The floor screed device today is perhaps one of the most common technologies for leveling the surface. Home craftsmen and professional builders know many different methods, among them laying a concrete floor, installing a semi-dry screed, as well as a method that involves arranging the floor on the ground.
Why choose a concrete screed
As for leveling with concrete, it allows you to achieve a high-strength surface that will undergo various kinds of loads without losing its quality characteristics. There is no need to invite specialists to carry out such work, because the process can be carried out independently.
Surface preparation before pouring concrete screed
The floor screed device necessarily involves preparatory work. If the floor will be laid on the ground, which is relevant for basementpremises and private houses, then first you need to remove the soil, deepening by 500 mm. A 100-mm sand cushion is poured at the bottom, which should be well compacted, and a gravel layer is poured on top.
Then you can pour concrete with the addition of expanded clay. As soon as the base hardens, it should be waterproofed with a dense polyethylene film or roofing material, which will prevent the penetration of ground moisture from below. The waterproofing layer should go to the wall. If necessary, another layer of insulation is poured on top, after which you can proceed to pouring the reinforced finishing layer of the screed.
Preparation of the floor surface in the apartment
The floor screed device in the apartment involves the removal of the old layer of the rough surface. These works are necessary because old materials can be damaged, have cracks and delaminations. In addition, one should not forget about the maximum loads on the floor slabs. For example, in high-rise buildings of an old building, such a load is approximately 400 kg per square meter. As for the dynamic load, it is equal to 150 kg. The weight of a square meter of concrete screed is 100 kg, this is true if the thickness is 50 mm.
If you do not remove the old screed, then the ceiling height in the apartment will be even less than before. You can dismantle the old layer with a perforator, but it is important to prevent the destruction of the floor slab. The base then needs to be examined. May need repair. If you are planningto lay a bonded screed, then the existing recesses should be cleaned, the cracks should be repaired to a width of 5 mm so that the concrete solution can penetrate there.
Expert Tips
If the floor screed device is planned to be carried out using floating technology, then the flaws must be repaired. It is not necessary to leave voids under the waterproofing layer, as condensation can accumulate there. Defects can be repaired with a repair compound, concrete mortar or epoxy putty. In the presence of rather impressive defects, polyurethane foam is used.
It is especially necessary to repair the corners between the floor and walls, because water from the concrete solution can easily penetrate deep into the ceiling and flow to the neighbors below. The surface is treated with a penetrating primer, this will remove dust from the base and increase the adhesive characteristics. Among other things, in this case, the overlap will not absorb moisture from the solution. The primer should be poured over the surface in strips and spread with a roller. In hard-to-reach places, you can use a brush.
Additional preparation tips
Before pouring the floor screed in the house, it is necessary to glue a damper elastic tape along the perimeter of the walls, which will compensate for the expansion of the concrete screed. This will prevent cracking and deformation of the material. Among other things, the screed will not come into contact with vertical structures, columns and partitions.
If the screed is laid on a separating layer, then the entire surfaceoverlappings must be covered with polyethylene film, the thickness of which is 0.2 mm. The sheets must be laid with an overlap of 100 mm, and the joints must be taped with waterproof construction tape.
Setting up beacons and reinforcement
The technology of the floor screed device at the next stage involves the placement of beacons. According to them, the master will level the surface of the future floor. It is important to markup by defining the zero level. To do this, draw a horizontal line, determining the highest corner of the room. A mark is indicated on the wall, and then, using the water level, it is transferred to all other walls. The distance between the risks should allow you to connect the marks with one line. The thickness of the screed must be subtracted from the value at the highest point. This parameter can be at least 30 mm. The resulting value will become the zero level.
Marking for beacons is carried out after applying the zero level. The distance between the parallel guide and the nearest wall should be 300mm. The distance between adjacent guides is not regulated, however, it should be slightly less than the length of the rule for leveling the solution. For reinforcement, a metal mesh made of galvanized wire is usually used. It is necessary to position the frame at some distance from the floor. For this, polymer coasters are used.
Filling the screed
Rough floor screed at the next stage involves pouring the solution. The optimum temperature for work is considered to be between 15 and 25 °C. If this value is lowered, thenthe curing time of concrete will increase. Filling work must begin from the far corner of the room, moving towards the exit. Filling is recommended to be completed during the day, in this case it will be possible to obtain the most durable and uniform screed.
The finished solution is laid out between the guides and distributed with a shovel or trowel. It is important to achieve maximum compaction of the solution and the release of air bubbles. To do this, you can use the bayonet method. The rule is set on the guides in the next step. Zigzag movements must be carried out in such a way that a flat surface is obtained. Concrete mortar can be added as needed. Its excess at the end of the fill is carefully removed.
Semi-dry screed technology
Alternatively, you can use a semi-dry floor screed. For this, a solution is prepared using fiberglass. For 120 liters of sand, you need to prepare 50 kg of cement and 150 g of fiber. If you have to work with a room whose area is 20 m22, then the fiber consumption will be 0.54 kg.
The ingredients are mixed for 3 minutes, then water is added to them, the solution is mixed again and placed on the surface. If the layer is additionally reinforced, then 3 parts of sifted sand will be needed for one part of Portland cement. The mixture can be prepared on site without the use of a concrete mixer. Water is gradually added to the dry composition. The solution should be semi-dry.
It is scattered over the surface, and the next layer will be a reinforced mesh, which is again covered with a semi-dry mixture. The composition is compacted, and alignment is carried out using a level and a rule. When bumps form, they are sprinkled with a solution.
The last step will be grouting and sanding. This allows you to achieve perfect smoothness. After the screed has hardened, the irregularities can be knocked down with a metal spatula. If depressions have formed, then they can be filled with a solution of sand and cement in a ratio of one to one. The base is grouted with a polyurethane or wooden float. If a semi-dry floor screed was laid using beacons, then they should be removed, and their locations should be wiped and sanded using a special machine.
Screed floor on the ground
After excavating the soil from the screed area, it is necessary to fill the bottom with sand. The thickness of this layer should be approximately 10 cm. The quality of compaction will be improved if special mechanisms such as vibrocompactors or vibrorammers are additionally used. In this case, the sand should form a horizontal surface.
Floor screed on the ground at this stage involves wetting the base, which will increase the degree of shrinkage of the layer. Water can be supplied from buckets or hoses. Next, a layer of crushed stone is poured, its thickness can vary from 5 to 10 cm. The layer is well rammed. This will increase the bearing characteristics of the base.
After the concrete mixture is prepared, which you can do yourself. The density of the composition should be medium. This will allow the concrete to pour on its own. One of the advantages of the liquid mixture is the absence of the need to use beacons for leveling. The masters only have to slightly correct the level in those places where the material is fed.
Reinforced floor screed at this stage provides for laying the grid. It is necessary to fix the frame 3 cm from the floor, and then pour the solution. It is possible to form a grid from wire elements that are twisted together. If the wire has a diameter greater than 6 mm, then it is better to use welding for the connection. However, the best solution would be to purchase a finished mesh.
Calculation of materials for screed
The calculation of the floor screed must be carried out so as not to interrupt work. Forming a 10 cm layer, cement must be purchased in an amount of 50 kg per square meter. For a more accurate calculation of cement and sand, a specific example can be considered. If you have to work with an area of \u200b\u200b60 m 2, then this value must be multiplied by 0.06 m. This will be the thickness of the screed. As a result, it will be possible to obtain 3 m3 solution.
The calculation of the floor screed may look like this: for 1 liter of the mixture you will need 1.4 kg of cement. This indicates that there will be only 36 liters in one bag, and the finished solution will be enough for 30% of the volume.
Conclusion
Before starting work, it is important to consider whether you will use the services of specialists. If you decideto carry out the work on their own, then you should evaluate your knowledge and skills. Most often, home craftsmen use concrete screed laying technology, you can also follow their example. But the floor screed in a new building is best laid using a semi-dry method.
