Individual developers often use a reliable and inexpensive low-impact 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 foundation of the house must be strong and provide durable construction. Therefore, it would be useful to familiarize yourself with the basic requirements for the quality of work performed and select, depending on the geodetic assessment, the best design option.
On the features of the foundation and its application in construction
Calculating a shallow foundation is not a difficult task. It is always located slightly above the freezing level of the soil (depending on the latitude, it is usually 1-1.5 meters). To equip the foundation of the building, it is necessary to dig small trenches, removing the top layer of soil. Whereinshallow foundation should rest on the ground. Despite the fact that in general the ground under the house will be prone to movement, stability for light structures will be ensured. The idea of such a foundation is based on two principles:
- The central force is balanced.
- The effect of heaving is reduced.
In order to achieve the best balance effect due to the mass of the building, an accurate calculation must be made. It should be taken into account the fact that the use of such a structure is considered normal for the construction of frame and wooden houses. It is not recommended to build massive buildings on it due to its weak resistance. The fact is that the foundation rests on a not very compacted soil layer, which has a small bearing capacity. In the construction work, brick and concrete are used, which are additionally reinforced. The undoubted advantage of a shallow bookmark is the savings in building material.
What are the types of foundation?
Production 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 groundwater. It is complemented 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 economy, good heaving resistance, low labor intensity.
- Slab foundation. It is ideal for unstable ground. The reason for this is that the presence of a monolithic slab allows it to “float” with the soil during off-season temperature fluctuations. In this case, it is necessary to dig a pit half a meter deep. A layer of sand twenty centimeters is poured, then the same amount of rubble. 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 heaving soils for the construction of outbuildings and small panel houses. The essence of this project lies in the fact that houses made of timber and massive log cabins are placed on the pillars. They are installed on rocky areas. This option is frost-resistant, does not require much reinforcement and is quickly manufactured. But it is not suitable for loose soil, and repair is quite problematic. The pillars 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 layer of crushed stone 10 cm below.
What about clay and general versatility?
When holes are dug, this question arises. After all, if a shallow foundation is being built for a house, then it is important that it performs its 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 scattered deformations of strongly heaving clay soil throughout the structure. But if the question is about general versatility and reliability, then it is better to focus on a monolithicfoundation made of reinforced concrete.
How to do everything?
First of all, there is the design of shallow foundations. A number of questions need to be answered. The creation process is as follows:
- A geodetic assessment of the site is being carried out, as well as its planning.
- The soil is being removed.
- Crushed stone and sand are poured, then they are rammed.
- Forms are being installed.
- Using reinforcement for knitting.
- Concrete is being poured.
- Formwork being removed.
Do not neglect pillows in the form of gravelly sand, slag or fine gravel. Their task is to strengthen the soil in order to further reduce the deformation of the base.
About waterproofing
Because the depth is shallow, care must be taken to prevent moisture from penetrating. After all, the foundation will be constantly under the influence of melt and groundwater, as well as precipitation. In addition, moisture promotes corrosion of reinforcing elements and cracking of concrete. There are four options to prevent this:
- Smear. It implies the use of mastic or hot bitumen. Is the cheapest option.
- Paste over. It implies the use of rolled waterproofing materials like glass isol, roofing material, glass roofing material. They are glued or fused. Fastened from the inside of the formwork. After its removal, they remain on the foundation wall. True, their service life is short - only five or six years. Therefore, more reliable and durable materials are often used, 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, after which they level out. However, they do not affect the integrity of the foundations of the building.
- Combined version. In this case, the surfaces are first coated with mastic, and then roll materials are mounted on it. If a column foundation is selected, then the columns are covered from the ground level to the pillows.
- Penetrating. Considered progressive. 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 the new properties, ventilation holes can be made in the finished foundation without disturbing the waterproofing.
How can I further increase moisture resistance?
If you are building a shallow foundation with your own hands and there is no significant finance, then there are several additional opportunities to reduce the harmful effects of melt water and precipitation. What needs to be done for this? First of all, you should take care of the drainage and drainage system. Care must be taken 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 must be made with a slope.
About the possibilities of aerated concrete
What to choose, if anyunstable ground and a lot of financial resources? In this case, you should consider a good option, which is a shallow foundation for a house made of aerated concrete, made in the form of a monolithic slab. This option is suitable for any soil. It will minimize the shrinkage of the house. This is a good shallow foundation. Heavily will not be able to critically harm him. But there are some downsides here. The most important is the price. It will be difficult to complete a project with your own hands. So, you need to dig a pit, and for this you will probably need a bulldozer. In addition, aerated concrete is quite specific. Therefore, it is advisable to purchase from the factory and install quickly. And now let's take a closer look at the work process. Despite its rather good qualities, it crumbles quite easily. Therefore, it is necessary to calculate all the nuances of use and, if necessary, strengthen it.
Preparatory work
Let's say we need a shallow foundation on heaving soil of mediocre parameters. And you need to start construction with preparatory work. Initially, you need to mark the site and clear it of grass, debris, and the like. Then the earth is dug up. The walls and bottom are aligned. But the bottom is filled with coarse sand (or something else from those listed earlier). Such a pillow levels the soil. Additionally, you can pour it with water and then tamp it well. We should get a solid and even surface. To prevent leakage of liquid, polyethylene is laid on the bottom.
Reinforcement and pouring
In order for the foundation to be reliable and durable, it must be reinforced with metal components. For this, rods with a diameter of one centimeter are well suited. Reinforcement can be either horizontal or vertical. Additionally, you can tie with wire or weld. And now for the filling. 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 formwork, you can use boards, chipboard or other material that will allow you to create a fairly solid structure. For this, reinforcement with struts is used. How to fill? To do this, you can use the following algorithm:
- Mix concrete mortar. Approach this responsibly, because the quality of the foundation will depend on it. You can take the following recipe: cement M400, sand and gravel are taken in a ratio of 1:3:5. The dry ingredients are mixed first. Then water is gradually added and mixed. The solution should be viscous.
- After that, the filling itself is carried out. The procedure must be completed in one go. But this is quite problematic, so care must be taken that the next layer is poured before the previous one hardens. In parallel, you need to tamp the mixture.
- When the concrete is poured, the 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 for the first few days.twice a day.
- 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, crushed stone, cement is needed. Particular attention must be paid to the amount of water: remember, if the mixture is too dry, this is easily corrected. Dealing with liquid is much more difficult. Therefore, be careful and get a viscous mixture.
