The surface of floor slabs is almost never smooth and strictly horizontal. This is due to the level of the upper edge of the bearing walls on which they are supported, and minor defects acceptable in the manufacture. Perfectly even horizontal floors in the room can be obtained by installing a screed, which is a leveling layer of concrete or cement mortar on the surface of the slabs.
Work on the device of such a layer begins with the beating of a single horizontal level in all neighboring rooms. This is a line drawn on the walls and located at such a height that at no point did the distance from it to the floor slab be less than 30 mm.
In the language of builders, the task of this operation is to level the existing surface errors in height.
Therefore, the leveling for floor screed begins with the determination of the highest point of the existing base. Accurate sex determination is a very important step. Underestimation of the layer thickness less than 30 mm can lead to its destruction during operation, and any overestimation - to cost overruns and increased financial costs.
Measurement and marking tools
To determine and apply horizontal or zero level to the walls, you must have:
- a device or instrument for marking an exact horizon called a “level”;
- yardstick;
- pencil with hard lead;
- a cord for beating, dyed purchased or plain, rubbed with coal dust or ground chalk;
- Plumb or building bubble level for accurate vertical line determination.
To determine the horizon when beating a zero mark of the floor level in the apartment, hydraulic or laser levels are used. The choice depends on the financial capabilities of the contractor and the multiplicity of the work of this type.
It makes no sense to buy a laser measuring device for 15-20 thousand rubles for a one-time repair. However, you can rent it, these relatively small costs will fully justify themselves due to the high accuracy of measurements and the quick execution of work.
Hydraulic type
The hydraulic level is the simplest and, at the same time, accurate device for determining the position of the horizon for pouring, which allows you to determine the flatness of the floor without a laser level. It was invented and successfully used before the invention of electricity and electronics. His work is based on the physical law of leveling the liquid in communicating vessels. However, the measurement itself will not work, you will need an assistant.
Structurally, this device consists of two small cylindrical flasks with applied divisions and a thin hose connecting them. If used correctly, then the hydraulic level is not inferior to the most modern laser devices in terms of measurement accuracy. At the same time, it is quite simple to make it yourself. It is enough to have a hose (flexible tube) with an inner diameter of 8-10 mm and two plastic flasks, for example, syringe cases of the appropriate size.
As a hydraulic level, you can use a flexible transparent plastic tube with a diameter of at least 12 mm. In this case, flasks are not required, and the necessary marks can be applied using a hard-to-wash marker. True, the amount of water poured will increase significantly.
Work with a hydraulic level
Despite the very simple structure of the hydraulic level, working with it requires skills and precise adherence to a certain sequence of actions. Measurements require 2 people. The step-by-step procedure for determining the sex level is as follows:
- at a height of 1.0-1.5 meters on the wall, make a mark, which is called the starting or initial;
- pour in such a quantity of water inside the hydraulic level that both flasks installed at the same height are approximately half full;
- apply a mark to the surface of the liquid on the surface of the measuring vessels or remember the indicator on the scale existing on them;
- attach one of the flasks to the wall near the previously marked initial mark so that it coincides with the mark on the flask;
- attach the second end of the hose to the wall, but at a distance of about a meter from the first, at about the same height;
- wait 20-30 seconds until the water fluctuations end;
- after that, slowly raising or lowering the second flask, ensure that the water level in the first coincides with the starting mark on the wall.
After the first step, the next one is done, only the last one applied is used as the starting mark. The transition to the next room occurs through the doors, when one person holds the first flask near the mark, and the second enters another room.
After all the rooms are marked with a horizontal level, they must be connected by a visible line. The easiest way to do this is with the help of a marking cord, and in its absence, along a long ruler. Already at this stage it will be possible to see that the line of existing floors is not parallel to the applied level of the horizon.
Laser level operation
Marking the floor level for the screed using the laser level is so simple that it can be done by anyone, even without experience. Especially if the device has a built-in self-leveling function. Before repelling the floor level with a laser level, the main thing is to understand the principle of installing the device in the working position.
The procedure for marking the floor using a laser level is as follows:
- install the laser in such a place so that not only this room, but also the neighboring rooms can be seen from it;
- direct the beam to the walls in all places where it can get, and make marks;
- transfer the device to an adjacent room and after its installation combine the laser beam with the mark applied from the next room;
- mark the horizon level in a new room and do it everywhere.
After that, draw a visible line on the wall, connecting all the marked marks.
Rotation level
In technical essence, this type of level is a laser level with the ability to measure over long distances. The beam from the device can reach a surface that is 400-600 meters away. In addition, its design provides for the presence of a large number of useful additional functions.
The technology for performing horizon marking with a rotational level is no different from how to set the floor level with a laser level, but it will be indispensable when taking measurements at a distance of more than 30-50 meters. Such a device is very expensive and is used only in the professional work of large construction companies.
Using the construction bubble level
Marking the horizon using a rack level with a bubble capsule is only possible theoretically. When taking measurements, the transition to the next mark cannot exceed the length of the staff. And the main problems with ensuring the accuracy of measurements occur:
- when moving to an adjacent room;
- while turning in a corner or bypassing a protruding element;
- when passing wide doorways.
Therefore, it is better to immediately abandon the seemingly simple, but very inaccurate measurement method. Mistakes can be too costly in the future.
Zero floor marking
After using the hydraulic level, a conventional or a rotary laser, the horizon level was marked at a height of 1.0-1.5 meters from existing floors, zeroing can be done to perform concrete pouring. To do this, in all rooms it is necessary to measure the height from the base to the line previously applied to the wall.
Where the height will be the smallest, you should step back 30 mm from the surface, measure the distance to the horizon line and remember it. In the corner, measure the control height from the horizon line and screw a self-tapping screw into the wall. In another corner, repeat this operation. Tighten the cord on the screws, which will show the zero floor level.
After this, you should check for places under the tensioned cord where the distance to the floor is less than 30 mm. If there are such places, then a mistake was made during the execution of the work and it must be corrected.