How to properly tie a foundation on driven piles. Description of the pile foundation piping. Methods of fastening the harness

The popularity of columnar and pile foundations is gaining momentum every year. And it’s not surprising - their installation requires less effort, time and money compared to strip or slab bases. Any hardworking owner can build a columnar foundation, but there is one point that should be given special attention - tying the pile foundation. This is exactly what our article will discuss.

Compared to installing the pillars or piles themselves, tying such a foundation is more labor-intensive work, so why is it needed? To understand this issue, it is necessary to understand the principle of operation of the pile foundation. As a rule, it is installed under light buildings such as frame houses, bathhouses, gazebos, verandas and terraces. At the same time, this type of foundation is quite cheap compared to others, and working on it takes much less time. A pile foundation consists of several elements - piles. These are pillars made of metal or reinforced concrete, driven into the ground to a certain depth (usually just below the freezing level of the soil). The pillars hold the house box above the ground, protecting its lower part from contact with the surface, moisture and destructive influences. However, the pillars themselves do a poor job of evenly distributing the load from the house, which ultimately leads to distortions and destruction of the building. Strapping allows you to prevent such developments. The strapping is the horizontal elements (beams, metal corners, channels) that connect all the pillars together into a single structure. The strapping simultaneously serves as the basis and support for laying the wall material: timber, logs, SIP panels, etc. Tying a pile foundation with timber is called a grillage, and it is one of the most reliable and durable. Types of harnesses The purpose of the piping is to combine the columnar foundation into a solid structure and distribute the load from the weight of the building onto the piles. In some cases, you can do without it, for example, if the height of the piles above the ground does not exceed 50 cm. But if this distance is more than 50-60 cm, the strapping is absolutely necessary, otherwise the house will not stand for long. Also, connecting piles should certainly be done if the house is built from foam blocks, bricks or aerated concrete. Types of strapping depending on the material used: Methods of fastening the harness Before you start tying the pile foundation, you need to clearly define the installation method for yourself, as well as select the materials. Modern builders use the following methods for installing strapping on piles: Threaded - this option is applicable for piles made of wood, since they are quite thick and durable, but at the same time amenable to processing. In this matter, it is extremely important to correctly calculate the thread, since if the pile is not thick enough, it may not withstand the load and crack. Welding - this fastening method is used for metal piles. In this case, the use of a welding machine is almost the only possible option, since any other fastener cannot provide such strength. Clamps are a universal method of attaching strapping to piles, which is suitable for both grillage and metal beams. Builders use it even in cases where the piles are not thick enough to install threads. But basically, experts recommend using clamps to strengthen the main connection method. I would also like to mention the fastening of beam purlins during the construction of a wooden grillage. This can be done in two ways: connect with a straight joint or an oblique cut, covering the joint with boards, or install a Gerber plate hinge. In the latter case, screw pins are used to splice the beams together in height, which makes the entire harness less susceptible to soil movements and subsidence of pillars. The external tying of the pile foundation with timber with your own hands should be done twice, which we will talk about a little later. For the manufacture of internal purlins, 150 mm timber is used. The end connections of the purlins and attachment points with transverse piles are made with galvanized clamp plates or steel angles. Strapping installation technology In the old days, almost all houses were built from wood, and even the foundations were built from durable wood. Nowadays, this approach may seem at least strange and ineffective, but, nevertheless, some of the houses built in this way still stand to this day. The secret of durability is quite simple - a cushion made of a mixture of clay and sand was laid on the ground, and a starting crown made of oak logs was placed on it. It was carefully coated with tar or tree resin. This crown simultaneously served as a foundation, a frame and a basis for the construction of walls. If you look at modern methods of installing frames, you can recognize the main stages of ancient technology: strong thick wood is laid on an insulated base, covered with protective compounds and walls are built on the resulting base. Strip foundation Strapping may be needed not only for pile foundations, but also for strip foundations. In this case, walls built from timber or rounded logs are quite problematic to attach to a concrete base. That is why the first crown is a thick wooden beam - a grillage. To fasten the timber to the reinforced concrete strip, anchor bolts or embedded pins are used. How to install a harness on a strip foundation: Check the evenness of the foundation surface using a building level. If necessary, smooth out any unevenness or fill in a leveling cement screed. Height differences of up to 10 mm can be corrected by placing planks of varying thicknesses under the timber. Cover the foundation strip with waterproofing material. You can use regular roofing felt or coat the tape with bitumen and lay the roofing felt on it. Drill holes in the beams, the size of which should be slightly larger than the diameter of the anchor studs concreted in the foundation strip. Place a spacer and a wide washer on each stud. Lay the timber on the waterproofing so that the studs fit into the drilled holes. The bars can be connected to each other using the “into the bowl” or “in the claw” method. Secure the washer with nuts, and in places where the corners of the beams meet each other with dowels or nails, you do not need to install anchors. After installing the bottom trim, you can begin installing the frame for the walls. The described technique is suitable not only for strip foundations, but also for other foundations with minor amendments and technical nuances. Pile foundation Professional builders in their practice of installing timber frames on screw piles use two technologies: threaded fastening and clamps. This double fixation gives confidence that the beam will last as long as possible and will reliably hold the box and all the foundation pillars. The only thing that should never be forgotten is the treatment of all wooden materials with antiseptics, and metal ones with anti-corrosion compounds. Moreover, it is recommended to do this once a year with the onset of warm and dry weather. How to tie a pile-screw foundation: First of all, the harness should be placed on the thread. It is most convenient to do this when the piles are in the shape of a bucket or an inverted “U” (flange). First, take a beam of the required length and place it between two posts. First, lay gaskets made of ordinary roofing felt impregnated with drying oil at all points where the timber will come into contact with the piles. The timber should be fastened to the side posts with self-tapping screws, and to the lower base with through pins or small anchor bolts. After fixing the timber, lightly tap it with a hammer. To give the strapping additional strength, reinforce the joints at the outer corners with spikes or small galvanized steel corners. They should be selected in exact accordance with the size of the angle between the pile and the beam, attaching them with galvanized screws. This method of fastening must be done with all piles, carefully ensuring that not a single untreated area is left. It should be taken into account that if the piles are located in such a way that it is impossible to fasten the beams between them at the bottom and on the sides (the piles are not located in the form of a flange), fixation with clamps is preferred to a threaded connection. To do this, beams are laid on the tops of the piles, fastening them with self-tapping screws or welding, if the pile foundation is tied with a channel. During the connection process, ensure that the upper plane of the beam is perfectly even. If it is skewed, the walls will turn out uneven, so use a water level or laser level regularly. Make connections around the entire perimeter. Between the pile beams, place wooden blocks in the shape of the letter “P” on the horizontal beams. These bars are called clamps, and they should be smaller in size than the main bars. This way you will provide additional fixation of the elements. The ends of the clamps should face down. Subsequently, they are fastened to adjacent pile pillars using threads or galvanized steel corners. If none of the fasteners are loose, then the work has been done efficiently. Finally, we suggest that you familiarize yourself with useful tips that will help you tie a pile foundation with an angle, channel or beam as efficiently and quickly as possible. First, before laying timber or metal beams on the piles, make sure that they (the piles) are the same height. Otherwise, the harness will not converge. Secondly, during the installation of the strapping, make sure that the screws are located strictly in the center of the beam, otherwise it may crack. The quality of the timber also plays an important role. It is necessary to buy pest-free and well-dried material with the least number of knots. The moisture level of the timber should not exceed 18%, otherwise it will become deformed during the drying process. Remember that the harness should be twice as wide as the posts. Only then can the structure be strong and durable. Video about tying a pile foundation with timber and the advantages of this method:

The pile-screw foundation remains one of the most popular solutions for individual construction due to its availability, simplicity and stability even on “floating” soils. However, in order for your home to be even more comfortable and not require repairs for as long as possible, you need to make its foundation even stronger and more durable. To do this, operations such as tying and closing screw piles are performed.

Inexperienced builders often confuse tying screw piles with covering the foundation. Although these two stages of the home foundation construction process are related in some way, they have slightly different goals.

Harness involves combining the heads of screw piles already installed in the ground into a single structure along the entire perimeter of the foundation and along the contour where the internal walls of the building will be erected.

The absence of strapping, which is done using timber, boards, channels and other materials, will lead to an uneven load on each pile. The consequence of this will be the rapid destruction of the foundation, which will simply “float”.

Closing screw piles gives the building a more aesthetic appearance and minimizes heat loss. After all, since there is no foundation and there is open space under the house, the floor in such a building is unlikely to be warm enough.

Many modern materials are used for closure.

Strapping options

Tying piles with timber

Owners of relatively light buildings - wooden or frame-panel - should give preference to this type of strapping. A timber grillage cannot be called very durable, but for such construction it is the most suitable and affordable option.

Often, timber made from coniferous wood is used for strapping, since its cost is several times less than similar products made from hardwood, and the differences in performance characteristics are minimal.

Before installing the grillage, special antiseptic compounds must be applied to the beam to prevent the destruction of wood under the influence of atmospheric factors and covered with a bitumen waterproofing layer. The latter gives the timber water-repellent properties.

When tying a pile-screw foundation with timber, do the following:

The pile head is mounted after leveling (cutting) the pile and after pouring concrete inside it (if necessary).

1. Carefully align the installed piles so that the pillars are exactly at the same level.
2. Heads are mounted on the piles.
3. Waterproof the material.
4. On the beam, which falls on the joints of the corners of the house, grooves of the required size are cut out for subsequent connection of the wooden parts with each other.
5. The timber is laid on the pile caps along the perimeter along the entire contour of the foundation so that the joints of the separate parts of the grillage are fastened together on the caps. The joints are laid with a rope for better compaction.
6. Level the grillage and carefully check the angle: it should not deviate from 90 degrees.
7. The timber is fixed to the pile heads using self-tapping screws.

Tying piles with boards

When installing a pile foundation, the boarding has a number of undeniable advantages compared to timber:

1. During work cracks may appear in timber with a cross-section that is too large or it is significantly deformed.
2. For making beams timber longer than 6 m is not suitable because of the serious problems that can arise from doing so.
3. Timber beams are quite heavy, so installing them will require a whole team of workers. At the same time, a beam from boards is made right next to the foundation, which is much simpler.
4. Beams made from boards do not require additional drying and are characterized by increased strength compared to analogues made from timber.

Tying screw piles using boards is performed according to the following algorithm:

There is another way to tie a board. The boards are glued together and additionally secured with screws and nails. If the boards are thin, you can line them with plywood for greater strength. During installation, it is important to separate the joints of the boards into different piles and use the proven “half-tree” method.

Tying piles with a channel (I-beam) or corrugated pipe

Metal grillages make it possible to use a pile-screw foundation when constructing not only wooden buildings, but also one-story buildings made of cinder blocks, foam concrete and gas silicate.

Sometimes, instead of a channel, an I-beam is used, which is highly resistant to compressive loads and provides greater structural rigidity. I-beams with a cross-section of 20 are often used. In the case of a channel, metal beams with a cross-section of about 30 mm are taken for load-bearing walls, for the rest - with a cross-section of approximately 20 mm.

The foundation is tied with a channel or I-beam as follows:

1. The pile pillars are installed at the same height and the metal framing elements are treated with an anti-corrosion agent.
2. Metal beams are placed on the piles so that they meet in the middle of the pile posts. The channel is cut at right angles at the corner joints of the grillage elements.
3. The beams are welded to each other and to the pile heads.

Tying a pile foundation with corrugated pipe is done in almost the same way, however, the resistance of such material to significant mechanical loads may be much less. Among the advantages of the pipe, we note its low cost and low weight.

Tying piles using a reinforced concrete grillage

Reinforced concrete piping is almost a third cheaper than metal, but it has a number of disadvantages, the main ones being the laboriousness of installation and the impossibility of continuing construction until the grillage has completely hardened. This usually takes at least a month.

When tying piles using a reinforced concrete grillage, you must proceed as follows:

How are the pile foundations covered?

A closed pile-screw foundation is reliable protection from rodents and other animals that can live in the empty space between the piles. Also, the cladding and finishing of such a base will prevent heat loss in the home and help create a good microclimate there without excess humidity.

The most popular methods of closing a pile-screw foundation:

• creation of a suspended plinth;
• creation of a shallow tape-type base.

For a suspended plinth, thin and not too powerful composite and polymer materials, as well as wood, are used. In this case, the load on the screw piles is minimal, and the simplicity and speed of installation, coupled with low cost, is often captivating.

Any type of finishing of the base on stilts requires the presence of two ventilation holes on opposite walls of the house. This will prevent moisture from accumulating on the piles and grillage, which will not corrode or rot (in the case of wood).

However, the pile foundation will last longer when installing a shallow strip plinth, which will become the best protection for the pile frame, guaranteeing its durability.

Thermal and waterproofing when closing the base

All types of basement finishing require the installation of a heat- and waterproofing layer, which is covered with asbestos-cement slabs, decorative thermal panels mounted on a sheathing of boards or a slate slab, or bricks. All these materials have their pros and cons:

Tying and closing screw piles is a very important stage in the construction of a house, which determines how soon it will need major repairs.

In contact with

The harness (grillage) is an important structural element of any pile foundation. The classification of grillages is carried out according to three factors: type of construction, level of placement and material of manufacture.

This page provides information about the technology for arranging different types of strapping. You will learn how to make a grillage from timber, channel and reinforced concrete with your own hands, and watch a video that reveals in detail the essence of the technology.

The timber grillage has a limited safety factor, which does not allow it to be used for the construction of heavy brick buildings, however, when constructing light wooden 1-2-storey houses from utility rooms - bathhouses, garages, verandas, in terms of economy and speed of installation, this is the preferred piping option.

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The typical size of timber for strapping is 15x15 and 20x20 cm. It is recommended to use coniferous wood, due to its greater durability compared to deciduous wood.

Important: only timber that has undergone chamber drying can be used for strapping, since the material having natural moisture will shrink, which can cause deformation of the walls of the house.

Before installation, the timber must be treated with an antiseptic agent that prevents wood from rotting, and covered with coating bitumen insulation, which will protect the material from moisture.

Technology for tying screw piles with timber:

• After installation, the supports are leveled to the zero level by trimming with a grinder;
• The heads are welded to the pile shafts. The welded joint is coated with an anti-corrosion primer;
• The surface of the head plate is covered with waterproofing material (roofing felt, glass insulation or glassine);
• The beam is adjusted in size according to the length of the walls of the house (one continuous beam goes to the side of the building) and groove joints are cut out with a grinder at the edges connecting at the corners of the house and at the intersections of the walls;

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• The timber is installed on top of the pile heads, and final adjustment to size is performed. The joints between the grillage elements are sealed with jute;
• With the help of “capercaillie” - wood bolts with hexagonal caps, the timber is secured to the pile heads (the plates have special holes for mounting the bolt).

Strapping with a steel grillage (I-beam, channel)

The strength and safety margin of metal framing exceeds the similar parameters of a timber grillage, which makes it possible to use it not only for the construction of frame houses, but also one-story structures made of foam concrete blocks.

Based on the material used, steel grillage is classified into two types:

• I-beam;
• From channel.

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Important: the choice of material must be made based on the mass of the building - a channel, due to its lower cost, is preferable when constructing light houses, while an I-beam has better resistance to compressive loads and greater rigidity, which makes it the optimal choice for heavy buildings.

• I-beam tying is performed using a beam 20 cm high;
• Channel - section 30 or 40 mm.

Tying with a steel grillage is practiced exclusively when arranging screw foundations. Installation of the grillage does not require installation of caps on the piles; the material is welded directly to the support shaft.

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Technology for tying screw piles with a channel grillage:

• Upon completion of installation of the foundation, the pillars are aligned to the zero level;
• The dimensions of the grillage parts are measured, the channel is marked and cut into sections of the required length;
• Rolled metal is treated with 1-2 layers of anti-corrosion primer;
• The channel is installed on piles and cut with a grinder at the joints at an angle of 900;
• The grillage is fixed to the piles by welding. Upon completion of fastening, the welds are coated with a primer.

Tying with reinforced concrete grillage

Tape grillage made of reinforced concrete is used for tying bored and driven piles. It is suitable for the construction of heavy brick and foam concrete buildings with a height of 1-3 floors. In terms of arrangement, this is the most labor-intensive option for piping, but its cost is lower than that of an I-beam grillage.

Important: a reinforced concrete grillage is subject to mandatory reinforcement, which is performed by a spatial reinforcement frame consisting of two longitudinal reinforcement belts connected by transverse and vertical jumpers. The step between the jumpers is 20-30 cm. These can be rectangular welded sections of reinforcement or clamps bent into the appropriate shape.

Rice. 1.7: Scheme of reinforced concrete grillage

To assemble the frame, corrugated rods with a diameter of 12 to 18 mm are used. The body of the grillage is created from concrete grade M300-M400 with granite crushed stone filler.

Technology of tying with reinforced concrete grillage:

• The shafts of concrete piles are leveled to the zero level using a grinder with a diamond wheel, a hammer or a special hydraulic hammer - a pile cutter. Only the concrete of the piles is destroyed, while the protrusions are left untouched;
• A sand bedding is placed around the perimeter of the piles (to the level of the trunks), on top of which the lower wall of the formwork is laid. Next, the side walls are installed, after which the structure is strengthened with stops and jumpers that tighten the walls along the upper contour;
• The formwork is covered with waterproofing from the inside;

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• The frame is being assembled - the reinforcement is joined by welding or wire. The finished frame on special mushroom stands is installed inside the formwork and welded to the rods protruding from the piles;
• The grillage is concreted; after pouring, the concrete is compacted by vibration or bayoneting with reinforcing bars.

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The grillage needs 25-30 days to reach its design strength, after which you can begin raising the walls of the house.

Features of tying

When tying piles, it is necessary to choose the correct level for its placement, according to which reinforced concrete grillages are classified into:

• Hanging;
• Ground;
• In-depth.

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In conditions of stable soil, the easiest method of tying will be a ground grillage, which is located on the soil surface. Piles with a ground grillage are classified as a pile-strip foundation - this is a reliable foundation with a high load-bearing capacity, which is achieved by increasing the supporting area of ​​the foundation with a tape in contact with the ground.

However, in soil prone to heaving, this tying option is not applicable due to the risk of the grillage being torn off from the pile shafts by buoyant loads. Here it is necessary to equip a hanging grillage raised above the ground to a height of 20-40 cm.

An in-depth grillage is a structure that is placed in the soil. Under the support base of the grillage, the soil is replaced with a non-heaving sand and gravel cushion. This grillage is used in the construction of heavy multi-story buildings, for which the safety margin of the hanging frame is insufficient.

Video of tying a pile foundation

Check out the videos that demonstrate the technology of tying piles with grillages of different types.

Video #1: Tying piles with timber

Video No. 2: Channel tying of piles

Video No. 3: Tying piles with reinforced concrete grillage

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To give the structure strength and reliability, separate supports are combined into a single rigid system using a grillage (). This is the foundation strapping, designed to evenly distribute the load from the building to the ground.

Depending on its location relative to the ground level, the harness can be:

• buried - immersed in the ground in such a way that its upper edge is flush with the ground;
• elevated – lying on the ground;
• high (hanging) – raised above the ground by 150 mm or higher.

The latter option is used on heaving soils. The first - buried - is used extremely rarely and only on sedentary soils.

Depending on the materials used, there are four types of piping for pile foundations:

• channel;
• I-beam;
• reinforced concrete monolithic tape;
• timber.

The metal harness is highly durable, but it is very difficult to install it without a truck crane.

Reinforced concrete grillage is superior in strength to metal grillage. You can build it yourself, but the labor costs for its arrangement are high. In addition, construction time is being delayed: work has to be suspended until the concrete gains the required strength.

When constructing private houses from light building materials, it is quite possible to get by with timber: wooden framing is cheaper than metal and reinforced concrete, is quickly installed and has sufficient strength.

Features of tying piles with timber

As a starting material, you can use timber with a cross-section of 150x200 mm or boards 50x200 mm, assembled into a composite beam. With a distance between supports not exceeding 2.5 meters, such a structure can easily support the weight of a two-story frame building.

The lower frame of a frame house on screw piles simultaneously plays the role of an intermediate link in attaching the walls of the structure to the foundation. Consequently, the responsibility for uniform distribution of the load lies with her. Therefore, it is especially important to prevent the screws from differing in height.

If such an incident occurs and the timber hangs in the void above one of the piles, the situation can be corrected by driving a wooden spacer into the void through the waterproofing layer.

But it’s better to avoid such a problem in the first place.

Video about the types of foundation lining on screw piles.

Each stage of foundation construction obliges builders to comply with technological procedures and a number of mandatory requirements. After all, the quality and service life of the building under construction will depend on this. At the final stage, it is necessary to perform the so-called strapping.

A lot depends on its quality, so its correct implementation is the most important stage in the process of constructing a foundation using piles. channel - one of the most popular types of this procedure.

Some features

I would like to note that the pile-screw foundation is the most versatile and quite reliable of all those existing today; its use in construction for various purposes is very popular. This is due to the fact that the technology used in its construction provides developers with the opportunity to engage in the construction of buildings even if there is mobile, unstable soil on the site.

In addition to the fact that screw piles are successfully used in construction, or rather, the construction of a foundation, they are also suitable for performing the procedure of strengthening the foundation of a house. This is done in the event of an increase in the load on the foundation or during reconstruction (repair) work aimed at increasing the reliability of the foundation.

1. Why is the harness needed? Its function is to support the supports (piles) in the desired position corresponding to the markings. For its installation, a channel or timber is most often used.
2. But don’t think that in any case you will have to do it. This is not true; if the piles are located at a distance of no more than 60 cm above the soil, then there is no need for it. In this case, you can simply use special heads, which are secured on top of the screw piles by welding.

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Harness: types and brief description

The most popular option and the most affordable financially is considered to be tying a screw foundation using timber.

It is best to use this type of strapping when building a house made of wood or when building a bathhouse. When performing tying, a prerequisite is to level the screw piles, without allowing distortions. Otherwise, you will have to level the piles using timber, cutting it where necessary and to the appropriate depth.

To join parts of the timber, you must first make cuts on both sides. Please note that one of the cuts is made at the top, the other at the bottom. Next, the parts of the beam are joined, maintaining a right angle. The joints formed between the cuts are processed using jute.

To perform timber strapping you may need the following tools:

• electric saw;
• level;
• roulette.

Also, stock up on assistants; you will definitely need them, since it is very difficult to process the timber and transport it to the installation site alone.

Another popular strapping option involves using a channel for this purpose. This method helps to make the foundation structure more rigid. But don’t forget, if your construction is on a large scale (large foundation area), then channel tying will require you to use special equipment (crane). It is precisely because of this circumstance that in private construction projects they do not very often use strapping using a metal channel.

1. When choosing a channel as a strapping, do not forget about fasteners. Experts recommend combining types of connections and, along with welding, also using bolts or rivets.
2. And one more nuance: when installing a metal channel strapping, you need to seriously think about how to protect the metal from corrosion.

Everyone knows that there is an air gap in the space between the soil and the foundation platform, and this definitely leads to the appearance of moisture, most often in the off-season. And these circumstances naturally lead to the occurrence of corrosion processes on the metal surface. But if you take care of corrosion prevention in advance, you will avoid these problems. Use primers, antiseptics and other agents aimed at combating corrosion to treat the finished structure.

Timber binding is no exception in this case, as it is also quite susceptible to moisture. It must be treated with special antiseptic substances or creosote. And then, no matter what the strapping is made of (channel or timber), it will serve you faithfully for many years, and you will not worry about the condition of your foundation.