Pros and cons, technology for constructing a pile foundation with a monolithic grillage

What is a pile-grillage foundation

Everyone probably imagines a pile foundation: it is a number of piles buried in the ground to the level of the load-bearing layer or below the freezing level. In its pure form, this type of foundation is rarely used. This is due to the peculiar design, which does not allow the load from the house to be redistributed between the piles. Therefore, pile foundations are mainly made for log buildings made of logs or timber, and sometimes for frame buildings. These types of building materials, due to their characteristics, themselves redistribute the load. They are not compatible with houses made of other materials.

Excavation.

Boer.
Using a hand drill, you can drill holes for piles up to 5 m deep and no more than 30 cm in diameter.

During excavation work, an earth drill is used to construct a pile foundation. It is a device of two rods with a loosening and cutting cup. The drill makes small holes under the piles. You can use a hand drill, which drills holes up to 5 m. It is used when the diameter of the foundation support is no more than 30 cm. A motorized drill is used when it is necessary to drill a hole of a large diameter (from 50 cm). That is, when constructing a small pile foundation with a grillage, you can use manual labor, and if screw piles are used in the structure, then you can simply abandon the excavation work. There are several varieties of this tool: TISE-F, TISE-2F, TISE-3F.

On one side the drill has a soil accumulator, and on the other there is a crossbar with handles. A folding plow is mounted above the soil accumulator. When drilling, the plow cuts off part of the earth. Under the influence of its own weight, the plow cuts the soil, gradually lowering down. The cut soil falls into the storage tank and rises to the top. This drill weighs 11 kg. When drilling, direction should be taken into account.

If, for example, you need to drill a well deeper, then the drill must be rotated clockwise. If anchor extension is required, the tool is rotated counterclockwise.

Sod should be removed before drilling. Depending on the type of soil, drilling can be done either by one person or by two people. A partner is involved if drilling occurs on clay or dense soils.

Main manufacturers and standard series of pile grillages

For private or small buildings, you can make lattice belts yourself directly at the construction site, but when constructing industrial buildings, multi-story buildings, etc. use factory-produced designs. Among the main manufacturers of precast concrete grillages from 35 tons, the following companies can be distinguished:

• JSC APSC "Gulkevichsky";
• CJSC "OBD";
• JSC "T-Beton";
• LLC "LSR. Construction-Ural" ;
• LLC "ZKPD Tomsk House-Building Company";
• JSC "PZSP".

The name used to designate typical grillages for pile foundations includes the mandatory letter indices RS and RB and serial numbers. Markings RS1 – RS5 are used on square supports, and RB – for rectangular piles.

Important! If it is necessary to order grillages from 50 tons, the concrete manufacturer must be chosen especially carefully to ensure the strength and durability of the entire structure.

What piles to use.

Any piles can be used in pile-grillage foundations. They are selected based on the soil and the planned load of the house. Piles are made of metal, concrete, and sometimes wood. They can have a round or square cross-section. They also differ in the installation method:

• Hammers. They are installed without drilling or excavation. Usually they get clogged, that’s why they are called that. They are rarely used in private construction: special equipment is required.

Pile grillage foundation.
Driven reinforced concrete piles are used more often in the construction of multi-storey buildings.

• Bored. First, a well is made in the ground, then formwork is installed and secured into it. It contains reinforcement that increases strength characteristics. Then the entire structure is filled with concrete.
• Reinforced concrete drilling rigs. In this case, wells are also drilled, but ready-made reinforced concrete piles are installed in them (driven, but with less effort).
• Screw. These are metal piles, pointed at the end and having screw blades that cut the soil. At greater depths, special equipment is required; small ones, up to 2-3 meters long, can be installed manually.

Pile grillage foundation.
One type of piles is screw piles. They can be used with grillages made of different materials for different houses.

In private construction, bored piles are most often used. They are especially popular in the construction of summer houses or baths. They can also be used in the construction of small houses. But if dachas and bathhouses can be built without calculations, then when building a house it is very advisable to order a project.

Different piles come in different shapes: square or triangular, round filled and round hollow, sometimes complex shapes are developed specifically for the project. Based on how piles transfer load to the ground, they are:

Pile grillage foundation.

How do piles differ by type of work?

Hanging piles have a large lateral surface and a significant part of the load (up to 60-70%) is transferred with its help. They are used if the bearing capacity of the soil at the achieved level is not enough to withstand the entire load, and further deepening is impractical. In this case, the presence of a “heel” changes almost nothing: the main load is transmitted by the surface, and not by the tip of the pile.

Rack piles, on the contrary, transfer most of the load through the tip. In this case, the side walls are undeveloped and smooth, and it makes sense to expand at the end of the pile. One type of this type is TISE piles. They have a cylindrical extension at the bottom, which is why they transfer the load to a larger area. Also, the heel prevents heaving forces from lifting the foundation.

The main dimensions of grillages - how their dimensions differ

Starting with this difficult topic, we can say that detailed information on the rules for calculating the height of grillage foundations, as well as other dimensions, is unlikely to be useful to the average person. The fact is that even knowing all the formulas necessary for calculations, a person not involved in design is unlikely to be able to calculate everything correctly. That is why we will try to outline such a topic as the dimensions of the pile foundation grillage as simply and in general terms as possible.

Let's try to understand how the load will be distributed after the construction of the building is completed. If we turn to the exact sciences, then with the correct construction of the structure, the load should be evenly distributed over the grillage, which (in turn) will distribute it across all involved piles. But it should be understood that if the structure contains vertical load-bearing beams, they must be located directly above the pile. In this case, the load will be distributed so that not the most powerful grillage can easily withstand it. Experts can freely calculate what dimensions are needed for a pile foundation in a cross-section of all dimensions.

A cross-section of a pile foundation looks something like this:

Important advice! It is quite possible to do without the help of engineers in such work, provided that a bathhouse, a good-quality barn or a storage room is being built. If you plan to build a permanent house, then it is better to involve professionals.

Installation stages.

The construction of a pile foundation with a grillage begins with driving the piles into the ground. A prerequisite when working is to accurately determine the level of soil freezing. The supports must be buried below this mark. Next, the piles are connected with grillages. By their nature, grillage joints can be made from the following materials:

Grillages protect against soil displacement. They counteract structural instability during freeze-thaw and provide rigid coupling of the building's structural elements. Piles are mounted at points where the heaviest load is expected; their length depends on the depth of soil freezing.

In practice, for the construction of low-rise buildings, supports from 1.5 to 3 m are used. The distance between adjacent elements is 1-1.5 m. The holes for the supports must be lined with roofing felt or similar material. It is possible to casing with asbestos-cement pipes.

4 reinforcing rods are vertically fixed and securely tied in the hole. The top of the pile must be above ground level. The reinforcing thread coming out of the pile support is tied to the grillage reinforcement. The holes are filled with concrete mixture.

Over the course of a week, the concrete will gain strength. After 7 days the indicator will reach 60%. After this, you can begin work on reinforcing the grillage. The process begins with formwork. Sand is poured into it or polystyrene foam is laid. Thus, the grillage will be raised above the ground (hanging on stilts).

Scheme of a pile-grillage foundation.

An important point before reinforcement is waterproofing the upper part of the pile pillars. This stage should not be skipped under any circumstances. Reinforcement is carried out according to the general scheme developed for a specific construction. This is due to the fact that the position of the supports and the distribution of loads on the grillage differs in different places of the structure. The backfill from under the grillage structure is removed after the concrete reaches half of its brand strength (no earlier than 7 days).

Taking into account the fact that for each specific case the position of the supports and the distribution of the load in the grillage is different, reinforcement is carried out on an individual basis. The reinforcement that comes out of the piles is connected to the grillage reinforcement. When the grillage reaches more than half of its brand strength, the bedding from under it is removed. The grillage structure hangs on stilts. The grillage is not allowed to rest on the ground between the piles.

A truly working legal way to save money. Everyone needs to know this!

Pros and cons of a pile-grillage foundation

Like every other building structure, the pile-grillage structure has its own advantages, disadvantages and limitations in application.

It involves minimal time spent on creating a foundation, provided that the work is carried out by experienced craftsmen with their own special equipment. A pile foundation for a brick house (or other type of structure) is installed in the shortest possible time. The customer receives a ready-made turnkey project.

It involves the use of a small amount of concrete due to the fact that there is no need to build a cushion in the ground.

In the cold season, when the soil freezes, the area of ​​interaction between the elements of the pile-grillage foundation and the frozen ground is minimal. Thus, the heat loss of the building is also small.

• The presence of vibration-isolating properties in the structure.

The peculiarities of connecting piles with a grillage provide reliable protection of the structure from vibration associated with the close location of the building relative to large highways, railways or subways. A pile foundation without a grillage is less effective in such cases.

It should be noted that the construction of a pile-grillage structure can be carried out at almost any time of the year. Restriction – work cannot be carried out at temperatures below -10 °C. Another advantage of such a foundation is the affordability of the materials used.

Bored piles.

Disadvantages and disadvantages:

• Use of special equipment.

It is impossible to build this type of foundation yourself. The technology requires the mandatory use of special equipment.

It is almost impossible to build this type of foundation with your own hands.

• The difficulty of constructing basement floors.

Features and layouts of supports complicate the arrangement of basements and basements. Often the space between piles has to be filled, which significantly increases the final cost.

• Low resistance to rollover.

Pile-grillage foundations on subsiding and swelling soils require special precision in adherence to technology.

Installation of driven supports.

Types of element and the main task of the grillage

The main purpose of the grillage is to absorb the load from the load-bearing elements of the building and distribute it evenly on the foundation. The most common and economically justified is a pile foundation.

A slab grillage on piles in the form of large-format reinforced concrete slabs is installed with significant dimensions of the building along its perimeter. This grillage is placed on a standard pie consisting of:

• sand and gravel cushion in the form of two layers of 10 cm each with vibration compaction;
• ring drainage located at the level of the grillage base;
• concrete preparation in the form of a screed without reinforcement;
• waterproofing.

If the groundwater lies quite high, then when constructing such a structure there is no need to make additional diversions.
Strip foundations on piles can be monolithic or prefabricated. The first option is used for bored piles. This is due to the fact that the materials have the same linear expansion and technical characteristics. It is also easier to wall up the heads with protruding reinforcement in the body of the grillage.

Prefabricated strip grillage is used in wood construction technology. Wooden beams are laid on the heads and joined into half a tree. This allows you to reduce construction costs and begin construction of the structure the very next day after laying the foundation.

A prefabricated strip grillage can be made in the form of reinforced concrete beams adjacent to the pile cap. This design is used primarily for screw piles tied with I-beams or channels.

Thanks to the base with a grillage, it is possible to build a foundation even in difficult places.

When installing reinforced concrete bored piles with a grillage, a glass type of structure can be used. The grillage is represented by a kneecap mounted on a pole, a multiple of 15 cm in height and 30 cm in width. Each glass must be supported by four piles. This type of base is used when installing columns. Most often used in agricultural and industrial construction.

Advantages and disadvantages

Types of pile foundations are divided primarily according to the method of construction into driven, driven and screw. Each model of a structural element is characterized by its own characteristics.

The general advantages of all types of piles include the following:

1. Applicability for all types of soils and reliefs of any complexity.
   Where laying a strip or slab base would be ineffective or impractical, supports are used. Pile foundations can be built on unstable, waterlogged soils, areas at risk of landslides or flooding, wetlands, as well as on slopes and depressions.
2. Economic expediency. Laying single load-bearing elements connected into a single structure with strapping costs 30–40% less than constructing a slab or strip buried foundation.
3. Possibility to select a power element for any conditions. The popularity of pile technology has led to an increase in offers from pile manufacturers. Today you can select supports with a load-bearing capacity from 0.8 to 15 tons or more, and composite elements are used for deep laying.
4. Small amount of excavation work. If, in the case of a buried strip or slab base, it is necessary to dig a pit to the design depth, then to install cast-in-place piles it is enough to drill holes in the ground, and the driven and screw pillars are immersed in the soil by force.

Disadvantages of pile technology:

1. Complexity of engineering calculations. Pile foundation technology can satisfy almost all hydrogeological and design conditions, but this will require a number of engineering calculations. Before designing, the designer needs to study the regulatory requirements for the construction of foundations in order to take into account possible nuances for each type of support.
2. Labor intensity of work on arrangement of basements. It is possible to organize the construction of underground premises in the space between the power elements, but this will lead to a significant increase in the cost of the project, which will practically cover the benefits of using pile technology.

For a private home

Private residential buildings and cottages are relatively light in weight compared to high-rise buildings and industrial facilities. This feature allows you to abandon the laying of an expensive reinforced concrete strip or slab foundation in favor of factory-made or home-made piles.

Advantages of pile technology for private construction:

• the possibility of laying the foundation with your own hands (screw piles, cast-in-place piles);
• if necessary, methods are available to strengthen the foundation (when building extensions, increasing the number of storeys, replacing floors in a house, etc.);
• maintainability.

Why you should not build a private house on a pile foundation:

• significant heat loss due to the elevation of the house above ground level;
• labor-intensive procedure of engineering calculations;
• There is high seismic activity in the area.

Different types of piles

The choice of piles is based on the results of hydrogeological soil surveys, as well as engineering calculations for design loads. Comparative table of pros and cons for various types of power structures:

We install the grillage foundation with our own hands

To save money, you can build a grillage on a columnar foundation or pile base with your own hands. This is, in principle, not very problematic. But before moving on to the process of building the object, it is necessary to select supports for the future structure.

What to use: pillars or piles?

Both piles and pillars are used in construction. The former are used to create houses intended for year-round use, and the latter - for the construction of small objects without constant load, for example, bathhouses, small country houses, gazebos, etc.

In general, piles are the best solution for the construction of a particular structure. But we will consider the installation of grillages for both pile foundations and columnar foundations.

Grillage technology

The grillage is usually called the upper part of the foundation, which ensures the connection of the pile foundation and the uniform distribution of the load-bearing load.

The main thing in its construction is the connection of the reinforcing elements of the pile foundation with the grillage reinforcement. The grillage can be one of three types:

• shallow foundation, which looks like a strip foundation and has the following dimensions: width - 40 cm;
• height - 20-30 cm.

  
  Drawing with dimensions of the grillage device

Types by placement

Depending on the placement of the grillage relative to the ground level, there are several options for its design. The choice of a specific project is carried out in accordance with the requirements for the foundation, the characteristics of the territory, and the future building.

High

A high grillage is located 25 centimeters or more above the soil surface. Thanks to this option, it is possible to achieve additional floor ventilation and eliminate the risk of dampness and mold. Raising the grillage above the ground allows you to regularly inspect the condition of the foundation and carry out repairs on time.

The underground space can be used to store tools, garden tools, and other things. The main disadvantage of this type of grillage is the inability to create a full-fledged basement.

Elevated

The raised grillage is the most popular in construction and is located at ground level. The base for the tape is a sand and gravel cushion 10-15 centimeters thick; for its construction, the required volume of soil is removed, replacing it with gravel. In this way, it is possible to create an anti-heaving cushion that prevents the soil from rising in the cold.

A gravel cushion reduces the level of moisture in the soil and prevents water from accumulating under the foundation. The main advantage of this type of grillage is the absence of a ventilated space between the ground and the ceiling, which significantly improves the heat-saving characteristics.

Recessed

Such a grillage is located below ground level, in a special trench where piles are installed, formwork is installed, and then filled with concrete mortar. A room on such a foundation is durable, reliable, and has excellent heat-saving properties.

Description and features

Slab foundation

This type of foundation has been used not so long ago, and is one of the most modern, improved structures. In large-scale construction, the combined foundation began to be used due to the widespread proliferation of high-rise buildings.

A pile-slab foundation consists of two parts: piles driven into the ground, and a massive concrete slab located directly on them. This slab acts as a grillage, optimally distributing the load-bearing load throughout the entire foundation. As a result of such a well-thought-out technology, the pile-slab foundation has high load-bearing characteristics and is capable of supporting the enormous weight of the building. But how the tying of a frame house on a strip foundation occurs is described in great detail in this article.

Pile slab foundation

To carry out the construction of this structure, accurate preliminary calculations are required, taking into account many important nuances and details. It is best to entrust the calculation to specialists, since this is truly a complex job that requires professionalism.

The grillage in the form of a monolithic slab connects all the piles into a single whole and optimally resists displacement. Piles in this tandem act as both a support and a kind of bridge through which the load-bearing load goes into the ground.

Because of this device, the level of foundation shrinkage is reduced, which is important. Due to the fact that the piles are driven below the freezing level of the soil, the foundation copes well with soil heaving during frosts

The pile-slab foundation, through its rigidity, ensures the necessary reliability of the supporting structure even when it is exposed to seismic processes occurring in the soil.

Piles for such a foundation can be either drilled or driven type. The method of introducing supports into the soil is selected individually, based on the type of soil.

The video shows a pile slab foundation:

If a skyscraper is being built, the thickness of the slab can be even five meters or more: you can imagine what kind of colossus this is. A reinforced belt is constructed on such a slab, which will then serve as the ground floor of a skyscraper. This floor is usually equipped with parking lots, utility rooms, and elevator shafts.

Application area

This exceptionally reliable design is ideal for seismic zones, areas with difficult soil, and other areas that require a special approach to construction.

Difficult soil includes problems such as:

• heaving soil;
• presence of groundwater and underground lakes;
• other water layers in the soil;
• frosty climate.

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What material is best to make it from?

For round or rectangular piles, the following are used: reinforced concrete, simple concrete mixture, different grades of steel, coniferous trees (especially larch).

Concrete grillages are easiest to construct when the cap ties the support piles to a height of 0.1 m. This option cannot be called a strong and durable structure, so concrete grillages are applicable in the construction of only one-story structures.

Heads made of reinforced concrete have a high margin of safety, reliability and rigidity and a long service life. Such structures are given greater strength by reinforcing the concrete grillage with a steel frame or individual rods.

Reference! Professionals know that with such a grillage foundation, this reinforcement must be provided with a protective layer.

The production of heads is also possible from rolled metal - I-beams and channels. Such grillages are rigid and durable, however, like all metal products, they are susceptible to rusting (especially at the joints).

Wood is used for the construction of grillages only in wooden structures. A waterproofing layer of roofing felt or roofing felt must be placed on the tops of the piles, and the connecting beams themselves must be treated with anti-parasitic and anti-mold compounds.

When can it be used?

It is recommended to install pile-grillage foundations in the following cases:

• When unstable and weak-bearing soils go to a sufficiently large depth. These are karst, forest, peat soils, quicksand, plant and fertile soils of great thickness (more than 1.4-1.5 meters). In this case, the load must be transferred to the dense soils located below with normal bearing capacity. It is not always possible to get to them, and even if it is possible, the foundation turns out to be too expensive. Therefore, transferring the load using piles is the best choice.
• In areas with large elevation differences. In this case, it is often much cheaper to use piles of different heights than to carry out work on leveling the ground or pouring a deep tape that can compensate for height differences.

Pile grillage foundation.

• At high groundwater levels. Pile foundations are the only ones for which the groundwater level does not matter. It is important that there is soil with load-bearing capacity under the heel. The level of water location affects only the type of grillage: if the water is close to the surface, the grillage is made high, if it lies deep, it can be made low.
• During construction in hard soils. In this case, small volumes of earthworks (compared to strip or slab foundations) have a positive effect.
• If you decide to build a house using frame technology. Making a tape for it is a waste of money: you get too much safety margin, which, in this case, is useless. In this case, a pile or pile-grillage foundation is the best choice.
• With a large mass of the building (more than 350 tons). Then it turns out that the tape or plate must be very massive and, therefore, expensive. In this case, a pile-grillage foundation often turns out to be cheaper.

Sometimes it’s even simpler: they start from the lowest cost. But you should always remember that any type of pile foundation is less reliable than slab and strip foundations. And all because we cannot know exactly what kind of soil is under each of the piles. That is why, when calculating parameters, an increased safety margin is included in the design. Not 1.2, as is usually believed, but 1.4. And still, no one can guarantee anything.

By type of design

The grillage foundation has its own characteristics. The load-distributing structure can be assembled in several ways. According to this classification, the grillage is:

• Monolithic.
• Prefabricated.
• Prefabricated - monolithic.

Each of these types has some features as well as materials. However, first things first.

Monolithic

This structure is made of concrete. The construction of this type of grillage involves pouring concrete and creating a solid area that connects the heads of pillars or piles.

Monoliths come in two types: strip and slab. In the first case, a tape is created that goes from one pile to another.

This is exactly how most monolithic grillages are made. The second type involves creating a slab connecting all the heads at once.

In this case, you need to shell out a lot more money for concrete (and reinforcement, if provided). Therefore, such grillages are made infrequently. But, if there are poor geological conditions, then this option is irreplaceable.

Made

As you probably already guessed, in this case the grillage is assembled. The materials used here are reinforced concrete blocks.
On the one hand, this design is simpler, because many people know how to properly make a prefabricated grillage, while not everyone knows how to build formwork on the top of the base and knit reinforcement.

On the other hand, constructing from blocks involves using machinery to unload parts and load them onto poles and piles. Therefore, when thinking about which option to choose (monolithic or prefabricated), many choose the first.

Prefabricated - monolithic

But this solution is no longer so simple, and in private construction it is practically not used. What are these hybrid grillages? In fact, they actually combine the two previous methods. The structure is built from prefabricated elements that are produced in a factory. For assembly into one piece, they are equipped with special locks and key connections.

Next, the seams are filled with concrete, and one continuous strip is obtained. In this way, the grillage dimensions are achieved on which industrial and residential buildings can be erected. This is where it is used. In private construction, this option is not used, since it is too expensive, is built only with the help of heavy construction equipment, and also requires high precision during assembly.

Advantages and disadvantages

The piles of the supporting structure in question, due to their large immersion depth, provide excellent stability to the entire mini strip foundation on top. And they cost much less than a reinforced concrete monolith of the same height. Moreover, if the support pillars are tied on top not with a concrete tape, but with a metal grillage, then you can save a little more. This option is one of the most inexpensive ways to create a support for a private home.

In terms of device speed, a pile foundation with a grillage is inferior only to an analogue made only of screw supports. Plus, a foundation made of wall foundation blocks will be ready to give a head start to the structure in question. In both cases, the high speed of work is due to the lack of concrete work, when it is necessary to wait several weeks until the concrete completes its strength.

If the building site has a slope, then pouring a monolith on it is problematic and expensive. It will be difficult to do without this type of foundation on such a site. Only with the help of piles will it be possible to create a stable and horizontally level base for the structure. This is one of the main advantages of the foundation. All other options are immediately inferior to him on construction sites with complex terrain.

Another undeniable advantage is the extreme simplicity of execution. It’s not difficult to make your own pressed supports from asbestos-cement pipes and concrete inside. It’s even easier to make a reinforced concrete strip of small size and weight on them.

Minor difficulties here can arise only when installing the formwork suspended. It cannot be immersed in the ground. The pillars must raise the grillage part above the ground by at least 30 cm, otherwise, if there is severe heaving, it may “float” from the supports along with the building on top.

The underground space of a cottage on a pile foundation with a grillage must be closed from the wind, otherwise constant drafts under the floor will blow all the heat out of the building. To do this, you can use facade panels from various materials or make masonry from beautiful facing bricks. Plus, the floor in such a house will definitely have to be insulated. It is better to immediately include these expenses in the overall estimate for housing construction.

Options for the location of piles and their types

Piles can be hanging or in the form of racks. In the first option, the load on the surrounding soil is transmitted through friction against the side walls. Such piles are characterized by a developed lateral surface along the entire length with many protrusions, which ensures good load-bearing capacity of the structure. This type is used for soils with a high groundwater level or having a thick layer of weak soil, under which there is a stronger one, but it is still not able to support the rack pile.

Rack piles transfer the load from the structure directly to the strong soil, which is located under the weak layer. The elements are characterized by a smooth surface to which the soil does not cling. The most important criterion for this type of pile is a wide base, which can bear more than 80% of the total load.

Helpful advice! For multi-storey and durable buildings, it is advisable to choose TISE rack piles, which have a significant widening in the lower part of the element, which eliminates further settlement.

Piles in the ground can be located in one of the following ways:

• single;
• tape;
• stripes;
• in the form of a bush;
• field.

Various options and types of piles

The first method is selected for a free-standing support. Depending on the terrain, the pile can be installed inclined. The tape method involves placing piles along the entire perimeter of the structure. For the construction of massive multi-story structures, piles are installed in several rows in the form of strips.

Cluster placement involves installing elements under load-bearing walls and objects with heavy loads. This method is used for the construction of canopies and structures with a large number of columns that hold the roof. For large buildings, piles are installed in a checkerboard pattern.

The choice of pile placement method depends on the construction project. Elements should be located in corners and at the intersections of piers. The optimal distance between piles in a grillage is 2–3 m.

Laying depth - what it depends on

The depth of placement depends on the condition of the soil on the site.

All related factors are taken into account:

• Groundwater level.
• Availability and volumes of soil water.
• Possibility of flooding in spring.
• The presence of seasonal changes in hydrogeology, an increase or decrease in the degree of filling of all aquifers.

To select the correct depth, it is often necessary to collect information from local geological and meteorological departments, consult with experienced builders, and refer to various SNiP applications.

It must be taken into account that all values ​​​​indicated in various sources are minimum, i.e. It is allowed to increase the lifting height, but it is impossible to reduce the gap height.

Installation of a pile-strip foundation with your own hands

Constructing a grillage on a columnar or pile foundation with your own hands is a feasible and feasible task. It is advisable to choose the first option for the construction of small structures without constant load, such as country houses and gazebos. Pile foundations are the most popular solution for the construction of buildings intended for permanent use.

It is advisable to construct a pile-grillage foundation with your own hands in late spring, early summer or early autumn. The first step is to prepare the site by clearing it of debris and vegetation.

The monolithic type of grillage is a one-piece structure

Helpful advice! It is recommended to treat the area for future construction with chemicals, which will prevent the growth of vegetation.

Next, the territory is marked based on the project, indicating the location of the piles. If screw piles are used, they should be screwed in without first creating holes. To do this, you can use a pipe or a crowbar, which must be inserted into the head of the support. For screw piles, it is more convenient to make a metal or wooden grillage. It is advisable to install a concrete lintel only under a future house made of stone, which requires high rigidity of the base.

Important! The piles must be positioned strictly perpendicular to the ground.

If you are installing bored piles, you will not be able to install them yourself. To create holes in the ground, you need to use special equipment. Bored piles can be made in two ways. The first option involves placing formwork in the form of a metal pipe of the required diameter in each drilled hole. The internal space is reinforced and filled with concrete. The second option eliminates the installation of formwork.

There is only one type of wooden grillage - prefabricated

To construct a pile foundation with a grillage, class B7.5-B15 concrete is used, which is the optimal solution for small buildings. For large buildings, concrete of class up to B25 can be used. It is not advisable to use a more durable building material for private housing construction. This is not economically justified, since the safety factor of the material exceeds the load from the building. Reinforcement with a diameter of 12-16 mm of class A400 is placed in each hole.

Laying a pile foundation with a monolithic grillage

For the work you will need the following tools and materials:

• bayonet and picking shovel;
• scrap;
• stakes;
• rope;
• wooden boards or chipboard sheets for formwork;
• set of steel screw piles;
• fittings for reinforcing piles and grillage;
• metal pipes;
• concrete solution;
• plumb line;
• level or hydraulic level;
• roulette;
• specialty chemicals;
• foam boards;
• sand;
• crushed stone;
• bitumen mastic.

Centerboards cannot be fixed to the grillage itself

The construction of a pile foundation with a monolithic grillage is carried out according to the following algorithm:

• cleaning and leveling the base;
• drilling holes in designated locations of the required depth and size for piles;
• compacting the soil and creating a cushion of medium or coarse sand 30-50 cm thick at the bottom of the holes;
• installation of screw or bored piles according to the work technology;
• preparing a sand cushion for a monolithic grillage;
• formwork installation;
• a frame made of reinforcement is lowered into the pit, consisting of at least 4 rods, the length of which is selected taking into account the height of the strapping;
• performing concrete pouring;
• creation of wooden formwork for a monolithic grillage;
• after the concrete has hardened, the reinforcement frame for the grillage is assembled;
• installation of formwork for strapping;
• concreting the grillage;
• removing the formwork after the concrete has gained the required strength;
• performing waterproofing.

A high grillage rises above 15 cm above the ground

Helpful advice! If an underground space is formed, it is better to cover it with a decorative base or fence.

The grillage is reinforced using rods of class A400, which can be joined into a frame by welding or tied using binding wire. The second option is more labor-intensive, but reliable. When laying the frame, you should leave a distance from the rod to the formwork of at least 3 cm - to create a protective layer of concrete, which will prevent the formation of corrosion.

Helpful advice! At the corners of the building, reinforcement bars must be tied with wire.

Creation of a monolithic foundation grillage on piles

Before installing the grillage, a layer of waterproofing should be laid on the piles. This is necessary in order to eliminate the possibility of the soles of the elements getting wet. Roofing felt, polyethylene films or membranes can be used as a waterproofing material. If a cushion of fine gravel is provided under the base of the grillage, which may compromise the integrity of the waterproofing layer, a concrete footing should be provided.

The process of constructing a monolithic grillage is labor-intensive and expensive

The next stage is the installation of formwork for the foundation on concrete piles. To do this, markings are carried out in increments of 0.5-0.8 m with driving in pegs with a cross-section of 5x5 cm along the entire perimeter of the building. Next, horizontal wooden boards are laid, in which holes for the piles are pre-cut.

Vertical formwork elements are installed and nailed to horizontal boards. For formwork, it is recommended to use durable wooden boards or chipboard sheets. The inside of the prefabricated formwork should be covered with plastic film. The dimensions of the formwork must exceed the height of the future grillage by at least 5 cm.

Helpful advice! In the case of a low grillage, you can use permanent formwork, which will subsequently become additional thermal insulation for the walls of the premises.

Grillage reinforcement: step-by-step instructions

The next step in constructing a pile foundation grillage is the creation of a reinforcement frame, which must subsequently be completely recessed into concrete on all sides. To do this, it is necessary to lay wooden blocks of any width on the bottom of the formwork in the transverse direction, but with the same thickness of 30-50 mm. The bottom row of reinforcement bars is laid on them, which must be tied together so as to ensure the same distance between the rods.

Instructions for knitting reinforcement

The upper chord of the reinforcement cage must be suspended from the transverse beams that connect the formwork posts. Then you should tie the lower and upper belts together.

For reinforcement of monolithic tape, class A400 reinforcement is usually used. The number of rods is calculated based on the ratio of the cross-sectional area of ​​the horizontal lintel to the sum of the cross-sections of all rods, which is 1000:1. The following calculation procedure is performed:

• it is necessary to multiply the width by the height of the grillage, dividing the result by 1000;
• the resulting value must be divided by the cross-sectional area of ​​one rod.

The result obtained is the minimum number of bars required for reinforcement.

Helpful advice! The distance between rows of reinforcement should not exceed 150 mm.

Installation of additional elements and concreting the grillage

Before pouring concrete on a horizontal lintel, special pipes should be laid through which utilities will pass, such as water supply, heating, sewerage and communications. Ventilation holes should also be provided in the base.

Grillages can vary both in design, location and material

Important! This stage should not be neglected, since then the integrity of the grillage will have to be compromised.

To create a monolithic grillage, it is recommended to use concrete grades M300 and M500. When filling the formwork with concrete mixture, you should use a vibrating machine that can shake the concrete to eliminate the possibility of cavities, which will increase the strength characteristics of the concrete.

Two hours after pouring the concrete, it is recommended to cover it with film. If it is hot outside, it is periodically necessary to remove the film and moisten the concrete with water so that cracks do not form on its surface. Complete hardening of the structure will not occur earlier than in a week, which depends on the ambient temperature.

If the outside temperature reaches 20 degrees, the formwork can be removed after 4 days, since the concrete base will gain more than half its strength. If the temperature does not rise above 10 degrees, the formwork does not need to be touched for 14 days. When the air temperature is below 10 degrees. it is necessary to provide additional heating and organize insulation of the foundation. After the concrete has completely hardened, you can begin to create a waterproofing layer using bitumen mastic.

The prefabricated grillage can be made of metal or wood

Calculation of a bored foundation with a grillage

Before you start installing a foundation made of bored piles with a grillage, you need to calculate everything very carefully. Only the correct parameters and numbers will allow you to achieve the desired result and ensure strength, reliability, and long service life of the future building.

Calculation of bored piles

In the process of calculating piles, the following values ​​are determined: length of supports, diameter, number and layout. The diameter is usually taken in the range of 15-40 centimeters, a section of 20 centimeters is considered optimal. For more accurate calculations, you can use special tables indicating the diameter of the supports and their load-bearing capacity, which is relevant for different materials.

• l – optimal distance between supports
• P – indicator of the load-bearing capacity of the pile
• Q – load per linear meter of the base (the mass of the building is divided by the length of the grillage itself)

So, for a house weighing 50 tons, which is built on clay soil on supports with a cross-section of 20 centimeters, you need 27 supports (50,000 kilograms / 1884 kilograms = 26.53). Also remember the rule: the distance between the piles must be equal to at least three of their diameters. That is, if piles with a cross-section of 20 centimeters are taken, the distance between them should be at least 60 centimeters. For dense soil, the figure is increased by a quarter.

It is also advisable to install supports under heavy elements (stove, fireplace, boiler room, etc.). The depth of drilling depends on the depth at which load-bearing soils are found and on the level of soil freezing in the region. Usually they drill to a depth of 1.5-3 meters.

Calculation of a monolithic grillage

When a bored foundation with a grillage is created, the technology involves an accurate calculation of the monolithic frame itself: its height and width. To get the width value, use the formula:

• B – belt width
• M – weight of the building
• L – grillage length indicator
• R – exact value of the bearing capacity of the top layer of soil

The grillage width is usually 35-50 centimeters. For a medium-sized cottage, a width of 40 centimeters and a height of 30-50 centimeters will be sufficient, which depends on the intended depth.

Reinforcement calculation

• The number of rods in the longitudinal belt is at least 4 with a distance of up to 10 centimeters
• The pitch between the transverse jumpers in the longitudinal belt is up to 30 centimeters, between the connecting vertical ones – up to 40 centimeters
• The thickness of the protective layer of concrete is at least 5 centimeters on all sides to avoid metal corrosion.

To understand how to calculate the amount of reinforcement, you can take a simple example. So, if a monolithic grillage with a perimeter of 9x7 meters is created, and the conventional dimensions of the strapping are 40x40 centimeters, two longitudinal belts with three rods with a diameter of 14 millimeters each are used for reinforcement. The pitch between the rods is 10 centimeters; the belts are connected by jumpers made of rods with a diameter of 11 millimeters with a pitch of 20 centimeters.

• Determination of the total length of the rods in the upper longitudinal belt: 9+9+7+7 = 32 meters (perimeter of the grillage), 32x3 = 96 (length of three rods) 96 x 2 = 192 (length needed for two belts).
• Jumpers are used with a length of 30 centimeters, located at a distance of 20 centimeters. For both grillage belts you need: 2x(32/0.2) = 320 pieces of 30 centimeters each = 96 meters.
• The length of the vertical jumpers connecting both frames. Their length is the same, 30 centimeters, for a square grillage = 96 meters.

Insulation of a pile foundation

Despite the fact that the modern market for construction products offers a huge selection of materials whose function is to insulate foundations, people still make a choice in favor of time-tested means.

In particular, due to the low cost and quality of materials. An example of this is the most commonly used polystyrene foam; it can easily be used to insulate the foundation using an adhesive base.

But polystyrene foam is not suitable for insulation in conditions of high humidity; in such conditions, insulation is carried out with waterproof materials.

Each insulation material has a number of its own advantages and disadvantages, so when choosing the method by which insulation will be carried out, you need to take into account many factors, ranging from price to the durability of the material.

The following insulation methods are also very often used:

filling the grooves of the beam grillage with expanded clay;

facing the grillage with extruded polystyrene foam.

Insulation of a foundation with a monolithic grillage is carried out only from the outside of the house. The sides in this case act as a base.

Here are the main stages in insulation:

the sides of the grillage are covered with a layer of bitumen, it protects them from moisture;

blocks of expanded polystyrene are mounted directly to the bitumen mass, before it hardens;

Using polyurethane foam, all gaps between the foam panels are sealed. If the insulation has a tongue-and-groove clutch system, this significantly speeds up and facilitates the process;

a reinforcing mesh is laid on top of the heat-insulating layer, which is then covered with a plaster layer;

After all these stages are completed, the facade is covered with a layer of waterproofing mortar and painted.

If you follow all the rules and advice, then foundation construction technology will become an easy task for you.

Production of a bored foundation with a monolithic grillage

A bored foundation with a grillage is a special design for the base of a building, which involves the presence of separately located supports connected by a single frame. The piles are laid to the required depth, which depends on the design features of the buildings and the geological conditions of the site.

Thanks to drilling wells to great depths, it is possible to significantly increase the area of ​​contact between the supports of the structure and the soil, increase friction, making the foundation capable of withstanding considerable loads.

Typically, a foundation on bored piles with a monolithic grillage is installed below the soil freezing level and wrapped in two layers of roofing material to protect the structure from soil heaving, excessive pressure, and moisture.

When arranging pile foundations, a concrete grillage plays a very important role - it unites individual supports and eliminates the risk of uneven settlement. Thanks to the grillage reinforcement, it is possible to increase the structure’s resistance to bending loads and create a single, reliable monolith.

Types of grillage, what are there?

Grillage caps differ in the nature of the introduction of support columns into the ground.

1. Drive-in: wells are drilled to a depth of one-third of the length of the pile using special construction equipment (without drilling or excavation), into which supports made of wood, steel or reinforced concrete are then inserted.
2. Drilled (drilled): wells are drilled, formwork is installed and the cavity is filled with concrete, used in the construction of small buildings.
3. Drilling: reinforced concrete supports are inserted into finished wells.
4. Screw: using special equipment (on a small scale - manually) hollow metal piles with a sharp tip and screw blades are screwed into the ground to cut the soil.

Types and purpose of grillages

The following types of foundation grillages are distinguished depending on their structure:

• Composite, which is assembled from several separate parts, is reinforced with steel reinforcement; It is erected using a construction crane and is used both for residential buildings and for light buildings such as a bathhouse or temporary summer cottage.
• A monolithic grillage made of reinforced concrete, which consists of screw piles connected at the top by a solid slab or concrete strip; it is poured on site; a pile foundation with a reinforced monolithic grillage is used in the construction of 1-2 storey permanent buildings.
• Prefabricated-monolithic - at the first stage, factory prefabricated supporting parts are introduced into the ground, which are turned into a monolith at the construction site with locks and connections.

Additional Information! A pile-grillage foundation for a house made of aerated concrete is rarely used, however, in some soil conditions of the site it is impossible to do without it.

The location relative to the ground level divides the grillage - foundations into three types:

1. low - planted in the ground on a gravel-sand cushion;
2. ground – displayed flush with ground level;
3. high - built above the surface on high supports and saves the structure from high-lying groundwater.

The first two types of grillages are quite economical, while the third requires digging a pit, installing a drainage system and formwork, which makes its construction more expensive.

Bored pile installation technology: step-by-step instructions

Before starting work, the soils are carefully studied, all important calculations are performed, material is purchased, all stages are thought through, and only after that they begin to construct a bored foundation with a concrete grillage.

Preparing the area and marking the future foundation

First, you need to clear the area of ​​debris and anything unnecessary, remove the fertile layer of soil, and carry out cast-offs so that the markings do not interfere with the excavation work. The cast-off is made of wood, installed with posts and lintels around the perimeter of the structure at a certain distance so that wells can be drilled freely.

Nails are attached to the cast-off boards, and a cord is tied to them, which marks the axes of the future building. All lines must be strictly parallel and perpendicular; evenness is checked with a level.

Well drilling

Wells are drilled according to markings to a depth calculated using the formula. The diameter of the well corresponds to the diameter of the supports. When the drill reaches the required depth, it is pulled out, loose soil is removed from the well, the supporting part is compacted, and a sand cushion is covered with a layer of 30-50 centimeters.

Installation of casing pipes

Casing pipes do not allow the walls of the well to crumble and guarantee the safety of work. On loams and dense clay soils you can do without pipes, but if the work is carried out in swampy areas or all stages are carried out with your own hands, it is better to install pipes. It is easier to create reinforcement inside them, which is determined by the load-bearing capacity of the pile.

Reinforcement

To create a reinforcement frame, corrugated rods of the required diameter are used. The technology is simple: 4-6 rods are installed inside the support around a circumference 3-5 centimeters smaller than the pipe. The rods are knitted with wire and secured with clamps. The finished reinforced frame is mounted in a well inside the pipe and buried in the soil (for this, the length of the rods should be 30 centimeters greater than the length of the pipes).

Pouring concrete mixture

For pouring, use concrete with a minimum strength of class B12.5, optimally B15. For filling, a funnel is installed at the wellhead, which helps prevent the appearance of voids. The mixture is poured slowly, in layers 50 centimeters thick, compacting for 10 minutes. After 5-7 days, you can begin installing the grillage.

Errors allowed

1. Violation of the rigid connection “grillage - pile”. Caused by:
   lack of ligation of grillage and pile reinforcement;
2. there is no removal of reinforcement from the pile, embedment is carried out only through the mass of concrete;
3. The pouring of the pile and grillage was carried out with a break of several days, and there was also no connection between the reinforcement.
4. When making a high grillage, there is no air gap. Caused by:
   incorrect initial calculation;
5. errors in markup;
6. weak marshy soil, which caused the piles to sink;
7. excess of the mass of the superstructure over the bearing capacity of the foundation.
8. Incorrect calculations during design. Called:
   elementary arithmetic errors at the design stage;
9. incorrectly entered numerical values ​​in drawings;
10. use of erroneous or incorrect data on the technical characteristics of the materials used;
11. incorrect assessment of the mass of the entire structure.
12. Insufficient foundation depth. Caused by:
    errors in calculations;
13. incorrect assessment of the depth of soil freezing;
14. incorrect assessment of the depth of groundwater;
15. errors during the preparation and installation of the foundation, including elementary carelessness on the part of the performers.

Turnkey foundation cost.

Due to the difficulties of independently implementing the idea of ​​arranging a foundation with a grillage, an important point is the price for the work of the team and the rental of special equipment. Another nuance that affects the final estimate is soil testing and design calculations. In both cases, a balanced approach is required from the customer. On the one hand, he cannot hire non-specialists, since the durability and reliability of the structure is at stake. But there is no need to pay an inflated price either. The optimal solution is to consult friends who have already gone through a similar stage of construction.

The construction price in the Moscow region averages 4,400 – 6,000 rubles per 1 linear meter. The total amount is affected by the number of piles, their quality and size, the total amount of materials, and installation technology.

Construction cost per linear meter.

Well drilling

The required number of piles that will be used is calculated. Their number can be calculated based on the weight of the future structure and the total load. The size of internal piles will be calculated based on the load created by the wall partitions, floor and roof.

When making calculations, you should take into account the fact that a hand drill has a maximum diameter of three hundred millimeters. It is sold at any construction market or store

The length of the drill rod is adjustable, which allows you to drill wells up to five meters. The arrangement of the cutting blades of the drill is designed so that during operation the applied force is insignificant. The industry began to produce hand drills that could significantly widen the lower area of ​​the well. In addition, during drilling, a support for the pile is formed, which in turn helps to save on concrete, since the number of required piles is reduced.

Foundation construction process

Such a base is quite easy to confuse with a combined pile-slab base. In fact, they have the same scheme and differ only in nuances, since there are several modifications of such bases, but the cost of different options is practically the same.

Before moving on to the procedure, you will need to carefully consider the nuances of creating each type of base - pile and slab. Their technologies have quite significant differences that will need to be taken into account during operation. The work itself is quite labor-intensive and complex, especially when it comes to the construction of multi-story buildings. But if a low-rise building is being built, most actions can be performed without the involvement of specialists.

The construction process consists of the following stages:

1. Preparatory work.
2. Installation of piles.
3. Installation of the stove.

Preparatory work

Preparation is an extremely important stage of work.
The initial steps are the same for any foundation. The area is cleared, planned, marked and calculated. The soil will need to be thoroughly compacted; gravel and sand are suitable for this. Also, do not forget about creating a drainage system, preparing the area and laying utilities.

The installation of the basement greatly influences the preparatory activities. If a decision has been made to develop it, you will need to excavate the soil and create a pit for the base. Reinforced concrete slabs will be installed vertically into it, which will serve as walls for the constructed basement.

Installation of piles

To install the piles, you will need to carry out additional calculations.

Methods for installing piles may differ depending on their type. For private buildings, asbestos-cement pipes are often used, which can save a lot of money. After installation, they are reinforced and filled with cement mixture.

When installing piles you will need to consider the following:

Due to the fact that the slab will be installed on top, the cuts of the piles must be located at the same level. The reinforcement in the piles is laid in excess. This will allow the two parts of the base to be firmly connected. The greater the number of supports, the greater the financial costs. It is best to install supports under load-bearing walls, at the junction of adjacent surfaces and in corners. The installation location also depends on the size and type of building being built. The interval between the supports of a pile-slab foundation. To determine the optimal distance, you will need to perform a calculation. The optimal interval is calculated based on the diameter of the piles

Carrying out the calculation is quite difficult, but extremely important, so it is better to seek help from a specialist. It will be much easier to calculate the required number of piles, knowing their approximate location.

Installation of the stove

To transport the slabs, you will need to use special equipment.

The slabs can be mounted with different depths, but the installation process itself is no different. The following factors must be taken into account during operation:

• The slab not only acts as a foundation, but also serves as the floor of the lower floor of the building. To ensure a higher level of waterproofing, it is better to pour a layer of clay onto the ground, then level and compact it. Then a cushion of sand and gravel is created, and foam slabs are installed on it. Such procedures will reduce the amount of heat loss, and, consequently, save on heating the house.
• When reinforcing the slab, you will need to tie the frame to the rods coming out of the piles.
• When preparing the mixture, it is necessary to use only fillers of small and medium fractions. Otherwise, significant complications may arise when compacting the frame.
• Concrete should be poured completely over the entire area of ​​the base. It is not recommended to delay installation of the slab until the next day, as seams and holes may form.

This completes the process of creating a pile-slab base. The following video will help you learn all the features and nuances of such work.

The pile-slab foundation has a number of features. Its use is necessary when constructing multi-story buildings or on poor-quality soil. The creation process itself is quite complicated, but if you follow the instructions, the work can be done on your own.

Foundation technology

To begin with, it should be noted that houses on a combined pile foundation must be built by professionals. It is simply impossible to independently equip such a technologically complex foundation. All work on the construction of the foundation is carried out in strict accordance with regulatory documents for construction, as well as in a clear sequence.

The entire process of constructing a combined foundation can be divided into several stages:

1. Preparing the area. The first thing you need to do before starting any construction work is to plan the site. To do this, any debris is removed from the territory allocated for construction, any green spaces are removed, and all holes and piles of earth are leveled. The holes can be filled with soil from the same area, and the piles must be leveled in accordance with the main surface. Then the area for installation of piles is marked. Special markings are installed directly on the ground in the places where the support will stand. The contours where the monolithic slab will pass are also marked.
2. Deepening of piles. At this stage, supports are brought to the site. The type of piles is selected depending on the nature of the building and the characteristics of the soil. Types of piles differ in the quality of the material, as well as in size. Reinforced concrete supports are considered the most durable; the size is usually selected depending on the depth of soil freezing. Then special equipment for driving piles is installed on the territory. As a rule, a piledriver and other equipment are used for this purpose. Each support is first installed directly at the point where it will be buried. Then it is leveled, after which it is driven into the ground using a hammer. There are various ways to bury supports in the ground, however, all of them involve the use of heavy equipment during such construction. After installing all the piles, they are leveled. To do this, using special equipment, the heads of the supports are cut to the zero level.
3. Pouring the monolith. After all the supports are ready, you need to start pouring the monolithic slab. For this purpose, the first step is to install the formwork. The resulting box is preliminarily equipped with waterproofing; most often in this case, roofing material is used. Then a special pillow is prepared. A layer of sand about 20 centimeters thick is poured into the box, the material is well compacted and leveled. Next, the same layer of crushed stone is poured and also leveled. The pad is then covered with a small layer of liquid concrete mortar, which will help secure the bulk materials. The thickness of the concrete should not exceed three centimeters. After this, a frame of reinforcement is constructed in the formwork, which is subsequently filled with concrete mortar. During the concrete pouring process, certain technology must be followed. For example, the solution should be poured into the box from both sides.

Expert advice:

• After the concrete solution is completely laid in the formwork, it must be leveled and compacted. This action is carried out using vibrating rammers. Next, the monolith is left to dry. Complete hardening of the concrete slab is observed 30 days after it is poured. While the concrete is drying, you need to take care of the slab. To do this, you need to cover the monolith with film and lightly moisten it several times a day.
• Caring for the surface of a monolithic slab helps prevent improper and uneven drying of the concrete solution. After the concrete has completely dried and the slab has become as strong as possible, you can begin constructing the remaining structural elements of the building.
• In some cases, USHP is used as a base - this is an insulated Swedish stove. USP is not just a concrete slab, it is the most modern and effective foundation that performs several functions at once. Such a slab includes a communications system, heating the entire area of ​​the house with heated floors, already installed sewerage systems, water supply and even marking electrical cables. USPs have a smooth surface, which allows you to lay the finished floor covering directly on the monolith.
• USP is often used in the construction of structures made of aerated concrete, frame houses, buildings made of logs and beams. The advantage of USP is that it can be erected in almost any area, regardless of the nature of the soil. The technology for constructing such a base involves various options for arranging a monolith, which makes it possible to make a base.

Grillage - what is it?

A grillage is a horizontally located element of the pile foundation of a structure (a kind of belt or cushion), which takes on the entire load of the building and, evenly distributing it, transfers it to the support columns. This is achieved by tying the piles into a complete structure. Since a grillage on a pile foundation increases the strength of the building, it is necessary to ensure sufficient rigidity for all connection points.

The advantage of such a foundation for a building is its durability, strength and the ability to build on sandy and clay soils, as well as on quicksand. In addition, due to the insignificant amount of preparatory work and the concrete mortar used, such a house foundation design is considered a less expensive option compared to other types of foundations.

To better understand what a grillage is, you need to know its classification into the following types:

• at the place of arrangement;
• on the building materials used;
• by constructive solution.

By location:

Shallow. This is the optimal type of construction to obtain reliable stability. Since the base of the belt is located directly on the ground, the entire future load from the structure will be distributed not only between the piles, but also over the entire foundation.

Shallow grillage

Sectional view of a recessed grillage

Hanging. The distance between the ground and the structure is 100 mm or more. In this case, the grillage is made of wood or steel to prevent the building from coming into contact with soil moisture. To prevent the structure from sagging under the weight of the structure, piles or pillars of impressive size are used.

Hanging type

By design:

A monolithic grillage is an integral reinforced concrete structure created at the site of the foundation. The most common type is the strip type, but a slab grillage is indispensable when building a structure on unstable soils. Its construction is associated with significant labor costs, frequent reinforcement and high cost.

This is what a solid reinforced concrete belt looks like

A prefabricated metal structure, the elements of which are fixed by welding. The disadvantage is the complexity of installation and insufficient rigidity and strength of the connections. The prefabricated grillage is installed on the tops of the piles and welded to them without subsequent pouring of concrete. Pile foundations with a prefabricated grillage are well suited for non-permanent buildings, the service life of which is about 10-20 years.

Prefabricated metal structure

A prefabricated monolithic belt is a combined option and includes industrially produced elements fastened together using keyed and locking connections. After the structure is assembled, all joints are poured with concrete to form a strong single strip. Such grillages are used in the construction of multi-storey residential and office buildings, as well as factory buildings. The installation of a prefabricated monolithic belt requires large material costs, the use of special equipment and great precision during installation.

Prefabricated monolithic grillage

When understanding what a grillage foundation is, it is also worth considering the materials used in the structure.

Installation of formwork

By this time, piles should be installed on the site

It doesn’t matter what they will be - lined with brick or poured with concrete

To form the formwork, edged boards with a thickness of 2.5 cm, chipboard, OSB, plywood and any similar material are suitable.

Once the entire volume of material has been prepared, you can begin assembling the formwork

It is important to know that the height of the grillage must be at least 30 cm, and the width at the base of the tape is 10 cm greater than the width of the pile

The shape of the grillage is made in the form of a rectangle or in the form of an inverted trapezoid. It can also be made stepped, but the top should be a little wider.

Let's consider one of the most popular formwork options step by step.

1. The first thing to do is to mark the edges of the future formwork and along this line, every 50-90 cm, hammer in wooden blocks with a section of 5x5 cm. The bars must be positioned strictly vertically.

2. The bars driven into the ground must be securely connected at the top using the same bars. You can use wire for this.

Next, the bottom bar is screwed on using self-tapping screws. For this, boards 3-4 cm thick are suitable. The lower part of the entire formwork will lie on these planks.

After which the boards are placed vertically. In order for them to hold securely, they are nailed to vertical bars that were driven in at the first stage.

This completes the assembly of the formwork frame.

If you are not sure of the reliability of the structure, you can add additional stiffeners and various stops.