DIY pile-strip foundation. How to make a pile foundation with your own hands Do-it-yourself concrete piles

Various conditions in construction sites require the use of an appropriate type of foundation. Thus, for weak peaty and swampy soils, the ideal option is to base a house in the form of separate vertical supports of round or rectangular cross-section, called piles. The types of such foundations and the features of their manufacture will be discussed further.

Pile foundations yesterday, today, tomorrow

The technology of manufacturing buildings for various purposes on free-standing supports has been known to mankind for thousands of years. And today it remains relevant and is being improved. The very first pile foundation consisted of hewn pillars of round cross-section driven into the ground, which were scraps of tree trunks. The installation process was quite complex and time-consuming, but was widely used, especially in areas of frequent flooding.

Currently, this technology has practically disappeared, since making a pile foundation for a house with your own hands from logs is unreasonably expensive and physically demanding. Already in the last century, they began to be widely used as supports vertically installed in the soil, which were also driven into the ground with the help of one or another. This support option had a number of advantages:

The strength of the rods was incomparably higher than that of wood, which preserved them during installation and further use;
Reinforced concrete supports made it possible to significantly increase the total load on the foundation, which made it possible to build multi-story structures on such foundations without fear;

According to their cross-sectional shape, such piles were produced mainly in three types - round, rectangular and hexagonal. Each of them was justified for certain specific soil and climatic conditions present in the construction area.

Gradually, the technology of pile foundations was adjusted and changed significantly. Instead of using ready-made reinforced concrete supports driven into the soil, they began to manufacture them directly in the construction zone, with a previously suitable diameter and depth. This technology is called a pile-rammed foundation, which can be made even by non-professional builders.

As noted above, building a foundation for a house on stilts with your own hands or by professional workers is advisable for fairly loose, unreliable soils. The pile is introduced to the depth of a solid geological layer and rests on it, thus transferring the entire load from the structure. In a similar way, the rods work with their entire lateral surface, using friction force.

The limitation for the use of pile foundations is rocky soils, as well as those with a high level of rock outcropping. In this case, the implementation of supports of any kind will be complicated and may not be achieved.

Making a pile foundation correctly

The general structure and construction of a pile foundation with your own hands in modern conditions can be presented as follows:

The basis of the structure is vertically located supports, buried several meters into the ground. The installation depth is determined based on the architectural features of the house, the materials used for its manufacture and the soil in the construction area.
To strengthen the pile foundation, the upper part of the reinforced concrete rods is combined with a concrete strip, which can be located at different levels relative to the soil. When using timber or logs as wall materials, it is possible to install them directly on the support platforms of the piles.

Below we will look at how to make concrete piles for the foundation yourself, i.e. with your own hands. To work you will need the following tools and accessories:

Garden auger or motor drill or automotive drilling rig;
Grinder with discs for metal and stone;
Electric concrete mixer;
Tools for planar marking - a strong cord and a set of pegs.

We mark the supports

Before making a foundation on concrete piles, it is necessary to calculate the required number of future supports. It is carried out on the basis of calculating the total mass of the future building, taking into account all the building materials used and even the furniture, windows and doors intended for installation. It is better to entrust this type of work to professionals, since mistakes at this stage can lead to the futility of all further efforts.

Having determined the required number of piles, it is necessary to calculate the step of their installation. To do this, divide the perimeter of the walls by the total number of supports. Now you can mark their installation locations. For this, pegs made of metal or wood and a strong long cord are useful. The process consists of burying the marks to a shallow depth along a pre-tensioned rope. Do not forget to mark a sufficient number of piles under the load-bearing partitions.

Drilling of the wells

In order to make drilled piles with your own hands, you must first make cylindrical depressions in the soil. They can be made using both hand and mechanical tools. The most affordable is a hand-held garden auger, which is a steel pipe with blades welded on the working end. To overcome ground resistance, there are transverse holes for handles in the upper part of the tool.

The mechanical drilling process is more productive. Motorized drills or car chassis are used for it. Of course, their rental will adjust the overall construction budget upward, but the speed of work will be incomparably higher. Regardless of the method of making wells, you must first decide at what depth to drill the piles for the foundation.

Ideally, it is desirable to achieve a cylindrical shape of the pile with a slight expansion at the bottom. In this way it will be possible to obtain a support base of a larger area. To achieve this result, special pile drilling cutters should be used. The diameter of the drill for piles must exceed the calculated parameters of the support for the thickness of the formwork.

Installation of pile formwork

To make reinforced concrete piles yourself, it is necessary to prevent the rapid removal of water from the concrete mixture. For this purpose, the side walls must be secured and insulated. For this purpose, builders recommend using the following materials:

– its sheets of the required length are rolled lengthwise and lowered into a pre-drilled well. Under the pressure of poured concrete, the material is pressed against the walls and copes well with the tasks described above.
Plastic sewer pipes of sufficient diameter are a worthy alternative to more expensive analogues. It is enough to purchase the required quantity at the construction base and connect them together.
For our conditions, only weather-resistant orange pipes are suitable.
Asbestos-cement pipes are a professional solution for the formwork of a do-it-yourself pile foundation. This is the most expensive option available. Its disadvantage is that the material is quite fragile.

Manufacturing and installation of reinforcing frame

Quite a long time ago, builders noticed that the introduction of steel rods into concrete, arranged and connected in a certain way, contributes to a significant increase in the strength characteristics of the mixture after hardening. It is recommended to reinforce bored piles after drilling wells for the foundation and installing the formwork.

Special steel rods with a corrugated surface are used as the basis for the reinforcing frame. Their diameter is selected depending on the diameter of the piles and the required strength. Typically, reinforcement from 12 to 16 mm is used. It is imperative that transverse inserts are secured between the longitudinal rods by welding or binding wire. For them, you can take reinforcement with a reduced diameter of up to 8 mm.

Immediately before installing the reinforcing frame into the cavity of the future pile, it is recommended to fill the bottom of the well with a layer of sand and crushed stone. It is already possible to install pre-connected reinforcing bars on it. Typically, a bored pile foundation design contains frames of four posts connected by inserts.

Making and pouring concrete

The use of high-quality concrete makes it possible to add strength to a pile foundation. It can be purchased at the nearest specialized enterprise or made independently. For this purpose, you should purchase or rent an electric concrete mixer. It will be difficult to prepare a sufficient amount of concrete manually.

Concrete is poured into the pile cavity in portions, compacting each with a special construction vibrator. This technique will allow you to get a high-quality foundation of concrete piles for your house and not harm the future structure. When using supports of small diameter, it is convenient to use special buckets.

Trimming pile heads

Drilling piles under the foundation yourself is not always carried out to the required depth. The reason for this may be various elements in the soil. Thus, the upper ends of the piles can be located at different levels. Trimming is used to bring them into a common horizontal plane.

Not required, pile foundations will be a real find. Simple types of pile foundations can be made with your own hands, spending several times less material compared to. Let's look at how to make a pile foundation with your own hands, learn the basic principles and techniques of this process.

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Video version of the article

Features of a pile foundation

A pile is a rod or pillar that is immersed (hammered, screwed, pressed) into the ground or made in a pre-drilled well. This rod transfers the load from the building to the base, resting against solid soil, as well as due to the frictional forces of the side surface (when the latter type of load transfer is the main or only one, then such piles are called “hanging”).

Pile foundations have a number of positive qualities: they do not require a foundation pit, which means there is no need for heavy earth-moving equipment. They are cheaper than massive ones. But the main argument in favor of choosing foundations of this type is the load-bearing properties of the soil:

If the top layer of soil is weak, it is necessary to transfer the load from the building to the lower dense layers.
In dense and strong soils, the use of piles minimizes labor-intensive excavation work.

Other types of foundations are discussed in the materials:, and in the material about.

Selecting the type of piles

According to the method of immersion into the ground, piles are divided into driven, driven and screwed (screw).

Driven piles are rarely used in individual construction, since the process requires the use of special expensive mechanisms.

It is much easier to install bored piles. To solve the problem of how to make a pile foundation with your own hands, this is perhaps the most successful choice. In addition, they are made directly in the ground, so there is no need to transport finished piles, which can be quite labor-intensive due to their length and weight.

Do-it-yourself work on installing a bored pile foundation

The installation of bored piles includes the following steps:

Drilling wells for piles

Using a hand-held gasoline or electric drill (see photos 1; 2.) we drill holes with a diameter of 30 cm and a depth of up to 5 m.

It is worth considering that expanding the base of the foundation increases the load-bearing capacity of the pile several times. For these works, there are special drill heads of various models that are commercially available.

In clay soils, peat bogs and shifting soils, supports are exposed to groundwater, cold and bending forces. Do-it-yourself bored or concrete foundation piles can be used on any soil and terrain, can be installed at any time of the year in 1-2 days, and also have a long service life and safety margin.

Reinforced concrete piles for foundations are pillars buried below the freezing level into the load-bearing soil layer. Suitable for a private home. Before installation, the foundation on reinforced concrete piles is calculated based on the load-bearing capacity of the soil and the total load of the house: the length, diameter, number of supports and size of the base are determined.

Drilling a well for reinforced concrete piles

Height is at least 1.5 m. Diameter range: 15-40 cm. To increase the supporting area and resistance of the house to heaving forces, using a foundation drill, the diameter of the well is expanded as it deepens, in particular, 20 cm. - on the surface, 40 or 60 see – sole.

When drilling with your own hands, a construction level is attached to the device. The vertical is controlled after each revolution and leveled if necessary.

The minimum distance between the supports of the house is not less than the sum of three diameters of the pillars, otherwise the bearing capacity of the foundation on reinforced concrete piles is reduced. For example, the diameter of the pillars is 45 cm, therefore, the step between them is at least 135 cm.

Installation of formwork for forming piles

Formwork is a hand-made frame made of wooden boards or cement pipes that supports the shape of the recess. It is used on weak and loose soils so that the walls of the well maintain their integrity. On dense soils, the formwork should be driven only above the surface of the ground to form the head.

Pipe as formwork for concrete piles

Roofing felt for formwork

A roll of roofing material or an asbestos-cement pipe, coated on the outside with a waterproofing material based on bitumen mastic or reinforced tape, is used as a frame.

Filling the well with concrete 1/3

After pouring, the frame is raised by 20-30 cm so that an expansion is formed in the load-bearing soil layer - the sole.

Vertical well reinforcement

Installation of reinforcement cage

From the side of the house, a compressive force acts on the reinforced concrete pile, and from the side of heaving soil - a tearing force. The tearing effect of the soil is caused by the pull of the upper part of the column to the surface by frozen layers and the clamping of the lower part by the load-bearing ones. Vertical reinforcement can reduce damage from compression and rupture.

A reinforcement frame made of rods 12 mm thick is installed. Every meter, the rods are connected with knitting wire or horizontal rods with a diameter of 8 mm. To connect with the grillage, the frame is made 10 cm longer than the pile.

Final pouring of concrete

Concrete is poured evenly, continuously, in one approach, in equal portions. Each portion is compacted with your own hands. The reinforcement must be lifted several times and then hammered to remove voids.

Formation of the pillar head

The head is formed under horizontal control with a level using formwork, steel wire or an anchor bolt. Necessary for installing piping on reinforced concrete piles.

Further construction of the house continues after the concrete has dried: maximum period is 2 weeks. In hot weather, the surface on the piles is moistened to prevent the formation of cracks.

Methods for installing a foundation on reinforced concrete piles depending on the soil

Name	Priming	Peculiarities
Dry method	Hard clayey, semi-solid, refractory	Without strengthening the walls. Drilling with a bucket drill or auger column. Well expansion is not necessary. The formwork is installed, but during the process of pouring concrete it is gradually removed from the recess. The head on the piles is protected with insulation in cold weather. Applicable for supports with a diameter of 40-120 cm and a height of up to 30 m. Do-it-yourself installation. Contraindications: industrial and stormy water flows on the territory of the house.
Casing method	Any	Drilling by rotary, impact or explosive methods. Using hydraulic jacks, driving or vibrating, casing pipes are deepened into the well: driven piles for the foundation are installed in the same way. Joints - locks or welding. The supports are reinforced. With the help of a jack system, the casing rotates and makes reciprocating movements, compacting the concrete.
Casing method using fundex technology	Seismically unstable	Gentle, without loss of soil properties. Drilling without excavation of soil - pressing with a roller or conical roller from the shaft. The rolling tip remains in the recess and is attached to the pipe using a lock. The pipe is reinforced, filled first with a mixture of equal volumes of sand, cement and water, and then with lamellar concrete. Pulled out by return rotation. Using fundex technology, you can drive piles under the foundation.
Clay-dissolving method	Unstable watered	A solution with a clay content of 1.2 g/cm 3 creates hydrostatic pressure, as a result of which the need for formwork disappears. A solution of bentonite clays is fed under pressure along a hollow drill rod into the well. Prepared at the construction site of the house. After pouring, it rises up the walls of the well, enters the voids, and is pumped out into the rod using a pump. The circulation is constant. The well is reinforced. Subsequently, the concrete displaces the mortar from the recess. Vertically movable (concrete or low-clogging) pipes are also used for pumping.

Note for casing option

An explosion is used to form the base: the casing is immersed in the well, a shell is placed on the bottom, the structure is filled with concrete - after the explosion, a cavity is formed at the site of the base, filled with a concrete mixture.

In order for any building, regardless of its purpose, to be reliable and durable, it is built on a solid foundation. Today, many different types of foundations are widely used in construction, and one of them is the pile-screw foundation. It is this variant of the design of the foundation for construction that raises the most questions. Therefore, we will devote this publication to the issue: a foundation on screw piles, its pros and cons, a general overview of its structure, the possibilities and feasibility of its construction. Such aspects are of interest to many land owners who are busy with the first “estimates” of the future construction of their home.

Before formulating all the advantages and disadvantages of such a design, we should probably consider some nuances that directly affect the strength and durability of a pile foundation.

Is it possible to use a pile foundation to build a residential building? It must be said that there are some builders who categorically do not advise doing this, preferring a strip, columnar or slab base for the house. Such craftsmen believe that piles are more suitable for outbuildings or light country houses.

However, it must be recalled that there are entire cities whose houses are built exclusively on stilts, and they have stood for decades. The practice of using such foundations has proven that they can serve as a reliable foundation even for massive houses.

Of course, in our climate it would hardly be reasonable to pile a two-story stone mansion on a pile foundation, although this is probably not an entirely impossible task. And yet, in private construction it is usually chosen for wood or covered with light roofing material.

In some cases, pile foundations are generally the only opportunity to build a house on a site, for example, if construction is planned on a site that is very rugged or constantly flooded by spring floods.

The use of such a design is also supported by the fact that such types of foundations have been used in construction since ancient times, only previously logs specially prepared for this purpose were used as piles. At first, the piles were simply driven into the ground, and only at the beginning of the 19th century was the screw installation method invented.

At first, screw supports were used to equip berths, but then the scope of their application began to expand. For example, it was screw piles that were used as the foundation for the construction of a lighthouse, which was erected in Great Britain on the unstable soil of the Thames.

Since the beginning of the 20th century, construction on pile foundations has acquired a “second wind”. This was facilitated by the emergence of new technology for precise and deep driving of piles, which significantly accelerated the work on constructing foundations for further construction of buildings. In the 50s, the active use of mechanical equipment for screwing in piles began, which gave another impetus to this field of construction, both industrial and individual.

This method of arranging foundations began to be used very widely in military construction, since through comprehensive research it was proven that such structures are reliable, durable and suitable for use on permafrost, heaving and water-logged soils - in a word, there are practically no restrictions on their use.

The first domestic scientific development, officially adopted as a standard for construction work, was the work prepared in 1955 on the basis of many years of experiments - TUVS-55 (“Technical instructions for the design and construction of foundations and bridge supports on screw piles”). Many of its provisions have spilled over into modern building codes and regulations.

Advantages and disadvantages of pile structures

The technology of building houses on screw piles is now used all over the world and has a large number of positive aspects.

To the obvious merits pile screw foundations include the following points:

The structure can be erected on almost any type of soil in different climatic regions, including swampy areas and in regions with permafrost.
The arrangement of this type is not significantly influenced by the groundwater level.
A screw foundation is excellent for building a house in areas with difficult terrain.
Screw piles can be installed at any time of the year, since weather conditions will not affect the quality and strength of the structure being created - at the depth of immersion of the screw tips, the soil temperature is always stable.

Pile-screw foundations are not susceptible to frost heaving when the soil freezes.
Installation work is carried out in the shortest possible time. For example, with a successful combination of all circumstances - good soil permeability, a well-coordinated team of craftsmen, etc., a pile field for a medium-sized house can be prepared literally in a day, especially if special equipment is used. At the same time, screw piles can be used for tying them and erecting walls immediately after installation, that is, they do not require time to set, mature, or gain strength, like any reinforced concrete structures. None of the other types of foundations even come close to these construction speed indicators.

Piles can be screwed in on the site allocated for building a house, or independently, with the assistance of several assistants, that is, without the use of special equipment. This factor is especially important if it is not possible to order such services in the construction area, or if the owner of the future home is simply limited in funds.

To install a pile-screw foundation, you will not have to dig a pit and install formwork, which means that there will be no debris on the site of the selected soil, which will also have to be disposed of by transporting it off-site, and which also requires additional material costs. In addition, under this foundation there will be no need to carry out work to level the construction site.
The pile-screw base does not draw capillary moisture from the soil, so the walls and floors of the house will be dry.
There is a full opportunity to carry out the design and installation of various utilities simultaneously with the installation of foundation elements or after its construction.
With the correct selection of high-quality piles and their reliable installation, the durability of the foundation is ensured, which is estimated for many decades.

By properly insulating the foundation around the entire perimeter, you can get a warm underground, which means that the floor in the house will also be warm, since it will not be cooled by the ground. In addition, in some cases it is possible to arrange a kind of “utility floor” under the house without carrying out large-scale excavation work.
The construction of a foundation made of screwed piles will cost 30–40% less than a concrete foundation. Considering the fact that building a foundation is always one of the most expensive stages of building a house, the cost savings can be quite impressive.

All of the above advantages of foundations on screw piles are available only to those structures that are built in compliance with all developed standards, from high-quality materials and with mandatory consideration of all terrain features.

But in cases of deviation from technology, when using handicraft piles, or other violations of the construction process, the disadvantages inherent in a pile-screw foundation may appear and worsen.

So, to " cons» Pile-screw foundation includes the following points that should be taken into account when drawing up the project and during construction work:

A disadvantage of such a foundation, independent of calculations and installation work, is the increased complexity or even the impossibility of its construction on very stony and rocky soils.

Excessive load on screw piles can lead to a weakening of the load-bearing capacity of the entire foundation, and as a result, to deformation of the strapping belt and destruction of the walls.
It is necessary to install effective drainage systems from installed piles, which leads to additional costs. However, storm and drainage drains are recommended for installation around any type of foundation.
It is impossible to completely exclude the influence of corrosion on the pile material. High-quality products, of course, receive the necessary protection during the production process - coating with a layer of zinc and polymer materials. However, sometimes the increased chemical aggressiveness of soils does its dirty work. It is not recommended to create pile-screw foundations in the immediate vicinity of electrified railways, cell phone towers, developed mines and quarries, large substations or high-voltage power lines. In such areas there is a high probability of the appearance of underground stray currents, which sharply activate metal corrosion processes. And the use of foundation piles to create a grounding loop for a house should be completely excluded.

The load-bearing capabilities of screw piles offered for sale are not limitless. However, this has a very indirect relation to low-rise private construction - large loads exceeding the characteristics of correctly selected piles are not expected.
No matter how hard you try, you won’t be able to get a full-fledged basement or ground floor using a pile foundation in private construction.
When building extensions to a house, there may be certain difficulties with screwing in piles at points located close to the walls of the old building. However, this is usually solved using special equipment.
It is not a disadvantage, but rather a unique cost, that the construction of a pile-screw foundation will require the owners-customers to constantly monitor the work of the invited team. Unfortunately, we have to admit that there are quite a few “would-be specialists” working in this field, and even outright “ballooners” who are trying in one way or another to benefit from violations of pile installation technology. Thus, to ensure high-quality protection against corrosion, the technology requires the pile cavity to be filled to the top with concrete. There are often cases when invited workers ignore this stage, immediately after screwing in they weld the ends.

There are examples when crews of “shabashniki”, working without control from the customer, did not screw in piles to the full calculated depth - and it is almost impossible to check this after cutting the pipes, welding the heads and piping. And such a violation will invariably entail rapid deformation of the created foundation with all the ensuing consequences.

And, without any doubt, it is necessary to expel workers from your construction site if it is noticed that when adjusting the piles in height, they rotate them in the direction opposite to screwing. Such a support can immediately be considered rejected, since it will no longer be able to have the calculated load-bearing capacity.

The conclusion is to invite a team only from an organization that has an impeccable reputation for the quality of the work performed, or not to lose sight of any stage of construction, to control every action required by the technology. Well, if you have the desire and confidence in your own abilities, install the piles yourself.

As you can see, the shortcomings are also quite serious. And in order to avoid them or reduce them to a possible minimum, it is necessary to choose the piles correctly, and the construction of the foundation should be carried out on the basis of calculations made, including an assessment of future loads and determination of the bearing capacity of the supports.

Types of screw piles

Screw piles are divided into several types, which have their own characteristics, consisting of a combination of design and technological characteristics. Each type of product is intended for use in various conditions, which depend on the characteristics of the soil and the expected load on the base. Moreover, it is also necessary to take into account the fact that sometimes different types of piles are used even when constructing one object, since in different zones the structure can produce a non-uniform load on the foundation. The use of different types of piles will provide a margin of safety for the base and increase the service life of the building.

Screw piles are divided according to the following parameters: by main purpose, by pipe diameter, the size of the blades and their number, by the type of tips, by the perceived loads (bearing capacity), by the grade and thickness of the steel, as well as by the type of anti-corrosion coating.

These parameters need to be considered in more detail in order to know which of the products are suitable for building a house on a site with specific types of soil.

Types of piles by area of application

The illustration below shows four main types, which are strikingly different even visually.

A– wide-bladed piles with one blade placed on the tip at the bottom of the pipe. The most common type in private construction, allowing the construction of foundations on most types of soil. Typically used for light outbuildings and one-story houses made of wood or frame panels. However, with the correct choice of the diameter of the blades and the number of piles, houses can also be built from gas silicate blocks on such foundations.

b– piles with increased load-bearing capacity, resistance to shrinkage and pull-out effects. A characteristic difference is the presence of two blades spaced apart along the height of the pile. Suitable for foundations of two-story houses. They are rarely used in independent private construction, since it is almost impossible to screw such a pile into the ground manually, without the use of special equipment.

V– narrow-bladed piles with a pronounced conical “screw” - are used for the construction of foundations on rocky soils.

G– special piles designed to create foundations in permafrost conditions. They require the use of special screwing technology, therefore they are not used in self-construction practice.

Of all the listed types, as you can see, the first one is most often used for independent construction, therefore, in the course of further presentation, more attention will be paid to it.

Standard sizes of screw piles for foundations

Depending on the composition of the soil and the loads on the structure, it is necessary to select the correct diameter of the pile shaft, which can vary from 57 to 133 mm. Along with the diameter of the pipe, the diameter of the blades also changes, and the higher it is, the greater the bearing capacity of the support.

The table below shows the main standard sizes of wide-bladed piles with a welded tip (they are usually called SWS - welded screw pile)

Illustration	main characteristics and scope of application of the pile	Approximate price for a product with a length of 2500 mm + additional surcharge for every 500 mm. Price of standard pile head
	SVS-57. Pipe diameter - 57 mm, blade - 150 mm. Such products do not have outstanding load-bearing capacity - the permissible load on the support is only up to 800 kg. This also determines a rather narrow area of use - lightweight fences that do not become a barrier to the wind, that is, made of chain-link mesh or sparsely spaced picket fences. Typically, 4-meter piles are purchased for such purposes, based on a two-meter immersion in the ground and two meters to the height of the fence.	1300 rub. + 100 rub. Head OVS-57/200/200 – 260 rub.
	SVS-76. Pipe diameter - 76 mm, blade - 200 mm. The bearing capacity of the pile is up to 3000 kg. A typical area of application is the construction of windproof fences, that is, those with windage (for example, from frequently spaced wooden or metal picket fences, flat slate, metal corrugated sheets, polycarbonate and other similar materials). The most commonly used length is 4000 mm, for the same reason as stated above.	1450 rub. + 100 rub. Head OVS-76/200/200 – 300 RUR/piece.
	SVS-89. Pipe diameter - 89 mm, blades - 250 mm. Load-bearing capacity, depending on the soil, can reach up to 4÷5 tons. The specific application is the construction of foundations for auxiliary outbuildings, light frame garages, garden gazebos, and other structures of a similar type and purpose. Often used when adding a veranda to a residential building. They can also be used to create additional supports required, for example, when installing heavy boiler equipment or when laying a stove or fireplace in a house.	1500 rub. + 150 rub. Head OVS-89/200/200 – 300 RUR/piece.
	SVS-108. Pipe diameter - 108 mm, blade - 300 mm. Load-bearing capacity is estimated at 5 - 9 tons. They are widely used in the construction of residential country houses of light construction - frame or timber, for log cabins. They have proven their effectiveness also on difficult soils - swampy or peaty.	1700 rub. + 250 rub. Head OVS-108/200/200 – 300 RUR/piece.
	SVS-133. Pipe diameter - 133 mm, blades - 350 mm. The most durable supports used in individual construction. The inherent load-bearing capacity reaches 14 tons. Such supports are used to create pile fields for the construction of houses made of fairly heavy wall materials - gas silicate blocks or even brickwork. Given the appropriate bearing capacity of the soil, tying piles with a monolithic reinforced concrete grillage is often used, as well as pouring concrete floors on the first floor.	2250 rub. + 350 rub. Head OVS-133/300/300 – 350 RUR/piece

Number of blades

Screw piles can have one blade, as shown in the table above, or several. Accordingly, they are called single- and multi-blade.

Single-blade piles are used for constructing foundations in areas with soils with high bearing capacity. However, when using this type of product, especially with welded tips, you need to be prepared for the fact that they may “fail” when they reach a critical load. In this case, the supports lose their load-bearing capacity, which will negatively affect the integrity of the foundation piping.

Multi-blade products are used for arranging foundations on a wide variety of soils, including weak ones. They have a high load-bearing capacity and are resistant to large loads of various types - pressing, horizontal or pulling.

A larger number of blades on the pile shaft makes it possible to use a product with a smaller diameter pipe that has sufficient wall thickness. The high efficiency of such piles is achieved by the optimal arrangement of the blades on their trunk. The distance between the blades, the pitch and their angle of inclination are calculated individually, taking into account the location of the soil layers and its composition at a specific construction site. Working with such supports certainly requires a qualified approach.

Tip Types

The tips of screw piles are divided into welded and cast.

Products with cast tips are certainly more reliable, since they are practically not subject to deformation when driving through the ground, in contrast to the welded type. Piles with cast tips can be used for installation in permafrost, especially dense soils, as well as those containing man-made or solid natural inclusions. This type of tip does not deform even when bumping into an obstacle and is capable of destroying it.

Welded tips are used in weaker soils, however, their strength directly depends on the grade and thickness of the steel, as well as the quality of workmanship. Their only advantage compared to cast ones is their much more affordable cost.

Thickness and grade of metal

Screw piles can be made from pipes with different wall thicknesses. They are divided into:

— thin-walled, made from pipes with a wall thickness of up to 3.5 mm;

- average thickness - from 3.5 to 6 mm;

- thick-walled piles - 6 or more millimeters.

The choice of piles according to this criterion will directly depend on the composition of the soil at the site of their installation, as well as on the expected load. This parameter of the piles is determined when drawing up the project, and the choice is made in accordance with the data obtained during studies of the corrosion activity of soil layers.

Using the same data, the thickness of the metal for the blades of the pile is selected, but it must be remembered that if the blades are made of steel up to 5 mm thick, they are suitable only for light buildings. If a large massive building is being erected, then the thickness of the blades should not be less than 6 mm.

Based on the soil studies, the steel grade of the products is selected:

— if the chemical aggressiveness of the soil is weak, St3 steel can be used;

— medium aggressiveness involves the use of products made of St20 steel;

- if the soil is very aggressive, piles made of steel 09G2S and 30KhMA are suitable.

Type of anti-corrosion coating

Due to the fact that the piles will be located in a humid soil environment that is aggressive to metal, it is recommended to purchase products with a protective coating applied to them at the factory. In addition, it is very important to keep the coating intact when screwing in the piles, since it protects not only the pipe itself located in the ground, but also its top, as well as the area located on the border of the underground and above-ground parts of the pile.

Today, manufacturers apply various protective compounds to screw piles - it can be cold or hot galvanizing, polyurethane, epoxy or polymer coating - each of them has its own characteristics. Based on the tests of various coatings, it was concluded that the greatest efficiency in protecting metal was shown by the cold galvanizing method, polyurethane and epoxy coating, as well as enamels and primers applied over rust without preliminary surface preparation, while hot galvanizing and conventional polymer coating are not highly durable.

If piles are purchased without a protective coating, then it must be applied independently, and different materials can be used for the underground and above-ground parts. But do not forget that all serious manufacturers necessarily provide anti-corrosion protection for their products. Therefore, if the piles are “bare metal”, then with a very high degree of probability we can say that they are handicraft. Well, if so, then who can guarantee compliance with other operational characteristics?

By the way, this is a very serious problem: there are a lot of small handicraft productions of screw piles, and most often there we can talk not only about non-compliance with standards, but even about the absence of clear technical conditions. Purchasing products from a completely incomprehensible manufacturer, thereby “planting a time bomb” under your foundation, is hardly wise, even at a super-attractive price.

Principles of calculation and design of a pile-screw foundation

If a user reads this article, that is, wants to learn about the advantages and disadvantages of a pile-screw foundation, then, most likely, he is “considering” it for his future construction. This means that he will be interested to know, at least in general terms, how such a foundation is calculated, and then from here - what he will have to focus on in further construction planning. Let's give him this opportunity.

To ensure that characteristic shortcomings do not appear during the operation of a pile-screw foundation, it must be correctly calculated and planned, taking into account all the nuances mentioned above. Designing anything is a task for qualified specialists. But preliminary “estimates” for building a house can be done independently. In addition, the proposed algorithm is quite suitable for the construction of utility buildings or other light buildings.

Assessment of the load-bearing capacity of the pile

First of all, it is necessary to assess the load-bearing capacity of a screw pile on a specific construction site. As can be seen from the table above, the spread of values even for a product of the same type is quite large (for example, for SBC-108 - from 5 to 9 tons). This, of course, is not the right approach to the matter - it is necessary to operate with more accurate values. Moreover, in some cases, depending on the specifics of the soil, the permissible load indicators may even go beyond the specified range in one direction or another.

Any type of soil is characterized by its load resistance indicator, that is, in essence, its load-bearing capacity. This is precisely why they “dance” further when calculating the permissible load on the screw support.

Below is a calculator that will help calculate the load-bearing capacity of piles of the most common SHS model range, which was discussed above. The calculation program has already included the necessary data on soil resistance at the average depth of the helical part of the pile (about 2.5 m), and on the “geometry” of various pile models.

And the most difficult thing in this matter, perhaps, is to correctly “diagnose” the soil on the building site. By the way, the correction factor, which lays down the operational safety margin of the support, will depend on this.

The most accurate way is to carry out geological survey work: drilling a well by specialists and accurately assessing all layers of the soil. The method has no drawbacks, it gives a very accurate picture, so the correction factor is minimal, only 1.2. However, there is still a drawback, and it lies in the excessively high cost of such services, which, in principle, predetermines that this approach is not very popular.

The second option, which also requires the involvement of specialists, but is no longer associated with too high financial costs, is the screwing in of an experimental (reference) pile. It consists in the fact that on a building site a pile is screwed into the ground, and as it passes through the layers, the torque applied to it is monitored. This gives a fairly objective picture of the bearing capacity of soils. True, the correction factor is already higher - 1.25.
Finally, if you have confidence in your knowledge and skills, you can simply dig a deep pit or drill a well to the depth of the intended location of the blades of the screw piles. Well, then - take a soil sample from this depth, classify it according to its characteristic features and, using tables, which are abundant on the Internet, find out the calculated value of its bearing capacity. Can you handle it? At the same time, we are, of course, no longer talking about high accuracy of the assessment, which affects the sharp increase in the correction factor - up to 1.6÷1.7.

During the test drilling process, it is necessary to immediately determine the required length of the piles. An incorrectly chosen length of pipes can lead to subsidence of the foundation and destruction of the walls of the house. Therefore, when calculating the length, they rely on two parameters:

— depth of dense load-bearing soil layers in the area where construction is planned;

— the relief of the site, that is, differences in height: as a result, it is necessary to reach a common horizontal plane at all points of the foundation.

With high groundwater levels and unstable soil, the foundation for a private house often has to be made of piles. It turns out to be too irrational to use other options in such a situation. They will either be too expensive or short-lived due to high soil moisture. Reinforced concrete pile foundation of bored type is cheaper and easier to implement. You can do it yourself without any problems.

What is a pile foundation?

Pile foundations are vertical reinforced concrete supports immersed in the ground. They are usually connected on top with a grillage or a monolithic slab, which serves as the base for the walls of the house. Depending on the type of piles, they are driven into the soil, twisted, or simply immersed in pre-drilled holes in the ground.

Scheme of one of the types with an underground grillage

The reinforced concrete grillage option in appearance and general design is a direct analogue of a strip foundation. Only the “tape” here is smaller in size and lies not in the ground, but on piles. This perfectly protects the grillage from moisture and heaving. Moreover, all the energy of seasonal expansion/contraction of soil layers passes by the pile supports. They initially sink below ground freezing levels, standing on a dense, stationary base.

Types of foundation on piles

Depending on the technology of immersion of supports, pile foundations are:

On hanging stilts;

On retaining piles.

In the first case, the pillars seem to hang in the ground without support from the supporting layer due to banal friction forces. In the second, on the contrary, they rest on solid layers of soil. A suspended foundation requires a large number of piles and more thorough calculations based on serious geodetic studies of the site. This technology is not used for the construction of private cottages with two or three floors.

In low-rise housing construction, the retaining option is more in demand. The piles here are not driven into a continuous field; much less of them are required. For an ordinary house outside the city, four supports in the corners and several under the load-bearing walls are enough. It is much easier to do such a pile foundation with your own hands.

Piles for constructing such a foundation can be taken:

Screw-in (screw-in) steel.

Driven reinforced concrete.

Bored from asbestos-cement pipe and reinforced concrete inside.

Private developers usually choose screw or injection (bored) technology for the construction of pile reinforced concrete foundations. At the same time, steel “screws” have a serious limitation - the depth of installation during self-assembly. If the dense layers are shallow (up to 2 meters), you can still screw them into the ground yourself, but for longer supports you will need specialized equipment.

With drilled analogues the situation is fundamentally different. They are made from pipes, to immerse them in the ground it is necessary to dig a hole of the appropriate size. Even if it is needed a couple of meters deep, it will not be difficult to dig such a pit with your own hands for the future foundation in dense, non-crumbling soil.

Pros and cons of a pile foundation

Each foundation has pros and cons. This is far from a universal option for any soil. It is not suitable for every site. But such a foundation for a private house is not as expensive as a slab foundation or a reinforced concrete strip analog buried below the freezing point. In the screw version, the support on piles will cost 30–40%, and in the bored version – 20–25% cheaper.

Among the advantages of the option under consideration are:

Possibility of installation where classical options cannot be made due to high groundwater level, heaving soil or large freezing depth;

High speed and extreme simplicity of work when doing it yourself;

Cost-effectiveness - by choosing a foundation on piles, in many cases you can save up to a third of the funds allocated for arranging a support for a house;

Minimum excavation work - for a strip or slab-monolithic analogue, you will have to dig many times more land.

The disadvantages of a pile foundation are as follows:

Difficulty in carrying out calculations during design;

Can only be used for light buildings;

The need for floor insulation and the impossibility of constructing a basement.

In order for such a foundation to last for a long time, it is better to entrust the preparation of its project to professionals. Careful soil research and competent calculations are very important here. It is necessary to foresee in advance how each pile will behave under load in the future. The slightest mistake - the grillage and the walls on it will immediately collapse. As a result, even the corrugated sheeting on the roof will be damaged, not to mention cracked partitions inside the building.

Example on driven piles

The second important point is the weight restrictions of the structure. It’s definitely not worth using heavy ceramic bricks or concrete for a cottage on a pile foundation. Frame or foam concrete technologies are more acceptable here. They allow you to build lightweight walls that will stand on screw or bored supports for a long time and without problems.

And in general, before choosing the type of foundation for your home, you should carefully study what SIP panels, brick, timber, logs, gas and foam blocks are with all their characteristics and pros and cons. The weight of the building materials of the walls greatly influences the choice of the type of foundation.

DIY bored pile foundation

The step-by-step instructions presented below provide for the independent construction of a bored pile foundation with a grillage on top. This is the most popular option among private owners, as it is easy to implement. For the work you only need asbestos cement pipes, concrete mortar and steel or fiberglass reinforcement.

The device is completed in five stages:

Excavation.

Installation of asbestos-cement pipes and laying fittings in them.

Pouring concrete.

Grillage arrangement.

Closing the base.

For the manufacture of bored piles, asbestos-cement pipes with a diameter of 300–400 mm are required. They will serve as a guarantee that the foundation will have good load-bearing capacity both vertically and horizontally. And unlike the steel version, asbestos cement will not rust in the ground.

The easiest way to make holes for supports is to use a hand drill with a gasoline or electric motor. The depth of these holes should ultimately be 30–40 cm below the freezing point of the soil.

Pile pillars are located around the perimeter of the building and under the load-bearing walls inside in increments of up to two meters. After drilling the wells, a sand cushion 10–15 cm thick is poured at their bottom. Then, another 25–30 cm of concrete is poured on top as a support for the piles. And asbestos-cement pipes are installed into this uncured solution. At the same time, they must protrude at least 30 cm above the ground.

To ensure that the pipes remain strictly vertical, they are sprinkled with sand, which is compacted during this process. Next, the support pillars are reinforced. For this, 3-4 rods made of steel or fiberglass with a cross-section of 10–12 mm are used.

Reinforcing rods must be placed in the center of the pipe at an equal distance from each other. To simplify installation, they can be tied together on the ground with wire crossbars. In height, these vertical rods should be higher than the upper edge of the pipe, protruding from the latter by 15–20 cm. After reinforcement, all that remains is to fill this permanent formwork with concrete, making sure that no voids form inside the solution.

After just 3-4 days, a grillage made of reinforced concrete (with laying of formwork, reinforcement and pouring of concrete mixture), steel channel or timber can be mounted on the resulting supports. As a result, there should be a gap of 25–30 cm between it and the ground. It is impossible to lay the grillage directly on the ground; when it heaves, it can simply be squeezed up and demolished along with the building.

At the end of the arrangement, it is best to cover the sides with sheathing after the walls have been erected. Corrugated sheeting for the roof or facade or decorative bricks are perfect here. Just first you need to lay out all communications. Fortunately, water supply and sewerage in a house on stilts are carried out between the supports without additional tricks or drilling of concrete.

The use of foundations on piles in construction

The foundation on reinforced concrete piles is perfect for many types of private low-rise buildings. Making it yourself, guided by the step-by-step instructions presented above, should not be difficult. But it’s better to order calculations from specialists. For a garage or bathhouse, a similar basis can be calculated independently. And for a cottage, the foundation design should only be completed by a professional.