The layer that serves as the basis for a finished floor covering is called a screed. The floor screed is necessary for leveling, giving the surface a certain rigidity, masking engineering communications, installing heat, sound and waterproofing materials, as well as the "warm floor" system. The better this layer is made, the more durable the floor itself will be.
Types of couplers by coupling method
According to the method of connection with the floor slab or with the foundation slab, the screed can be connected, floating or on a separating layer. The bonded one is laid directly on the work surface, and there is no heat or waterproofing between the layer and the floor. One square meter of such a screed weighs up to 150 kg. An important feature: the beacons after pouring remain in the cement mortar, and are not removed.
The screed on the separating layer is separated from the base by hydro or thermal insulation and does not come into contact with the walls of the room. Thermal insulation is placed under the screed to reduce thermallosses. Usually this is a layer of rigid mineral plates with a thickness of 30 to 90 mm. Sometimes foam boards with foil are used. The thickness of the heat-insulating layer depends on the characteristics of the room and the heating mode. So, for the first floor of a building, 30 mm is enough, for the basement floors, 90 mm is needed.
Floating floor screed is a cement layer on an insulating pad: heat, hydro or sound. This solution is most relevant in cases where the floor needs insulation or good sound insulation. Plasticizers are additionally used for the construction of the structure, the screed itself must be reinforced. If you plan to lay an electric underfloor heating, you must additionally lay a heat insulator under the screed.
This type of screed rarely cracks, because the hardened mortar is not tightly bonded to the base. As for the device, it is necessary to separate it from the walls with insulation, which will avoid unnecessary stress on the building structure. This is especially important when arranging a warm floor, which is characterized by a significant percentage of thermal expansion. The floating screed in this case reduces heat loss through the walls.
Types of screeds by laying method
For different floor coverings, the screed is made solid, self-leveling or semi-dry. A solid floor screed is the most common leveling method. A solution is made, which is then leveled with a special tool. When pouring, it must be borne in mind that if water comes to the surface, then shrinkage will be significant. Eventuallycracks will appear.
The classic method of screed is gradually replacing semi-dry. The device of such a screed does not require additional alignment, and even non-professionals will cope with the work process. Usually the semi-dry method is used to reduce the cost of repairs, because you can save a lot on building materials or the amount of water for quick drying. To make the base durable, special compounds are added to improve the final quality of the floor.
Semi-dry screed gives a perfectly flat surface, allows you to equip a warm floor in a short time, has a minimal risk of cracking and is able to withstand heavy loads. With minimal repair costs, you can get excellent final quality. This type of floor screed is also called dry, because the leveling itself occurs due to loose material and laying slabs.
Self-Leveling Floor Screed is the most fluid floor leveling compound available. It is applied to a sealed base and creates a perfectly flat surface under its own weight. A prefabricated screed is a set of ready-to-lay elements that are assembled from large-sized chipboard, fiberboard, plywood and similar materials. You can start laying the face covering on the same day, because there are no “wet” processes.
Types of screeds by material composition
Do-it-yourself floor screed (photo and description of the workflow below) is usually done with a cement-sand mortar. The coating is suitable for almost all types of finishes,durable and understandable in execution technology. Under such a screed, it is desirable to lay hydro and sound insulation. When installing, it is important to avoid air bubbles and cracks, because these are not just cosmetic defects, but a serious construction flaw.
Gypsum floor screed will provide the necessary temperature and humidity in the room. Gypsum is quite popular, and is also an absolute environmentally friendly material (unlike cement). An industrial screed provides for increased loads, therefore, during production, the plates are separated to prevent cracks. Plates are treated with special impregnations to ensure chemical resistance and give additional strength. Semi-dry cement-sand (with fiber) floor screed is a composition with the addition of fibers from metal or plastic, which are necessary to give strength.
Often, special plasticizers are added to the floor screed solution, which increase thermal conductivity, increase the mass of the coating, and reduce the surface tension of water. It is enough to add 10% of the plasticizer by weight of pure cement. But it should be borne in mind that some plasticizers prevent the cement from hardening, which means that the work may be delayed, and the strength will eventually be 20% less.
Types of couplers by purpose
The screed for its intended purpose can be leveling or leveling and heat-insulating. Leveling is used to give the base the necessary parameters, namely a certain slope (may be zero),height and evenness. The second type of screed additionally creates the effect of thermal insulation of the room. The best floor screed in each case depends on the purpose of the coating, the characteristics of the room and the wishes of the owners.
Which screed is suitable for the room
What should be the correct floor screed? Technology and material must correspond to the characteristics of the room. The layer that is laid between the base and the finish coating performs such important functions as providing thermal, hydro and sound insulation, forming the necessary slopes, leveling the surface, strengthening the base, masking communications (laying a screed on a warm floor).
A tie screed is laid in cases where it is not possible to raise the floor level, the coating should be very light, the area is quite large, and the existing base is even. The screed on the separating layer is indispensable for the arrangement of the basement, attic under the roof, bathrooms, toilets and on the floors of the first floors. A floating screed is used in rooms where it is impossible to prepare the base with high quality, if underfloor heating, hydro, sound and heat insulation are planned, there is a high risk of cracking.
Combined screed is suitable for different types of premises. The coating is durable and warm, does not dust, does not collapse, is not afraid of moisture, and has good sound insulation. In case of improper laying, the floor can be dismantled, but the dismantling of the cement floor screed is an extremely time-consuming and expensive task. But it is worth considering what to equip the national teamthe screed on the upper floors is quite difficult, because the plates are inconvenient to lift. It is also undesirable to choose a prefabricated structure for those rooms where there is high humidity.
The most popular alignment method
Most often, the floor in private houses and city apartments is leveled in the most affordable, popular and budgetary way - with the help of sand and cement. The process of arranging a floor screed with your own hands (step-by-step instructions with a photo below) is available even to a non-professional, but this work is time-consuming and not fast. In general terms, floor leveling involves the following steps:
- Preparing the surface for work, cleaning the floor and (if possible) leveling.
- Installing beacons that match the desired height, which will ensure the evenness and smoothness of the floor.
- Laying reinforcing mesh to strengthen the structure. Preparation of a mortar for floor screed and pouring over beacons.
- Dismantling the beacons after the surface has dried and processing the remaining seams. Removal of residues of the mixture and grouting.
Preparing the work surface
Before the start of the main work, the floor base must be brought to normal, if necessary, the remains of the old screed should be dismantled and the surface cleaned. Old boards or parquet are removed, the floor is cleaned of dirt and dust with ordinary detergents. It is more convenient to use a special construction vacuum cleaner. All existing cracks at this stage must be repaired, and then the cleaned surface should be coveredprimer. If the screed is made directly on the ground, then you need to tamp the base well and fill in the bitumen composition for smoothness. Ignoring this point will cause the base to sag over time, and cracks will appear on the finished surface. If the surface is uneven, you can fill up a layer of sand or expanded clay.
Marking the room in height
At a height of one meter, you need to set a horizon line on the walls, from which, using a tape measure, the distance to the floor is canceled at all points. You need to find the highest point, and then decide on the thickness of the screed. This line should be marked near the floor. If you plan to fill up a layer of expanded clay for sound and heat insulation, then one more line should be marked from the mark, retreating a few centimeters down. Below this line, gravel, expanded clay or sand will fall asleep.
Installation of leveling beacons
Beacons are installed, which are best reinforced with gypsum or cement mortar. The number of beacons depends on the length of the rule that will be used when working. In a small room, two guides installed at a slight distance from the walls may be enough. If you plan to make a warm floor, then you need to additionally lay a layer of heat-insulating material under the beacons.
At this stage, you need to attach a plastic film to the walls, which will protect against moisture. The top edge of the film should rise above the finished floor by 15 cm, the bottom edge should slightly go under the screed. When leveling the surface by about 4 cm, it is better to dotied tie. In this case, a layer of polyethylene film between the floor and walls is not needed.
Filling floor screed
After the completion of the preparatory work and marking, a solution for the screed is being prepared. The proportions are approximately as follows: add four buckets of sand to one bucket of cement. You should first read the recommendations of the cement manufacturer, because some mixtures are prepared in a different ratio for better results. It is advisable to pre-moisten the floor surface so that the adhesion is more reliable. The mortar itself should be thick enough and flow freely a little above the level of the beacons, because the floor will settle a little when it dries.
A reinforcing stack is laid out on the base of the floor before pouring. This is necessary if the coating will be subjected to significant loads in the future. Then the filling is done. To get rid of the formed air bubbles, after pouring the floor is compacted with a vibrating screed. Old lighthouses are dismantled until completely dry. When the floor is completely dry, it will not be easy to do. The seams must be covered with a solution. The rest of the mixture is removed and the grout is made. The process is not particularly difficult. It is enough to wet the surface of the screed with water and smooth it.
It may take up to two weeks for the floor to dry completely. The exact time depends on the thickness of the layer. As it dries, the surface must be regularly moistened with water so that cracks do not form. After complete drying, you can finally wipe out small irregularities andclose up bad places with mortar.
Should I hire professionals
Floor screeding is hard and time-consuming work, but quite affordable even for those who have no experience in construction. Professional screed is carried out using a pneumatic blower, which mixes the solution and delivers it to the object. Therefore, a team of workers will qualitatively perform floor screed laying in Moscow or another city in a semi-dry way on an area of up to 250 m2 in one day. Self-assembly will take much longer.
Theoretically, you can save on the services of builders and make a screed yourself, especially if the area is small and the existing base does not require cardinal alignment. But with a large area or the need to carry out work on the upper floors of buildings, it is better to turn to professionals. In this case, the labor costs when working manually and using special equipment (this is a mechanized floor screed) are incommensurable.
