There are often situations where construction conditions do not satisfy at least the minimum requirements of the standards.
Most often this is due to unsuitable soil conditions.
Excessive plasticity or fluidity, waterlogged or excessively loose soils, peat bogs and other problem areas force us to abandon generally accepted and traditional support structures.
In such cases, it is used which depends little on the quality of the upper layers of the soil, since it is based on deep dense rocks.
Considering the abundance of problem regions, the technologies for constructing pile foundations have been developed for a long time and allow some types to be installed independently.
Pile foundation is a system of point supports immersed in the ground to a certain depth until contact with solid layers.
The length of the vertical elements can be significant, depending on the depth of stable soils and often exceeds the height of the above-ground part of the building.
The upper part of the supports is rigidly connected to unified system, which allows you to distribute the load across all piles and obtain the most efficient mode of operation of the base. The strapping is called a grillage, it is designed to receive and transmit loads to the support rods.
According to the principle of operation, the operation of the grillage is in many ways similar to the functions strip base, but the difference between them is that the tape rests on the prepared soil surface along its entire length, and the strapping is installed on the top points of the piles.
This difference puts forward special requirements for the rigidity and strength of the grillage beams, the spans of which work only due to their own rigidity and strength of the walls.
Kinds
There are various design options for a pile foundation, each with its own specific characteristics.
According to the material of the supports there are:
- Wooden. Sanded logs with a pointed end are used. The most ancient type of piles, which has practically disappeared at present. The reasons for this were the disadvantages of wood such as building material and the availability of stronger, more durable options. Occasionally found in private construction as supports for auxiliary or outbuildings.
- Metal. There are two types of metal piles - screw and driven. Screw piles resemble screws that are driven into the ground using cutting spiral blades on a pointed tip. Driven piles are not specially produced and are segments various types rolled metal - channel, I-beam, rail, etc. They have high strength and are able to bend plastically while maintaining load-bearing capabilities. The disadvantage is the tendency to corrosion, which shortens the service life of the supports.
- Reinforced concrete. There are two types of reinforced concrete piles - driven and cast-in-place. The first ones are produced in specialized production conditions, have a robust design with stressed longitudinal reinforcement and are resistant to all loads. The latter are made directly on the site by filling the formwork (waterproof pipes) placed in the well with dense grades of concrete.
By load transfer method:
- Rack piles. They are supports that are in rigid contact with dense layers of soil. The depth of the shafts depends on the level of hard rocks.
- Hanging piles. They do not have support in the lower part of the trunk, using only friction on the side walls and partial support on the ground. There are both driven and cast-in-place friction piles. The load-bearing capacity depends only on the depth of immersion; for stuffed ones, it is enhanced by thickening in the lower part of the well.
By design:
- Drivers. They are a monolithic rod with a pointed end, immersed using mechanical action at the upper end.
- Printed. They are a concrete casting into a pre-prepared well. They have a lower load-bearing capacity than driven piles, but can be made independently.
- Screw. They are made from a pipe with a pointed tip and spiral blades. They can be installed independently, although in practice this is only used for auxiliary buildings or structures.
All types of piles, regardless of design or material, are capable of working effectively on complex or problematic soils.
Device
The main part of the work on creating a pile foundation comes down to immersing the trunks in the ground.
This is the most difficult and critical stage, which determines the strength and stability of the entire system.
If failure, failure, or other problems occur during immersion, the ability of the entire base to perform its function is compromised. Any deviations during the work indicate non-compliance with the technology, unscrupulous geological survey of the site or low quality of piles.
The second stage is the creation of a grillage. It performs equally important functions and must meet all existing requirements.
The technology of creation directly depends on the type of piles, material of manufacture and parameters of the future home.
For light buildings, the grillage can be made of wood (a beam or a bundle assembled from an edged board until the desired thickness is obtained).
When using metal piles, it is customary to create a grillage from metal- channel, I-beam or profiled pipe.
For reinforced concrete piles, the grillage is cast from concrete using a technology reminiscent of manufacturing strip foundation.
NOTE!
Both stages of creating a pile foundation must be carried out by experienced builders or, at a minimum, under the supervision of a competent specialist. Possible violations of technology or deviations from calculated parameters, which must be noticed and corrected in a timely manner, which is not always possible for unprepared people.
How to calculate diving depth
The depth of immersion of piles is determined based on their type:
- Rack piles are immersed to the depth of dense layers of soil. IN in this case no calculation will help, it is necessary to drill test wells and determine the true level of solid soils.
- Friction piles have a load-bearing capacity that is determined by the properties of the soil and the length of the side surfaces. The higher the load, the longer and, accordingly, deeper the pile must be immersed.
- Bored piles rest primarily on a wide platform - a cushion. Its area is determined by the soil resistance and the magnitude of the vertical load.
- For screw piles The depth of immersion is determined by the level of soil freezing in winter. This parameter is relevant for all types of piles, but other species usually dive much lower anyway.
A complete engineering calculation of immersion depths is a complex and responsible task, which not all specialists risk taking on.
Therefore, independent calculation is strongly not recommended; you should contact a specialized design organization.
At a minimum, you can use an online calculator.
Calculating height above ground
The height of the pile foundation above ground level is determined by the height of the top line of the grillage.
Selecting the correct value is determined by several factors:
- Snow cover thickness in winter.
- Possibility of flooding, water level during spring floods.
- Bedding level groundwater.
- Temperature conditions in the region.
By comparing these parameters, we come to the choice of the optimal height of the grillage.
The possibility of equipping a basement room is extremely rare; most often, a technical underground is installed in which communications are located.
Step-by-step DIY installation instructions
Let's consider the procedure for creating a pile-screw foundation.
The work is carried out in stages, the sequence of actions has a strictly defined sequence:
Preparation
The pile-screw foundation has important feature- it can be created on uneven terrain that does not require preliminary leveling (planning).
It is possible to build on slopes or in folds, which makes it possible to effectively use areas that are inconvenient from the point of view of traditional construction. That's why preparatory work can be reduced to clearing the area of plants and foreign interfering objects.
Make markings and mark all pile installation points with pegs. Then, small (up to 30 cm) recesses are made at the installation sites, which facilitate the entry of the blades into the ground.
The fertile layer of soil creates noticeable resistance due to the abundance of roots, plant stems and other obstacles, so it is better to remove it.
Driving piles
Installation of screw piles is done either manually or mechanically. Manual installation is possible in the presence of relatively soft soil without man-made inclusions or rock debris.
The diameter of the barrels available for manual immersion is limited to 87 mm.
The most common 108mm diameter piles are often too difficult to construct due to high soil resistance.
The machine method allows you to obtain high-quality installation of screw piles, observing a certain angle, screwing force and depth.
The power of construction equipment allows you to freely work with piles up to 159 mm in diameter, which is quite enough for the construction of a fairly large private house.
The piles are driven to a predetermined depth. Usually it is determined by the level of occurrence of dense layers, or the soil resistance force exceeds the force permissible for a given shaft, which breaks off the technological hole.
A pile that has reached the required level of adhesion to the ground rotates with great effort or stops doing so altogether.
You cannot try to continue rotating - the welding may fail, the blades will come off and the pile will become unable to perform its functions.
Harness
After installation of all piles, trimming is carried out. This is a procedure that allows you to adjust the height of trunks protruding from the ground to a single level and form them into an even horizontal plane.
Install a laser level with the function of constructing planes at the required height and cut off excess sections of pipes.
After trimming, the internal cavities of the piles are filled with concrete, increasing their strength.
Then they install the strapping (grillage) - a belt that connects all the piles into a single system and at the same time serves as a supporting element for the walls of the house. The cut tops are covered with caps with horizontal platforms on which metal or wooden beams are installed.
For fixing on the platforms there are technological holes for bolted connections.
Sometimes the trim and grillage are different elements. The piping is performed below the level of installation of the grillage and connects all the piles together, forming a system like a lattice. Metal sections of a channel or I-beam are used, welded to the walls of the trunks.
Scheme for creating a bored base
Construction of a bored foundation is a more labor-intensive task.
Procedure:
Site marking
Excess vegetation or objects are removed. The surface of the site is planned, if necessary, the top layer of soil is removed.
Then, using pegs, the points for creating bored piles are marked.
It is necessary to monitor the accuracy of compliance with the design data, carefully measure all distances.
Be sure to check the diagonals and make sure they are equal. If any discrepancies are found, errors are corrected immediately.
Drilling of the wells
Based on the marking results, wells are drilled. The depth is determined in the project; only the creation of depressions in the ground is required.
Sometimes a hand drill is used, more often special equipment is used, which significantly speeds up the work and improves quality.
If you need deep wells - from 3 m or more, manual methods cannot be used.
Reinforcement
Formwork is lowered into the finished well, the role of which is played by a segment plastic pipe required length and diameter.
They often make do with a pipe rolled from roofing felt. It remains in the well and performs waterproofing functions.
Then the reinforcement frame is assembled. Usually it is a spatial lattice of 4 vertical working rods connected by transverse sections of thin smooth reinforcement.
The dimensions of the frame should allow it to be lowered freely into the well, but not allow it to dangle too freely in it.
Optimal distance vertical rods to the walls of the well - 3-5 cm.
Pouring concrete
Heavy grades of concrete from M200 and above are used for pouring. Used either ready material, or made independently right there on the spot.
The entire cavity of the well is filled with concrete and bayonet is performed - a long rod is used to pierce the concrete, removing air bubbles from it.
After pouring, the concrete should be cured to gain structural strength. This period lasts from 20 to 30 days depending on the diameter of the wells.
Harness
The piping of drilled wells involves the creation of a grillage - reinforced concrete tape.
Its dimensions are close to the parameters of a shallow strip base, therefore the entire method of manufacturing a concrete grillage is as close as possible to the tape casting technology.
The only difference between them is the lack of support on the ground, which forces the construction of formwork in the form of a trench with a durable bottom.
The result is a powerful and durable concrete belt located under all load-bearing walls and connecting bored piles into a single support system.
Grillage technology
Installation of a grillage is the process of creating a load-bearing belt for walls.
Procedure:
- Construction of formwork. A durable gutter is installed from board panels, the internal dimensions of which repeat the cross-sectional shape of the grillage.
- The inner surface of the formwork is hermetically covered with a layer of polyethylene or roofing felt. This is necessary to prevent concrete leaks during pouring.
- The reinforcement cage is assembled and placed inside the formwork. It is welded to the armored well belt, forming a single frame for all elements.
- Concrete is being poured. The process must be completed in one go, interruptions are not allowed. Pouring is carried out from different points, evenly distributing concrete along the entire length of the formwork.
- After pouring, the tape is covered with burlap or polyethylene and kept for 28 days. Formwork can be removed after 10 days.
- The finished grillage is carefully waterproofed and proceeds to further construction.
Useful video
In this section, you can visually familiarize yourself with how to properly make a pile foundation with your own hands, as well as how to strengthen it:
Conclusion
To create a pile foundation yourself in any case requires certain training and experience.
At a minimum, constant supervision of a specialist is required, ready at any time to advise the owner of the site, or to intervene in the construction process to get rid of errors.
Support structures represent a responsible and vital important element buildings, the creation of which must be carried out taking into account all the norms and requirements of SNiP and SP.
It is necessary to first study these documents in detail in sections related to pile foundations and the conditions for their installation.
Careful observance technical requirements will eliminate deformation or destruction of elements of the support system and ensure maximum long-term operation.
In contact with
Pile-strip foundation is a type for heaving and weak soils. Its peculiarity is that the walls of the building rest on a solid perimeter, and strong adhesion to hard layers of soil is ensured by piles buried below the freezing depth. This design allows, on the one hand, to reduce construction costs, and on the other, to ensure the strength and high load characteristics of the building.
Advantages of a pile-strip foundation
- Low price;
- It is carried out quickly, you can make a pile-strip foundation with your own hands without the use of special equipment;
- Can be installed in areas with any terrain;
- Excellent resistance to heaving and seasonal soil movements.
Among the disadvantages, one can note the impossibility of constructing a full-fledged basement.
Design and scope of application of pile-strip foundations
The pile-strip foundation transfers the building load to the ground using two structural parts: foundation tape installed along the perimeter of the building and under load-bearing partitions, and piles that ensure the strength of the foundation during seasonal ground movements. The piles and foundation strip are reinforced with reinforcement. Piles can be made either using the bored method or using asbestos-cement pipes filled with concrete. Recently, metal screw piles with drill blades at the lower end have become very popular. The foundation strip is made by pouring concrete.
Pile-strip foundations are used for private low-rise construction houses, cottages, and other buildings with a basement. They can be installed on soils prone to heaving, as well as in areas with large elevation differences. Such a foundation is much cheaper and is completed faster than a buried one.
Execution technology
- Site preparation comes down to clearing debris, leveling and marking. A shallow trench is dug under the foundation strip, up to half a meter. The bottom of the trench is covered with sand or gravel, which ensures water drainage from the foundation and reduces heaving of adjacent soil layers. At corners, at intersections load-bearing structures, as well as along the perimeter of the walls, about 2 meters apart, holes are drilled for piles. The depth of the wells is 0.3-0.5 m greater than the depth of soil freezing. The diameter of the wells is chosen so that the piles fit freely into the well.
- River sand is poured into the wells, forming a cushion 15-20 cm thick. The sand is spilled with water and compacted. Afterwards, asbestos-cement or metal pipes are installed, filled with 30-40 cm of concrete and raised by 20 cm. Concrete, flowing into the space under the pile, forms an expansion, the so-called sole. It provides stronger adhesion of piles to hard layers of soil. Until the concrete has set, level the vertical position of the supports. After the concrete hardens, a reinforcement cage made of several metal rods connected with wire and forming a lattice is inserted into the pipe. The height of the reinforcement should be such that it extends out of the pipe and reaches almost to the top of the foundation strip.
- Wooden formwork of the required height is placed above the ground surface. The formwork is assembled using nails or self-tapping screws, and reinforced with bars in the corners. All protruding structures are located on the outside of the formwork. The walls are reinforced with struts and ties. Reinforcement is placed inside the formwork: a rod with a diameter of 8-16 cm, depending on the design load, is laid in all three directions, forming a three-dimensional mesh. At the intersection points, the rods are tied with wire using a hook for tying reinforcement. Be sure to connect the reinforcement of the piles and the foundation strips - this connection ensures the strength of the structure.
- First the piles are poured with concrete, and then the entire foundation strip. Be sure to remove remaining air from the structure using a deep vibrator or a regular reinforcing bar, piercing the thickness of the solution in several places on each section of the foundation. The foundation mirror is leveled, smoothed with a rule and isolated from precipitation with covering material or plastic film. During the process of drying the foundation, its moisture content is checked and it is not allowed to dry out; to do this, in too hot weather it must be slightly moistened.
- After the concrete has hardened and gained the necessary strength, you can begin waterproofing and. Concrete is a hygroscopic and thermally conductive material. Wet concrete cracks when it freezes, leading to the destruction of the foundation. Therefore, it is recommended to waterproof it immediately after constructing the foundation. Typically, bitumen or polymer mastics or roll materials are used for this purpose: roofing felt or self-adhesive membrane films. Before waterproofing, the concrete surface must be primed with a special solution, as well as an antiseptic. After the primer has dried, the walls are covered with waterproofing.
- Insulating the foundation of a house is an important step towards creating a warm and stable microclimate. The use of modern materials and techniques will allow you to raise the temperature in the semi-basement space to positive values, even in the midst of frost. The most popular methods of thermal insulation are insulation using polystyrene or polyurethane foam. Polystyrene is a new modification of the well-known foam plastic, resistant to mechanical stress and providing good thermal insulation. The slabs are glued with special glue, and after it dries, they are additionally secured with dowels.
- Polyurethane foam is a sprayed coating similar in principle to polyurethane foam, but its thermal insulation characteristics are much higher. To apply it you need a special installation.
- A pile-strip foundation is an excellent solution for constructing an inexpensive and reliable foundation for a house; if constructed correctly, its service life is more than a hundred years.
A foundation that uses cast-in-place piles to transfer the load from a structure is called a bored foundation.
Bored piles are individual elements of the foundation system that you can install yourself.
Conditions for using cast piles
It is advisable to use a foundation on poured piles in cases where the soils have low bearing capacity, the freezing depth is more than 1.5 m, and groundwater is close to each other.
When constructing on a site with a large slope, good option will become a pile foundation.
Such a foundation will be an ideal option for the construction of wooden and frame houses, bathhouses, outbuildings, gazebos with a small total weight.
For houses with no more than two floors, the diameter of cast piles can be about 200 mm. For heavier buildings, supports with a thickness of 250 mm or more are required.
Advantages of foundations on poured piles
When comparing a bored foundation with other types of foundations, we can say that it has a number of significant advantages.
- When laying such a foundation, dynamic impacts on neighboring buildings are eliminated.
- Self-leveling piles do not have a harmful effect on environment, after installing the foundation there is no need to carry out reclamation.
- Possibility to make a foundation in peat and wetlands. And also directly near bodies of water.
- Can be used for any types of buildings.
- Unlike metal and ready-made reinforced concrete piles, cast-in-place piles do not require the use of special lifting equipment and mechanisms. The entire process of constructing a foundation can be done with your own hands.
- A bored foundation is the most economical option, which allows you to reduce total cost construction.
- Pouring piles with concrete can be carried out at sub-zero temperatures.
- Depending on the number of poured piles, the work can be completed within 5-10 days.
But along with all the advantages, there are times when installing a bored foundation is not practical.
- If available on construction site moving soils.
- High-rise construction.
Cast-in-place pile technology
If you plan to do the work on constructing a bored foundation yourself, you need to know what technology is used for this and the stages of production.
IMPORTANT! The depth of the holes should be below the freezing level. This indicator is individual in each climate zone.
IMPORTANT! Such shells are necessary in order to prevent freezing of the piles with the soil in winter, to prevent the concrete from becoming saturated with ground moisture, and also to prevent the laitance from being absorbed by the soil. The technology predetermines that asbestos-cement and metal pipes must be covered on the outside with a layer of waterproofing.
IMPORTANT! The concrete mixture must be liquid so that it can independently fill the void formed under the pipe.
IMPORTANT! Do not neglect the installation of reinforcement, since any, even insignificant, lateral load can break the pile. Make sure that the reinforcement does not touch the ground, this will protect it from corrosion processes and premature destruction.
IMPORTANT! Pouring of piles with concrete should be carried out without significant interruptions, this will ensure proper solidity.
For unstable soils, it is better not to use classic foundations in the form of a strip of reinforced concrete. In order for a house to stand on such a support stably, the technology will have to deepen it too much. And this is an increase in volumes earthworks and spending on concrete. It would be much more rational to create a combined pile-strip foundation with your own hands, which incorporates the best aspects of both piles and strip construction.
What is a strip foundation on piles?
In terms of structure, a pile-strip foundation is a structure made of piles dug into the ground to a depth below the freezing point, and a reinforced concrete grillage on them. It combines the advantages of two types of foundation structures. The grillage tape serves to evenly redistribute loads. And the buried pile foundation plays the role of anchors, which prevent the reinforced concrete from above from “floating away” during soil heaving and a strong rise in groundwater.
Scheme: 1- reinforced frame, 2-asbestos-cement piles, 3-concrete tape, 4-technical conclusions, 5-waterproofing, 6-ventilation holes
A conventional pile-screw foundation is somewhat inferior to the type of supports for houses under consideration in terms of distribution of vertical loads. A reinforced concrete tape laid on piles is more resistant to spot raising or lowering of one of the support pillars. On the other hand, this design outperforms its purely strip counterpart in terms of construction costs, as well as stability on heaving and waterlogged soils.
Types and subtypes of foundation
A strip foundation on piles is ideal in the presence of soils with weak heaving. In such areas it can be used for the construction of two-story brick cottages. But in general, such a design is more intended for light frame or timber buildings.
However, if the site for the house has a slope, then it will be difficult to do without a pile strip foundation. Monolithic slab here it will be too expensive to fill, and other options will not be able to withstand all the loads that arise in the future as well.
Based on the depth of immersion of the grillage into the ground, pile foundations with it are divided into two types:
Shallow.
Not buried.
Non-recessed option
In the first case, the tape is immersed in the soil by 20–50 cm, and in the second, it hangs above the ground. Due to its greater strength, heavier buildings can be erected on a foundation with a shallow grillage. However, if the soil is heavily heaving, then the strip part of the structure on piles will simply be destroyed by heaving. It is not made too high, so it is simply not able to withstand strong loads from rising soil.
Advantages and disadvantages
Among the advantages pile-strip foundation are listed:
Sufficiently high installation speed;
Possibility to erect buildings on construction sites with a slope;
A simple technology that makes it easy to build such a foundation with your own hands;
High resistance to movement of heaving soils;
No need to use special equipment.
If the grillage is not buried, then it is not afraid of heaving and moisture in the soil. In terms of service life, this option outperforms its buried counterpart on piles and its shallow-depth strip foundation. It also beats them in terms of cost and the complexity of the work. You will have to dig several times less, the depth of immersion is the same, but you only need to remove the soil under the support pillars. Plus, all construction materials can be delivered to the site without the use of heavy cargo and lifting equipment.
When independently constructing pile-grillage foundations, bored supports made of asbestos pipes are usually used, which are reinforced and filled with concrete inside. It is this option that is discussed in the step-by-step instructions below. In terms of speed of construction, only a foundation made of FBS or screw piles made of steel can compete with such a foundation for a house.
There are only three disadvantages:
The need for additional floor insulation in the cottage;
Inability to use for arranging a basement or basement;
Building weight restrictions.
All types of pile foundations have one common problem - drafts in the underground. In the far north, piles help avoid heating the permafrost layer. At the same time, in other regions, wind freely flowing under a building is a serious problem.
Step-by-step instructions for building a foundation
When preparing to make a pile-strip foundation, you must either plan in advance for high heating costs, or immediately include insulation of the basement-foundation part of the building in the estimate and project. In the second case, you will need moisture-resistant insulation for the walls and cladding, but the home will definitely be warm.
It will be necessary to construct a false wall around the perimeter of the cottage to cover the pile pillars and prevent drafts between them. To do this, you can take facade panels for exterior finishing or corrugated sheets. If you want something more beautiful and elegant, then there are clinker tiles and decorative bricks. There are many finishing materials for the exterior of a building.
The entire process of constructing a belt on piles can be divided into two stages. First, the pile part is made from bored pipes. And then a strip structure is laid on them. You just need to remember to tie them together with reinforcement before pouring the concrete.
In general, the step-by-step instructions for a strip foundation on concrete piles are divided into five steps:
Preparatory and drawing work
Excavation of earth, installation of asbestos cement pipes and their reinforcement.
Pouring permanent asbestos-cement formwork with concrete.
Creation of strip formwork from boards and bars.
Reinforcing the tape on piles and filling it with concrete mortar.
Waterproofing reinforced concrete.
We draw on paper or in the program the future foundation - tape and piles
Marking wells with “stakes” for the piles of the future foundation
Piles must be immersed to a depth below the freezing level of the soil at the construction site. Holes for them will have to be dug 40–50 cm below this mark. The foundation must rest on a stable soil foundation.
After preparing wells with dimensions 10–15 cm wider than the outer diameter of asbestos cement pipes, 30 cm thick is poured at their bottom. sand cushion. The pipe formwork is installed precisely on this compacted sand. The diameter of the pipes themselves is selected at the rate of 1/3 of the width of the reinforced concrete grillage.
Next, each pile is reinforced with three or four vertical steel rods with a cross-section of 10–12 mm and a length equal to the sum of the heights of the support and the tape on it. They are placed in the pipe at approximately equal distances from each other and from the asbestos-cement walls. To simplify, they can be tied with wire into the desired structure on the ground before installation.
The next stage is pouring the pipes with concrete solution. This is usually done before reinforcing the foundation strip on the piles. But the instructions given may be slightly modified. Then, first, the reinforcement is laid in the grillage and formwork is made for it, and then the whole thing is poured with concrete. The cells of the reinforcing belt are knitted with a size of 30–40 cm, depending on the width and height of the tape.
We fill the piles to the level of the tape reinforcement. The photo shows a situation where the pile was “overflowed” and had to be drilled out to install the strip frame
We dig up the “tape”, add sand, lay down roofing material and knit tape reinforcement
To perform waterproofing, it is enough to take ordinary roofing material and wrap it around the grillage. This is the cheapest option. You can also use bitumen or polymer mastic. On this, the foundation of the house in the form of a strip on stilts is made. In the future, it will only need to be covered with cladding and, if necessary, insulated.
Done - you can lay out the walls
Where to use?
When comparing the pros and cons of using a pile-strip foundation, first of all you need to focus on the material of the cottage walls and the characteristics of the soil. If a dwelling is being built from lightweight building materials and on water-logged soils, then the support discussed above with a grillage raised above the ground is an ideal option. Such a foundation will last for many years and will definitely not be damaged by heaving, and it is not difficult to make. Fortunately brought step-by-step instruction allows you to avoid unnecessary mistakes.
Typically, the construction of pile foundations is carried out on weak soil foundations. In some cases, they make a pile foundation with their own hands on dense soils. The fact is that a foundation made for a house on stilts will cost much less than a building on a monolithic strip foundation.
The construction of a pile foundation does not require large volumes of excavation work. Great time savings, independence from the seasons - all this attracts developers to use piles in the construction of their houses. We will tell you how to make a pile foundation with your own hands in this article.
Piles immersed in the soil are tied with a grillage The base of buildings of this type is a grillage that combines the upper parts of the piles into a single supporting structure. The supports and grillage can be made from various materials.
The choice of the type of these structures is influenced by factors such as the bearing capacity of the soil layers, the groundwater level, the depth of soil freezing and the actual load from the weight of the structure.
How to choose the right one the right type piles? Let's consider the types of pile supports that the developer can install independently.
Supports made from wooden logs are built for the house with your own hands. Recently, this is not the most popular material for pile foundations.
The installation of wooden supports is carried out in places where clayey, peat and other weak soils predominate.
The support should be of such length that the end of the pile can rest against dense soil.
A vertical survey taken from the local architecture department will show how deep a do-it-yourself pile foundation on piles should be. You can also determine the depth of dense soil by test drilling.
One end of a wooden pile is sharpened with an ax The logs are sharpened with an ax so that under the blows of the hammer they can reach a dense base without much difficulty.
The wood is planed to obtain a smooth surface. The racks are impregnated with antiseptics. Treated piles will remain in the ground for decades.
The upper ends of the piles are cut to one level. Installing a grillage made of thick boards, logs or timber will create a reliable foundation for wooden and panel houses. Walls made of foam blocks are also erected on such a pile foundation.
To know how to build a house on bored pillars, you need to carefully study the structure of the soil foundation and calculate the weight of the future structure. This will make it possible to select the desired type of piles. There are several types of bored piles:
- frameless poles;
- removable casing pipes;
- permanent casing frames;
- piles with an extended heel;
Frameless poles
Piles mounted without a frame are the cheapest One of the cheapest ways to build a pile foundation with your own hands is to build the foundation of a building on frameless bored piles.
A hand drill is used to drill holes in the soil. Reinforced frames are lowered into the wells. The holes are then filled with concrete.
The reinforced frame is prepared from several vertical reinforcement rods with a diameter of 10 to 20 mm. The rods are knitted with wire with transverse steel sections of reinforcement. The height of the reinforced frame must be such that its upper part can serve as a connecting link with the metal grillage.
The fittings outlets are welded to the metal elements of the grillage. After this, the well is filled with concrete mixture using a layer-by-layer tamper.
The thickness of each concrete layer should be no more than 200 - 250 mm. The liquid mixture is tamped with a hand-held electric vibrator. If the diameter of the well is small, then the concrete is bayoneted with a piece of reinforcement.
Removable casing pipes
To increase the load-bearing capacity, rammed supports are formed from concrete in removable casing pipes. The frame of the piles is made of metal pipes. Before installation, the inner surface of the removable shell is coated with a lubricant, which will prevent the hardened concrete from sticking.
The piles are concreted and reinforced in the same way as frameless supports. Two weeks after pouring liquid concrete, the casing pipes are removed from the wells. The earth around the pillars is being vigorously compacted.
Permanent casing frames
In very weak soils, it is advisable to make the pile shell from asbestos-cement pipes. This will prevent soil particles from penetrating into the mass of liquid concrete. For details on the manufacture of bored piles, see this video:
The penetration of foreign bodies and moisture into the concrete structure can weaken the bearing capacity of the bored support.
An asbestos-cement pipe lowered into the well becomes part of the support structure. A reinforced frame is installed inside the asbestos shell. Pouring concrete and compacting the layers of the mixture is carried out in exactly the same way as when forming piles with removable formwork.
Piles with an expanded heel will be more stable than conventional ones 
The bottom of the well is expanded with a special device Bored supports with an extended heel have a high load-bearing capacity. Foundations made from piles of this type can withstand the load of low-rise buildings. If a developer plans to build a suburban two-storey house on weak ground, then supports with a widened heel will be the most suitable solution to the question of how to make a foundation.
The base of the well is widened with a special device that has a cutting blade at the end of the barrel.
Rotational movements of the blade at the base of the pit expand the area of support for the pile.
The resulting space is filled with concrete. Then complete installation of the bored support is carried out.
In addition to this, there are other ways to widen the heel of the pile, but they can only be carried out at the bottom of the pit using special equipment.
The use of the explosive method is possible only with the involvement of specialists who have permission to carry out such work.
The use of such methods for self-construction It is impossible to build a pile foundation with your own hands. Such methods of widening the support heel are used in the construction of industrial or civil facilities. For more information about the expansion device, watch this video:
Screw piles
Screw piles are one of the cheapest ways to build a house foundation Recently, screw piles have gained wide popularity among the population. A house built on a pile foundation made of screw supports will cost the developer much less than building a house on any other foundation.
Considering their high cost-effectiveness and ease of installation in any soil except rocky foundations, screw piles are increasingly used in private construction.
The screw rack is manufactured in the factory. The support consists of several steel elements:
- support pipe;
- tip;
- screw.
Support pipe
The main part of the support is a steel pipe. Its diameter depends on the load the screw pile is designed for. This table shows where and how screw supports of a certain diameter are used:
| № | Support diameter | Soil foundation | Application area | |
|---|---|---|---|---|
| 1 | 57 mm | Up to 800 kg | Watered soil | One-story houses, light buildings. |
| 2 | 89 mm | Up to 1.4 t | Wet, clay and peaty soils | Country houses, garages. |
| 3 | 108 mm | Up to 3.5 t | Everything except rocky soils | Log, panel frame houses. Buildings made of foam blocks. |
| 4 | 133 mm | Up to 6 t | Everything except rocky soils | Brick and monolithic houses. |
Support tip
The tip of the support is a cast or all-welded steel cone.
The speed of its immersion into the soil to the design mark depends on how well the end of the screw support is made.
A poorly welded cone may collapse when the screw post is immersed.
As a result, the support has to be replaced with another pile.
In the construction of small structures and fences, piles with a beveled end are used. The end of the stand, cut at an angle of 45 degrees, is welded with an oval-shaped steel sheet.
Screw
Typically screw piles have two blades at the pointed end The barrel screw consists of 2 blades. The size of the blades is directly proportional to the diameter of the trunk. In some cases, 3 blades are welded to the pipe. This, of course, causes some difficulties in driving the pile, but significantly increases its load-bearing capacity.
To quickly build a pile foundation with your own hands, the edges of the blades are ground with a grinding machine. The sharpened edges of the screw greatly facilitate the entry of the support into the ground.
The grillage on metal screw posts is mounted from various materials depending on the type of structure. These can be connecting elements made of timber, a metal channel or a corner. Reinforced concrete beams, welded with their embedded parts to the supporting platforms of screw piles, form a reliable foundation for two-story houses. For more information about the use of screw piles, see this video:
The installation of a high ground part of the foundation will allow you to make a high base. This will protect the house from seasonal flooding of the area and the penetration of dampness into the premises.
Installing a pile foundation on screw supports with your own hands
Screw piles are installed by a team of 3 people. Mounting holes are made in the upper part of the supports through which steel pipes are threaded. Two workers use these levers to screw a screw post into the ground. The third worker uses a plumb line or theodolite to control the vertical position of the support
After installing the pile field, the upper ends of the racks are cut to one level. Then the headrests are installed, which by their design ensure reliable fastening of the grillage elements.
The durability of steel racks depends on the quality of the anti-corrosion coating. Since the cavity of the supports is filled with concrete, the inner surface of the pile is not coated with an anti-corrosion compound.
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