Foundations - a monolithic slab

The most popular type of foundation for the construction of a building is considered to be a strip foundation. But sometimes its construction is impractical, for example, with a high level of groundwater. As an alternative solution, a monolithic slab is suitable.

General information

Why is a monolithic slab good? It evenly distributes the load over the entire land area where the structure will be erected. This feature becomes relevant when the upper layers of the soil have a low bearing capacity. In addition, the arrangement of such a foundation is not very difficult, which has long been appreciated not only by professional builders, but also by private traders on personal subsidiary plots.

A monolithic slab belongs to shallow structures, since it does not require digging a deep pit. Small deepening allows the foundation to remain stable when the properties of the soil change in conditions of negative temperatures and low vibration.

Advantages and disadvantages

Foundations - monolithic slabIn order to prevent typical mistakes when building a foundation from a monolithic slab, you need to know its positive and negative qualities, as well as some nuances.


  • An undoubted advantage is the ability to install this type of foundation foundation on any type of soil, in any area and in any climate, that is, everywhere.
  • The resistance to ground vibrations makes the monolithic slab an excellent option for places with seismic activity.

A monolithic slab is the only correct option for soils with a low level of bearing capacity. It is indispensable in cases where there is no possibility of a columnar base device.


  • It is forbidden to build multi-storey houses on a monolithic foundation. The best option is considered buildings in 1-2 with a maximum of 3 floors.
  • During construction, it is necessary to ensure that the slab rests on the ground with its entire surface, there should be no voids.
  • Since the installation requires many components due to the large area of ​​the foundation, the financial costs are significant.

It is imperative to remember about communications, the planning and implementation of which should be in advance, before installing a monolithic slab.

Erection of a monolithic slab

The main element of the considered type of foundation is a reinforced concrete slab. But before she is ready, it is necessary to carry out a number of works.

Pit and Layer Pie

  • After the approval of the construction project, they begin to mark the future foundation on the ground, using rope and pegs for this. Then they start excavation work - they dig a pit. It is better to use an excavator for this purpose, although this is not necessary.
  • After the pit has been dug, the walls are aligned at right angles to the horizon, a thorough compaction of the soil is performed. Then a sand cushion is poured onto the bottom and compacted with a vibrating plate. The sand can be replaced with a gravel-sand mixture. The selection of material is made taking into account the soil characteristics.
  • Further, all surfaces of the pit are covered with geotextiles in several layers. This prevents the erosion of sand by groundwater. On top of the material, a sand cushion is laid on the bottom, the thickness of which is at least 200 mm, and a drainage system is carried out to remove moisture from the base.
  • The next layer is a crushed stone pillow with a thickness of 150 mm. Crushed stone is designed to drain moisture from under the foundation. In swampy areas, it is recommended to make this layer 1.5-2 times thicker.
  • Then a foundation is made, for which low-grade concrete is used, and the layer thickness is about 60 mm. Pouring is done with a concrete pump or buckets. The cake should stand for 2-4 weeks.
  • Work continues with the installation of a waterproofing layer. In its capacity, you can use dense polyethylene or special compounds.
  • Before installing the formwork, the last layer, if necessary, is insulated. You can not use foam or mineral wool, it is better to opt for extruded polystyrene foam.

Formwork and reinforcement

A polymer membrane is installed on top of the crushed stone backfill. This will prevent excess moisture from entering the foundation. After that, the formwork panels are mounted, which must be well fixed so that they are not squeezed out by a large volume of concrete.

The next step is the construction of a reinforced mesh. The connection of the reinforcing rods is carried out using a knitting wire. In this case, the welding connection cannot be used, since it can significantly weaken the entire structure.

The final stage

Next, a concrete base is poured. For concreting the slab, a concrete mixture of the M300 or M350 brand is used. When placing concrete, be sure to use a deep vibrator to exclude air from entering the mixture. After completing the pouring, the surface should be covered with plastic wrap. This will allow the concrete to gain strength faster and prevent cracking. You also need to moisten the monolithic foundation within a week, if the weather is hot or windy.

After the concrete base has hardened, you can remove the formwork and proceed to the final waterproofing. For this purpose, bituminous mastic and roofing material are used.

Subject to the construction technology, the foundation from a monolithic slab will turn out to be strong and will last for many years.

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