Construction of houses

How to check the quality of the foundation

The foundation, first of all, is not just the underground part and the base of the house, it acts as a transition element between the uneven ground surface and the flat plane of the house box. The quality of the erected house directly depends on the quality of this structure. If the foundation is poorly built without observing technology, then the house can collapse at any moment, since all loads are transferred from all other parts of the structure, such as floors and walls, through this structure. Therefore, it is so important to know how to determine the quality of the foundation of a house..


Features of the device of a high-quality foundation

The load on the foundation is equal to the load on the soil itself. It’s good if you have a large granite slab under your house that has been unshakable for a million years. But in practice this is not at all the case! Therefore, before starting the construction of a country house, it is necessary to find out in more detail what type of soil is in a given area, as well as what properties it is characterized by.

When laying the foundations, you cannot do without preliminary engineering and survey work (at least in minimal volumes). Such surveys will help you understand whether the soil will be stable, whether there will be a distortion or landslide of the foundation, whether the basement will flood during the spring floods. In general, remember that you can conquer nature and put a house in a place you like, the main thing is to know what to do in this or that case..

It’s pretty good when the foundation is laid on an embankment of stones of natural origin: in this case, the reliability of the foundation under the house will not cause concern, and there will also be no non-lifting costs for the foundation. The most reliable are sandy homogeneous soils, which consist of coarse sand. With a correctly installed foundation, a uniform settlement occurs in the soil and, as a rule, in the future, the foundation does not warp and does not experience strong loads from the soil.

Clay soils, dusty and fine-grained sand show approximate “behavior” only in dry weather. With a large amount of moisture, they become fluid, and in the winter cold season, swelling occurs, and because of this, they press with tremendous force on the foundation structure. And this suggests that the structure may skew, and cracks may appear on the walls. To prevent this from happening, you need to take special measures, that is, deepen the base of the foundation below the freezing of the soil.

The most unfavorable option is a peat base, which is also found in our area. It is clear that only a madman who does not appreciate the life of loved ones and his own can put a capital structure on peat. And yet, if you come across such an unsuccessful site, you need to remove all the peat and fill the pit with sand, thus making a sand pillow.

Another important factor that affects the quality and structure of the foundation is the design of the house itself. It is not necessary to be a master in the field of housing construction in order to understand: a relatively light frame house or a heavy brick cottage, of course, requires a different approach to laying the foundation. In the case of large financial resources, you can build a huge reinforced concrete slab for a light structure, but the question of reasonable savings will not leave anyone indifferent.

Foundation technologies

Before characterizing the technologies for constructing foundations, it is necessary to discard such an option as driving powerful piles to a great depth, because this method is excellent only for the construction of skyscrapers. Business does not come to such radical methods of construction in private housing construction. The most common structures are strip, columnar and slab foundations..

Slab foundation

Complex heaving and bulk soil often requires a monolithic reinforced concrete slab to be brought under the structure. The reliability of the foundation with this structure will increase, since incredible efforts are required to move such a foundation. But, naturally, a reinforced concrete slab needs a lot of material..

If the slab is very thick, then the slab foundation will in some cases be even cheaper than the strip one. But if, in addition to everything else, the slab foundation is also recessed, then, in addition to a large amount of concrete, you will also have to bring in a lot of crushed stone and sand for the construction of a “pillow”.

Strip foundation

The most common option is a tape-type foundation. At the same time, the concrete foundation is made under the supporting structures inside and around the perimeter of the building. Pouring concrete is not at all necessary; if necessary, such a base can be made from ready-made blocks and from bricks. At the same time, it is important to understand how to check the quality of the foundation for the house..

It happens that strip foundations are made in profile, while the base of the foundation lies below the freezing depth by about twenty centimeters, and sometimes shallowly buried – 50-70 centimeters from the surface of the earth. Usually, the upper part of the strip foundation is a plinth, which can be sinking, protruding or flush with the outer wall of a residential building.

As a rule, rather heavy houses are installed on a strip foundation with varying degrees of depth. If the house has a basement, ground floor or a garage under the house, then you need to give preference to the strip foundation. Proceed in the same way if the ground plinth serves as a retaining wall.

Column foundation

When conditions permit, it is possible to make a columnar foundation, while significantly saving on materials. See for yourself: in this case, the foundation is not solid, but a point foundation – supporting the structure only at certain reference points: at the intersection of the walls, under the supports of very loaded girders, in the corners. At the same time, much less building materials are needed than when constructing a strip or slab foundation, hence the savings.

Basically, a columnar foundation is used for frame, log or panel houses of light weight. The cheapest pillars are wooden ones, which are still used when it is necessary to erect a light temporary structure. If you have to demolish the building in a couple of years and build something new in its place, then there is no point in spending money on expensive reinforced concrete, and then dismantling the foundation, this is very laborious and costly.

Column-strip foundation

In addition to the listed varieties, completely different types of foundations are also used, and every year various novelties appear in this traditional field of construction. For example, on deep-freezing and difficult soils, sometimes a columnar-strip foundation is built. In this case, first, wells are drilled to a depth that is slightly below the level of soil freezing..

The lower part of such a well is expanded using a special plow. Further, reinforcement is inserted into the wells and they are poured with concrete. Such a pillar can withstand a load of 5 or even 10 tons, and the most interesting thing is that even the Arctic frost cannot squeeze it out of the ground. Next, a grillage tape is cast between the pillars in a conventional formwork, which is reinforced and then placed at a short distance from the ground, taking into account the fact that frost heaving of the soil may occur.

Subtleties of checking the quality of the foundation

If the house has already been built, and you have doubts about the quality of the foundation, or you are buying a plot with a foundation and want to build your house on this basis, then you must perform a technical survey of the foundation, since the future of your house depends on the quality of the foundation. It often happens that the owners started building a house, but they are not sure how well the foundation is poured. In this case, there is a need to control the quality of the foundation, because there is a likelihood of the formation of cracks in the concrete when piles are directly driven into the ground..

Visual inspection of the foundation

So, the first thing we do when checking the quality of the foundation is to visually inspect the structure. You have to make sure that the correct foundation has been made for the soil on which you will build the house. After all, all types of foundations are specially designed for different conditions – both tape, and monolithic, and on piles..

It is best to check the foundation, of course, after winter time due to the fact that the soil will pass a kind of “defrost-freeze” test. So the ideal option would be to let the building overwinter at least once, in which case all the shortcomings will surface..

A visual inspection of the foundation is carried out in the following sequence:

Foundation tester

To check the quality of the foundation, you can use a special device called a pile diagnostic device. The principle of operation of such a device is quite simple, it is based on the method of seismic spectral flaw detection: according to the design, the operator strikes with a special hammer, which fixes the force of the impact, and a special vibration sensor is responsible for fixing vibrations that are reflected from internal defects and the edges of the structure in it.

Such an examination will take much less time, and the human factor will be reduced to almost a minimum: the automatic equipment will not miss flaws that the eye can overlook. Such equipment is not only intended for pile quality control. It can also be used to inspect other support elements such as floors and columns. Such devices, as a rule, can also perform sonar functions (sound fault detection).

Thus, you know how important a well-executed foundation is. Remember that before pouring the foundation for a house, you must: do an engineering and geological survey, develop a project for a house and foundation, perform a design calculation of the foundation and foundation for a power load, use only high-quality building materials and specialized equipment, and also comply with all technologies and standards.