Under suburban and multi-storey buildings, bases of various types can be erected. For example, in some cases, solid slab foundations are poured under the houses. Such grounds, in turn, can also be classified into several types. Before starting the pouring of a solid foundation, of course, his project is compiled without fail.
Need for application
Slab foundations are one of the most reliable types of foundations of houses. Tape and columnar in this respect, they are in any case superior. However, the area of construction of this type are very large. They are solid foundations of a solid thick slab under the whole house.
The construction of such structures is, of course, very expensive. In addition, for example, during the construction of a low-rise country house, the foundations of this type, unlike others, cannot be poured with concrete using artisanal means. In this case, cement mortar has to be ordered ready. Liquid concrete is poured into the formwork when such a foundation is erected from the tank using a hose. And this, of course, makes the construction of the foundation even more expensive.
Due to the high cost, foundations are erected with a solid slab under the houses quite rarely. Their construction is considered advisable mainly only when the building is being built on non-static soils. In this case, a continuous slab can maintain the integrity of other building structures during movements.
Also, bases of this type can be erected under various kinds of buildings of a small area. For example, sometimes garden gazebos are built on such a foundation. Most often, under similar constructions, of course, the bases are still constructed columnar. A solid foundation, however, in this case can also be a good solution.
The stove under the gazebo or small extension, of course, will have very small dimensions. With a small depth of concrete, it will not take much. In addition, it will be possible to fill the plate under the gazebo without using special equipment with assistants - manually at a time.
Basic types by fill method
During the construction of houses, solid foundations can be erected:
shallow;
shallow;
heavily buried.
The first type of base can only be used in areas where there is no frost heaving. Extremely light houses of small area are built on unfilled foundations. The thickness of such structures, depending on the type of soil, can vary between 30-50 cm. Sometimes heavy brick houses are also built on such foundations. But it is allowed to use undecked base slabs under such structures only on rocky soils.
Shallow foundations are usually built during the construction of small private houses. The foundation pit under them is dug up very shallow. In most cases, when pouring such a base on the marking area, the upper fertile soil layer is simply removed. Heavily buried foundations are erected only on heaving soils under heavy buildings.
Design Types
In this regard, continuous foundations are distinguished:
The first type of foundation is a regular concrete slab. Solid monolithic foundations are the simplest and most popular variety of such structures. But on very unreliable soils, bases with stiffeners can also be equipped. The latter are poured directly under the stove.
Sometimes the ribs at the trellised bases can be directed upwards. In this case, the walls of the building are erected on them using approximately the same technology as on strip foundations. When using this type of solid foundation in the building, among other things, you can equip the basement. In this way, for example, heavily buried slab foundations are often poured.
Design
When developing drawings of a solid foundation, of course, you should first determine its thickness. When constructing high-rise city houses, such calculations are done exclusively by specialists using various kinds of formulas.
In individual construction, the project of a solid reinforced concrete foundation for a small house can be developed independently. To calculate in this case, most likely, you don’t even have to. There are standard indicators of the thickness of such bases for various types of buildings, which can be guided in the process of designing.
So, for example:
gazebos and light extensions are built on solid foundations with a thickness of 100-150 mm;
under light frame private houses, as well as single-storey log and stone blocks, the foundations of this type are most often poured by 200-300 mm;
solid foundations with a thickness of 250-350 mm are erected under concrete structures or brick buildings or two-story chopped ones;
under two- or three-story houses made of brick or concrete, it is supposed to fill the slab bases with 300-400 mm.
Load collection
If you wish, of course, you can independently make a more accurate calculation of the solid foundation during the construction of a country house. The collection of loads during pouring of such a structure is determined taking into account:
constant pressure from the roof, floors, walls, etc .;
temporary loads - snow, furniture, people.
The constant load is calculated depending on the materials used for the assembly of the building structures and their parameters. The mass of walls according to the standards is supposed to be taken minus the openings.
The weight of the plate itself when performing calculations of solid foundations:
on sandy soils is not taken into account;
divided into clay divided in half;
on quicksand is fully accounted for.
Snow temporary load on the foundation is determined by table 10.1 SP. In this case, the parameter is taken for this particular area. Evenly distributed loads for residential buildings are accepted at 150 kg / m 2 . The weight of very heavy items, which are supposed to be placed in the house, is taken into account separately.
Material selection
The collection of loads on such bases is calculated, thus, in exactly the same way as on columnar and strip foundations. A solid foundation, like any other, is poured in most cases, of course, from concrete mix. Having determined the thickness of such a foundation, you can easily calculate the amount of material needed for its construction.
Concrete for the construction of solid foundations is usually used grades B15-B25. You can, of course, fill the slab foundations with a better and more durable mortar. However, this is usually considered impractical due to the cost of work. One of the undoubted advantages of slab bases in any case is increased strength.
In addition to concrete, for the construction of such a foundation, materials such as sand, reinforcing bars and a waterproofing insulator will also be needed. To assemble the formwork, you will need to prepare boards. To use for creating the casting form of the slab base of the house, according to the standards, lumber is supposed to be at least 30 mm thick. Before pouring mortar, it is recommended to lay the formwork boards with plastic wrap.
Concrete and reinforcement
The amount of material necessary for pouring such a base is calculated, in addition to the plate thickness, taking into account that:
at the edges, the foundation should extend at least 10 cm outside the building;
reinforcement rods for the slab should be 6 cm shorter;
rods are installed when pouring in increments of 40 cm;
the sand cushion should also go beyond the construction by 10 cm;
waterproofing when filling is laid with a small margin.
As a waterproofing agent for pouring such a foundation, it is desirable to use roofing material.
Work procedure
Slab foundations are poured in a few steps. Previously, a pit of design depth is excavated at the site.
Further, crushed stone is poured at the bottom of the pit to equip the drainage layer. Sand is laid on top to create a reinforcing pad. The thickness of this layer should be at least 15 cm.
At the next stage, when arranging a continuous slab foundation, a multi-tier reinforcing cage connected with the use of wire is installed on the sand cushion. In order for the volumetric mesh to subsequently be in the thickness of concrete, special plastic supports or bars of 5 cm thickness are pre-arranged at the bottom of the pit.
Further along the edges of the pit, formwork is mounted from the boards. For its assembly, self-tapping screws and props from timber are used.
At the final stage, concrete from the tank is poured into the pit. In the process of laying the mixture manually eliminate emerging defects. From time to time, a layer of concrete in the pit is pierced with shovels to eliminate air bubbles. At the final stage, the surface of the plate is carefully leveled.
To fill the lattice continuous foundation, longitudinal trenches are dug in the foundation pit before backfill. Concrete poured into them subsequently forms ribs.
The final stage
After the foundation is poured, it is desirable to cover the plate with plastic wrap. Subsequently, the stove should be periodically moistened with water for 2 weeks. This will prevent surface cracks. To erect walls on such a basis, as on any other, is allowed only after the concrete has fully matured. That is, approximately 28 days after pouring.