Do-it-yourself installation of screw piles. Do-it-yourself pile foundation step by step instructions How to make a screw foundation with your own hands

Pile foundation - a foundation consisting of elements vertically installed in the ground, interconnected, which perceive the total weight of the structure and all existing loads. Pile foundations in Russia in the field of private housing construction began to be widely used for 15-20 years with the advent of frame construction and light piece building materials. Today, in the middle zone of our country, every tenth cottage is built on a pile foundation, and in the northern and southern regions of such buildings, about 50%.

The choice in favor of a pile foundation is appropriate in the following cases:

1. The characteristics of the soil on the site do not allow the use of shallow and ground-type foundations. Such soils include: peat bogs, swampy soils, unstable loams, heaving, loess-like and swelling soils, quicksand, etc.
2. The high level of groundwater in the area, as well as the existing threat of flooding during seasonal floods.
3. Construction is carried out in a seismically unfavorable region.
4. In areas of permafrost or when soils freeze more than 2 meters.
5. The presence of elevation differences on the site, the construction of a house on a slope.

On soils with medium characteristics, where a ground foundation is possible, the choice in favor of piles can significantly reduce the amount of earthwork and concrete work, which leads to a reduction in construction costs. The foundation on piles is excellent for wooden, timber and frame houses, as well as buildings made of light piece materials: gas and foam blocks, silicate bricks, expanded clay and cinder concrete. For cottages made of reinforced concrete slabs and ceramic bricks, it is also possible to use a pile foundation, but at the same time, the load, as a rule, is taken not by individual supports, but by pile bushes, the calculation of which should only be done by a professional.

Pile foundation: pros and cons

Advantages of pile supports used as a foundation:

• versatility, can be used for a wide range of soils;
• the ability to save on earthwork and concrete work;
• the possibility of application in areas with difficult terrain;
• the minimum level of mechanization, you can do it yourself;
• high reliability and bearing capacity;
• operational construction at any time of the year;
• the ability to preserve the existing landscaping on the site;
• low cost in comparison with the slab-monolithic base.

Flaws:

• the need for calculations;
• if the calculation is incorrect, shrinkage and deformation of the base are possible;
• lack of a basement;
• the impossibility of the device on rocky and dense soils;
• necessarily insulation and high-quality waterproofing of the ground part;
• difficulties with strapping - connecting piles into a single structure.

Almost all the disadvantages of a pile foundation are completely eliminated if you approach the design, calculations and construction responsibly. The current regulatory documents, which are recommended to be studied before starting work, will help to do this.

Expert opinion

Sergei Fedorov

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Regulatory documents for the construction of pile-type foundations:

SP 24.13330.2011 or SNiP 2.02.03-85.
SP 50-101-2004 Design and arrangement of bases and foundations for buildings and structures.
SP 50-102-2003 Design and installation of pile foundations.

SNiP 2.02.04-88 Bases and foundations on permafrost soils.
SNiP 2.02.05-87 Foundations of machines with dynamic loads.
SNiP 3.02.01-87 Earthworks, foundations and foundations.

Types of pile foundations

Currently, the construction industry uses more than 30 types of pile foundations. Almost all of them belong to the bases of the combined type, which consist not only of the underground part - piles, but also of the ground. The ground part performs two main functions: 1) connects the pile supports into a single structure; 2) takes on up to 50% of the load from the weight of the structure.

In private construction, the following types of foundations are most in demand:

• Pile-slab combined foundation. The ground part is a monolithic concrete slab, inside of which there is a reinforcing frame.

Application: for houses made of heavy materials. It is built only on dense soils!

Expert opinion

Sergei Fedorov

Professional builder. Experience 18 years

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Advantages: the highest bearing capacity.

Flaws:

• complexity of calculations;
• a large amount of concrete work;
• the complexity of the implementation;
• high price.

The foundation of a pile-slab type for a house is used quite rarely. A monolithic slab has a huge weight, so the piles must be of large diameter. Such piles cannot be installed manually, therefore, it is necessary to use specialized equipment, which significantly increases the cost of construction.

Pile-grillage foundation. For its device, both bored and screw piles are used, the ground parts of which are interconnected by a grillage. The grillage material can also be different: wood, metal, monolithic reinforced concrete or prefabricated.

Application: light structures (country houses, gazebos, outbuildings, baths).

Advantages:

• ease of installation;
• minimum settlements;
• low cost.

Expert opinion

Sergei Fedorov

Professional builder. Experience 18 years

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Disadvantages: small bearing capacity.

The cost and technology of performing work on the installation of a pile-grillage foundation depend on the type of piles and the material of the grillage. In many cases, the grillage is not only a binding for the pile part, but also perceives the load from the structure.

• Pile-strip foundation. The ground part of such a base is a monolithic or prefabricated reinforced concrete tape installed along the perimeter and load-bearing walls of the future house. In terms of bearing capacity, cost and labor intensity, a pile-strip foundation is the best option for a cottage made of light building materials.

Application: for houses made of light materials, frame structures.

Advantages:

• simple and fast installation;
• the minimum volume of concrete and earthworks;
• wide scope of application;
• low cost.

Expert opinion

Sergei Fedorov

Professional builder. Experience 18 years

Ask an expert

Disadvantages: not suitable for massive buildings

Design and calculation of pile foundations

Calculations and design for pile foundations are carried out on the basis of hydrogeological survey data, the purpose of which is to determine the type and characteristics of soils on the site. When conducting surveys, the most important parameter is determined - the depth of the piles, which depends on the depth of the bearing soils and freezing.

During the calculation of a pile foundation of any type, the following data are established:

1. Pile field parameters. The distance between the piles, the diameter of the supports, their number are calculated. For a screw foundation, the standard size of metal piles, the number and location of the blades are determined. For a bored foundation, reinforcement is additionally calculated.
2. The depth of the ground part. There are shallow and deep-seated types of a monolithic slab and tape. There are also options with an elevated and hanging base. Each type of penetration uses its own calculation method. In most cases, private construction uses shallow foundations or elevated foundations for a wooden house.
3. Foundation dimensions. The width and height of the reinforced concrete tape or grillage is determined based on the total loads that will act on the base. The calculation takes into account permanent and temporary loads, soil properties, etc.
4. Calculation of the final draft. This calculation is complex, it is impossible to make it yourself. When piles are supported on dense soils with normal physical and mechanical characteristics, shrinkage for a 2-3-storey building will be no more than 1.5%, so this calculation can be neglected so as not to pay designers for it. However, if the cottage is being built in difficult hydrogeological conditions, on swampy soil or in a seismic zone, then the calculation of the draft is required.

The result of the development of the foundation project on piles, which you carried out on your own, should be a drawing or diagram, which indicates the location of the pile supports, taking into account the selected step, the parameters of the piles and the ground part: slabs, tapes or grillage.

Pile foundation technology

The technology for arranging the foundation on piles for all types of foundation is the same:

1. Installation of pile supports.
2. Binding of pile heads and arrangement of the ground part.
3. Warming and waterproofing.
4. Finishing the basement, arranging the blind area and drainage.

Regardless of the chosen type of pile-combined foundation, work on its installation always begins with clearing the territory and planning. If necessary, a foundation pit or a trench is dug under a shallow base, and the "cushion" is backfilled.

Installation of a pile foundation: installation of supports

Step-by-step installation instructions will be different for each type of pile. Most often, the following types of piles are used for a private house, barn or bath:

1. Screw piles. Products are produced by the manufacturer, have their own sizes and varieties. For the production of screw supports, metal alloys with different characteristics are used. The most durable and expensive are galvanized products. The supports are very easy to install. They are screwed into the ground, without pre-drilling a well, and heads are welded to them from above.
2. Bored piles. Supports are arranged directly on the construction site in pre-prepared wells. Bored piles are durable, low cost and excellent bearing capacity. The base of the bored type can be made independently without buying supports. How to make piles for the foundation with your own hands is described in detail in SNiP 2.02.03-85.

After the installation of the supports, the heads are aligned in height and interconnected into a single structure by strapping.

Pile foundation tying

For tying a pile foundation, a bar, metal products can be used, and if we are talking about a massive structure, then a reinforced concrete or metal grillage is used as a strapping. The choice of the type and material of the strapping depends on the mass of the house and the material from which it will be built, pile supports, and the type of ground part.

1. Strapping with timber is used for wooden and frame houses. To connect the piles with the strapping beam, it is necessary that the heads are metal, therefore this connection is used mainly for screw supports.
2. Channel strapping is used for buildings made of piece materials. The channel is welded to the heads of screw piles or special metal heads-platforms of bored supports, creating a rigid structure that has increased strength and stability.
3. Tying with a profile pipe is possible only for light houses and outbuildings. The strapping technology in this case repeats the design with a channel, but instead of a rolled metal product, a thick-walled hollow pipe is used.

Separately, it is worth mentioning the strapping, which is used to connect bored piles and a monolithic ground part. In this case, the two parts of the foundation are connected with reinforcement, forming a reinforcement assembly. The rods are connected to each other by wire and welding in accordance with the previously selected scheme.

Pouring the ground part of the pile foundation

The ground part of the pile foundation is a slab, tape or grillage. All elements according to the variation of execution can be both prefabricated and monolithic. Prefabricated structures are used infrequently due to their high cost, the need for transportation and use for the installation of lifting mechanisms. Monolithic structures can be easily made on your own, while the step-by-step instructions for pouring the ground part of the pile foundation will not differ much for the slab, tape and grillage.

The issue of strengthening the pile foundation should be addressed at the design stage. It must be remembered that the reinforcement will put an additional load on the supports.

Waterproofing and insulation of the pile foundation

Waterproofing is essential for any pile foundation. The choice and application of waterproofing depends on the design of the base, for example, for a pile-grillage foundation using metal products or timber, the best option would be coating waterproofing, which is applied to the pile heads and piping elements. Roll waterproofing is suitable for reinforced concrete slabs, strips and grillage: the material is placed at the junction of the supports and the ground part, as well as on top.

When pouring a reinforced concrete foundation, regardless of its position relative to the zero level, the structure will draw heat from the future home and be blown by the wind. That is why pile foundations need high-quality thermal insulation, while only the ground part is subjected to insulation. There are many options and ways to insulate pile foundations. The simplest and cheapest is thermal insulation using foam boards. Many manufacturers produce product lines marked "Foundation". Insulation plates are attached inside, outside and on the sides of the monolithic tape.

The false base needs insulation, therefore, for its arrangement, choose materials that can withstand the load of thermal insulation and decorative finishes.

For a private house, the blind area is very important, which should have a slight slope. It is necessary to build a blind area for the following reasons:

• preventing the penetration of precipitation under the foundation;
• prevention of soil erosion around piles;
• reduction of the destructive effect of heaving soils.

In addition, the blind area gives the structure a finished aesthetic appearance. The width depends on the size of the house: the larger the building, the wider the blind area should be. The minimum width is 0.2 m. The blind area must be insulated with high density insulation boards. The material of the blind area can be different: concrete, tile, cobblestone, granite. The most commonly used traditional option is facing with paving slabs. If the blind area will play the role of a path, then it should be reinforced with a layer of concrete.

How much does a pile foundation cost?

A pile-combined foundation that you can do yourself is one of the cheapest types of foundation for a cottage. The cost of construction depends on the type of piles and the ground part. An economical option is a pile-strip foundation on bored supports. The foundation device on screw piles will cost more due to the purchase of ready-made metal supports.

This technology is used to speed up the construction of not too heavy buildings, other architectural structures. It is suitable for the construction of reliable foundations even on weak soils. Its use helps prudent owners. As part of this guide, we will tell you what it is on screw piles, with your own hands or with the involvement of specialists, it should be built, what pros and cons you should pay attention to, as well as how the repair and finishing of pile structures is carried out.

Read in the article

Foundation on screw piles

When preparing for the construction of a house, it is necessary to correctly answer various practical questions:

• You should find out if a pile-screw foundation is really suitable for a building of a certain size, made of.
• Information on how to select the main materials and component parts for the implementation of the project at a reasonable cost will be useful.
• It is imperative to learn how to make the calculation correctly so that the created structure remains stable for a long service life.
• It is necessary to clarify how to properly mount the base, so as not to complicate subsequent construction operations, is it necessary.
• After finding out if a strapping is needed, you will have to decide how to sheathe the base in order to get a good appearance and improve consumer characteristics.

The answers to these questions are given in this article. When studying it, one must not forget about the individual features of the use of the building. So, for example, the load will increase significantly if the house is often used to receive a large number of guests.

For your information! It must be remembered that sewers and other engineering networks are laid in a residential building.

Pile foundation with monolithic grillage

This design is installed according to the following scheme:

• Calculate the loads that will be created during operation.
• Depending on it and taking into account the characteristics of the soil, products that are suitable for the technical parameters are selected.

If the soils are classified as heaving, or there is frequent flooding of the site, enlarged blades are used. To pass the frozen layer in winter, they use not a sharp tip, but a drill (a jagged edge of a pipe).

Piles are suitable for working in areas with difficult terrain. On them you can install not only the house itself, but also the pier. They will provide a solid service life when placing an object near an open reservoir. They can be installed in frosty weather, so you can eliminate the corresponding restrictions when working with pouring concrete products.

An experienced team, even without the use of power drives, is able to screw in more than 20 piles per day.

For your information! The figure shows that for a qualitative reproduction of the technique, at least four people are required. Two - create the necessary efforts with the help of levers. One - supports the column during rotation. The manager controls the verticality of the installation, coordinates the actions of workers.

In this embodiment, a gearbox with a large gear ratio is used. A powerful drill is suitable for the drive. If there is no 220 V network on the site yet, a mobile power generator is used.

Such equipment will allow you to quickly create a large reference field. When comparing different options, all real costs must be taken into account in the aggregate. Sometimes ordering specialists with equipment is cheaper than independent experiments. It should be remembered that for manual technology, assistants will be needed.

Will a typical concrete foundation be reliable without preliminary calculations? Does the base settle or not over time, if it is not installed on the site? These questions are answered above. But the following nuances also deserve attention:

• Piles of this type do not draw moisture from the soil, so the structure is not exposed to the corresponding negative impacts.
• In a building raised on supports, it is necessary. It is much easier and more efficient than a standard concrete foundation.
• The use of this technique is not accompanied by large earthworks. No need for a level ground reduces overall costs. Compared to a typical strip foundation for a similar load, they will be 25-45% less.

For a complete analysis, you need to find out which is better, TISE or screw supports.

These products are created as follows:

• With the help of a drill, a hole is formed in the ground.
• A special lower nozzle allows you to form a dome-shaped extension in the lower part.
• A tube of roofing material is installed in the well channel, pins of the structure.
• Next, the concrete is poured.

The main advantage of TISE piles is the absence of corrosive processes. But they cannot be used immediately. It is required to wait for the mortar to harden, which under normal temperature conditions is from 7 to 10 days. On the other hand, it should be noted that the reinforced concrete structure has a relatively higher bearing capacity.

Do-it-yourself pile foundation: step by step instructions, video

The video below shows the relevant technology. But its simple copying is not permissible to use. A project should be prepared. Let it be made not according to the canons of engineering standards. But even an elementary scheme for the arrangement of supports is better compared to the complete absence of working documentation.

You yourself need to find out what new products the manufacturers offer. Some new types of piles are inexpensive, but have excellent consumer characteristics.

The arrangement of a platform for a foundation in this case is simpler than carefully leveling a part of the land plot under a monolithic slab. Nevertheless, we must not forget about the possibility of using high plinths to solve economic issues. It should be remembered about the need for laying, networks and communications.

Important! Below is a detailed step by step guide. She will help with her own hands to build a reliable foundation without errors. But we must add to this description the corrections that are determined by the parameters of a particular structure and its application.

Screw piles for the foundation

Above were only some types of metal products in this category.

Increasing the number of blades simplifies screwing, provides greater support strength and increases load capacity. To simplify the connection of levers, other devices, holes are cut out. To simplify the attachment of grillages, flat, or "P" - shaped platforms are welded. A second screw is added to make it easier to maintain the upright position.

To strengthen the head structure, stiffeners (2) are added to it. The surface is protected from corrosion by multi-layer paint coatings (3).

These items are made from cast iron. Casting helps eliminate flaws in welded joints. These tips, even without special treatment, are highly resistant to corrosion. They are not damaged when passing through dense rocks, they retain an excellent functional state after decades of operation.

Responsible manufacturers use GOST standards to prevent destructive oxidation processes. Cold technology is cheaper than hot galvanizing. But the second version of the protective coating is more firmly held on the surface of the base metal. Powder provides high quality of a layer. But in the presence of stray currents in the ground, it can be damaged in 30-40 years.

To extend the service life, experts recommend paying special attention to the ground-to-air transition area. In some cases, it is proposed to wrap the corresponding area with a polymer film. Also apply regular inspections with updating the paint layer. Polyurethane-based enamel in combination with a high-quality primer can provide durability up to 60-70 years. This solution is used to protect sea and river vessels from corrosion.

The design value of the bearing capacity is determined by multiplying the screw area (projection onto a horizontal plane) by the soil resistance to loads. The second parameter is taken from a specialized table. It is given in kilograms per cm square. according to the level. For soft loams, for example, use the value: 3.5 units.

The correction factor is more difficult to determine:

• From 1.1 to 1.2 is used if the composition of soils is determined using a comprehensive geological survey of the site. The corresponding task is entrusted to the relevant organization. Its experts take samples at several points down to the depth of hard rock, which are checked in the laboratory. You will have to spend some money and time, but the most accurate result will be obtained.
• The second method is easier and cheaper. A drill is used with the measurement of dynamometric characteristics as it sinks into the soil. If such a technique is chosen, the correction factor is set at the level of 1.2-1.25.
This will speed up the process and will make it possible to make an additional margin of safety for the supporting structure.
• The area of ​​each floor is not difficult to find out. The calculator has a drop-down "window" where the presence of reinforcement should be noted. When working with this point, one must not forget to take into account the empty spaces of double levels, .
• Similarly, using program prompts, select the type . A wide variety of materials does not allow to enter all possible options. Therefore, when filling, analogs close in weight are used. The calculator itself will add the loads that create the corresponding truss structures.
• In a separate paragraph, calculations of the mass of snow cover are provided. Here you need to indicate the slope of the roof, mark the number of the zone using the map.
• The relatively small weight of a wooden grillage allows you to make the necessary correction by increasing the height of the walls. Other options (metal, concrete) are taken into account in a separate section.

For your information! It should be remembered that significant loads are created by furniture, the residents of the house themselves, their guests, heavy decor elements, household appliances, utilities.

Piles are installed at the joints of building structures, under pillars, in the corners. The distance between them is not made more than 3000 mm. The exact plan for the arrangement of supports must be agreed with the installation of other heavy technological equipment.

Article

It is difficult to make screw piles, but it is possible. Therefore, we will take the liberty of describing this technology. And the advice of FORUMHOUSE users will help us in this.

Consider the manufacturing process of the main elements indicated in the drawing.

Trunk

The base (trunk) is a hollow metal pipe.

In all cases, trunks are recommended to be made of steel with a strength of at least St. 20 according to GOST 8732-74 (for ordinary structural steels). If stronger alloyed steels are used, then GOST 19281 is suitable (but at home you can limit yourself to the first option).

The first thing the creator needs to do is determine the length of its trunk. With various "tricks" he will have to find out at what depth of the construction site the solid ground is located. The most correct (but expensive) solution would be to contact the geological exploration service. But among the sociable neighbors, there can be found a person who has a reasonable idea of ​​​​the state of underground layers.

The length of the pipe should exceed the depth of the bearing layer by about 300 ... 500 mm (if the pile protrudes from the ground higher, this distance may be greater). People who are wise with practical experience recommend making the length of the piles with a margin so that later they do not have to be increased.

BSergeyM FORUMHOUSE user

We twisted 17 pieces (house 9 by 8). Site on the slope. Part of the piles was cut, part was built up and filled with concrete.

In order to determine the diameter of the pipe, you can refer to SNiP 2.02.03-85 (with its tables and formulas). But those who are not familiar with the design of building structures in practice are guided by less sophisticated calculations:

• A pipe with a diameter of 47 to 76 mm is used in the construction of light fences and all kinds of fortifications
• Piles with a diameter of 89 mm are used in the construction of courtyard buildings (arbors, bathhouses, etc.), as well as in the construction of brick fences
• For the construction of frame houses and log buildings, options with a diameter of 108 mm are used.

At home, do-it-yourself screw piles with a diameter exceeding 108 mm (which can withstand high loads) are not recommended. They will need a reinforced blade, and it will be very difficult to provide such a product with high quality in self-manufacturing.

Alexey Oreshkov FORUMHOUSE user

The larger the diameter, the more difficult it is to make the screw, that is, the blade itself for extension.

The minimum wall thickness of the barrel should be 4 mm. Its calculation is simple - the thicker the better. But, when choosing the wall thickness, it should be remembered that the pile cone will have to be bent with a hammer.

Alexey Oreshkov

I made screw piles for myself, it’s real to do it myself. Pipe - 68x4 mm, screw - 168 mm in diameter, screw thickness - 5 mm, pitch on the screw - 50 mm, length of the tetrahedral tip - 150 mm. Everything is very well cooked semi-automatically.

Do-it-yourself screw piles. Cone

As can be seen in the drawing, the cone is the tip of the pile. Its length is from 1.5 to 2 pipe diameters. This is the standard, but some make the length a little longer so that the cone is sharper and the pile enters the ground more easily.

At home, the cone is made tetrahedral or hexagonal. To do this, special sectors are cut out on the edge of the trunk, which are bent into a cone with a hammer and scalded by welding.

Bone FORUMHOUSE user

I made a template from thick paper, after dividing the circumference of the pipe into equal parts. Then I marked the pipe with a marker and made saw cuts with a grinder. The result is the so-called crown. The thickness of the pipe makes it easy to bend it with a hammer. At first it turned out very clumsily, but welding managed to eliminate all the defects, and the tip turned out to be completely airtight, which made it possible to immediately fill the pipe with concrete after twisting.

Here's how it looks in the photo:

Do-it-yourself screw pile, manufacturing.

As you can see, the marking of the trunk was carried out according to a paper template. It's pretty easy to make. To do this, the diameter of the pipe circumference must be divided by the number of sectors. The found value is the distance between the upper points of adjacent sectors. It is easy to transfer data to a paper drawing and get a ready-made template. Further actions consist in cutting out the "crown", in bending the petals and in welding the resulting joints.

Before bending the petals of the cone, small cuts should be made at the base of the crown. Then it will be easier to form the tip.

Screw pile design. Blade

The blade is the main working part. It should be made of sheet steel with a thickness of 5 mm. This is how many people prefer to do it. Someone manages to make a blade 6 mm thick, but it is much more difficult to bend such a part correctly. The blade material is ordinary quality carbon steel (GOST 380-71). It is optimal to use grade 3 (it is used even in the industrial production of piles).

Now it's time to talk about the shape of the blade. The creation of its geometry is the most important stage of work. And if you make a mistake, then the pile simply will not be screwed into the ground.

First, let's determine the inner and outer diameter of the blank for the blade. The outer diameter of the blade (pile width) is directly related to the diameter of the pile shaft. Take a look at the table.

The inner diameter of the blade corresponds to the diameter of the pipe. Only now the dimensions of the workpiece (taking into account the fact that it will bend, forming a screw pitch) are slightly different from the diameter already known to us. A user of the FORUMHOUSE portal offers us a simple solution for determining the dimensions of the workpiece.

Ergali FORUMHOUSE user

Take a pipe and measure the screw pitch on it. After that, measure the length of the coil on the pipe, divide by Pi and get the inner diameter of the workpiece. Add the width of the blade to the inner radius of the workpiece and get the outer radius of the workpiece.

Now a little about how to determine the pitch of the screw. Typically, the pitch of the screw is 0.2 ... 0.4 of the outer diameter of the blade. If the screw pitch is smaller, then small solid inclusions in the ground will get stuck between the blades, preventing the pile from moving. If this indicator is greater, then more efforts will have to be made to screw into the ground.

Which specific step to use - it depends on what soil the piles are to be screwed into. It is easier to focus on the characteristics of the soil: the harder the soil in your area, the smaller the screw pitch should be. On sandy ground (predominant in the east of Moscow), we make the maximum step.

After all dimensions have been determined, you can start marking the steel sheet and cutting the workpiece. To cut the contour of the workpiece, we need plasma cutting of sufficient power, and that it is available should be taken care of in advance.

At the next stage, the cut blank is bent in accordance with the selected screw pitch. At home, this can be done with the help of an ordinary vise and improvised means.

FORUMHOUSE user BSergeyM offers its own version of the device for unbending the blade.

Screw piles: manufacturing.

Please note that the bend on the cutting edge of the blade is very small. This is how it is always done. Such a bend is enough for the pile, like a self-tapping screw, to go into the ground.

On the part of the blade that will first go into the ground, it is necessary to make a cut at 45 °. This will help the pile to easily bypass solid mechanical inclusions in the ground.

At the next stage, the finished part is welded to the pile shaft. The seam is laid on the top and bottom of the blade. The blade must be welded perpendicularly. Otherwise, the pile during screwing will loosen the soil, destroying and weakening its structure. And on weakened soil, the pile will not be able to cope with the loads placed on it.

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 pile-screw. It is this version of the design of the foundation for construction that raises the most questions. Therefore, we will devote this publication to the question: the foundation on screw piles, pluses and minuses, a general overview of its structure, the possibilities and expediency of 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, one should probably consider some of the nuances that directly affect the strength and durability of the pile foundation.

House on stilts - fantasy or reality?

Can a pile foundation be used to build a residential building? I must say that there are some builders who categorically do not advise doing this, preferring a tape, columnar or slab base for a 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 piles, and they have been standing for decades. The practice of using such foundations has proved that they can serve as a reliable foundation even for massive houses.

By the way, with the help of screw piles, you can make not only a foundation or lifting / moving a house, but also a complete or partial reconstruction of it!

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

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

The use of such a design is also supported by the fact that such variants of foundations have been used in construction since antiquity, only earlier logs specially prepared for this purpose were used as piles. At first, 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 for arranging berths, but then the scope of their application began to expand. So, for example, it was screw piles that were used as a foundation for the construction of a lighthouse, which was built in the UK 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 equipment for accurate and deep driving of piles, which significantly accelerated the work on the construction of foundations for the further construction of buildings. In the 50s, the active use of mechanical equipment for screwing piles began, which gave another impetus to such a field of construction, both industrial and individual.

Very widely this method of arranging foundations began to be used in military construction, since through comprehensive studies it was proved that such structures are reliable, durable and suitable for use on permafrost, heaving and watered 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 installation of foundations, bridge supports on screw piles"). Many of its provisions have flowed 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 explicit virtues pile screw foundations include the following points:

• The structure can be erected on soils of almost any type in different climatic regions, including marshy areas and regions with permafrost.
• The level of location of groundwater does not have any significant effect on the arrangement of this type.
• The screw foundation is great for building a house on a terrain with difficult terrain.
• Screw piles can be installed at any time of the year, as weather conditions will not affect the quality and strength of the structure being created - at the depth of immersion of screw tips, the soil temperature is always stable.

• Pile-screw foundations are not subject 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 in just 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 for setting, maturation, curing, like any reinforced concrete structures. None of the other types of foundation is even close to such indicators of construction speed.

• Piles can be screwed in on the site allotted for the construction of the house, and independently, with the involvement of several assistants, that is, without the use of special equipment. This factor is especially important if there is no opportunity to order such services in the construction area, or the owner of the future home is simply limited in funds.

• For the arrangement of the pile-screw foundation, it is not necessary to dig a pit and equip the formwork, which means that there will be no blockages of the selected soil on the site, which will also have to be disposed of by taking it outside the site, and which also requires additional material costs. In addition, under this foundation, it will not be necessary to carry out work to level the construction site.
• The pile-screw base does not pull capillary moisture from the ground, 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 engineering communications simultaneously with the installation of foundation elements or after its construction.
• With the right choice of high-quality piles and their reliable installation, the durability of the foundation is ensured, which is estimated for many decades.

• Having well insulated 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 cool down from the ground. In addition, in some cases it is possible to equip a kind of “utility floor” under the house without carrying out large-scale earthworks.
• The construction of a foundation made of screwed piles will cost 30÷40% cheaper than a concrete foundation. Given the fact that the construction of the foundation is always among the most costly stages of building a house, the cost savings can be quite impressive.

Prices for screw piles

screw piles

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

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

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

• The disadvantage of such a foundation, independent of calculations and installation work, can be called 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 bearing capacity of the entire foundation, and as a result, to deformation of the piping belt and destruction of the walls.
• It is necessary to equip systems for efficient drainage from the installed piles, which leads to additional costs. However, storm and drainage sewers are recommended for installation around foundations of any type.
• It is impossible to completely exclude the effect of corrosion on the pile material. Quality products, of course, receive the necessary protection during the production process - coating with a layer of zinc and polymeric materials. However, sometimes the increased chemical aggressiveness of soils does its "dirty deed". It is not recommended to create pile-screw foundations in the immediate vicinity of electrified railways, cell 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 the processes of metal corrosion. And it should absolutely be excluded the use of foundation piles to create a ground loop at home.

• The bearing possibilities of the screw piles offered for sale are not unlimited. However, this has a very indirect relation to low-rise private construction - large loads exceeding the characteristics of properly selected piles are not expected.
• No matter how hard you try, you won’t be able to get a full-fledged basement or basement using a pile foundation in private construction.
• During the construction of extensions to the house, certain difficulties are possible with screwing in piles at points located close to the walls of the old building. However, this is usually solved using special equipment.
• The fact that the construction of a pile-screw foundation will require constant monitoring of the work of the invited team from the owners-customers can be attributed not to shortcomings, but rather to peculiar costs. Unfortunately, we have to state that in this field there are a lot of “unfortunate specialists”, and even frank “sharomyzhnikov”, who are trying in one way or another to benefit from the violation of the installation technology of piles. So, to ensure high-quality protection against corrosion, the cavity of the pile according to the technology is required to be filled to the top with concrete. It is not uncommon for invited workers to ignore this stage, immediately after screwing in, welding the heads.

There are known examples when teams of "shabashniks", working without the control of the customer, did not screw the piles to the full estimated depth - and it is almost impossible to check this after cutting the pipes, welding on the heads and strapping. And such a violation will invariably entail a quick deformation of the created foundation with all the ensuing consequences.

And, without any doubt, it is necessary to drive workers from their construction site if it is noticed that by adjusting the piles in height, they rotate them in the opposite direction to screwing in. Such a support can immediately be considered rejected, since it will no longer be able to have the calculated 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 miss a single stage of construction from the field of view, to control every action required by technology. Well, if there is a desire and self-confidence - to carry out the installation of piles on your own.

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 right piles, and carry out the construction of the foundation on the basis of the calculations made, including the assessment of future loads and the 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 necessary to take into account the factor that sometimes different types of piles are used even during the construction of one object, since in different zones the structure can give a non-uniform load on the foundation. The use of different types of piles will provide a margin of safety for the foundation and increase the operational life of the building.

Screw piles are subdivided according to the following parameters: according to the main purpose, according to the diameter of the pipe, the size of the blades and their number, according to the type of tips, according to the perceived loads (bearing capacity), according to the grade and thickness of the steel, and also according to 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.

Varieties of piles by scope

The illustration below shows four main types that differ dramatically 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, which allows you to build foundations on most types of soil. It is usually used for light outbuildings and one-story houses made of wood or frame panels. However, with the right choice of the diameter of the blades and the number of piles on such foundations, houses are also built from gas silicate blocks.

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

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, in the practice of independent construction, they are not used.

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

cement prices

Standard sizes of screw piles for the foundation

Depending on the composition of the soil and the loads on the structure, it is necessary to choose 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 sizes of wide-blade piles with a welded tip (they usually act under the name SVS - welded screw pile)

Illustration	main characteristics and scope of the pile	Approximate price for a product with a length of 2500 mm + surcharge for each additional 500 mm. The price of a regular pile head
	SVS-57. Pipe diameter - 57 mm, blades - 150 mm. Such products have not an outstanding bearing capacity - the permissible load on the support is only up to 800 kg. This also leads to a rather narrow area of ​​\u200b\u200buse - lightweight fences that do not become an obstacle to the wind, that is, from a chain-link mesh or a rarely located picket fence. Usually, 4-meter piles are purchased for such purposes, based on a two-meter immersion in the ground and two meters - on the height of the fence.	1300 rub. + 100 rub. OBC-57/200/200 head - 260 rubles.
	SVS-76. Pipe diameter - 76 mm, blades - 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 often located wooden or metal picket fence, flat slate, metal corrugated board, polycarbonate and other similar materials). The most commonly used length is 4000 mm, for the same reason as mentioned above.	1450 rub. + 100 rub. Head OVS-76/200/200 - 300 rubles / piece.
	SVS-89. Pipe diameter - 89 mm, blades - 250 mm. The bearing capacity, depending on the soil, can reach up to 4÷5 tons. The specifics of the 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 attaching 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 the house.	1500 rub. + 150 rub. OBC-89/200/200 head - 300 rubles / piece.
	SVS-108. Pipe diameter - 108 mm, blades - 300 mm. The 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 proved their effectiveness, including on difficult soils - swampy or peaty.	1700 rub. + 250 rub. Head OVS-108/200/200 - 300 rubles / piece.
	SVS-133. Pipe diameter - 133 mm, blades - 350 mm. The most durable supports used in individual construction. The laid potential of the bearing capacity reaches 14 tons. Such supports are used to create pile fields for the construction of houses from fairly heavy wall materials - gas silicate blocks or even brickwork. With an appropriate bearing capacity of the soil, tying the piles with a monolithic reinforced concrete grillage is often used, as well as pouring the concrete floors of the first floor.	2250 rub. + 350 rub. Head OVS-133/300/300 - 350 rubles / 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-bladed.

Single-blade piles are used for arranging foundations on terrain with soils that have a high bearing capacity. However, when using this type of product, especially with welded tips, you need to be prepared for the fact that they can go into a “breakdown” when they reach a critical load. At the same time, the supports lose their bearing capacity, which will negatively affect the integrity of the foundation strapping.

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

A larger number of blades on the pile shaft makes it possible to use a product with a smaller pipe diameter having 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 the angle of their inclination is calculated individually, taking into account the location of the soil layers and its composition at a particular construction site. Working with such supports, of course, 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, as 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 with man-made or solid natural inclusions. This type of tip is not deformed, even bumping into an obstacle, and is able to destroy it.

Welded tips are used in weaker soils, however, their strength is directly dependent on the grade and thickness of the steel, as well as the quality of workmanship. Their only advantage compared to cast ones is a 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 of pipes with a wall thickness of up to 3.5 mm;

- medium 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 piles is determined during the preparation of the project, and the choice is made in accordance with the data obtained during the study of the corrosive activity of soil layers.

According to the same data, the thickness of the metal for the pile blades is also 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 conducted soil studies, the steel grade of the products is also selected:

- with a weak chemical aggressiveness of the soil, St3 steel can be used;

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

- with a strong aggressiveness of the soil, piles made of steel 09G2S and 30XMA are suitable.

Type of anti-corrosion coating

Due to the fact that the piles will be in a damp soil environment that is aggressive for 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, which is in the ground, but also its top, as well as the area located on the border of the underground and aboveground 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. According to the tests of various coatings, it was concluded that the cold galvanizing method, polyurethane and epoxy coatings, as well as enamels and primers applied over rust without preliminary surface preparation, showed the greatest efficiency in metal protection, while hot galvanizing and ordinary 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 aboveground parts. But do not forget that all serious manufacturers necessarily provide for anti-corrosion protection of their products. Therefore, if the piles are "bare metal", then with a very high degree of probability it can be argued that they are handicraft. Well, if so, then who can guarantee compliance with other performance characteristics?

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

Principles of calculation and design of a pile-screw foundation

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

In order to avoid characteristic shortcomings during the operation of the pile-screw foundation, it must be correctly calculated and planned, taking into account all the nuances mentioned above. Designing any 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 outbuildings or other light buildings.

Evaluation of the bearing capacity of the pile

First of all, it is necessary to evaluate the bearing capacity of the screw pile at 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 very large (for example, for SVS-108 - from 5 to 9 tons). This, of course, is not an approach to business - it is necessary to operate with more accurate values. Moreover, in some cases, depending on the specifics of the soil, the permissible load indicators can even go beyond the boundaries of the specified range in one direction or another.

Any type of soil is characterized by its load resistance index, that is, in fact, by its bearing capacity. It is from this that they “dance” further when calculating the permissible load on the screw support.

Below is a calculator that will help calculate the bearing capacity of piles of the most common SVS model range, which was discussed above. The calculation program has already included the necessary data on soil resistance at an 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 margin of safety of the support, will also depend on this.

• The most accurate way is to carry out geological survey work: drilling wells by specialists and an accurate assessment of all soil layers. The method - without flaws, 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 the not too great popularity of this approach.

• The second option, which also requires the involvement of specialists, but is no longer associated with too high financial costs, is screwing in an experimental (reference) pile. It consists in the fact that a pile is screwed into the ground at the building site, and in the process of its passage 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 are confident in your knowledge and skills, you can simply dig a deep hole or drill a well to the depth of the expected location of the screw pile blades. Well, then - take a soil sample from this depth, classify it according to characteristic features and, using tables that are in abundance on the Internet, find out the calculated value of its bearing capacity. Can you handle it? At the same time, we are certainly not talking about high accuracy of the assessment, which affects the sharp increase in the correction factor - up to 1.6 ÷ 1.7.

In the process of test drilling, it is necessary to immediately determine the required length of piles. Incorrectly selected pipe lengths can lead to subsidence of the foundation and the destruction of the walls of the house. Therefore, when calculating the length, they rely on two parameters:

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

- 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.

If you managed to buy a wonderful plot at a surprisingly low price, do not rush to rejoice - it is quite possible that the groundwater on the purchased plot comes close to the surface, or you got heaving soil. These factors can lead to the fact that the construction of the foundation will take much more money than expected. In addition, you still need to choose the right type of foundation so that uneven settlement of the house does not occur in the spring.

What is a pile-screw foundation

The best option in such cases is a foundation on screw piles, suitable for any terrain and for any "problem" soils.

The pile screw foundation has been successfully used in construction since 1850, when the first lighthouse on piles was built in the United States. The fact that the lighthouse is still standing today confirms the high strength of the screw foundation and explains why this technology has gained such popularity around the world in a relatively short time.

Installation of the foundation on screw piles is possible on any terrain

The peculiarity of the screw pile is that this steel pipe has a pointed tip with a thread and blades or a combined thread for screwing into the ground. The most expensive are screw piles equipped with blades, but they also compact the soil better due to their design. There is no specific standard for screw piles. They are solid and hollow, of various diameters and lengths, with a cap in the upper part of the tube of a rectangular, round or U-shaped shape.

Video about the foundation on screw piles

Installation of the foundation on screw piles is possible on any terrain: on uneven or flooded areas, on slopes, on peat soils, on well-groomed lawns without the risk of harming the lawn, next to large trees. Thus, there is no need to carry out any preliminary work on clearing the site and leveling it, and there is no need to disturb the natural relief.

Benefits of a screw foundation :

• there is no need for earthworks;
• no need to provide access roads for equipment;
• installation can be carried out in winter;
• three people are enough to build the foundation;
• all foundation works take from one to three days;
• you can always easily attach a new structure to a house built on stilts.

All foundation works take from one to three days

Piles can be screwed into the ground, both with the help of special equipment, and manually - the pillars make their own way in the soil to a given depth. If necessary, the screw foundation can be quickly dismantled (if the hollow pillars are not filled with concrete) and moved to another location. Thanks to the listed advantages, the foundation on screw piles invariably deserves the best reviews and is successfully used in industrial and private construction.

How to deal with a screw foundation on your own

Screw piles under the foundation must cut into solid layers of soil that lie lower than the soil freezes through, in which case the pillars will not be subjected to the force of heaving of the soil. To correctly determine at what depth a stable layer of soil is, it is best to contact a specialist. In addition, for the correct calculation of the future foundation, you will need to take into account the weight of the future structure, seasonal fluctuations in groundwater, soil type, wind load and climatic features of your region. It's not easy to figure this out on your own.

The number of piles is determined depending on the dimensions of the building under construction. The pillars will need to be evenly distributed under the base of the building with the same pitch, not forgetting about the nodes of the internal walls and about the corners. The length of the ground part is usually about half a meter, the visible part of the piles can be hidden behind a false plinth or left open.

The number of piles is determined depending on the dimensions of the building under construction

The construction of the screw foundation is carried out as follows:

• markings are applied to the site with pegs exactly in the places where the piles will be located;
• piles are twisted using a special rod manually, while using a level, their even position is checked;
• the installed piles are aligned to one level with a laser level, the longest pillars are cut by a grinder;
• concrete is poured into the cavity of the pipes in order to protect the internal surfaces of the piles from corrosion;
• outside, the ground parts of the pillars are recommended to be coated with an anti-corrosion compound;
• a metal frame is welded to the supports and painted in two layers with protective paint.

Video about the screw foundation

Insulation of the foundation on screw piles is not required, since this type of foundation is ventilated. High supports protect the house from the cold that comes from the ground. You can insulate the grillage, but keep in mind that improper thermal insulation will lead to dampness, which will negatively affect the entire structure. To make the house warmer, it is better to pay attention to the insulation of the floor, and not the screw foundation.

If you come across reviews about the pile screw foundation that are not too positive, this means that some mistakes were made during the construction of the foundation (pits for the pillars were dug out, the position of the pile was not controlled during twisting, the pipes were not protected from corrosion, etc.) . But even if, due to improper installation, the building sank a little, it is always possible to repair the foundation with screw piles, replacing the sagging pillars with new ones. The ability to quickly repair is another great advantage of a screw foundation.