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Foundation reinforcement: how is it done?

The design of a concrete foundation determines the stability and resistance of a building to the forces it experiences and requires reinforcement. Indeed, to ensure these functionalities, a metal reinforcement comes in composition with the concrete, so as to compensate for the lack of resistance of the latter to certain attacks. This is the foundation reinforcement. The realization of this preliminary work follows a few steps, making it possible to guarantee its good design.

The concept of foundation reinforcement

The reinforcement of a foundation consists of adding iron reinforcements wrapped in concrete. It is possible to buy ready-to-install structures called "foundation footings". Before installing the reinforcement, a geotechnical study is essential to define what diameter the reinforcement should have, depending on the stability of the ground.

The foundation reinforcement elements must be established in the trenches. Also, care must be taken that they are installed on wedges so that the soles or reinforcements can come into direct contact with the ground. Then, they will have to be grouped together using steel or iron wire to properly contain the foundation reinforcement. Furthermore, it would be wise to complete the work by providing additional reinforcement, to be placed on the corners. But we must not neglect the integration stage of the posts as well as the other essential structural details.

It is after the laying of the reinforcement that the channeling stages can be carried out. This is an essential process before spreading concrete on the foundations. With the channels in place, the concrete can be poured into the reinforcement, a step to be completed as soon as possible in order to prevent all the work from being spoiled by soil or rainwater.

The importance of a foundation reinforcement feasibility study

Being the base of the construction, it is the foundation that will transfer the weight of the structure to the ground and ensure its stability. The characteristics of the ground will condition the foundation reinforcement technique to be implemented. Added to this are the construction method envisaged and the geographical constraints of the region. This is why, before tackling the subject of the foundation itself and the reinforcement, it is advisable to consider the nature of the soil.

For this purpose, a feasibility study, which can also be referred to as a soil study or a geotechnical study, must take place. It is only after this analysis that the geotechnical engineer can inquire about the nature of the ground, in order to be able to determine its bearing capacity. In other words, the weight of the load that it will be able to support. Without this, it is impossible for this technician to determine the correct depth of the foundation.

Before carrying out the foundation reinforcement, a concrete study will complete this geotechnical study. The objective is to know the type of concrete to be used for the construction of the foundation. Note that a field analysis alone costs on average between 1500 and 2000 euros. A complete study generally costs more than 2500 euros.

Laying the reinforcement: a decisive step

This phase can be organized in different ways depending on the techniques used. The reinforcement is indeed different from one construction to another, both in configuration, in size and in the materials used. But basically, its implementation involves common operations, knowing that in all cases, the idea is to ensure the immobility of metal structures, especially when the concrete pouring phase comes.

The reinforcement is arranged in a trellis in each trench. It begins with the installation of square irons at each corner, which are held together by concrete planks. On these brackets are aligned the slender frames. The latter are placed on wedges to avoid contact with the ground. It is then necessary to add brackets above the device in place. Each part of the reinforcement is finally assembled with iron or steel wire, to always ensure the immobility of the structures.

The type of iron to be used for reinforcement

In construction, the use of irons of standard diameter, i.e. from 6 iron to 40 iron, is customary. They must be chosen according to the thickness of the foundations, but also in consideration of the constraints that the structure will undergo. This choice therefore varies from a single-family house to a high-rise building, including technical devices such as electric poles. Like any product and construction material, iron for reinforcement comes from different manufacturers whose techniques are not necessarily alike.

But in any case, for concrete reinforcement, it is necessary to use twisted or dug iron, so as to maximize its adhesion with the concrete. From this strong reinforcement/concrete connection results the resistance of the foundations. But despite compliance with these quality and design standards, the configuration of the reinforcement requires in-depth study and the intervention of an expert.

Prerequisites for foundation reinforcement work

Prior to the foundations, a geotechnical study is recommended. It is only after this that all the information concerning the nature of the soil will be known, and they are decisive in the choice of the foundation. Do not forget that such a project requires the rigor and know-how of a seasoned professional. Before the reinforcement, the preparation of the ground is of use so that the foundation is correctly carried out.

This requires terracing the ground. According to the plans of the house, we will delimit the land with stakes. These will be connected by a cord. Then, we will come and dig the foundations using a digger. After this step, it is time to dig trenches for the foundation. It usually needs a depth of at least 60 cm, a width of 50 cm. A laser level will be useful to check the depth of the trenches.

Finally, after digging the trenches, it is time to pour the first layer of clean concrete. Note that the characteristics of the concrete and the diameter of the corresponding irons will be the subject of a study and instructions from an engineer.

What must be done concretely and before the reinforcement

Shims must be placed so that the concrete does not come into direct contact with the ground. Then it's time to build the armatures. For this, we will need a worm wire which will be used to create armatures using an assembly of trellis panels also designed in iron. Using an excavator, we will dig trenches, in which we will install the reinforcements. The wedges are to be installed vertically in the corners. This is to better tie the foundation to the rest of the structure.

The realization of a reinforcement of a house: how is it done?

A wet foundation concrete due to rain falling directly after its completion will certainly affect its texture and resistance. Thus, it is important that this work is carried out in good weather. In addition, when the casting is done, masonry professionals recommend letting it rest for at least a fortnight to ensure good stability. The ideal is even to wait as long as possible before the work begins. At the same time, the construction must be done step by step.