The completion of a large stage of construction work is the installation of floor slabs on the foundation. Most often, laying reinforced concrete floor slabs on a base is used for brick buildings or houses and foam concrete blocks. The work on the subsequent floors and types of floors is described in detail in the article “Installation of floor slabs”. Further, we will focus only on closing the basement. To properly put the elements on the basement wall, it is necessary to take into account the features of the work.
Monolithic reinforced concrete belt
If the foundation for the building is made of prefabricated concrete blocks, you will need to take additional measures to strengthen the structure before starting the installation. Laying a concrete belt on the wall under the slabs is necessary to:
- to ensure uniform load distribution from individual floor elements to individual foundation blocks;
- increase the strength of the foundation tape in bending;
- align the edge of the foundation in order to properly lay the slabs;
- increase the rigidity of the building with small movements of the soil.
The fact is that the factory-made foundation blocks do not have reinforcement. They are designed for central compression.
Floor slabs on the foundation under the outer walls rest only on their inner part, which creates an eccentricity of the load (displacement relative to the center), as a result of which a bending force appears, which the concrete cannot withstand without reinforcement.
According to the normative documents for cutting the foundation wall, a belt of concrete B20 with a thickness of 200 mm is provided. The belt is made using monolithic technology. With laying of longitudinal reinforcing bars in two rows.
Reinforcement is a spatial framework, most often consisting of four longitudinal rods connected to each other in the horizontal and vertical plane by smaller diameter reinforcement rods (clamps).
Thanks to the reinforcement, the structure easily copes with bending. Due to the monolithic manufacturing technology, the tape has no vertical joints and provides spatial rigidity along the entire perimeter of the building.
Filling is performed in two ways:
- the entire perimeter at a time;
- in layers.
Layered work may be necessary if the height of the belt is greater than the recommended one, and circumstances have arisen that interrupt the execution of the work. Correctly fill the entire mixture at a time. In this case, joints of the concrete mix with different characteristics and degree of solidification are not formed, which will significantly increase the strength of the entire structure.
Plate mounting
Installation of floor elements in the design position begins with determining the amount of support of the structure to the foundation. Laying the slab according to regulatory documents is necessary in compliance with the following requirements:
- support on a brick socle of plates up to 4 m long - 70 mm;
- support on a brick socle of plates from 4 m long -90 mm;
- resting on concrete - 60 mm.
The above values are the minimum requirements. It is best to provide stock. When erecting buildings, specialists most often provide for the support of plates on 120 mm. This value allows you not to worry about the fact that workers can stack the product with a slight displacement.
Lay on the foundation of the floor should be supported on two sides, without intermediate. The appearance of abutment points in the middle leads to the formation of cracks and, as a result, to fracture of the plate in the place of support.
Thermal insulation material is applied to the end of the product, which is necessary to prevent cold bridges. Cold bridges are dangerous because they lead to the following unpleasant consequences:
- condensation at the point of support;
- the appearance of mold and fungus;
- decrease in the efficiency of thermal protection of the building, the appearance of a section through which heat leakage occurs;
- violation of temperature and humidity conditions.
As a heat-insulating material used:
- pieces of mineral wool wrapped in polyethylene;
- polystyrene wrapped in polyethylene;
- extruded polystyrene foam (penoplex).
It is necessary to wrap polystyrene foam and mineral wool in polyethylene to prevent moisture from penetrating the insulation. Water affects these materials in different ways, but there is only one result - a decrease in thermal performance. In the case of mineral wool, which is highly hygroscopic, the performance is reduced due to the presence of moisture.
Polyfoam is not capable of absorbing liquid so well, but even a small amount of it between the granules of the material at low temperatures leads to the scattering of the plate into small balls.
Important! The lifting equipment on the site must be placed so that it does not damage the building structure.
After preparatory work and determining the amount of support, the laying of plates on the foundation begins. Installation of the ceiling is carried out in the following order:
- The voids of the slab at the points of support are sealed with lightweight concrete or mineral wool insulation. This is done to increase the strength of the structure in places of crushing the wall.
- A layer of brand mortar from M100 and more with a thickness of 20 mm is applied to the foundation.
- The plate must not be turned over. The product is different at the top and bottom. The stretchable lower surface has a stronger reinforcement than the compressible upper. If installed incorrectly, the item may break in half. Visually, the upper and lower surfaces can be distinguished by the smoothness of the base. Overlappings in the upper part have an uneven and rough appearance. the lower surface will serve as a ceiling in the future, so it is made smooth. This difference is due to the fact that the manufacturing process takes place in forms. The solidification of the surface at the bottom of the mold gives a smooth strontium. The upper part in contact with air is rough.
- For work, you will need three to four people. One of the workers secures the plate to the crane hook. For the installation of the ceiling, a special four-branch line is used, which is fixed to the mounting loops provided in the plate. Two workers lay the slab in the design position and unfasten it from the sling. Another person may be needed to give commands to the crane operator if his eye contact with the workers is not possible.
- You need to mount the plates tightly to each other. If the size of the room does not allow to completely cover it in width with standard products, provide for a monolithic termination of a small area that does not allow to fit a reinforced concrete element in width.
- Installation on the foundation ends with anchoring of the plates between themselves and with the walls. This will create a hard drive floors and provide increased stability of the building. Anchors along the length of the wall are located every 2-3 meters.
The installation of reinforced concrete elements on the foundation in compliance with the technology will ensure a long service life of the building and the safety of residents.