Individual developers often use a reliable and inexpensive, slightly buried foundation. What is the reason for its popularity? What is the structure of a shallow foundation? Is it difficult to build it alone? These and other important questions of the construction process will be answered.
general information
The base of the house must be solid and provide a durable construction. Therefore, it is worthwhile to get acquainted with the basic requirements for the quality of work performed and select, depending on the geodetic assessment, the optimal design option.
About the features of the foundation and its application in construction
Calculation of a shallow foundation is not difficult. It is always located a little higher than the level of freezing of the soil (depending on latitude it is usually 1-1.5 meters). To equip the base of the building, it is necessary to dig up small trenches, removing the top layer of soil. At the same time, the shallow foundation should rest on the ground. Despite the fact that in general the land under the house will be prone to shifts, stability for light structures will be provided. The idea of such a foundation is based on two principles:
- The central force is balanced.
- The influence of heaving is reduced.
To achieve the best balance effect due to the mass of the building, an accurate calculation is necessary. It should be borne in mind that the use of such a design is considered normal for the construction of frame and wooden houses. Massive buildings to build on it is not recommended due to poor durability. The fact is that the foundation is based on a not very compacted soil layer, which has a small bearing capacity. In the construction works, brick and concrete are used, which are additionally reinforced. The undoubted advantage of small bookmarks is the saving of building material.
What are the types of foundation?
Manufacturing technology depends on the type of soil:
- Strip foundation. It is a strip that is laid along the contour of the building. This option is built on soil of medium antinode and with a low level of subsoil water. It is supplemented by a reinforcing frame, for which steel bars and wires are used. The depth of the bookmark for him is half a meter. The advantages of this option are profitability, good resistance to heaving, low laboriousness.
- Slab foundation. It is ideal for unstable soils. The reason for this is that the presence of a monolithic slab allows you to "float" together with soil during the temperature fluctuations of the off-season. In this case, it is necessary to dig a pit half a meter deep. A layer of sand is poured into twenty centimeters, then as much crushed stone. The reinforcing mesh is laid. All this is poured with concrete. The thickness of the slab depends on the estimated weight of the building.
- Shallow columnar foundation. It is used on non- and slightly porous soils for the construction of household buildings and small panel houses. The essence of this project is that houses made of timber and massive log houses are placed on poles. They are installed on rocky areas. This option is resistant to frost, requires not so much reinforcement and is quickly manufactured. But it is not suitable for loose soil, and the repair is quite problematic. Poles are made of brick or concrete and installed at a distance of up to two meters between them. The dimensions of the pits for them are chosen 50 (40) x 50 (40) centimeters, pouring a crushed stone layer of 10 cm below.
What about clay and general versatility?
When digging holes, this question arises. After all, if a shallow foundation is being built for the house, then it is important that he carry out his task well. On clay, it is better to build a strip foundation. This option is suitable due to the fact that it is connected in one structure and allows you to redistribute uneven and disparate deformations of highly clay clay soil throughout the structure. But if the question is about general universality and reliability, then it is better to focus on a monolithic foundation made of reinforced concrete.
How to do everything?
First of all, the design of shallow foundations is in progress. It is necessary to answer a number of questions. The creation process is as follows:
- Geodetic assessment of the site, as well as its layout.
- Soil is taken out.
- Crushed stone and sand are poured, then they are compacted.
- Formwork is installed.
- Used fittings for knitting.
- Concrete mixture is poured.
- Formwork is removed.
Pillows in the form of gravelly sand, slag or small gravel should not be neglected. Their task is to strengthen the soil in order to further reduce the deformation of the base.
About waterproofing
Since the depth is shallow, care must be taken that moisture does not penetrate. After all, the foundation will be constantly affected by melt and groundwater, as well as precipitation. Additionally, moisture contributes to corrosion of reinforcing elements and cracking of concrete. There are four options to prevent this:
- Coat. It involves the use of mastic or hot bitumen. It is the cheapest option.
- To paste over. It implies the use of roll waterproofing agents like glassisol, roofing material, glassroberoid. They stick or fuse. Mounted on the inside of the formwork. After its removal, they remain on the wall of the foundation. True, their service life is short - only five to six years. Therefore, they often use more reliable and durable materials such as stabilized polyethylene or PVC compound. At the same time they are glued with wide sheets. When temperature fluctuations occur or precipitation occurs, the elastic sheets are deformed and then leveled. However, they do not affect the integrity of the building.
- Combined option. In this case, the surfaces are first coated with mastic, and then roll materials are mounted on it. If a columnar foundation is selected, then the pillars are covered from the ground level to the pillows.
- Penetrating. It is considered a progressive way. It implies the addition of special additives to concrete, which will increase the moisture resistance of the structure. An example is Aquatron, Kalmatron, Penetron. Thanks to new properties, ventilation holes can be made in the finished foundation without violating the waterproofing.
How can moisture resistance be further enhanced?
If you build a shallow foundation with your own hands and there is no significant finances, then there are several additional opportunities to reduce the harmful effects of melt water and rainfall. What needs to be done for this? First of all, care should be taken about the drainage and drainage system. It is necessary to ensure that they divert liquids as far as possible from the structure. And so that water does not leak under the building, the blind area needs to be done with a slope.
About the possibilities of aerated concrete
What to choose if there is unstable soil and a lot of financial resources? In this case, you should consider a good option, which is a shallow foundation for the house of aerated concrete, made in the form of a monolithic slab. This option is suitable for any soil. It will minimize shrinkage at home. This is a good, shallow foundation. A fouler cannot critically harm him. But there are some disadvantages. The most important thing is the price. Do-it-yourself project will be difficult. So, you need to dig a pit, and for this, you probably need a bulldozer. In addition, aerated concrete is quite specific. Therefore, it is advisable to purchase from the factory and quickly install. Now let's take a closer look at the work process. Despite its pretty good qualities, it crumbles quite easily. Therefore, it is necessary to calculate all the nuances of use and, if necessary, strengthen it.
Preparatory work
Suppose we need a shallow foundation on a heaving ground of mediocre parameters. And you need to start construction with preparatory work. Initially, you need to mark the site and clean it of grass, debris and the like. Then the earth is dug up. The walls and bottom are aligned. But the bottom is covered with coarse sand (or something else from those listed above). Such a pillow levels the soil. In addition, you can pour it with water and after that, well-rammed. We should get a solid and even surface. To prevent fluid leakage, polyethylene is placed on the bottom.
Reinforcement and filling
For the foundation to be reliable and durable, it must be strengthened with metal components. For this, rods having a diameter of one centimeter are well suited. Reinforcement can be either horizontal or vertical. Additionally, you can wire or weld. And now for the fill. Before you start doing it, you need to install the formwork for the basement of the foundation. To better control the shape of the walls, it is better to place it not on the surface of the earth, but at the bottom of the trench. As a formwork, you can use boards, chipboards or other material that will allow you to create a fairly solid structure. To do this, use reinforcement struts. How to fill in? To do this, you can use the following algorithm:
- Knead the concrete solution. Approach this responsibly, because the quality of the foundation will depend on it. You can take the following recipe: M400 cement, sand and gravel in a ratio of 1: 3: 5 are taken. Dry components are initially mixed. Then water is gradually added and mixed. The solution should be viscous.
- After that, the filling itself is carried out. The procedure should be performed in one go. But this is quite problematic, so you need to make sure that the next layer is filled before the previous one hardens. In parallel, you need to ram the mixture.
- When concrete is poured, work must be stopped. After the solution has set, it must be covered with plastic wrap. In order for the mixture to dry evenly, the surface must be moistened with water twice a day for the first few days.
- If necessary, trim the upper part after drying.
Conclusion
Making a shallow foundation is easy. But in order to avoid disappointment, for the first time it is necessary to calculate everything that is possible: how much sand, gravel, and cement are needed. Particular attention should be paid to the amount of water: remember, if the mixture is too dry, it is easily fixed. Dealing with liquid is much more difficult. Therefore, be careful and get a viscous mixture.