The device of floor screed today is perhaps one of the most common technologies for leveling the surface. Home craftsmen and professional builders know many different techniques, among which it is especially worth highlighting the laying of a concrete floor, installing a semi-dry screed, as well as a method that involves arranging the floor on the ground.
Why choose concrete screed
As for the leveling with concrete, it allows you to achieve a high-strength surface, which will undergo all sorts 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 device screed floor necessarily involves preparatory work. If the floor will be laid on the ground, which is important for basement rooms and private houses, first you need to take out the soil, deepening by 500 mm. A 100 mm sand cushion is poured at the bottom, which should be well tamped, and a gravel layer should be poured on top.
Then it is possible to fill with concrete with expanded clay. As soon as the base hardens, it should be waterproofed with a dense plastic film or roofing material, which will prevent the penetration of soil moisture from below. The waterproofing layer should go on the wall. If necessary, another layer of insulation is poured on top, after which you can proceed to pouring the reinforced finish layer of the screed.
Floor surface preparation in an apartment
The device screed floor in the apartment involves the removal of the old layer of the rough surface. These works are necessary for the reason that old materials can be damaged, have cracks and delamination. In addition, one should not forget about the ultimate loads on 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 punch, but it is important to eliminate the destruction of the floor slab. The base must then be inspected. Repair may be required. If you plan to lay the coupled screed, then the existing recesses should be cleaned, cracks should be repaired to a width of 5 mm, so that concrete mortar can penetrate there.
Specialist advice
If the floor screed device is planned to be carried out using floating technology, then the flaws must be repaired. There is no need to leave voids under the waterproofing layer, since condensation can accumulate there. Damage can be repaired with a repair compound, concrete mortar or epoxy putty. In the presence of rather impressive defects, assembly foam is used.
It is especially necessary to carefully repair the corners between the floor and walls, because water from a concrete mortar can easily penetrate deep into the floor and flow to the neighbors from below. The surface is treated with a penetrating primer, this will remove dust from the base and increase adhesion characteristics. Among other things, in this case, the overlap will not absorb moisture from the solution. The primer must be spread over the surface in strips and distributed with a roller. In hard to reach places you can use a brush.
Additional preparation guidelines
Before filling the floor screed in the house, it is necessary to glue a damper elastic tape around 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 in contact with vertical structures, columns and partitions.
If the screed is laid on the separation layer, then the entire surface of the overlap must be covered with a plastic film, the thickness of which is 0.2 mm. Cloths should be laid with an overlap of 100 mm, and the joints glued with waterproof construction tape.
Lighthouse and reinforcement
The technology of the floor screed device in the next step involves the installation of beacons. According to them, the master will level the surface of the future floor. It is important to markup, determining the zero level. To do this, draw a horizontal line, determining the highest angle 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 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 a zero level. The step between the parallel guide and the nearest wall should be 300 mm. 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 galvanized wire mesh is usually used. Position the frame at a certain distance from the floor. For this, polymer stands are used.
Pouring screed
The rough floor screed in the next step involves pouring the mortar. The optimum temperature for work is considered to be a limit of 15 to 25 ยฐ C. If this value is reduced, the ripening period of concrete will increase. Pouring work must begin from the far corner of the room, moving to the exit. It is recommended to complete the filling during the day, in which case it will be possible to obtain the most durable and uniform screed.
The finished solution is laid out between the guides and distributed using a shovel or trowel. It is important to achieve maximum compaction of the solution and the release of air bubbles. For this, you can use the bayonet method. On the guides in the next step, a rule is established. Zigzag movements must be carried out in such a way that a smooth 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
As an alternative solution, you can use a semi-dry floor screed. To do this, prepare a solution using fiber. 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 with an area of โโ20 m 2 , then the fiber consumption will be 0.54 kg.
The ingredients are mixed for 3 minutes, after which water is added to them, the solution is mixed again and laid on the surface. If the layer is further reinforced, then one part of Portland cement will need 3 parts of sifted sand. 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 on 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 the level and the rule. With the formation of irregularities, they are sprinkled with a solution.
The final step will be grouting and grinding. This allows for perfect smoothness. After the screed hardens, irregularities can be knocked down with a metal spatula. If cavities have formed, then they can be filled with a solution of sand and cement in a ratio of one to one. Grouting of the base is carried out with a polyurethane or wooden grater. If a semi-dry floor screed was laid using beacons, then they should be removed, and their location should be wiped and sanded using a special machine.
Floor screed
After excavation from the territory of pouring screeds, it is necessary to fill the bottom with sand. The thickness of this layer should be approximately 10 cm. The quality of tamping will be improved if we additionally use special mechanisms such as vibration seals or rammers. In this case, the sand should form a horizontal surface.
The device for screeding the floor 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 compacted. This will increase the bearing characteristics of the base.
After the concrete mixture is prepared, which can be done independently. The density of the composition should be medium. This will allow the concrete to spill on its own. As one of the advantages of the liquid mixture is the absence of the need to use beacons for leveling. Masters have only to slightly adjust the level in those places where the material is supplied.
Reinforced floor screed at this stage provides for laying the net. It is necessary to fix the frame 3 cm from the floor, and then pour the solution. You can form a grid of wire elements that are twisted together. If the wire has a diameter greater than 6 mm, then it is better to use welding for connection. However, the optimal solution would be to purchase a finished grid.
Calculation of materials for screed
Calculation of floor screed must be done so as not to interrupt the work. Forming a 10-cm layer, cement should be purchased in the amount of 50 kg per square meter. For a more accurate calculation of cement and sand, you can consider a specific example. If you have to work with an area of โโ60 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 a 3 m 3 solution.
The calculation of the floor screed can look like this: for 1 liter of the mixture, 1.4 kg of cement will be needed. This indicates that in one bag there will be only 36 liters, and the finished solution will be enough for 30% of the volume.
Conclusion
Before starting work, it is important to think about whether you will use the services of specialists. If you decide to carry out the work yourself, then you should evaluate your knowledge and skills. Most often, home craftsmen use the technology of laying concrete screed, you can also follow their example. But the floor screed in a new building is best laid on a semi-dry technique.