The foundation is the base of the house, which allows more even distribution of the load from the building to the ground. There are several types of foundations. The choice is carried out depending on various factors: the weight of the future structure, which depends on the number of floors of the building and material of manufacture (brick, gas silicate, timber, etc.), type of soil , presence / absence of basement .
If you make the wrong choice and calculation, the weak foundation under the weight of the structure will sooner or later begin to collapse , the basement and walls of the house will crack .
First the characteristics of the soil at the construction site are taken into account. To determine them, you need to dig several holes. However, you can simply ask the nearest residents about the results of their geological surveys.
Table 1. Types of soil.
|Rock and stony||By themselves, they are a good base and do not change their properties under any seasonal climatic phenomena|
|Cartilaginous||High-strength soil from stone fragments. When calculating the depth of foundations on such soil, you can not take into account the freezing depth|
|Sandy||Weakly freezing to a depth of no more than a meter maximum|
|Clay||Strongly swell, as they perfectly hold moisture. Compacted clay swells less|
|Loams and sandy loams||Mixtures in different ratios of clay and sand. Their properties depend on what prevails in the composition|
|Peat||Dried soils, which are characterized by high GWL|
Since rocky and semi-rocky soils have high bearing capacity , you can arrange any foundations on them, except for the pile, which is almost impossible to make on stony ground. The remaining types of soils are heaving and the choice of the base design for them depends on various factors:
If it is located at a depth of about one meter, it is worth giving preference to a slab or piles. If the waters are located below, shallow belts can be taken into account;
At frosty temperatures, the water in the soil freezes and becomes ice. Moreover, it grows significantly in volume. This process is called frost heaving .
Heaving causes the movement of soils and their strongest effect on the structural elements of the house, leading to their deformation and gradual destruction .The following factors influence the depth of soil freezing:
The choice of the type of building is influenced by the total load , rendered by the proposed structure on the future sole of the base. The calculation of the calculation of the sole area is carried out taking into account all types of loads:
For the middle lane, 100kg per sq. m. roof area, for the south - 50kg , but for the north - already 190kg .
The value obtained as a result of these calculations is used when drawing up a project: for a tape - to select its width, for a columnar and pile - for a shoe area.
However, all these calculations can be avoided by building the most expensive type of foundation - slab .
This solution cannot be called economical, since the slab base is quite expensive, however, the soles of the poured under the entire area of the house will be enough to solve all the problems that may ever arise with this house.
The question of the economy of building a foundation for a house is important. The foundation is a fairly expensive construction . If there is a choice between several options, it is worth calculating the costs of building materials ( concrete, pipes, fittings , etc.) and directly to the work process: you may have to order a concrete mixer, a team of workers, take a vibrator and a vibropress for rent.
Any financial overspending in this area is not justified.
A foundation is required to evenly redistribute the weight of the constructed object to the ground. Naturally, the load on the underground base of a frame house will be less than that of a brick cottage with slab floors. The desire to make a cellar will also matter. Therefore, for each building, in different areas, its own foundation is selected.
However, in any case, its lower part should be located below the freezing line.
What types of foundations are the most common? They can be different:
Let's take a closer look at the types of bases.
Tape is a tape of equal section, passing under the main walls. It is a universal base that can be poured on various soils for houses built from different building materials.
The thickness of the tape mainly depends on the thickness of the walls. By the depth of occurrence, they are distinguished:
However, this is a rather costly technology economically;
Column foundation - the most popular due to its versatility and budget costs for it. It is reliable and does not require excessive waterproofing.
However, it is ideal for light buildings and not suitable for heavy ones. It is also a poor choice for low bearing soils.
For the installation of a columnar base in the corners, at the joints of the walls and under the zones under load (concrete stairs, fireplaces), pillars are erected or poured. The optimal distance between them should be two and a half meters.
Pillars can be laid from bricks, concrete, reinforced concrete supports, metal pipes, construction waste .
Such a foundation is built very quickly . On moving soils, a dressing is laid between them. Even very heavy brick houses can be built on the posts with a bandage. All attached buildings - porch, terrace are built on a separate foundation.
This is the most expensive type of foundation representing a reinforced concrete slab.
It can be poured on any type of soil and under houses with any weight. However, it is better to initially calculate its economic feasibility, since it will be economically unprofitable for light buildings. This is an excellent option for sandy and highly loamy soils, as well as for structures of objects in which the slab is intended to become the base of the floor.Building a basement or basement under a slab is difficult.
The foundation on piles will be advisable, if the object is being built:
Pile can be made from standard pipes or with blades. In the first case, for the construction of lighter structures, pipes are simply driven in with a sledgehammer or special equipment or screwed into the ground, leveled and cut along the top one level at a time. All work can be done manually using special devices or using special equipment. If the piles are installed with special equipment, then you can literally put piles for a cottage, a fence, a terrace, a gazebo and other buildings within one day. A feature of this type of foundation is that it must be loaded for the winter with the weight of the building so that the forces of frost heaving do not push the pipes out.
That is, it is necessary to plan the construction so that at least the box of the house is built during the summer after piling.
A screw pile is a steel pipe with a specially designed configuration blade welded to it. It is screwed into the ground to a depth of at least 1.5 m . The compaction of the earth during screwing is due to the blade.
From above, the piles are cut one level and concreted to the very top. The erection of such a base structure does not require work with the ground, leveling the territory, ordering heavy special equipment. Screwing in can be done manually using conventional tools.
For more details about the device, as well as installation options in winter, you can read in our separate article - Do-it-yourself installation of a pile-screw foundation.
TISE technology has been popular since the mid-90s.
The TISE foundation is a pile-tape type foundation formed from bored piles, which are broadened from below, and a suspended reinforced concrete grillage. In section, such a foundation looks like nails growing out of the ground with their heads down. Such a base cannot be pushed out by any heaving forces. You can literally place it on lands with any composition.
TISE technology is used for construction:
TISE is considered the best alternative to traditional tape for heaving soils. Tapes on such soils should be laid below the freezing line, which is often simply financially ruinous.
Another plus of the technology - no need to use heavy special equipment .
All work is performed independently using a TISE hand drill. In addition, there is no need to load such a foundation for the winter, since the structure of the foundation will withstand the forces acting on it even without load.
Let's take a closer look at how the TISE is poured.
Step 1. Drilling to the planned depth is carried out according to the marking.
The broadenings are formed in turn: the blades are first put in their original state to create a recess 50cm, then in the finishing one - the broadening reaches 60cm .
Step 2. Reinforcement of the pile body with rods with a diameter of 12 mm . The length of the rods should be 5 cm longer than the pile, so that they can be connected with the future reinforcing frame of the grillage. The rods are tied with wire.
Step 3. Partial filling of the well is carried out to fill the widening with concrete. Then a formwork is placed in the well, made of a roofing material rolled into a cylinder, which should protrude above the surface to a height of 15-20cm. The body of the pile is poured with concrete to the top. The formwork is tied from above with wire to prevent deformation.
Step 4. The pillars are strapped with a grillage.
Aerated concrete - lightweight building material, therefore it does not have any restrictions on the choice of foundation ...
For the choice of the base, they are guided by other data: characteristics of the soil, the structure of the site, groundwater level. The only condition is the availability of sufficient waterproofing . The hygroscopic structure of aerated concrete facilitates the penetration of moisture into the structure.
If the freezing of the soil is not significant, the groundwater is deep enough, then the simplest, most economical and quick solution will be shallow tape . When pouring it under a house made of aerated concrete, you should adhere to some rules:
The use of a columnar base also has a number of conditions:
If the waters are near the surface, you should opt for piles. If the characteristics of the soil leave much to be desired, the choice is only a monolithic slab. Unfortunately, in this case, the economic benefits of building from available materials may be lost.
A log house is also considered an easy building, therefore, to select a basis, it is necessary to approach from the parameters of economic feasibility, such as soil, the level of its freezing, etc. On ordinary soils, the best solution would be shallow-buried tape , on difficult terrain or unstable soils - pile foundations .
A nuance that must be considered when arranging a base for log house - the ability to grip the first lower row of the timber with it. To do this, when pouring concrete, anchor rods are inserted into it at the rate of 2-3 pieces for each beam. The bar is put on them through the drilled holes and fixed with nuts and washers, which are sunk into the tree, for which the holes at the top are expanded.
Important! Another nuance is providing waterproofing so that moisture from the foundation does not rise into the timber. For this, 2 layers of waterproofing are placed on its surface, and the lower crown itself is additionally impregnated with bituminous mastic.
Gas silicate blocks are light weight and more dense than aerated concrete. Therefore, the choice of a base for buildings made of gas silicate does not cause difficulties. Tape and pile foundations are optimal and financially viable options.
In areas with a high groundwater level and with heaving soils, it is advisable to pour the slab. For sandy or gravelly soils with a groundwater level below 2 meters, the best choice would be the construction of a monolithic grillage along the heads.
For a one-story building, a columnar base is often chosen, however, the grillage must be hanging so that the gas silicate masonry rises above the ground at least 40 cm .
Frameworks - light structure , which is erected on all types of foundations, guided by the principle of economic expediency. Often used for this purpose is shallow tape . However, if you can buy inexpensively nearby pipes, then the device of the pile foundation will be more profitable due to the saving of time for carrying out construction work. An excellent option for a frame house on heaving soils is TISE .
A light house with a foundation on extended pillars will not walk during seasonal soil movements.
The choice of foundation for a heavy brick house depends on several factors: the type of soil, ground level, the number of storeys of the building. For all cases, monolithic slab is suitable. They will also withstand a high load - recessed strip foundation and reinforced concrete pile for loose soils. To increase stability, the foundation is placed on a concrete pad.
Thus, for a house built from any material on any type of soil, you can choose from several types of foundations ... Which one to give preference is chosen by the future homeowner himself. The choice is made towards those materials that are available at a cheap price near the construction site.
Someone has a concrete plant nearby, and someone else has a plant for the production of metal structures. The principle of economic expediency is not the last in the list of selection criteria.
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