To ensure the stability of the buildings under construction, various types of foundations are used, including pile foundations. Such a base has proven itself when working on frozen soils, in conditions of an inclined construction site, as well as on weak soils with closely spaced groundwater. Strengthening the grillage structure with steel reinforcement allows you to form a solid foundation for the future structure. Reinforcement of the pile foundation grillage is carried out on the basis of the drawing and the results of preliminary calculations.

What is a grillage

Not all private developers are familiar with special construction terms. Among professionals, you can often hear the word "grillage". Let's consider what it is.

This is a loaded element of the pile foundation, which performs a number of important tasks:

• unites the heads of the supports with a common power circuit, reinforced with reinforcement;
• prevents the possibility of shifting the support elements from the vertical axis.

Based on the previously developed documentation and special calculations, the dimensions and design features of the grillage are determined.

A grillage is a monolithic element of the foundation of a building, connecting free-standing pillars or piles into a single system.

For bases with supporting columns, the following structures are used:

• tape. It combines the supports located under the load-bearing walls into a power circuit using a solid concrete tape;
• slab. The configuration repeats the shape of the building and combines the heads of the supports with a monolithic slab.

There are various options for grillage foundation, each of which has its own characteristics:

• monolithic. The integral structure is formed as a result of the hardening of the concrete solution, poured into the prefabricated panel formwork;
• made. It consists of industrially manufactured reinforced concrete elements supported by columns.

Despite the differences in design, all types of grillage form a solid foundation that ensures the stability of the main walls of the building. Tying the heads of pile supports located in the ground provides an increased margin of safety. This makes the spatial system more rigid and less susceptible to the influence of loads. Strengthening the pile and strip foundation with steel rods increases the service life of the building, forming a monolithic foundation.

The construction of the grillage foundation

The foundation grillage of the pile type, which is a solid reinforced concrete strip, can be located at different levels relative to the ground.

The grillage is a tape structure connecting free-standing piles to each other

For the erection of walls of buildings, various types of grillages are constructed, differing in location relative to the zero mark:

• towering. The lower plane of the power circuit is located at least 15 cm above the soil level. A high structure is being built for lightweight buildings, the construction of which is carried out on all types of soil. It is indispensable for problematic soils and requires reliable reinforcement with steel reinforcement. This is due to the presence of free space between the soil surface and the concrete edging;
• located at the level of the soil or ground grillage. It is formed on a sand and gravel cushion without sinking into the ground. The main feature of the ground structure is the contact of the concrete monolith with the soil surface with zero clearance. This design is used on stable soils that are not subject to deformation as a result of frost heaving. When the soil freezes, there is a high probability of violating the integrity of the concrete contour;
• not deeply buried. The reference plane of the concrete reinforcement rests on the crushed stone-sand bedding, located below the zero mark in the depth of the pit. Structurally, such a foundation is similar to a tape-type foundation, which is carried out on pile supports. The construction process is quite laborious and associated with significant costs. This design is used on soils with reduced bearing capacity for the construction of large buildings.

Pile foundations are constructed for the construction of lightweight buildings. The design of the foundation grillage, which is a concrete edging, ensures the stability of such buildings. The width of the tape corresponds to the thickness of the walls, and the height of the contour is no more than 0.4 m.

Also, the grillage acts as a supporting surface on which the walls of the building are erected.

What is the purpose of reinforcing the grillage of a pile foundation

The need to strengthen the foundation of the structure with the help of a reinforcing mesh is associated with the properties of the concrete composition. Concrete is susceptible to the effects of deformation causing tension and bending. As a result of such deformation processes, the destruction of the base is possible, although the material is able to perceive significant compressive loads.

Reinforcement of the pile foundation grillage with steel reinforcement strengthens the structure, increases its stability, and also has a positive effect on the durability of the structure under construction. A powerful frame, concreted in a concrete belt, increases the strength of the base, compensates for various types of loads and torques.

In order to improve the strength characteristics of the pile foundation, it is also necessary to strengthen the supporting columns. The reinforcing bars located inside the supports are combined with the grillage tape into a common power circuit.

Strengthening the pile foundation grillage with the help of reinforcement provides:

• stability of the concrete mass perceiving the reaction of frost heaving forces;
• increasing the strength characteristics of the base, which is affected by the weight of the building;
• protection of the base, which is constructed from low-strength concrete.

Using steel reinforcement to strengthen the grillage base, you can prevent the influence of negative factors.

The need to strengthen the monolithic grillage with reinforcement is due to the fact that concrete as a material has a high resistance to compressive loads, but at the same time it is characterized by low resistance to bending and tension loads.

Strengthening the pile and strip foundation - recommendations of experts

Professional builders advise using a spatial frame consisting of the following elements to perform reinforcement:

• strong horizontal rods with a helical corrugation of the surface. Reinforcing bars with the A3 marking, made by hot rolling, are used. With a diameter of 1.2–1.6 cm, they are able to compensate for an extended range of loads;
• perpendicularly located jumpers, reduced diameter. They can be made of corrugated wire with a diameter of 0.6–0.8 cm. Steel bridges encircling the longitudinal bars provide rigidity to the lattice and give it a square or triangular shape.

To form a spatial frame, along with standard reinforcement, the following can also be used:

• straight segments of steel wire of the appropriate diameter;
• finished jumpers without corrugation, having the required section after bending.

When carrying out measures to strengthen the tape base based on supporting columns, observe the following requirements:

• use at least four rods located in pairs in the upper and lower planes of the spatial frame;

Scheme of pile-grillage foundation

• when assembling, place horizontal reinforcement bars at a distance of 100–200 mm;
• observe an interval of 250–350 mm between vertically arranged connecting elements;
• ensure a guaranteed gap from the bars of the reinforcement metal structure to the concrete surface of more than 50 mm;
• securely fix the assembled frame, ensuring that it cannot be displaced when pouring concrete.

The gap between the bars and concrete allows:

• protect the frame elements from moisture ingress, which causes the corrosion process;
• correctly position the frame in concrete and evenly distribute the loads.

To ensure a stable gap, special linings made of plastic are used.

What is a drawing for?

For the correct implementation of reinforcement measures, it is necessary to develop documentation. The drawing can be developed independently or use the services of professional developers.

The drawing allows:

• determine the need for steel bars for assembly;
• make a load-bearing structure in accordance with the documentation.

Reinforcement of the Strip Foundation

A professional drawing contains the following information:

• frame dimensions;
• rod diameter;
• bar profile;
• step between wire jumpers;
• interval between power fittings;
• design features of the belt.

Based on the drawing, you can independently calculate the length of the rods in the belts and the total number of jumpers. After breaking down the applied reinforcement into assortments, it is easy to calculate the total length by summation. To order bars, you need to know their total weight. To do this, the total footage for each standard size should be multiplied by the weight of a running meter for a particular rod.

To ensure the necessary strength, instead of electric welding, use a knitting wire to connect the elements. Welding creates stress zones, and the binding wire firmly connects the bars without disturbing the metal structure. Knowing that it takes 25–30 cm to secure the two bars, it is not difficult to calculate the total need for tie wire. To do this, multiply the number of joints by the specified length.

Reinforcement of the tape grillage is carried out by means of a spatial reinforcement cage, consisting of two longitudinal belts of reinforcement

What materials and tools will be required

To perform reinforcement work, it is necessary to prepare the following materials, as well as tools:

• reinforcement, the diameter of which meets the requirements of the drawing;
• a special device that facilitates the bending of the rods;
• wire for knitting elements of a spatial frame;
• a crochet hook that speeds up the production of work;
• a grinder that allows you to cut the reinforcement into blanks.

The assembled reinforcing cage is placed inside the pre-assembled formwork on special supports and poured with concrete mortar.

Reinforcement of the pile-grillage foundation - stages of work

After the installation of the supporting columns, reinforced with reinforcement, and the installation of the formwork, the assembly of the spatial frame can begin. It is attached to the parts of the reinforcing bars protruding from the piles. Fixation is done with knitting wire.

Sequence of operations:

1. Cut the blanks with a grinder, guided by the requirements of the drawing.
2. Install the lower tier of horizontal rods on plastic supports.
3. Connect the elements of the lower belt with the help of transverse rods.
4. Fasten the special square clamps to the horizontal reinforcement.
5. Tie longitudinally located reinforcing bars of the upper tier.
6. Reinforce the corner areas of the grillage using curved rods.

It is important to securely fix the corner sections in which significant loads act. To create a solid foundation for the future building, it is important to properly reinforce the grillage that unites the piles with reinforcement. The drawing will allow you to calculate the need for material and facilitate independent work.

The pile foundation consists of vertical rods (piles) buried in the ground and serving as a support for the rest of the structure. According to the type of construction, piles are:

• flood piles, when concrete is poured into wells prepared in the ground;
• driven piles - finished reinforced concrete pillars are driven into the ground by a special machine;
• screw piles made of metal, having the shape of a screw or self-tapping screw, are simply screwed into the ground.

Of all the above, we are interested in piles of the first type - jellied. Set up in the following order:

• using a manual or mechanized drill, a hole is drilled in the ground, the depth is equal to the length of the future pile plus 15 - 20 cm on a gravel pad;
• coarse sand or fine gravel (shock-absorbing cushion) is poured into the bottom of the well and rammed;
• prepare a structure of three or four bars of reinforcement, which are interconnected by welding using short lengths and knitting wire;

• a formwork of a round or other section is arranged above the well up to the estimated height of the pile above the ground;
• the reinforcing structure is immersed in the well, and the well itself, together with the towering formwork, is poured with concrete;
• after the concrete has cured, the remnants of the reinforcement are cut off, sometimes leaving segments of small length, to which the supporting elements are attached by welding.

Strip foundation

Tape is widespread due to its strength, the ability to withstand buildings of any mass and withstand any processes occurring in the soil. It is a tape, as it were, a continuation of the outer walls of the house, directed downward. The thickness of the strip foundation in private construction is assumed to be 40 - 50 cm, it is recommended to lower the foundation into the ground below the maximum freezing depth of the soil. This is done so that heaving processes do not occur under the base.

Reinforcement of the tape foundation is made after the installation of the trench and formwork.

The structure of the skeleton consists of two tiers, each consisting of at least two veins.

Requirements for the location of reinforcement in a concrete mass:

• the distance from the outer side wall to the reinforcement should not be less than 50 - 55 mm .;
• the distance from the lower and upper planes of the array to the horizontal reinforcement should not be less than 70 - 75 mm;
• the distance between the upper and lower reinforcing layers is not less than 300 - 350 mm, but it is better to make this distance maximum;
• the distance between the jumpers: vertical 400 - 700 mm, horizontal 800 - 1400, the distance is chosen so as to ensure the immobility of the reinforcement during pouring of concrete and compacting it with vibrators and other devices.

A few tips to make it easier to assemble a reinforcing cage for a strip foundation:

• some of the vertical reinforcement is made of increased length, so that it is convenient to mount the entire skeleton on them, driven into the bottom of the trench;
• the upper horizontal reinforcement is made with a length equal to the width of the foundation, due to which they, resting against the walls of the formwork, fix the position of the entire reinforcement structure in space.

Pile with grillage

A pile foundation with a grillage is a symbiosis of strip and pile foundations. The support is piles buried below the freezing point. The number of piles is determined by their diameter and the bearing capacity of the soil. In the upper part there is a grillage - a tape with a thickness equal to or slightly greater than the diameter of the piles. The reinforcement in piles is mounted in the same way as in pile foundations, the reinforcement of the grillage is no different from the reinforcement of the tape base. The only nuance of a pile foundation with a grillage is the connection of the reinforcing cage of the piles with the grillage frame. This is done as follows:

• concrete is initially poured into reinforced wells to the level of the lower plane of the grillage tape;
• after that, a trench is arranged under the grillage (if everything is done correctly, then the plane of the bottom of the trench will coincide with the top of the concrete poured into the wells);
• the result of the work is as follows: there is a trench, from the bottom of which the ends of the reinforcing bars rise at a certain interval (continuation of the reinforcement of the piles);
• further actions completely repeat the algorithm for knitting the reinforcement of the strip foundation, only the ends of the reinforcement of the piles serve not as the basis specially driven into the bottom of the trench, but.

Tiled

Of all the types of building foundations under consideration, it is the tiled (floating) foundation that most needs a high-quality reinforcing cage. The foundation is a flat reinforced concrete product, completely repeating the contours of the building, with a thickness of only about 30 cm. Needless to say, only proper reinforcement of the foundation from slabs can guarantee the strength of the structure, its ability to withstand the weight of the building, sometimes several floors.

The slab foundation is a real find in the construction of buildings and structures on difficult soils. No matter what processes take place, no matter what local zones of heaving or subsidence of the soil are formed, if the reinforcement of the slab is carried out qualitatively, the composition of the concrete mixture is correctly determined and the pouring technology is not violated, the geometric parameters of our parallelepiped (even despite a possible slight slope) will still remain unchanged . And this guarantees the integrity of the structure, as it excludes the formation of stress zones in the supporting building structures. All stresses are assumed and extinguished by a monolithic slab.

The process of reinforcing the foundation: reinforcement is mounted after the pit is dug, sand and drainage (crushed stone) pillows are laid on its bottom, and formwork panels are installed around the perimeter. Elongated vertical reinforcement bars are driven into the bottom of the pit, on which the lower and then the upper reinforcing tiers are mounted first. By the way, it is not necessary to supply absolutely all nodes with vertical segments. Their number should only ensure the immobility of the tiers in space during the filling and compaction process.

After the reinforcement of the foundation is completed, the structure is filled with concrete along the upper edge of the formwork.

Any sane architect will tell you that the use of reinforcement inside concrete load-bearing structures is a must. Without properly installed reinforcing mesh, any concrete structure will quickly collapse, or simply become much weaker.

Moreover, reinforcement helps to increase the strength of not only foundations, but also various types of screeds, blind areas and other auxiliary elements, which, nevertheless, also need a sufficient margin of safety.

This article will consider the methods and technology of reinforcing different types of foundations with your own hands, in accordance with the requirements of the current SNiP, the accompanying schemes and the necessary calculations are given. You will also learn how to properly apply the technology of reinforcing the blind area around the house, the corners of the structures, and what equipment is needed for this.

Strip foundation reinforcement

To begin with, consider the scheme and technology of reinforcing the strip foundation of the house, as the most popular and in demand in our area. The strip foundation during the operation of the house transfers a large number of diverse loads:

• bearing load - coming from the mass of the house itself;
• dynamic load - arising from soil movements;
• negative effects of heaving - which occur due to freezing of groundwater in the upper layers of the rock, which provokes a seasonal change in soil volume.

Soils prone to heaving, in general, are the main enemy of any foundation, since in winter their volume increases, as a result of which the foundation is pushed out.

Well, in the spring, when groundwater melts, on the contrary, the volume of soil decreases, which provokes subsidence of foundations that were not built in accordance with SNiP technology.

In order for the foundation of your house to be reliably protected and successfully endure any load, you need to take its reinforcement very seriously, which will significantly increase its strength and improve its bearing capacity.

Reinforcement features

Since the entire compressive load is on the concrete of the foundation beams, and the tensile load is on the reinforcement located in it, it makes sense to reinforce only the upper and lower parts of the foundation.

For example, SNiP does not provide for reinforcement of the middle section of foundation beams, since they do not experience serious loads. In this part of the foundation, reinforcement is carried out only pointwise, through the use of clamp supports.

To create a reinforcing cage, it is necessary to use class A3 corrugated rebar, manufactured using hot-rolled technology, with a diameter of 10-15 mm. For vertical jumpers, A1 smooth reinforcement is used, with a diameter of 6-8 millimeters.

The step between vertical jumpers when reinforcing a monolithic foundation should be at least 25 cm. Knitting wire is used to connect the reinforcement. The frame must be recessed inside the concrete beams by at least 5 cm.

It is extremely important to perform the correct reinforcement for the corners of the foundation - so that the quality of the work carried out meets the standards of SNiP. SNiP does not allow it to be performed in the usual cross way, since such a connection of corners does not provide the necessary final structural strength.

Pile foundation reinforcement

The pile foundation is not so widespread, but it is also common. Reinforcing the foundation of piles has its own interesting features. Reinforcement of the pile foundation is necessary in two cases:

• when creating a grillage;
• when arranging.

Reinforcement of screw bases is not carried out, as well as driven bases, which are already reinforced and completely ready for use from the factory.

First, we turn to the reinforcement of bored piles. And let's start the analysis, performing the calculation of all the necessary materials and picking up the working equipment.

Calculation and necessary equipment

When calculating the reinforcement that will be required to reinforce bored piles, it must be performed based on the design height and diameter of the pile.

For example, let's calculate the metal or required for reinforcing the foundation of sixteen bored piles, the distance between which is conventionally 200 cm, the height of one pile is 200 cm, and the diameter is 20 cm.

To reinforce a pile 2 meters high, we need reinforcement bars 2.35 m high. 200 cm of which will go to the underground column, and 35 centimeters to the joints of the pile and grillage beams. According to the requirements of SNiP, four reinforcement bars should be used per bored string, which are connected into one frame.

Based on the above data, we perform the calculation: 4 * 2.35 = 9.4 meters of corrugated reinforcement with a diameter of 10 mm will take one bored pile. The total length of the reinforcement that will go to the foundation is: 16 * 9.4 = 150.4 meters.

It is also necessary to calculate the binding wire, or smooth fittings of small diameter, through which the rods will be connected into one frame. There are two methods of making a reinforcing cage that meet the requirements of SNiP - connections by welding, and using a knitting wire.

It is best to do it yourself with the help of a knitting wire and, since such a connection will give the frame greater strength and resistance to dynamic loads.

The reinforcing cage for the pile will be connected in three places, while one connection will take 3.14 * 20 = 62.8 cm of knitting wire, and 1.9 meters for three connections. Based on this, we calculate the total amount of necessary knitting wire: 1.9 * 16 = 30.4 meters.

If you plan to reinforce the base of the pile widening, then the amount of corrugated reinforcement must be increased by 10-15%, since additional length of the rods will be required to give the frame an L-shape.

No additional equipment is required for reinforcing bored piles; all actions are done by hand. You will only need standard equipment for the arrangement - a shovel, drill, concrete mixer, buckets, or a wheelbarrow for transporting concrete.

Features of the reinforcement process

First of all, a well is drilled under the pile, and, in the case of arranging the base of the broadening, giving it a conical shape. Further, a casing pipe is plunged into the well (there are ways to significantly save at this stage - for example, using a self-rolled roofing material as a pile casing).

To give the bored pile greater strength, it is recommended to take care of the compaction of concrete, for this special vibration machines are used, but this can be done with your own hands by bayoneting.

Reinforcement grillage

Now let's pay attention to similar works, but already related to the strengthening of the grillage. It also plays an important role in creating a stable foundation.

Calculation of the amount of materials

The calculation of the required amount of reinforcement is carried out based on the characteristics of the soil, and the loads that the load-bearing walls of the building will exert on the grillage.

For example, let's give an algorithm for correctly calculated the amount of reinforcement required for a small building with an area of ​​​​6 * 10 meters, with two internal walls.

To reinforce the beams of any foundation, including the grillage, only reinforcement with a ribbed surface should be used, since the adhesion of such rods to concrete is several times better than that of smooth reinforcement.

In seismically safe regions with normal soils, reinforcement with a diameter of 10 millimeters can be successfully used to reinforce the foundation of a house (corners and other parts of the structure).

However, on problematic soil, prone to shifts and heaving, it makes sense to use rods with a diameter of 14-16 millimeters, which will significantly increase the overall reliability of the foundation.

In normal soils, the generally accepted distance between the elements that the frame mesh has is 20 centimeters (0.2 meters). You can find out about the number of elements that the circuit will include by calculating the required amount of reinforcement: 10 / 0.2 +1 = 51 rods of 10 meters each, and 6 / 0.2 + 1 = 31 rods of 6 meters each, in total - 51 +31 = 82.

Reinforcement features

The arrangement of a pile foundation is impossible without properly performed reinforcement of the grillage beams, which is required to give it high strength characteristics.

An unreinforced grillage under the influence of external dynamic loads, due to the deformation of the soil, which produces buoyant pressure on the piles, can simply crack, as a result of which the house will immediately be in an emergency position.

The reinforcement of the blind area around the house is often neglected due to the fact that the requirements of SNiP do not provide for its mandatory implementation. However, practice shows that a properly reinforced blind area has a much longer operational life than a structure whose scheme was not reinforced.

Moreover, even if the blind area is damaged, the reinforcing mesh will help reduce damage and the integrity of the entire structure, which will allow you to repair it yourself without any problems.

The reinforcing mesh allows the blind area to endure large compressive and tensile external loads that occur due to seasonal heaving (freezing of groundwater in the upper layers of the soil, which leads to a change in its volume).

To strengthen the blind area, a reinforcing mesh with 100 * 100 * 4 cells is used, or a smaller mesh, which can be purchased at any hardware store or metal warehouse.

Additional equipment that requires reinforcement of the blind area is a grinder with 125 or 230 metal discs, it will be needed to cut the mesh into sections of the desired size. It also does not interfere with welding, which can grab the edges of the mesh, however, such equipment can be replaced with ordinary knitting wire.

After cutting the mesh into pieces 2-3 meters long, it is placed in a pre-prepared one (a well-compacted bedding sole made of fine gravel and sand is required).

It is necessary to lay the mesh not directly on the surface of the backfill sole, but place it at a height of 2-3 cm above it, so that after pouring the mesh is in the middle of the concrete blind area.

To do this, you need to put small blocks of wood under it, or crushed stone of a suitable size. For areas where the blind area wraps around the corners of the house, it is recommended to cut additional pieces of mesh and lay them in a second layer, on top of the main structure.

The reinforcement scheme can be any - you can first lay straight sections, and then cover the corners of the blind area. After laying the entire grid, the blind area is poured with concrete grades M 150 or M 250.

An example of reinforcing a strip foundation (video)

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In order for the building to serve for a long time, it is necessary to reinforce the grillage of the pile foundation in accordance with regulatory requirements. House building transfers gravity to the concrete belt, which serves to evenly distribute the load on the piles, and through them to stable soil layers. The need to reinforce a concrete monolithic grillage with reinforcement arises from the fact that concrete responds well to compressive force, but weakly resists tensile and bending loads. In the absence of a reinforcing frame, the structure may be deformed.

Why do you need a grillage

The house gives an uneven load, some of its parts weigh much more than others. It depends on the arrangement of furniture and other items.

The grillage is a structure that connects the supports into a single system. It serves to evenly distribute the load of the building and transfer it through piles (pillars) to the ground. Protects the building from uneven shrinkage.

It is made in the form of a monolithic concrete tape, which must be reinforced with a reinforcing cage, and can be made of wooden, reinforced concrete, steel products that are stacked on poles and interconnected into a single whole.

The grillage can be located at a distance above ground level, lie along the upper edge of the soil, or be buried in the soil. For the basis of a hanging structure, horizontal beams or a concrete tape can be used. For the recessed option, the installation of a monolithic concrete structure is most often used.

Reinforcement technology

Reinforcement of the tape concrete tape is performed by two rows of metal rods laid along the structure. To obtain sufficient strength, the upper and lower rows of reinforcement are fastened together by vertical and horizontal jumpers.

The rods laid along the grillage must have increased strength. They are made of hot-rolled corrugated profile of class A3, with a diameter of 13-16 mm. Sometimes fiberglass reinforcement is used, it is good because it is not subject to corrosion.

As jumpers between the longitudinal rows are used:

• Rectangular reinforcement, curved in the form of clamps, made of class A smooth rods, with a section of 8-10 mm. Such jumpers are more reliable and have a long service life due to a smaller number of welded joints. In terms of labor intensity, this type of reinforcement is more complex and lengthy.
• Separate steel bars are welded to the top and bottom rows. The rods must be made of the same material as the longitudinal piping. Welded seams do not have sufficient strength, subject to corrosion. It is easier and faster to do this work than in the first case.

In the longitudinal rows, the rods are laid at a distance of 100 mm from each other, there should be at least 3-4 rows of rods in each belt. Transverse jumpers of longitudinal reinforcement are installed in increments of 200-300 mm. Vertical bars are fixed at a distance of at least 400 mm from each other.

At the bottom of the grillage leave a place in order to pour the concrete solution. To do this, steel reinforcement bars are raised above the formwork, substituting mushroom-shaped plastic stands under them.

Be sure to place a layer of concrete between the extreme contours of the metal frame, at least 50 mm thick. If its thickness is less, the rods will corrode, and the structure itself will be unable to evenly redistribute the bearing load.

Calculation of the base with a grillage

In order to correctly perform all calculations, it is necessary to take into account the characteristics of the soil, the proximity of groundwater and the load from furnished housing construction, taking into account the maximum gravity. It is better to show all calculations, schemes to specialists so that they check their correctness.

Based on the data obtained, the required number of piles and the depth of their penetration are calculated. The support should be deepened below the freezing point of the soil by 20 cm. Piles or poles are located at each corner, at the intersection of load-bearing walls with lintels, under the heaviest structures of the house (under columns, fireplace). The remaining supports are installed at a certain distance from each other.

After installing the piles, the grillage is mounted, if it is arranged in the form of a monolithic concrete tape, it is imperative to reinforce it with reinforcement.

Calculation of the amount of reinforcement

As an example, a monolithic concrete grillage 8 m long, 6 m wide, 400 x 400 mm thick is presented. For reinforcement, you will need two longitudinal belts of 3 rods each. You will need metal rods with a section of 14 mm class A3. The distance between them should be 100 mm, taking into account the fact that a layer of concrete occupies 50 mm on each side.

For the installation of jumpers, you will need rods with a cross section of 11 mm, class A1. Install them at a distance of 200 mm from each other.

Calculation formula:

1. Calculate the length of the rods in the upper longitudinal row. Determine the length of the entire grillage. To do this, add up the length of all four of its sides: (8 * 2) + (6 * 2) \u003d 16 +12 \u003d 28 m. Since three rods are used in a row, the resulting number is multiplied by three: 28 m * 3 pcs. = 84 m. Since two rows need to be laid, the resulting value is multiplied by two: 84 * 2 = 168 m of reinforcement will be needed to mount two longitudinal rows.
2. Jumpers are calculated for both grillage circuits. They are placed at a distance of 200 mm from each other. The length of the jumpers will be 300 mm. Calculate the quantity according to the formula: (30 / 0.2) * 2 = 300 pcs. Calculate the length of metal rods: 300 * 0.3 = 90 m.

In a grillage, in which the thickness is the same on all sides, you will need the same number of vertical jumpers as transverse ones.

It will take 168 m of A3 class metal rods and 180 m of A2 class rods.

Stronger connections are obtained if the reinforcement is fastened together with wire, and not by welding. About 40 cm of wire is consumed for each connection. Its quantity is determined by the formula: (30 / 0.2) * 4 \u003d 600 pcs. 0.4 m = 240 m.

Installation of a monolithic grillage

After installing the piles, they begin to install the grillage. His device includes:

• formwork installation;
• laying reinforcement according to design indicators;
• filling the form with concrete mortar;
• formwork dismantling;
• waterproofing work.

The design of the formwork depends on how the grillage is located above ground level.

Formwork installation

The strength and appearance of the grillage will depend on the correct installation of the formwork. The removable form is most often assembled from boards, sometimes plywood is used.

Be sure to control the vertical level of the installation of the side walls. The corners should be set to 90 degrees unless otherwise specified in the project. The walls are reinforced with supports so that the concrete solution does not destroy the formwork.

If the grillage is located above ground level, it is necessary to calculate the load from the reinforcement and concrete mortar on the bottom wall of the form. If the bottom falls out, work will need to start over.

After mounting the formwork, a layer of sand is poured into it, 150 mm thick. Wet it, tamp it well. Lay waterproofing material.

Reinforcement

Reinforcement of hanging grillages is performed with metal rods. Fiberglass reinforcement, as experience shows, is good in cases where it is based on the soil. The type of reinforcement and the type of beams for the grillage device are determined at the design stage of the house.

After cutting the supports to the desired size, reinforcement will protrude from them. It will be used as a connecting element between the grillage and the support.

Before performing reinforcement, a drawing of the location of metal rods is drawn. All work is carried out, focusing on this scheme. If the reinforcement is not laid correctly, the structure may not withstand the load and deform.

Metal rods, interconnected by 3-4 pieces with wire, are lowered into the formwork. The reinforcement should not touch the edges of the wooden form under the concrete, so that later it turns out that its edges protrude from the concrete base.

In order for the space under the floor of the house to be ventilated, air is left in the structure by inserting pipes with a diameter of 100 mm into the formwork.

After installing the metal frame, all construction debris is removed from the formwork using an industrial vacuum cleaner with high power.

Before pouring the foundation, you need to clean the future grillage from water and dirt. When weather conditions do not allow pumping water near the foundation, a small hole is dug below its level with a bevel from the base of the house, into which water will drain.

pouring concrete

They check the geometry and reliability of the formwork and the reinforced frame, so that the structure does not fall apart during the filling with concrete.

Prepare cement mortar. It should be homogeneous, without lumps. The mortar is mixed at the construction site with a mixer or ordered from the factory in a concrete mixer.

After the concrete has hardened, the formwork is dismantled, sand is removed from under the grillage. You can disassemble the form no earlier than the concrete base is completely dry.

Waterproofing

A hanging grillage can be isolated from moisture by coating the structure with bituminous mastics.

When installing a buried concrete tape and before pouring concrete, a roofing material is laid on the bottom of the formwork, and after dismantling the formwork, the entire grillage is covered with roll insulation.

Grill reinforcement rules

By adhering to these rules, you can avoid many mistakes when building a grillage:

• reinforcing cage and formwork are set strictly according to the level;
• the piles cut off the upper part so that all the heads are in a horizontal plane;
• when mounting a metal frame, jumpers are installed at a distance of 200-400 mm from each other;
• corner elements are connected with bent L- and U-shaped elements;
• the cross section of the support must be at least 300 mm, the number of rods in the longitudinal belt is 3 or more, the reinforcement allowance for the grillage must be 50 cm or more;
• welded joints are less durable than wire.

You can not save on the quality and quantity of metal rods.

You can learn more about how to reinforce a pile-grillage foundation from specialized books or videos:

Reinforcement of a monolithic-concrete grillage is an obligatory technological process. Subject to all norms and reinforcement technology, the building will last more than half a century.

No modern house can now be imagined without a foundation. It is the foundation that collects all the loads from the supporting structures and transfers them to the soil. There are different types of foundations.

In some cases, it is appropriate to create strip monolithic foundations, while in others, one-piece monolithic structures are used. We will now talk about the features of the pile foundation, as well as such an important process as the reinforcement of all the supporting structures of the foundation.

Features and design of the pile foundation

A pile foundation is one of the types of load-bearing supporting structures, on which the rest of the structure is then mounted.

Just like other foundations, this type of foundation is designed and built using SNIP and other regulatory documentation. However, the drawing, calculation and type of specific elements will be slightly different from the tape or solid one, since its tasks are slightly different.

Unlike tape bearing structures, in pile foundations, piles are the bearing elements and the main stress transmitters.

They are great for use when you need to mount a house on soft soils. In such cases, the large sole of the tape foundation models is too expensive, but the creation of spot piles is considered more appropriate.

When constructing such a structure, piles of bored, driven and several other manufacturing technologies are used. Their calculation and rationing is regulated by the appropriate SNIP.

It is forbidden to create such important elements of the future structure without taking into account regulatory documentation, as this can lead to rather unpleasant consequences. Moreover, it does not matter what type of structure you have to build, in any case, SNIP will be a priority document.

In addition to a pile foundation of several dozen elements, not a single pile foundation design can do without a grillage. It should be understood that the type of pile foundation provides for the installation of piles directly at a distance of about 2-4 meters from each other.

The specific distance regulates the drawing, SNIP, type of foundation and a few more parameters. But in any case, it will be quite impressive.

To assemble this entire structure together, they use the creation of a grillage tying belt or slab. Moreover, it does not matter whether a grillage is used for tying bored or driven piles. In any case, its presence is simply necessary.

The grillage itself is a consistent and rather impressive part of the pile foundation; it can consist of a large number of beams or a monolithic slab.

It is on the structure of the grillage that all the main load from the supporting structures of the house falls, and he, in turn, transfers it to the piles, which put pressure on the ground and distribute the load over the soil.

The pile foundation is characterized by the use of different types of piles (bored, driven) and different materials. In this case, we consider only as the most durable, reliable and in need of reinforcement.

Reinforcing piles and directly the entire pile foundation is an absolutely necessary process. Without reinforcement, concrete, although it performs its functions, is not so good.

The fact is that concrete itself is a fairly strong material, but any SNIP, GOST or the results of official studies indicate that, for all its strength, it does not work well in bending. Namely, bending loads put pressure on the structure of the grillage pile foundation.

If all these structures are not reinforced, then there is a high risk of their destruction or serious damage. In this case, the whole house will have to be recognized as emergency, since the foundation is perhaps the most important part of it.

For the implementation of high-quality reinforcement, a specific calculation is used. It is also regulated by the current design drawing, as well as its type and regulatory documentation, which will give you all the additional information (SNIP, GOST, reference books, etc.).

For reinforcement, welded reinforcing cages are used in the form of a grid with a certain step. The specific type of metal or, its length and all other parameters determine the design calculation. The type of reinforcement section determines how the welded mesh will be assembled.

Types and differences of grillage foundations

As we mentioned above, there are several varieties of grillage-type foundations, as well as grillage and pile structures. All of them are of rather serious importance not only due to the features of their design, but also due to how the reinforcing welded mesh will be used to reinforce them.

It is quite obvious that the tape grillage in its shape, dimensions and purpose differs from the solid one. This means that the welded mesh for reinforcement will be different for them.

Foundations of this type start from piles. Piles can be assembled and mounted according to:

• bored technology;
• Driving technology.

The bored technology of arrangement is characterized by the creation of piles with a powerful bottom cushion. They are formed according to the technology of immersing special tools into the ground and its displacement, and then laying the reinforcing mesh and concreting the entire structure.

Calculation of grillage mesh reinforcement

Now let's move on to the most important point - the calculation of the reinforcing mesh (framework). The welded mesh for the grillage will differ primarily depending on its type.

The use of bored, driven or other types of piles will be of secondary importance, since in this case the piles are only required to release connecting reinforcing pins to the outside, to which the grid of the grillage will be attached. But no more.

The calculation is performed according to the drawing of a specific type of grillage. So, a linear grillage has the shape of a large beam. He ties all the piles, forming a kind of belt. According to the same scheme, columns are tied in load-bearing frame structures.

The lower part of the grid will be assembled from thicker reinforcement with a diameter of 20 mm or more. The upper one will have a cross section of 8-15 millimeters.

Since the main loads on the surface bending will put pressure on the grillage tape only at the points of contact with the piles, serious reinforcement should be done in the sections of the tape under the piles.

Moreover, it is enough just to stretch the reinforcement by 1.5-2 meters from the center of the pile along the tape in both directions. In other places, it is recommended to make such powerful structures of the upper grid, but not at all necessary.

The welded mesh-frame in this case is calculated quite easily. Take into account the width of the tape and its height. The reinforcement of the lower level is laid in increments of 8-10 cm. As a rule, at least 4 rods go to the lower grid of one of the grillage tapes. On the top can go from 6 rods.

This calculation applies to tapes 25 centimeters wide. If the tape is much wider, then the reinforcement will have to be spent on it more. Also, the upper and lower nets are tied and fastened to each other with resistant clamps made of durable reinforcement. This should also be taken into account.

Thus, having calculated the length and width of the grillage tapes, as well as creating a drawing of its grid, you can perform a full calculation of reinforcement, find out the amount of material needed, its cost and a bunch of other useful points.

For a solid grillage, since it is, in fact, an enlarged monolithic floor slab, the welded mesh will already be a little different. First, it will cover the entire area of ​​​​the house. Secondly, it must be very durable and reliable.

Here, in increments of 20-25 cm, it is necessary to lay reinforcement with a minimum diameter of 20-25 mm. The rebar is laid crosswise to create an extremely strong foundation.

But the upper grid has interesting features. It is not always necessary to mount it over the entire area. This is due to the fact that the lower reinforcement mesh dampens almost all loads.

Any upper mesh must dampen the bending loads that come from the interaction of load-bearing structures and the upper elements of the building. And this means that it needs to be installed only near the load-bearing elements that will be placed on top or the load-bearing elements that support it.

In frame monolithic houses, the upper reinforcing mesh of the floors covers only areas of 2 × 2 or 3 × 3 square meters, with a center in each supporting column. All other places are either supplied with a safety net made of thin reinforcement, or remain without it at all.

If you calculate the dimensions of a solid grillage, as well as its usable area, you can find out all the information you need in the same way.

Grill reinforcement technology

It is quite easy to describe the reinforcement technology itself, since it is, in fact, almost identical in all cases.

Stages of work:

1. We assemble the formwork, monitor its strength and reliability.
2. We collect the lower frame of the reinforcing mesh.
3. We mount the clamps supporting the racks and other elements.
4. We collect the top in the right places.

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