One of the most important elements of any home is the foundation. If you execute it correctly, then the structure after a short time will not become worthless. The slab foundation is characterized by high reliability and durability, therefore it is more often chosen by home craftsmen and builders.
But if you use the services of specialized companies, then they will request for such a design more than a third of the cost of the building. From your own experience you can make sure that the costs of this part of the construction are not so high. The slab foundation you can do yourself.
When to use?
A monolithic foundation is a slab, which is suitable for the construction of residential and non-residential buildings. This applies to those buildings that will not have a basement. One of the main advantages is that you do not have to lay logs under the floor, since concrete can appear as a ready-made rough coating.
Such a base is distinguished by earthquake resistance, high strength and is not washed by water, because the area is quite large. This construction under the house will be appropriate if there is problem soil on the site.
Technology features
A monolithic foundation is a slab that can be created using one of two technologies. If you plan to make the structure monolithic, then first you need to install the formwork, and then assemble the reinforcement cage. Concrete is poured into one approach. When the foundation is planned to be prefabricated, it is constructed of reinforced concrete slabs, the seams of which are poured with concrete. The design does not require formwork, as well as the installation of a reinforcing cage.
But this approach has its drawbacks: you can’t achieve the required thickness, because the plates are made at the factory and have certain parameters. In fact, such a design will not be monolithic, which makes it less durable. To lay the plates you need a crane. If the soil has irregularities, then it will be quite difficult to lay the products, it will be necessary to level them, which is almost impossible to do manually.
How to make a stove
A monolithic slab under the foundation is made by technology, which provides for the preparation of a foundation pit of the desired depth and size. A layer of sand or gravel is poured onto the bottom, after which communications are laid, for example, pipes for water supply and sewage. A concrete screed is placed on top. This design must be insulated, and then install the formwork, as well as the reinforcing frame. The slab in the next step can be filled with concrete.
Determination of plate thickness
The thickness of the foundation plate depends on which house you plan to build. The heavier the building, the thicker the slab should be. If the structure is shallow, the thickness should not exceed 30 cm. However, the foundation can be made deep. In this case, its thickness will be 1.5 m.
For private construction, a foundation is usually used, the thickness of which is not more than 40 cm. The foundation slabs are poured with concrete of the M-200 brand. The mobility of the solution should be P-3, and the resistance to cold is equal to the limit of F200. It is important to take into account the waterproof marking, which should not be less than W8.
Construction stages
The first step in the construction of the slab foundation will be the marking of the territory. In order to make it more convenient to work with formwork, it is necessary to add about a meter on the sides of the pit. The platform needs to be leveled: the only way to normalize the pressure on the plate, which should be uniform. The bottom of the pit is leveled, it is important to get rid of differences and mounds.
To form a drainage system, it is necessary to dig transverse trenches through which water will be discharged. Geotextiles are laid at the bottom of the trench. Then you should lay the plastic pipes with perforation. All this is covered with fine gravel, and then covered with geotextiles.
Formwork installation
The foundation plate is poured into the formwork. It is knocked around the perimeter of the boards. The outer side must be strengthened by struts. Once the fence is ready, you need to make a pillow, which consists of a layer of sand and gravel. Such preparation is needed to remove moisture from the structure and cushion the soil. The pillow may have a thickness ranging from 15 to 30 cm.
If the earth is moist, then you can add finely grained gravel. The preparation is well compacted. No traces of shoes should be left on the sand. After it is necessary to make waterproofing. It is necessary to prepare a solution of sand and cement, which is filled with a pillow. The thickness of this layer will be 5 cm. After that, you can lay the waterproofing in the form of a rolled material, such as roofing material. It is laid with an overlap on the formwork.
After the waterproofing is ready, you can proceed with the reinforcement. For this, fittings are used, welding is excluded. The rods are pulled together by wire. At the next stage, you can start pouring the foundation slab. It is better to order a machine with a ready-made mortar, in this case you can work out the concrete at a time, it will turn out homogeneous and will not be covered with cracks.
Thickness calculation
The simplest calculation of the thickness is carried out by summing the gap between the reinforcing mesh, the thickness of the reinforcement and the concrete layer. The optimal value is 30 cm. The final result is determined by the composition of the soil and the uniformity of the bedding. You must consider the width of the sand cushion and the drainage layer.
For a slab foundation, remove the topsoil and dig a pit, the depth of which can be 0.5 m. This value is determined taking into account that the crushed stone is 20 cm in layer and 30 cm in sand. If you add up the available data, you can understand that the minimum thickness of the foundation slab cannot be less than 60 cm. This indicator varies depending on the characteristics of the soil and the weight of the future building.
For a brick building, the slab can be 5 cm thicker of the same base for a foam concrete house. If the building has a second floor, and the walls are made of brick, then the thickness of the monolithic slab can be increased to 40 cm. This value can be more, which depends on the configuration of the structure and its weight. During the construction of a two-story house made of foam concrete, it can be 35 cm.
Example of calculating volume and thickness
If you intend to calculate the foundation slab, you can determine the amount of concrete for pouring. For this, the sole area is multiplied by the thickness. You can deal with the calculation by referring to a specific example. If the house will have a size of 10 x 10 m, and a monolithic foundation - a thickness of 0.25 m, then the volume of the slab will be 25 m 3 . This value is obtained by multiplying the three figures mentioned.
If you plan to build a foundation slab with your own hands, you should know how much concrete is needed to carry out the work. It is also necessary to take into account the installation of stiffeners, which are necessary to ensure resistance to deformation. They will be located along and across the plate at a distance of 3 m, forming squares. For the calculation, it is necessary to determine the height and length of the stiffeners. The last indicator is 10 m. A total of 8 ribs will be required, so the total length will be 80 m. For rectangular ribs, the volume will be 16 m 3 . This value is obtained as follows: 0.25 x 0.8 x 80. For trapezoidal ribs, the lower base is 1.5 times the thickness of the foundation, and the upper is 0.8.
Slabs for tape bases
Slabs of strip foundations are also called foundation pillows and are used as the foundations of low-rise buildings. With their help, you can extend the life of the bearing foundation and distribute the load between the elements. This approach to building a building is especially relevant if the soil tends to sag in the winter. The foundation blocks have a rectangular shape, so the load on the soil from the bottom product increases with each stacked row.
If the base is too high, then due to the load on the ground subsidence of the structure may occur, which will lead to a distortion of the geometry of the building. The only sure way out of this situation is to reduce the load on the soil. This can be done by reducing the mass of the foundation structure or increasing the area. For the second method, tape plates were invented that act as an adapter between the soil and the foundation blocks.
Finally
The foundation, which is based on a plate, is a solid foundation. It contains reinforced concrete, which is laid over the entire area of construction. Such designs are very durable and have less pressure on the ground. But only the monolithic foundation possesses such advantages, the thickness of which is determined taking into account the laying depth and loads, the nature of the soil, as well as the weight of the concrete.