Correctly make a pile screw foundation. Do-it-yourself screw foundation for a house. Types of pile foundations
This page contains information about the pile-screw foundation: calculation of the foundation, materials for construction, we build a pile-screw foundation with our own hands, videos and prices are shown on the page. We will tell you where you can order a foundation in Moscow.
Pile-screw foundations- this is a type of foundations that is rapidly gaining popularity, which is characterized by high construction speed, economy and excellent performance. This is the best foundation for wooden houses, buildings made of foam concrete and gas silicate, as well as for small brick buildings.
The page discusses in detail the technology for calculating the pile-screw foundation, the features of its construction by one's own hands and the current prices for the construction of pile foundations when contacting the services of construction companies.
Fig 1.0: Construction of a frame house on a pile-screw foundation
Calculation of the pile-screw foundation
Correct calculation is a necessary condition for the reliability and durability of a pile-screw foundation, therefore, its implementation must be approached with the utmost responsibility.
First you need to determine which type of pile is suitable for the type of soil on which you plan to start construction.
Figure 1.1: Piles with a widened foot
Figure 1.1 depicts piles intended for use in problematic soils - floating, loose and prone to heaving. They differ in a broadened heel, which helps to improve the fixation of the structure in the soil and increase its bearing capacity. The wall thickness in such piles can vary from 4 to 16 mm, length - 3-15 meters, diameter - 159-325 mm.
One pile with a wide heel, depending on the size, has a bearing capacity of 1-3.5 tons. They are placed with a step of 3 meters from each other. The estimated cost of the pile is around 3500 rubles.
Rice. 1.2: Standard screw piles
Figure 1.2 depicts piles used in ordinary soils. This is the best option in terms of price-performance ratio, which can be used for the construction of light houses made of wood or aerated concrete, one-story brick buildings and fences.
The length of such screw piles varies from 2.5 to 15 meters, diameter - from 47 to 325 mm, bearing capacity - from 0.7 to 2.5 tons. According to the requirements of SNiP, they must be placed in increments of 2.5 meters. The cost of one pile starts from two thousand rubles.
Rice. 1.3: Hollow screw piles
Figure 1.3 you can see screw piles for compact soils, sandstones and permafrost. Such designs differ from other types in the absence of a tapering tip, they are hollow inside and at the same time have open ends. In the process of immersion, such piles are filled with a column of soil, which provides additional fixation.
Hollow piles, as a rule, are not subject to concreting. However, if it is necessary to give the pile foundation maximum bearing capacity, after immersion, the soil from the pile is removed by a bailer and concrete mortar is poured into the pipe. This technology makes it possible to build large brick buildings (3-5 floors) on pile-screw foundations even in marshy areas or permafrost.
Rice. 1.4: Hollow piles for permafrost soils
The wall thickness of hollow screw piles can be 8-20 mm, the diameter is either 219 or 325 mm. Length - 4-16 meters, carrying capacity up to 4.5 tons. The cost of one hollow pile starts from 4.5 thousand rubles.
If you plan to build on a pile-screw foundation wooden house, piles must be completed headroom. You can see it in image 1.2:
Rice. 1.5: Head for screw piles
The dimensions of the head are the same for all types of screw piles, only the size of the seat differs depending on their diameter.
Fig 1.7: Types of pile-screw foundation grillages
Related materials
Method for calculating the pile-screw foundation
The calculation of the pile-screw foundation for the construction of 1-2 storey wooden and brick houses is carried out according to the following algorithm:
- We determine the mass of individual elements of the future building;
- We calculate the load from precipitation (snow and wind) that will be applied to the building;
- We calculate the total load of the building on the pile-screw base;
- Based on the construction area and the standard distance between individual piles, we determine the number of required piles;
- By bearing capacity different types piles determine the appropriate size of piles;
- We draw up a drawing of a pile field based on the standard step between piles;
- Based on the standard size of the selected piles and the calculated load from the building, we determine the parameters of the grillage.
Fig 1.6: Pile-screw foundation with a metal grillage
How to determine the weight of individual parts of a structure?
This is done on the basis of the normative weight of the materials used in construction and the total area of \u200b\u200bthe building.
Walls:
- From a bar - 600 kg / m3;
- From brick - 600-1200 kg / m3 (depending on which brick is used - monolithic or hollow);
- From aerated concrete and foam block - 400-900 kg / m3;
- From frame panels (up to 150 mm thick) - 20-30 kg/m3.
Roof:
- From slate - 60-80 kg / m2;
- From tin or sheet steel - 20-30 kg / m2;
Interfloor floors:
- Wooden - 70-100 kg / m2;
- Basement - 100-150 kg / m2;
- From a monolithic concrete slab - 500 kg / m2;
- From a hollow concrete slab - 350 kg / m2.
The average indicator of household load on the foundation is 100 kg / m2.
How to determine the atmospheric load on a building?
- h is the total height of the building (from the bottom point to the ridge);
- S - building area.
The load from snow depends on the climatic conditions of a particular region. Here are the averaged data for different areas:
- Chernozem region and southern regions - 50 kg per m2;
- Middle band - 100 kg/m2;
- Latitude from Arkhangelsk to Novgorod - 150 kg/m2;
- North of Arkhangelsk - 200 kg/m2;
- Siberia - 350 kg/m2.
We determine the number, diameter and required length of piles
When calculating the actual number of piles, the area and weight of the building must be taken into account. The minimum step between piles on ordinary soils of medium latitude should be at least 1.7.
The maximum step is determined by the type of building:
- For log houses or houses made of timber and frame buildings - 3 meters;
- For buildings made of aerated concrete, cinder block and foam block - 2.5 meters;
- For brick buildings - 2 m.
If the step is less than the norm, the foundation will lead, since the soil will not be able to evenly distribute the load coming from the piles, if the norm is exceeded, there is a high risk of foundation settlement under the weight of the house.
It is also necessary to take into account that one pile must be installed at each corner of the house and at the intersections of the walls.
Fig 1.7: Log house on a pile-screw foundation
The required bearing capacity of piles is determined by dividing the total mass of the building and the load from precipitation by the number of piles. Knowing what bearing capacity piles should have, it becomes possible to choose the appropriate diameter of screw structures.
For building foundations one-story frame houses , as a rule, screw piles of the 89th are used diameter, for houses made of timber and foam concrete - the 108th, and for one-story brick buildings - the 133rd.
Pile length is determined based on the characteristics of the construction site - the type of soil, the depth of its freezing and the height differences at the construction site.
According to the requirements of SNiP, a geological study must be carried out for this, however, at home, you can use an ordinary garden drill (you need to drill until you start to remove dense lumps of yellowish clay from the hole).
Fig 1.8: Correct location piles in the soil
It is also necessary to take into account the height differences at the construction site. It is possible that in order to ensure the same height of the heads, it is necessary to use piles of different lengths.
Preparatory work, materials, tools
To perform the installation of a pile-screw foundation with your own hands, you will need the following tools:
- Scrap and cuttings of metal pipes (50 mm in diameter, 2.5 m long), which will be used as levers for screwing the pile;
- Hose and magnetic level;
- Garden drill for creating guide holes, its diameter must be less than the diameter of the screwed piles;
- Shovel and trolley for removal of soil from the construction site;
- Bulgarian for trimming piles;
- Roulette and marker;
- Welding for fastening a metal grillage or heads.
Of the materials, in addition to the screw piles themselves and the grillage, you will need a wear-resistant primer for metal. Priming of metal piles provides their protection from the aggressive effects of groundwater. If this point is neglected, over time, the bearing capacity of piles will greatly decrease.
Preparatory work before starting work consists in clearing the construction site of vegetation and debris, after which all necessary tools and materials are delivered to the construction site.
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Fences on screw piles
In suburban construction, when constructing fences for summer cottages, forestries, farms and agricultural enterprises, laying a concrete foundation, as a rule, is not required. Pillars on screw piles are used as fence posts.
Do-it-yourself pile-screw foundation
The construction of a pile-screw foundation is carried out in the following sequence:
- The position of the piles is marked according to the design data. To mark the places of screwing the piles, reinforcing pegs or wooden bars are used, interconnected with twine. First of all, a "starting line" is created, which is one of the walls of the building, based on it, further marking is performed
Fig 1.9: Marking the place of screwing piles
- Next, the piles are primed in 2 layers, after the coating has dried, work begins on screwing them in. First of all, the installation of the corner pile is carried out at the highest point of the construction site, then - diagonal to it and the rest of the piles in the corners. A garden drill creates a guide hole at the place where the pile is screwed in, its depth should be half a meter less than the length of the pile.
Rice. 2.0
- A pile with a magnetic level fixed on it is placed in the well. Scrap is threaded into the holes on the pile, on the ends of which pipe trimmings are put on. Using a crowbar as a perpendicular lever, the pile is screwed, for this you need at least 2 people.
Figure 2.1: Screw pile screwing process
- After all the piles are immersed in the soil to the required depth, the trunks are trimmed. A hose level is used to determine the exact cutting height.
Rice. 2.2: Trimming the pile shaft with a grinder
- Concrete screw piles or not - it's up to you. If the diameter and length of the piles are chosen correctly, their bearing capacity will be enough even without concreting, in which case you will only incur unnecessary costs. If you still decide to concrete - to prepare a solution poured into the cavity of the pile, use cement of a class not lower than M300.
Rice. 2.3: Screw pile shaft concreting
- To create a grillage of a pile-screw foundation, I-beams or a channel can be used, in the construction of light frame houses - timber, for brick houses - a monolithic concrete grillage. If the grillage is metal, it must be primed to avoid corrosion in the future. The binding is carried out by welding the grillage to the pile shafts. To give the structure greater rigidity, reinforcing bars are welded to the junction of the grillage and piles.
Figure 2.4: Fastening the grillage from the channel to the shaft of the screw pile
Pile screw foundation video
For a better understanding of the technology of building a pile-screw foundation, check out the videos that explain the most important points construction.
Video #1- How to mark the places for screwing piles on a construction site
Video #2- We twist the screw piles with our own hands
Video #3- How to properly mark piles before cutting
Video #4- Features of the installation of a concrete grillage
Part 1
Part 2
Pile-screw foundation - prices
The cost of such a foundation depends on the number and size of piles used to create the foundation. For reference, here are the average prices for foundations of different sizes:
Foundation size | Number of piles | Cost (thousand rubles) |
Under a wooden bath 6 * 6 m. | 9 | 30 |
Under frame house 6*4 m. | 12 | 40 |
Under a log house 6 * 9 m. | 18 | 63 |
Under the house of foam blocks 6.5 * 6.5 m | 16 | 66 |
Under the brick house 8*8 m | 24 | 95 |
Pile-screw foundation reviews
We bring to your attention reviews of people with experience in self-construction of pile-screw foundations.
Oleg, 30 years old, Moscow:
"I recently completed the construction of a wooden bathhouse on a pile-screw foundation. All the work was done by myself, two friends helped me. I can only say positive things about the foundation - it was not expensive, all the piles were twisted within two days. We were pleased with the pace of construction, because we had to wait for the concrete to harden strip foundation would take a very long time. I recommend!"
Dmitry, 35 years old, Zelenograd:
"I have been working in a company that has been building pile-screw foundations for the past 10 years. They are ordered, as a rule, for light wooden and foam concrete houses, less often for brick ones. Among the advantages of such a foundation, I can single out the speed of arrangement and low cost. Among the disadvantages - the complexity of erecting with your own hands.If you want the pile-screw foundation to be reliable and durable, it is better to entrust its construction to specialists"
Reasons to contact us for a screw foundation
If, when reading this article, you have the impression that it is extremely difficult to equip a pile-screw foundation with your own hands, you are not far from the truth, in practice it is.
Firstly- direct construction should be preceded by detailed calculations, which can only be fully performed by specialists.
Secondly- how reliable the pile foundation will be, strongly depends on compliance with all the norms and rules of its construction technology, which, without proper experience, are simply impossible to take into account.
If you do not want to risk your money and time, and want to get a well-made screw pile foundation, contact construction company"Bogatyr".
We guarantee that:
- The foundation will be built in the shortest possible time - the mechanization of the workflow makes it possible to implement any project within several work shifts;
- Only high-quality materials will be used to create the foundation - we have been working with one pile manufacturer for a long time, the quality of its products has been repeatedly tested in practice and does not raise any doubts;
- All calculations, from the analysis of the bearing capacity of the soil to the determination of the required pile size, will be carried out by the best designers.
"What about the prices?" - you ask? Our prices are more than reasonable. In Moscow and the region there is not a single construction company involved in the construction of pile-screw foundations at prices lower than those offered by Bogatyr.
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Useful materials
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The use of a foundation on screw piles in the shortest possible time and at a minimum of costs allows you to independently make a foundation for a bathhouse, a private house or a garage. Even a novice builder is able to handle the installation of piles in the form of steel screws. There are several types of such foundation supports with different bearing capacity; it is not difficult to select them for a specific building and soil.
What is a pile-screw foundation?
According to the constructive device, a screw pile is an iron pipe hollow inside, on the lower cone-shaped end of which drill blades are welded for screwing it into the ground. After immersion in the ground, these supporting pillars are connected with a grillage or the lower rows of a log house. As a result, each of the supports takes on part of the load from the building, distributing it throughout the pile field.
This is what the base looks like
The blade at the end of the tip from below, on the one hand, simplifies screwing the pipe into dense soil layers, and on the other hand, it plays the role of a holding anchor. In some cases, if necessary, such a support is simply twisted out of the ground and used in a new place for a new pile foundation. The main thing is that it does not rust by this time, being in the ground.
Types of screw foundation
According to the configuration and purpose of the blades, there are:
Wide-bladed - a typical variant with one blade in 1–1.5 passes.
Multi-blade - with several blades.
Narrow-bladed - with a tip in the form of a screw for 5-8 turns of the screw.
Various types depending on the soil
The first option is designed for light buildings and stable soils. The second type of screw piles is used when it is necessary to improve the bearing capacity of the support with compensation for its vertical movements, as well as for high and heavy cottages of 2-3 floors in terms of total weight.
The third variety is for foundations on soils with an abundance of stones. For permafrost conditions, it is also recommended to take a narrow-bladed analogue, only having not a pointed end, but an open cut with teeth along the perimeters.
The pile tip can be cast (VSL) or welded (SVS). The first one costs more. However, it is more durable and able to withstand heavy loads than the fatty counterpart. If the soils at the construction site are dense or the foundation needs to be made for a large house, then it is better to spend money and take it with a cast tip.
Pros and cons of foundation on piles
Benefits of using these bases include:
Durability and high bearing capacity - such piles withstand seasonal heaving without problems and serve 50–80 years;
Profitability - costs 20-30% cheaper than other options;
Lack of construction debris and large volumes of excavation;
High speed of construction - for an independent foundation of screw piles, two to three days are enough;
Ability to create on almost any type of soil;
Ease of implementation - do-it-yourself slab or strip foundation is much more difficult to do;
A large number of modifications of tips and heads;
Possibility of reuse;
The absence of seasonality of work as such - you can screw in screw supports even in winter, if only the soil allows it.
There are also disadvantages to the screw foundation, but they are much smaller and only worth mentioning:
The impossibility of arranging below under the floor ground floor or basement;
Additional costs for warming the house from below.
Considering the pros and cons, it is clearly seen that the advantages greatly prevail over the disadvantages. However, there is one big "BUT".
Electromechanical corrosion
The screw support must be made in accordance with standards and from high-quality steel. And after it, it is also mandatory to check in the Quality Control Department with the help of ultrasound or X-ray. The main problems for developers who have opted for a pile-screw foundation usually arise precisely because of defective materials.
Installation of a pile-screw base
The technology for arranging the foundation with your own hands from screw piles is as follows:
Control screwing is carried out to determine the strength of soils.
Calculations are carried out with the preparation of a plan for the placement of supports.
The area is marked.
The installation of supporting piles is carried out with their subsequent trimming according to the level.
Concrete is being poured inside the support.
The created pile field is tied up.
For each type and modification of a pile in the form of a screw, its bearing capacity is indicated in the passport. Both the size and configuration of the blades, as well as the wall thickness and barrel length, play a role here. Depending on the GWL, the depth of freezing and the composition of the soil, the layout of the pile field is calculated in each case separately.
When designing, it is also necessary to take into account the mass of the entire future structure, under which the foundation is laid on screw piles. Moreover, the calculation should include the weight of not only walls and ceilings, but also roofing and loads from snow with wind. After all, ondulin or membrane roofing weighs obviously less than slate or tiles. And all this must be foreseen in advance.
The stage of project preparation is best entrusted to a specialist. If you plan to make a screw foundation with your own hands, then the calculations should be carried out on the basis of SP 24.13330. Or you will have to install supports in larger quantities with a margin, increasing the construction estimate.
Step by step photo instruction
Marking the first support of the foundation according to the landmarks of the site
Markup shouldn't be a problem. You just need to mark on the site places for supports in accordance with the project. The main thing during construction is the strict vertical of the pillars screwed into the ground.
We dig a "pit" 20-30 cm deep for the first support
Insert into pit
We twist with the help of special levers (steel pipes)
To simplify the positioning of pile supports when they are immersed in the ground, you can use a drill or a shovel to dig a small pit half a meter deep. Next, the supports are screwed into the soil with a crowbar acting as a lever, a powerful electric drill with a gearbox or automotive special equipment. This is done in increments of 1-3 meters.
When the pile stands firmly enough, we hang the magnetic level and adjust the last part of the screwing according to the level - we level it with weight
The first is screwed exactly on the level
We mark the second - angular on the same side of the first
We dig a pit, put the second support, level it and check the distance from the first
When installing and screwing them in, it is extremely important to ensure that the supports do not go to the side. This immediately reduces the ability of the column to withstand the design loads. It is better to unscrew such piles and do it all over again. At the same time, it is strictly forbidden to put them on a new one in the same place. It will be necessary to shift this “screw” a little to the side.
When the support has risen to the desired distance, we twist it in the same way as the first
Similarly, by slopes, we adjust the distance between the pillars
After observing the distances - we twist the third
In the same way, we mark and twist the fourth, observing the dimensions along the diagonal and side
We stretch the twine around the entire perimeter and mark intermediate supports with a marker on the twine
We install each support in the pits according to the marks and level and ram it with earth
After spinning all the pillars, we mark the same marks with a hydraulic level
We cut all the supports according to the level with a grinder
We fill the pile with cement-sand mortar up to 10 cm of the level to the end
We fill the rest with ready-made dry cement-sand mixture
After the piles are installed in their place, they are cut at the right level from the ground. Then these supports, of which the considered version of the foundation consists, are recommended to be poured from the inside with concrete. This allows you to protect the metal from corrosion and further strengthens the entire pile helical field.
On top of each installed pole, a head is welded in the form of a square steel plate measuring about 25 x 25 cm. And at the end, all welds are treated with protective compounds. Further on this pile foundation, you can already lay the grillage or immediately the crowns of the log house.
So that the wind does not walk under the house and does not cool it down, the pillars must be closed with an outer lining around the entire perimeter of the building. For this, corrugated board is perfect either. But you can also use facing bricks. All at the choice of the owner of the cottage.
Application of the foundation on screw piles
For the construction of a screw foundation made of iron piles, a team of 5–7 people often takes one day. At the same time, it is not necessary to wait for precipitation or setting of concrete. Such a base is completely ready for the further construction of the building. This is a strip or monolithic foundation with a slab that must withstand at least 20–30 days. With screw supports, the stage of arranging supports under the house takes much less time.
House from SIP-Panels
Modern technologies have somehow completely imperceptibly introduced another innovation into our lives, previously available mainly only to the military and geologists (lovers of hard-to-reach places) - a screw foundation. At the same time, the relative simplicity and speed of creating such a structure using special piles gradually "push" aside the tape and column foundations that are familiar to us.
But is such a foundation really a universal solution for building a solid and durable foundation for a house? In the article we will tell you how to do it, give detailed step-by-step instructions,
screw pile
This is a metal pipe (treated with a special compound that slows down the corrosion process), to the lower pointed end of which a blade is welded. Such a pile is screwed (screwed) into the ground (like a self-tapping screw into wood), practically without damaging it (only compacting it by immersing the pipe) and, therefore, without reducing its bearing capacity at all.
These piles are available in several types:
- with a helical blade (used on soils with poor bearing capacity) or imitation of threading along most of the length of the pile (such piles are usually used in northern regions where it is required not to particularly disturb permafrost when building a foundation for buildings and structures);
- with different pipe diameters - the larger the diameter, the greater the weight of the building is able to perceive the pile (without its deformation), but do not forget that thicker piles (whose diameter exceeds 108 mm) cannot be manually twisted;
- with different blade diameters - for less durable and water-saturated soils, the blade diameter will be larger than for dry and dense soils.
And, of course, the type and shape of the pile also depends on the manufacturer that produces it.
screw foundation as follows:
- in the corners and at the intersections of the internal walls, as well as along the length of the wall of the structure, piles are screwed into the ground (the pitch of the piles ranges from 1 to 3 meters);
- from above, all piles are cut to the same level and fastened with either metal or wooden beams to create a single rigid structure - a grillage;
- between the ground level and the bottom of the building (grillage) there is a freely ventilated space.
Advantages and disadvantages
This is a fairly simple design. However, here you are waiting for "pitfalls":
- piles should be selected strictly in accordance with the calculation made by the designer on the basis of hydrogeological surveys at your site. land plot, the depth of soil freezing, as well as the weight of the future building and the weight of the snow cover applied to the building in winter (otherwise you risk either overpaying for piles of a greater length or diameter, or getting a completely unstable structure that will “lead” in a year);
- depending on the soil, manually screwing piles into the ground can be quite difficult (even if 4-5 people take part in this process);
- the presence of trees, tall shrubs, fences or other structures in the immediate vicinity of the foundation site creates problems for driving piles manually;
- Not all firms do their work with high quality, observing the technology.
However, the screw foundation also has advantages:
- no extensive earthworks are required;
- can be installed on any terrain, without prior leveling of the terrain;
- works on immersion of piles into the ground are carried out almost at any time of the year.
The foundations can be arranged on any soil, with the exception of rocky ones, since the rock itself is an excellent strong foundation (for tape or columnar).
Preparatory work
It is quite possible to make the basis for a small building (garage, gazebo, veranda, one-story wooden frame house):
- you can weld the pile yourself, using the drawings posted on the Internet, or weld the piles in the likeness (for this you will need to order a calculation, and then purchase one recommended pile at the factory);
- also independently (with the help of friends) you can immerse the piles into the ground, guided by the existing drawings when placing them, and perform the grillage.
For a screw foundation, you should not save on material. Piles should be made only from new pipes of the required thickness, while they should be thoroughly cleaned of rust and coated with a protective compound. Particular attention is paid to the quality of the welding joint at the point of attachment of the blade, since on sufficiently dense soils the seam can burst, unable to withstand the load applied to the pile.
To facilitate the process of screwing the pile in its upper part (which you will then cut off with a “grinder”), you need to make two holes - you will thread “rods” into them, with which the pile is screwed into the ground.
Installation should be carried out as accurately and competently as possible. The maximum allowable error in the vertical section and between the piles is no more than 2 cm. Otherwise, in the future you may face the need to repair the grillage due to its sagging. And this, in turn, will lead to a violation of the bearing wall and even the distortion of the building.
The base on screw piles should be located so that the load on it and on the ground is distributed as evenly as possible. Therefore, take the plan of the house and break it into rectangles. Support blocks should be located on their sides and diagonals, taking into account the required distance between them. With all this, each pile should be in the center of all the load-bearing beams of the house.
So, break the house plan into rectangles, having previously determined the size of each of them. So, you can calculate the number of piles and distribute them over the area so as to evenly distribute the load on the foundation. After finishing the layout, transfer the markings from the paper to the surface of the earth on which the stilt house will stand. Drive in pegs at the installation points of the piles.
Stages of work
Work is performed in the following sequence:
- Dig a leader hole for each pile (just remove the top layer of earth with grass in this place), the depth of which should not exceed 10-15 cm, and the width should be 2-3 cm more than the diameter of the pile blade. Some professionals advise to do without digging leader holes, which increases the stability of the pile, but at the same time increases the effort to screw it into the ground manually. You can not dig deep holes and simply install piles in them, deepening them by only a few tens of centimeters. One of necessary conditions The quality of driving screw piles is the untouched soil around it, which allows the pile to transfer the load from the structure not only by the lower end and the blade, but also by its entire side surface.
- Install the pile and, together with assistants, screw it into the ground using a special rod, constantly checking the verticality of its position. The pile must sink into the ground below the level of soil freezing in winter.
- Align the top of all piles to one level (mark it on each pile with a leveler), cut off the excess with a grinder.
- Pour concrete into the pile (this will increase its strength and reduce the rate of metal corrosion).
- Weld a metal plate (at least 8-10 mm thick) to the top of each pile, protruding beyond the boundaries of the pile by a few centimeters on all sides.
- Make the grillage by attaching the beams to the plate with welding or bolts.
Video
Learn all about arranging a screw foundation by watching the following video:
Until recently, pile foundations were almost never used in individual construction, with the exception of regions with a difficult climate and soils. The pile foundation for the house gained its popularity simultaneously with the technology frame construction. It was the companies that produce light-weight houses suitable for year-round use that first began to use them quite widely.
An example of a finished pile foundation
They were looking for a way to reduce the cost of construction without sacrificing quality, and the solution turned out to be to replace the traditional strip foundation with a pile foundation.
It is far from always possible to directly support the foundation structures of buildings on the underlying soil layer. Depending on the conditions, the soil may be of little use for this, having a low or insufficient bearing capacity, an unstable nature of occurrence, being in the permafrost zone, and the like.
In such cases, the design of piled foundations and their installation is carried out, which allows for the transfer of load from the building to underlying, stronger and denser soil layers with predictable characteristics.
Pile foundation project on shaky ground
Pile foundations are widely used in construction, so a huge number of options have been developed that take into account almost any construction conditions and offer a variety of solutions, both taking into account technological capabilities and economic aspects.
Today, the foundation on piles is one of the most popular in the private and commercial construction market. Since in terms of its price indicators it turns out to be much more profitable than classical solutions, and in terms of its technical specifications and service life even surpasses traditional foundations.
In most Russian regions, pile foundations are used to build houses on soft soils. These will be peatlands and swampy soils. By the way, he will be where enough high level ground water.
Scheme of installation of a pile foundationSlab or shallowly recessed strip foundation will be ineffective on such land, since the topsoil simply cannot withstand a large load.
The design and installation of pile foundations is regulated not only by Building Codes and Rules, in particular, SNiP 2.02.03-85, but also by others. normative documents which include, for example "Pile Foundation Design Guide". It sets out all the recommended solutions used for the device of this type of foundations, defines the parameters of the necessary survey work, methods for performing design and types of calculation and design work carried out.
The issues of calculation of piles by bearing capacity, calculation of pile foundations and foundations by deformations, general issues of designing pile foundations are considered.
Finished project pile foundation
Separately, design features in specific conditions, such as subsiding soils, swelling soils, undermined territories or seismic areas, are highlighted.
A pile foundation is a more complex system than just a set of piles, therefore, for the qualified calculation of other elements, other materials recommended for use are also used, for example, "Manual for the design of reinforced concrete grillages of pile foundations."
The use of normative literature makes it possible to ensure high quality design work and sound economic decision-making without compromising the safety and durability of buildings and structures.
That is what piles are used for. Vertical structures sink to a sufficient depth in the ground and transfer the load to the denser soil layers that are located below. The price of such a foundation is lower than for classical types of foundations with excavation.
Also, the installation of a pile foundation will be the best solution in permafrost areas and where there are moving soils.
A holiday house on the banks of a river or near a reservoir is also better to put on a pile foundation. When using high-quality waterproofing, the structure will last much longer than other types of foundations.
Types of piles used
Pile foundations differ in several ways. A certain type is suitable for operation in specific conditions. The cost of arranging the foundation, which includes the required building materials and the work of specialized equipment, also depends on this.
According to the materials used
Piles can be made from various materials. For foundations for various buildings and structures, piles made of wood, metal, concrete and reinforced concrete, as well as combined types of piles, are used.
The latter type is considered one of the most reliable, since different materials corrode differently, as a result, they retain their original appearance longer and perform the main functions.
by immersion method
The first and main difference between piles is the use of fully finished units that are lowered into the ground and piles that require on-site fabrication.
The first type includes driven, bored and screw piles. To the second -
bored and combined.
Driven and bored piles are more often used in the construction of foundations in multi-storey buildings. They are very voluminous concrete or reinforced concrete beams. The price of the structures themselves is quite high, and their installation requires large construction equipment.
Rental of special vehicles for individual construction will cost a pretty penny.
All piles are divided into two main types:
- Post piles that pass through soft and unreliable layers of soil and, ultimately, rest on hard rock.
- Piles that remain "hanging" in the ground. Such piles are used when solid rock is at an inaccessible depth or it simply does not exist, for example, in permafrost conditions, or in swamps and peat bogs.
In the first case, the entire bearing load transferred from the building to the foundation passes to the solid layers of rock, and the building, it turns out, has a reliable support under it.
In the second case, a different principle applies. The load is distributed evenly on all piles, and the piles are held in the ground due to the friction force between the surfaces of the pile and the ground. Both of them have proven themselves well and are used in construction on equal terms.
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Structures and foundation for a private house
Types of pile foundations
The pile foundation is a field of individual piles. Their number, the distance between the piles, the method of distribution and strapping is calculated individually for each house project. From above, each pile can have a small platform or rebar. This is necessary for the subsequent installation of the strapping.
Foundation on screw piles
Screw piles are the undisputed leader in the field of private construction. Most frame projects are based on a foundation on screw piles. The pile is a metal pipe, pointed at the bottom and with a welded helical blade.
In fact, this is nothing more than a large self-tapping screw, only without a hat. Such a pile is simply screwed into the ground. For this, construction equipment can be used, or it is possible to equip a pile foundation with your own hands. One of the most budgetary and labor-intensive technologies.
Finished foundation on screw piles
Screw piles can be combined. If the classic screw pile is a hollow metal pipe, then the combined one involves filling the void with concrete or reinforced concrete mortar.
The advantages of the foundation on screw piles include its low cost, the ability to install without the use of heavy equipment, use in permafrost and marshy soils.
The disadvantages of such a foundation are fragility, according to reviews, it can stand for about 70 years. Another drawback is that the foundation on screw piles without a grillage can only withstand lightweight structures, such as wooden or frame houses. For stone, brick or block buildings, it is better to use other, more durable foundations.
Foundation on bored piles
Bored piles are a type of piles that are made on site using concrete or reinforced concrete mortar and reinforcement. To begin with, wells are drilled on the construction field, marked out according to the drawing. Vertical shafts are reinforced with reinforcement and then filled with mortar.
Depending on the type of soil on which the foundation is being installed on bored piles, various casing materials can be used.
For example, in the case of loose and sandy soils, a special hollow pipe can be lowered into the mine. The technology allows insulating the wall with roofing material, roofing felt, polyethylene film. Depending on the material used, after pouring, the casing can be removed, or it can be left in the shaft, performing the function of waterproofing.
Installation of bored piles
Piles made according to the latest scheme, using casing-insulating materials, last longer than simple bored piles.
The advantages of such a foundation are ease of installation. One of the varieties of bored foundation is columnar. Such a foundation can be equipped without the use of special equipment. Dig holes for piles or drill manually, make a mortar yourself and pour the base.
Another advantage is the ability to put the house even in a place that is hard to reach for equipment, almost close to other buildings.
However, such a foundation will be short-lived and less durable. Without special waterproofing, flood piles quickly collapse. The disadvantages include the impossibility of their operation in regions where horizontal ground movements are observed.
Scheme for the construction of a bored pile foundation
Types of strapping used
The piles themselves are just pillars or racks. In order for them to turn into a full-fledged foundation, it is necessary to tie a pile foundation. The pile-grillage foundation surpasses strip and monolithic slab foundations in its characteristics. It is considered more resistant to any soil movements. Depending on the weight of the structure, different solutions are used.
Piles-columns
The simplest type of pile is a column pile, which is used as a foundation for a fence or a light summer house. It will also be a continuation and basis of the structure, which will be mounted around the pile. No binding is required in this case.
Beam strapping
It is most often used in the arrangement of a pile-screw foundation for the construction of a light frame or log house.
The function of the grillage in this case is performed by the 200th larch beam. If you make a pile foundation with your own hands, then the timber should be laid on special platforms with which each pile is equipped, and securely fastened with bolts and ties. The joints of the two strapping elements are formed with a groove.
metal strapping
A grillage on a pile-screw foundation can be made of a profile, a channel or a corner. In this case, the installation takes place using welding.
It is also possible to fasten with bolts, if the pile-grillage foundation initially provides for such a design. To do this, each pile must be equipped with a small platform with holes for two or four bolts, as well as the strapping that comes with the kit.
An example of tying a pile-grillage foundation
In this case, the pile field must be installed with the minimum allowable error, otherwise the arrangement of the grillage will become impossible.
Monolithic grillage
The pile-grillage foundation is a hybrid of a pile foundation and a classic strip or slab foundation. In the case when special structural rigidity is required, the following scheme is applied: formwork is assembled over the piles and a monolithic grillage is made in the form of a slab or tape.
This design is best combined with bored piles. In this case, the reinforcing elements of each pile are brought up and become the basis of the grillage. At the same time, additional reinforcement of the grillage is also necessary.
Stages of work in the construction of pile foundations
Entrust the specialists or equip the pile foundation with your own hands - both options are possible. Work can be performed both using construction equipment, and use an electric or hand drill for holes, or even dig mines manually.
Land Surveys
The device of pile foundations takes place on rather difficult soils. To avoid errors in design and calculate the settlement of the pile foundation, it is advisable to order land surveys. Several drilled information shafts and a detailed analysis of a specialist, which will be presented in the form of official documents - soil maps, will make it possible to make an accurate calculation and determine the optimal depth of the shafts for piles.
In the event that a pile foundation is ordered without geological exploration, there is a risk of making piles of insufficient length.
Scheme of the pile foundation
The second problem that you may encounter is to rest against the rock in one of the sections of the pile field, which will not allow you to screw the piles to the required depth.
Design
The device of pile foundations provides not only for the process of physical work, but also includes a mandatory paper period. During the design of pile foundations, calculations are made that allow you to determine the size of the pile field, the depth of the shafts and their number, the distance between the piles.
Lighter structures allow piles to be placed in the foundation at a distance of 2.5 meters from each other. The calculation of the foundation for heavy structures and on difficult soil requires an increase in frequency - the distance can be reduced to 1 meter. Also, piles can be lowered into the ground not vertically, but at a certain angle, which strengthens the structure.
The foundation is an important foundation for any structure. The durability of the entire building depends on its quality and performance characteristics. The foundation is an almost inaccessible element of the building. Therefore, developers are faced with a priority task: choosing a unique foundation that can last for many years without requiring repair costs.
Types of pile foundations
Piles have been used to build the foundations of buildings since ancient times. For example, many ancient buildings in Venice are installed on larch wooden piles.
Now piles are made of various materials and, depending on the material chosen, are divided into three groups: reinforced concrete, steel and wood. Depending on the installation method, all groups of piles are divided into screw and driven types.
The driving technology for installing foundation supports is very complex and is performed only with the help of special equipment. It is almost impossible to independently carry out work on installing piles in a driven way. The screw mounting method is much easier. It does not require special equipment and is carried out by only two workers.
The screw method of installing foundation supports minimizes mechanical work, so that the cost of construction work will be much lower, while the quality of the foundation will remain at a high level.
Features of the pile-screw scheme
Screw piles are very practical and convenient for the construction of low-rise buildings, cottages and country houses. When erecting a pile-screw foundation, you do not need to spend a lot of time and effort, since their installation does not require special skills and equipment.
The screw piles developed by the designers have a shape that can withstand any difficult soil, so they are preferred when carrying out the following works:
- unstable soil layers. Helical blades pass through swollen and loose layers until they stop into a hard, durable layer. The pointed lower part of the column penetrates freely down, excluding soil pressure on the trunk, thanks to the blades.
- In areas with proximity to groundwater, significant swampiness. The quality of screw piles ensures their long term operation.
- Reconstruction of old wooden houses and outbuildings.
- Construction of frame buildings.
Types of screw piles
The design of the screw pile is an anti-corrosion metal pipe. Outwardly, it has a sharp lower part with helical blades. This form of construction allows the pile to enter the ground almost independently, without disturbing the soil structure. This at the same time ensures its stability in the ground.
The standard pile diameter is 14 cm, with a metal thickness of 4 mm. But when building a building on particularly difficult ground, it is possible to manufacture screw piles on special order. From the calculated indicators of the expected load, its diameter is selected.
In the upper part of the cylindrical pipe, special holes are provided for attaching the levers necessary for screwing the pile.
Piles are produced in the following versions:
- With a blade or its imitation placed along a significant part of the trunk.
- Various diameters and thicknesses of the pipe for structures that create a large load
- With different blade diameters, designed for soils of different structures
- A different shape of the upper part, which is called the "heel". It can be rectangular or U-shaped.
If for the construction of residential or country house a plot with high soil moisture has been allocated, thanks to the pile-screw technology of the foundation, soil moisture will not damage the walls and floor of the building.
Stages of construction of a pile-screw foundation
The pile-screw technology for laying the foundation is quite simple and saves the developer from laying a trench for laying the foundation. It is necessary to start the installation of a pile-screw foundation by marking the site on which it is planned to build a house. Pegs are installed along the perimeter, indicating the installation points for screw piles. A cord is stretched between the marking elements, creating the outline of the future foundation of the building. At this stage, accuracy is very important.
After that, it is necessary to remove the soil to a depth of 10-15 cm, with an area equal to the diameter of the pile with blades. Excavation are minimal, but their implementation is also necessary.
According to the markings made, it is necessary to screw the pipes into the ground. To do this, use the holes in the top of the pile. Inserted metal pipes or pins serve as levers to rotate the structure.
Install a metal pile perpendicular to the surface of the earth. The metal rod is immersed in the ground with a small margin, leaving about 15 cm.
The next step is to check the installed piles in height. The excess length is cut off with a grinder.
Important! The horizontality and the same height of the base must be constantly monitored, these characteristics ensure the stability of the mounted devices.
After completing all measurements and strengthening, it is necessary to fill the piles with concrete. This operation is necessary in order to prevent moisture from entering the rod. As a rule, packaged sand-cement composition M300 is used for this purpose; this dry mixture forms a strong monolithic form under the influence of moisture. Pouring concrete mortar increases the overall rigidity of the base.
After the concrete mixture has hardened, it is necessary to weld a special element of the supporting structure, the head, after which you can begin to form the foundation of the building.
The head is a part welded to the end of the pile. A slab or beam of a grillage is installed on it, which combines the installed piles into single system foundation. A slight skew of the head will cause the whole structure to skew.
On the welded heads, the strapping is installed along the equipped metal or wooden jumpers, which must first be treated with an antiseptic or paint with protective functions.
In some cases, heads are not used during construction, the grillage is fixed immediately to the top of the pile to evenly distribute the load.
Disadvantages of a pile-screw foundation
Like any technology, the pile-screw foundation has some disadvantages:
- The impossibility of using this type of foundation for the construction and repair of heavy and multi-storey structures.
- Screwing piles is out of control. It is impossible to assess the degree of damage to the blade or anti-corrosion coating.
- Different depths of piles, requiring at the final stage the alignment of the supports in height by trimming.
- The lower part of the house remains open, that is, additional protection and insulation of the base of the house is necessary.
When planning a pile-screw foundation for a house, it is necessary to provide for the construction of utility rooms on the adjacent plot, since this foundation technology will not make it possible to create a basement.