reduce energy losses. The reinforcing mesh is installed on special chairs, the height of which must be at least 1/3 of the thickness of the screed. During the installation process, damage to the waterproofing layer must not be allowed.
How to do it?
When all the preparatory work is completed, you can proceed directly to the screed device. All methods have their own nuances, so it makes sense to consider each of them in stages and get acquainted with the detailed step-by-step instructions on how to properly make a floor screed with your own hands.
For a screed made of concrete or cement-sand mixture with a thickness of 3 cm or more, it is necessary to install beacons along which the mortar will be leveled. In an apartment, it is most convenient to use an aluminum T-shaped profile as lighthouses. It does not need to be dismantled and does not weigh down the floor structure … The only drawback of such material is if, during the installation of the profile and laying the screed, the protective fromIf the aluminum is damaged, rust may develop over time.
Lighthouses made of wooden slats and steel pipes must be removed from the partially frozen screed, and the resulting grooves should be covered with the same solution. When screed on the ground, steel pipes with a diameter of up to 70 mm are used. Instead of pipes, you can use a steel rectangular profile.
Lighthouses are attached to a gypsum mixture or cement-sand mortar, laid out in small slides at a distance of 15-20 cm from each other. Gypsum dries faster without affecting the strength of the coating, therefore it is more convenient to use it in residential premises.
In rooms with high humidity, plaster mounting is not allowed. If a waterproofing layer was not laid on the base, the beacons can be fixed on self-tapping screws.
It is necessary to place beacons along one of the walls of the room in such a way that the distance from the beacon to the wall is no more than 10 cm, and the step between them is a quarter less than the length of the rule. After placing on the floor surface, the profile must be leveled using a laser or building level according to the marks of the highest point of the floor. When leveling, the beacons are pressed closer to the floor or raised with pieces of brick.
After the beacons are exposed, you need to check the evenness with the level again and, if necessary, correct. It is recommended to divide a large room into several sections with solid beacons so that you can take a break during work. A solid lighthouse or fence must be installed on the threshold of the room. The thermal insulation material should be laid between the beacons, and after the fasteners of the beacons have dried, you can start pouring the screed.
The cement-sand mixture is kneaded in a concrete mixer or a construction mixer. To get a solid foundation, you must strictly follow the mixing sequence. Place 2 parts of water and 4 parts of perlite in a prepared container, mix all this very thoroughly until a homogeneous consistency. Then add 1 part water and 1 part cement, mix again. At the end, add 10 parts of water and 2 parts of sand and mix until a plastic consistency.
During the mixing process, the consistency of the solution must be constantly monitored. If wet sand is used, the amount of water must be reduced. In finished form, the solution should easily spread, and not spread, resemble dough in consistency. If necessary, plasticizers can be added to the mixture. Such a screed must be laid within an hour. Complete drying takes 2-3 days.
The concrete solution is denser than the cement-sand mortar, therefore, it is much more difficult to knead it with a construction mixer. If opportunities permit, it is better to rent a small concrete mixer. The simplest composition of sand and cement is made as follows: for 10 kg of a mixture of 3 parts of sand and 1 part of cement, add 2 liters of water and mix. To increase the strength, 50 g of fiber can be added per 100 kg of the mixture. It is necessary to use the solution within 1-1.5 hours, it will reach complete solidification in 28 days.
How to align?
Starting from the wall farthest from the entrance, the solution is laid out between the beacons and leveled with the rule. It should be perfectly flat, without chipping and cracking on the working side. Pressing lightly, the mass must be pulled towards you, making leveling movements to the left and to the right. To remove air bubbles, the solution should be pierced with a shovel or metal rod. You can use a special deep vibrator. The surface is treated with it until cement milk appears on it.
At the walls and in hard-to-reach places, the screed is leveled with a spatula. Work can be stopped only when the whole room or the fenced off area is done. When the concrete has set and can withstand human weight (after about 12-20 hours), you need to remove all irregularities on the surface of the screed and beacons.
The technology of the dry floor screed device also implies a layer of waterproofing, gluing a damper tape and the installation of beacons. A selected dry mixture of materials is poured and leveled between the beacons. More often than others, it is recommended to use expanded clay sand. Then the boards are mounted on double-threaded screws and glue. Once the glue has dried, you can apply a self-leveling floor or start laying the flooring right away. Fill the remaining indentations with the same compound and level with a spatula.
Finishing fill
If the floor height differences are within 3 cm, you can start filling with self-leveling liquid mixtures. The principles of the device of the finishing and rough self-leveling floor are identical, and the difference lies only in the thickness of the poured layer. To make the coating perfectly smooth, you need to be guided by the marks applied to the wall so that the mixture reaches them, but does not completely cover them.
On a surface with a large number of irregularities and drops, dowel-nails or special beacons-benchmarks can be installed as beacons.
Such lighthouses look like tripods and are adjusted according to the building level. It is necessary to dilute the self-leveling floor strictly according to the instructions. Also, the instructions indicate the minimum and maximum layer, which must be adhered to exactly. Water is poured into a specially prepared container and the mixture is gradually poured, which is stirred with a construction mixer at low speeds. You need to use the ready-made mixture within 15-20 minutes.
Pouring the floor begins from the corner of the room farthest from the entrance. Smoothing is done with a squeegee or trowel. Between pouring the strips, you need to maintain a time interval of no more than 10 minutes. Walking on the flooded floor is possible only with paint shoes. Next, you need to remove the reference beacons and roll the entire surface with a needle roller to remove all air bubbles.
There must be a fence on the threshold of the room so that the mixture does not pour out of it. After seven days, you can start laying the flooring. The poured topcoat can be made into a stand-alone floor covering by adding color pigments or applying a pattern.
In this case, after drying, the surface must be covered with a special varnish.
How to repair cracks?
In order to prevent cracks or other defects from appearing on the concrete screed during the drying process, it needs to be followed by simple, but daily maintenance during the first 7-10 days. For this, the surface must be watered with water 2 times a day and covered with plastic wrap. If the room is hot, it is recommended to increase the regularity of watering up to 4 times a day.
If cracks and irregularities do appear on the surface of the screed, they can be removed with a grinder or filled with the same compound that was used to make the screed. You can also use self-leveling bulk mixes. To do this, apply a primer mixture to the floor surface, and after it dries, pour a thin layer of finishing casting.
Helpful advice from professionals
If you have not had experience with screed construction before, it is recommended that you first practice in a small room, for example, a pantry. And even experienced professionals in this matter need assistants, so you need to start work at least together.
When choosing materials for a screed, you need to pay attention to the following points:
- The color of the mixture should be gray, without foreign inclusions of a dirty color. Most often this happens with poor-quality mixtures, into which clay gets along with the sand. A screed based on such material will quickly crack and become unusable;
- In no case should you use mixtures in which PVA glue is indicated as a plasticizer;
- The sand for the screed must be marine;
- If the concrete layer needs to be made thicker, it is recommended to add expanded clay to the composition of the solution. This will not affect the strength of the screed, and the load on the base and the consumption of material will become less.
Do not neglect the use of a damper tape. This will not have a big impact on costs and will avoid deformations of the walls and floor. It is necessary to fasten such a tape not only to the walls, but also to the columns and other structures with which the screed is in contact.
It is recommended to rinse the construction mixer after each use in working mode in a separate container with water. This will simplify the task of its further cleaning, and foreign inclusions will not get into solutions.
To prevent cracking of the screed, expansion joints can be cut in it. The depth of such joints should be equal to 1/3 of the concrete thickness. Cutting is carried out on the set, but not completely solidified concrete. After the screed has completely dried, the joints are filled with sealant. There are three types of seams:
- Insulating … They are made at the joints of the concrete floor and other structures.
- Structural … Cut in the place of uneven concrete hardening during breaks in pouring for more than 4 hours.
- Shrinkage … It is necessary in order to avoid possible deformation during the shrinkage of the screed during the drying process.
It will not be superfluous to check the result of the work. You can assess the evenness of the coating using a building level, applying it to the floor in different parts of the room. The allowable size of the gap is 4 mm. The presence of voids inside the screed is checked by tapping with a wooden bar. The sound around the entire perimeter of the room should be the same - solid and ringing.
See the following video for a do-it-yourself floor screed master class.
