Foundation with basement
Dimensions of the location of reinforcement in the foundation. Typical strip foundation reinforcement schemes

Dimensions of the location of reinforcement in the foundation. Typical strip foundation reinforcement schemes

Any building cannot do without a reliable and strong foundation. Construction of the foundation is the most important and time-consuming stage. But in this case, all rules and requirements for strengthening the foundation must be observed. For this purpose, a strip foundation is erected, which can make the foundation of the structure strong and reliable. It is worth considering in more detail the features of the strip foundation, as well as the technology for reinforcing the structure.

Peculiarities

The strip foundation is a monolithic concrete strip without breaks at doorways, which becomes the basis for the construction of all walls and partitions of the structure. The basis of the strip structure is a concrete mortar, which is made from M250 cement, water, and sand mixture. To strengthen it, a reinforcement frame is used, made of metal rods of different diameters. The tape goes deep into the soil a certain distance, while at the same time protruding above the surface. But the strip foundation is subject to serious loads (groundwater movement, massive structure).

In any situation, you need to be prepared for the fact that various negative influences on structures can affect the condition of the foundation. Therefore, if the reinforcement is not done correctly, at the first slightest threat the foundation may collapse, which will lead to the destruction of the entire building.

Reinforcement has the following advantages:

prevents soil subsidence under the building;
has a positive effect on the soundproofing qualities of the foundation;
increases the stability of the foundation to sudden changes in temperature conditions.

Requirements

Calculations of reinforcing materials and reinforcement schemes are carried out in accordance with the rules of the functioning SNiPA 52-01-2003. The certificate has specific rules and requirements that must be met when reinforcing strip foundations. The most important indicators of the strength of concrete structures are the coefficients of resistance to compression, tension and transverse fracture. Depending on the established standardized indicators of concrete, a specific brand and group is selected. When reinforcing a strip foundation, the type and controlled quality indicators of the reinforcing material are determined. According to GOST, the use of hot-rolled construction reinforcement of a repeating profile is allowed. The reinforcement group is selected depending on the yield strength at extreme loads; it must have ductility, resistance to rust and low temperature indicators.

Kinds

To reinforce the strip foundation, two types of rods are used. For axial ones that carry a key load, class AII or III is required. In this case, the profile should be ribbed, because it has better adhesion to the concrete solution, and also transfers the load in accordance with the norm. For superstructural lintels, cheaper reinforcement is used: smooth class AI, the thickness of which can be 6–8 millimeters. Lately, fiberglass reinforcement has become in great demand, because it has better strength properties and long service life.

Most designers do not recommend using it for residential foundations. According to the rules, these must be reinforced concrete structures. The features of such building materials have long been known. Specialized reinforcing profiles have been developed that help ensure that concrete and metal are combined into an integral structure. How concrete will behave with fiberglass, how reliably this reinforcement will be connected to the concrete mixture, and whether this pair will successfully cope with various loads - all this is little known and practically untested. If you want to experiment, you can use fiberglass or reinforced concrete reinforcement.

Calculation

The consumption of reinforcement must be carried out at the stage of planning the foundation drawings, in order to know with accuracy in the future how much building material will be required. It is worth familiarizing yourself with how to calculate the amount of reinforcement for a shallow foundation 70 cm high and 40 cm wide. First, you need to establish the appearance of the metal frame. It will be made of upper and lower reinforced belts, each with 3 reinforcing rods. The gap between the rods will be 10 cm, and you also need to add another 10 cm for a protective concrete layer. The connection will be made by welding sections of reinforcement of identical parameters in increments of 30 cm. The diameter of the reinforcement product is 12 mm, group A3.

Calculation of the required amount of reinforcement is carried out as follows:

to determine the consumption of rods on the axial belt, you need to calculate the perimeter of the foundation. You should take a symbolic room with a perimeter of 50 m. Since there are 3 rods in two armored belts (6 pieces in total), the consumption will be: 50x6 = 300 meters;
Now you need to calculate how many connections are required to join the belts. To do this, it is necessary to divide the total perimeter by the step between the jumpers: 50: 0.3 = 167 pieces;
observing a certain thickness of the enclosing concrete layer (about 5 cm), the size of the perpendicular lintel will be 60 cm, and the axial lintel - 30 cm. The number of separate types of lintels per connection is 2 pieces;
you need to calculate the consumption of rods for axial jumpers: 167x0.6x2=200.4 m;
consumption of products for perpendicular jumpers: 167x0.3x2=100.2 m.

As a result, the calculation of reinforcing materials showed that the total amount to be consumed would be 600.6 m. But this number is not final; it is necessary to purchase products with a reserve (10–15%), since it will be necessary to strengthen the foundation in corner areas.

Scheme

The constant movement of soil puts serious pressure on the strip foundation. In order for it to firmly withstand such loads, and also eliminate the sources of crack formation at the planning stage, experts recommend taking care of the correctly chosen reinforcement scheme. The foundation reinforcement scheme is a specific arrangement of axial and perpendicular rods, which are assembled into a single structure.

SNiP No. 52-01-2003 clearly discusses how reinforcing materials are laid in the foundation, with what steps in different directions.

It is worth considering the following rules from this document:

the step of laying the rods depends on the diameter of the reinforcement product, the dimensions of the crushed stone granules, the method of laying the concrete solution and its compaction;
working hardening step is a distance that is equal to two cross-sectional heights of the reinforcing tape, but not more than 40 cm;
transverse strengthening - this distance between the rods is half the width of the section itself (no more than 30 cm).

When deciding on the reinforcement scheme, it is necessary to take into account the fact that the frame assembled into one piece is mounted into the formwork, and only the corner sections will be tied inside. The number of axial reinforced layers must be at least 3 along the entire contour of the foundation, because it is impossible to determine in advance the areas with the heaviest loads. The most popular are schemes in which the reinforcement is connected in such a way that cells of geometric shapes are formed. In this case, a strong and reliable fundamental foundation is guaranteed.

Work technology

Reinforcement of strip foundations is carried out taking into account the following rules:

for functioning fittings, rods of group A400 are used, but not lower;
experts do not recommend using welding as a connection, since it blunts the cross-section;
at the corners, the reinforcement is necessarily tied, but not welded;

It is not allowed to use threadless fittings for clamps;
it is necessary to strictly implement a protective concrete layer (4–5 cm), because it protects metal products from corrosion;
when making frames, the rods in the axial direction are connected with an overlap, which should be at least 20 rod diameters and at least 25 cm;
when placing metal products frequently, it is necessary to maintain the size of the aggregate in the concrete solution; it should not get stuck between the rods.

Preparatory work

Before starting work, it is necessary to clear the work area of various debris and interfering objects. Using pre-prepared markings, a trench is dug, which can be done manually or using specialized equipment. To ensure that the walls are perfectly level, it is recommended to install formwork. Basically, the frame is placed in a trench along with the formwork. After this, concrete is poured, and the structure must be waterproofed using roofing felt sheets.

Methods of knitting reinforcement

The scheme for strengthening the strip foundation allows the connection of rods using the tying method. The bonded metal frame has increased strength compared to the welded version. This is explained by the fact that the risk of burning through metal products increases. But this does not apply to factory products. To speed up the work, it is allowed to perform reinforcement in straight sections by welding. But reinforcement of corners is carried out only with the use of binding wire.

Before knitting the reinforcement, you need to prepare the necessary tools and building materials.

There are two ways to bind metal products:

specialized hook;
knitting machine.

The first method is suitable for small volumes. Laying reinforcement in this case will take too much time and effort. Annealed wire with a diameter of 0.8–1.4 mm is used as a connecting material. The use of other building materials is prohibited. The reinforcement can be tied separately and then lowered into the trench. Or tie the reinforcement inside the pit. Both methods are rational, but there are some differences. If you make it on the surface of the earth, you can do it yourself, but in a trench you will need an assistant.

How to properly tie reinforcement in the corners of a strip foundation?

For corner walls, several bonding methods are used.

With a paw. To carry out the work, a foot is made at the end of each rod at an angle of 90 degrees. In this case, the rod resembles a poker. The size of the foot must be at least 35 diameters. The bent section of the rod is connected to the corresponding vertical section. As a result, it turns out that the outer rods of the frame of one wall are connected to the outer ones of the other wall, and the inner ones are connected to the outer ones.

Using L-shaped clamps. The principle of execution is similar to the previous variation. But here you don’t need to make a foot, but take a special L-shaped element, the size of which is at least 50 diameters. One part is tied to the metal frame of one wall surface, and the second to the vertical metal frame. In this case, the internal and external clamps are connected. The spacing of the clamps should be ¾ of the height of the basement wall.

Using U-shaped clamps. For the corner you will need 2 clamps, the size of which is 50 diameters. Each of the clamps is welded to 2 parallel rods and 1 perpendicular rod.

How to properly reinforce the corners of a strip foundation, see the following video.

How to perform reinforcement at obtuse angles?

To do this, the outer rod is bent to a certain degree value and an additional rod is attached to it to qualitatively enhance the strength. Internal special elements are connected to the external one.

How to knit a reinforcing structure with your own hands?

It is worth taking a closer look at how reinforcement is knitted on the surface of the earth. First, only straight sections of the mesh are made, after which the structure is installed in the trench, where the corners are reinforced. Reinforcement sections are being prepared. The standardized size of the rods is 6 meters; if possible, it is better not to touch them. If you don’t have confidence in your own abilities that you can cope with such rods, they can be cut in half.

Experts recommend starting to knit reinforcing bars for the shortest section of the strip foundation, which makes it possible to acquire certain experience and skill, and in the future it will be easier to cope with long structures. It is undesirable to cut them, because this will lead to an increase in metal consumption and reduce the strength of the foundation. The parameters of the workpieces should be considered using the example of a foundation, the height of which is 120 cm and the width is 40 cm. The reinforcement products must be filled on all sides with concrete mixture (thickness about 5 cm), which is the initial condition. Taking these data into account, the net parameters of the reinforcing metal frame should be no more than 110 cm in height and 30 cm in width. For knitting, you need to add 2 centimeters from each side, this is necessary for the overlap. Therefore, blanks for horizontal jumpers should have a size of 34 centimeters, blanks for axial jumpers - 144 centimeters.

After calculations, the knitting of the reinforcing structure occurs as follows:

you should choose a flat piece of land, put two long rods, the ends of which need to be trimmed;
At a distance of 20 cm from the ends, horizontal struts are tied along the outer edges. For tying, you will need a 20 cm wire. It is folded in half, pulled under the tying area and tightened with a crochet hook. But it is necessary to tighten it with care so that the wire does not break off;
at a distance of about 50 cm, the remaining horizontal struts are tied alternately. When everything is ready, the structure is removed to a free place and another frame is tied in an identical way. As a result, you will get the upper and lower parts, which need to be connected to each other;
Next, you need to install stops for the two parts of the mesh; you can rest them against various objects. The main thing is to ensure that the associated structures have a reliable profile arrangement; the distance between them should be equal to the height of the associated reinforcement;

At each end two axial struts are tied, the parameters of which are already known. When the frame product resembles a finished fixture, you can begin tying the remaining pieces of reinforcement. All procedures are carried out with checking the dimensions of the structure, although the workpieces are made of the same dimensions, an extra check will not hurt;
Using a similar method, all other straight sections of the frame are connected;
A gasket is placed at the bottom of the trench, the height of which is at least 5 cm; the lower part of the mesh will be laid on it. Side supports are installed, the mesh is mounted in the correct position;
The parameters of unconnected joints and corners are taken, and sections of reinforcement products are prepared for connecting the metal frame to the overall system. It is worth noting that the overlap of the ends of the reinforcement should be at least 50 bar diameters;
the bottom turn is attached, then the perpendicular posts and the top turn is tied to them. The distance of reinforcement to all sides of the formwork is checked. The strengthening of the structure ends here; now you can proceed to pouring the foundation with concrete mixture.

Knitting reinforcement using a specialized device

To make such a mechanism, you will need several boards 20 millimeters thick.

The process itself looks like this:

4 boards are cut according to the size of the reinforcement product, they are connected in 2 pieces at a distance equal to the pitch of the vertical posts. The result should be two boards of an identical pattern. It is necessary to ensure that the marking of the distance between the slats is the same, otherwise the axial arrangement of the connecting special elements will not work;
2 vertical supports are made, the height of which should be equal to the height of the reinforcing mesh. The collections must have profile corner supports that will prevent them from tipping over. The finished structure is checked for strength;
The legs of the support are installed on 2 nailed together boards, and the two outer boards are placed on the top shelf of the supports. Fixation is performed using any convenient method.

As a result, a model of the reinforcing mesh should be formed; now the work can be carried out without outside help. Vertical braces of the reinforcement product are installed in the planned areas, and their position is fixed in advance using ordinary nails for a certain time. A reinforcement rod is installed on each horizontal metal lintel. This procedure is performed on all sides of the frame. If everything is done correctly, you can start knitting with wire and hook. The design must be made if there are identical sections of mesh made of reinforcement products.

Knitting reinforced mesh in trenches

Carrying out work in a trench is quite difficult due to the tightness.

It is necessary to carefully consider the knitting pattern for each special element.

Stones or bricks no more than 5 cm high are placed at the bottom of the trench; they will lift the metal products from the surface of the earth and allow the concrete to cover the reinforcement products on all sides. The distance between the bricks should be equal to the width of the mesh.
Longitudinal rods are placed on top of the stones. Horizontal and vertical rods must be cut to the required parameters.

They begin to form the base of the frame on one side of the foundation. The work will be easier if you tie horizontal struts to the lying rods in advance. An assistant must support the ends of the rods until they are mounted in the desired position.
The reinforcement is knitted alternately, the distance between the spacer elements must be at least 50 cm. The reinforcement is tied in a similar way on all straight sections of the foundation tape.
The parameters and spatial location of the frame are checked, if necessary, it is necessary to correct the position, and also to prevent metal products from touching the formwork.

You should familiarize yourself with the repeated mistakes that inexperienced craftsmen make when performing reinforcement without following certain rules.

Initially, it is necessary to develop a plan according to which further calculations will be performed to determine the load on the foundation.
During the manufacture of the formwork, no gaps should be formed, otherwise the concrete mixture will flow out through these holes and the strength of the structure will decrease.
The soil must be waterproofed; in its absence, the quality of the slab will decrease.
It is prohibited for the reinforcing bars to come into contact with the soil; such contact will lead to rust.

If you decide to reinforce the frame by welding, then it is better to use rods with index C. These are specialized materials that are intended for welding, so they do not lose their technical characteristics under the influence of temperature conditions.
It is not recommended to use smooth rods for reinforcement. The concrete solution will have nothing to fasten to, and the rods themselves will slide in it. When the soil moves, such a structure will crack.
It is not recommended to arrange corners by direct intersection; reinforcement products bend very hard. Sometimes, when reinforcing corners, they come up with tricks: they heat the metal product to a pliable state, or use a grinder to saw down the structure. Both options are prohibited, because with these procedures the material loses its strength, which will lead to negative consequences in the future.

Foundation reinforcement is a process necessary to strengthen the structure and increase the service life of the building. In other words, this is an assembly of a “skeleton” that plays the role of a protective component that restrains soil pressure on the walls of the base. But in order for this function to be implemented to the maximum extent, it is necessary not only to correctly calculate the reinforcement for a strip foundation, but also to know how to organize the progress of construction work.

The basis of a strip foundation is a concrete solution consisting of cement, sand and water. Unfortunately, the physical characteristics of the building material do not guarantee the absence of deformation of the base of the building. To increase the ability to withstand foundation shifts, temperature changes and other negative factors, the presence of metal in the structure is necessary.
This material is plastic, but provides reliable fixation, so reinforcement is an important stage in the complex of works.

Reinforcement for strip foundation - steel bar with stiffeners

Foundation reinforcement is required in areas where tension zones may occur. It is noted that the greatest tension appears on the surface of the base, which creates the prerequisites for reinforcement close to the upper level. On the other hand, in order to avoid corrosion of the frame, it must be protected from external influences by a layer of concrete.

Important! The optimal distance of reinforcement for the foundation is 5 cm from the surface.

Since the progression of deformation cannot be predicted, stretch zones can appear both in the lower part (when the middle bends down) and in the upper part (when the frame bends upward). Based on this, reinforcement should pass from below and above with reinforcement with a diameter of 10-12 mm, and this reinforcement for a strip foundation should have a ribbed surface.

This ensures perfect contact with the concrete.

Strip foundation stretch zones

The remaining parts of the skeleton (horizontal and vertical transverse rods) may have a smooth surface and a smaller diameter.
When reinforcing a monolithic strip foundation, the width of which usually does not exceed 40 cm, it is allowed to use 4 reinforcement rods (10-16 m), connected into a frame with a diameter of 8 mm.

Important! The distance between the horizontal rods (with a width of 40 cm) is 30 cm.

The strip foundation, although long, has a small width, so longitudinal tensions will appear in it, while there will be no transverse ones at all. It follows from this that transverse vertical and horizontal rods, which will be smooth and thin, are needed only to create a frame, and not to bear loads.

Particular attention must be paid to corner reinforcement

Particular attention must be paid to the reinforcement of corners: there are often cases when deformation occurs not in the middle, but in the corner parts. The corners should be reinforced so that one end of the bent reinforcement element goes into one wall, and the other into the other.
Experts advise connecting rods using wire. After all, not every type of reinforcement is made from steel that can be welded. But even if welding is permissible, problems often arise that can be avoided by using wire, for example, overheating of the steel, leading to a change in properties, thinning of the rod at the welding site, insufficient strength of the weld, etc.

Reinforcement structure construction diagram

Reinforcement begins with the installation of formwork, the inner surface of which is lined with parchment, making it easier to remove the structure in the future. The frame is created according to the following scheme:
1. Reinforcing bars with a length equal to the depth of the foundation are driven into the trench soil. A distance from the formwork of 50 mm and a pitch of 400-600 mm should be maintained.
2. Stands (80-100 mm) are installed at the bottom, on which 2-3 threads of the bottom row of reinforcement need to be laid. Bricks placed on edge will work well as stands.

3. The upper and lower rows of reinforcement are secured together with the transverse jumpers to the vertical pins.
4. At intersections, fastening is carried out using wire tying or welding.

The video will introduce you to a convenient way to knit reinforcement using a template:

Important! The distance to the outer surfaces of the future foundation should be strictly observed. It is better to do this with the help of bricks. This is one of the most important conditions, because metal structures should not be based directly on the bottom. They must be raised above ground level by at least 8 cm.

After installing the reinforcement, all that remains is to make ventilation holes and pour concrete mortar.

You need to know this!
Ventilation holes not only help to increase the depreciation characteristics of the foundation, but also prevent the occurrence of putrefactive processes.

Calculation of material consumption

To calculate a strip foundation, you need to know some parameters in advance. Let's look at an example. Let's assume that our foundation has a rectangular shape and the following dimensions: width - 3.5 meters, length - 10 meters, casting height - 0.2 meters, belt width - 0.18.
First of all, you need to calculate the total volume of the casting, for which you need to find out the dimensions of the base as if it had the shape of a parallelepiped. To do this, we will perform several simple manipulations: find out the perimeter of the base, and then multiply the perimeter by the width and height of the casting.
P = AB + BC + CD + AD = 3.5 + 10 = 3.5 + 10 = 27
V = 27 x 0.2 x 0.18 = 0.972

But the calculation of a monolithic foundation does not end there. We learned that the base itself, or rather the casting, occupies a volume approximately equal to 0.97 m3. Now you need to find out the volume of the internal part of the foundation, i.e. what is inside our feed.

We get the volume of the “filling”: multiply the width and length of the base by the height of the casting and find out the total volume:
10 x 3.5 x 0.2 = 7 (cubic meters)
Subtract the volume of the casting:
7 – 0.97 = 6.03 m3

Result: casting volume - 0.97 m3, internal filler volume - 6.03 m3.

Now you need to calculate the amount of reinforcement. Let's say the diameter will be 12 mm, the casting will have 2 horizontal threads, i.e. 2 rods, and vertically, for example, the rods will be located every half a meter. The perimeter is known - 27 meters. This means we multiply 27 by 2 (horizontal rods) and get 54 meters.

Vertical rods: 54/2 + 2 = 110 rods (108 0.5 m intervals and two at the edges). We add one more rod per corner and we get 114 rods.
Let's say the height of the rod is 70 cm. It turns out: 114 x 0.7 = 79.8 meters.

The final touch is the formwork. Suppose we build it from boards 2.5 cm thick, 6 meters long and 20 cm wide.
We calculate the area of the side surfaces: multiply the perimeter by the height of the casting, and then by 2 (with a margin, not taking into account the decrease in the internal perimeter versus the external): (27 x 0.2) x 2 = 10.8 m2
Board area: 6 x 0.2 = 1.2 m2; 10.8/1.2 = 9
We need 9 boards 6 meters long. Don't forget to add connection boards (optional).

Result: 1 m3 of concrete will be required; 6.5 m3 of aggregate; 134 meters of reinforcement and 27 linear meters of boards (20 cm wide), screws and bars. The values given have been rounded.

The results of painstaking calculation work

Now you know not only how to properly reinforce a strip foundation, but also how to calculate the necessary components. This means that the foundation you build will be reliable and strong, allowing the construction of monolithic structures of any configuration.

To properly reinforce the foundation of a private house, it is necessary to calculate the reinforcement, its proper installation and tying. An incorrect calculation will lead to damage to the foundation or unnecessary costs. We will discuss the reinforcement of foundations of various structures and the principle of calculating steel reinforcement, accompanied by diagrams and summary tables.

Reinforcement of the foundation requires elaboration of the structure of the frame made of reinforcement, selection and calculation of the cross-section, length and weight of rolled profiles. Insufficient reinforcement leads to a decrease in strength and a possible violation of the integrity of the building, and its excess leads to unreasonably inflated costs for this stage.

What you need to know about fittings

When strengthening a concrete base, two types of construction reinforcement are used:

class A-I - smooth;
class A-III - ribbed.

Smooth reinforcement is used in unloaded areas. It only forms the frame. Ribbed reinforcement, due to its developed surface, provides better adhesion to concrete. Such rods are used to compensate for the load. Therefore, the diameter of such reinforcement is, as a rule, larger than that of smooth reinforcement within the same foundation.

The diameter of the rod depends on the type of soil and the weight of the structure.

Table No. 1. Minimum standard diameters of reinforcement

Location and operating conditions		Minimum size	Regulatory document
Longitudinal reinforcement, no more than 3 m long		Ø 10 mm
Longitudinal reinforcement, length more than 3 m		Ø 12 mm	Appendix No. 1 to the design manual “Reinforcement of elements of monolithic reinforced concrete buildings”, M. 2007
Structural reinforcement in beams and slabs over 700 mm high		Sectional area not less than 0.1% of the cross-sectional area of concrete
Transverse reinforcement (clamps) in knitted frames of eccentrically compressed elements		Not less than 0.25 of the largest diameter of the longitudinal reinforcement and not less than 6 mm
Transverse reinforcement (clamps) in knitted frames of bending elements		Ø 6 mm	“Concrete and reinforced concrete structures without prestressing reinforcement” SP 52-101-2003
Transverse reinforcement (clamps) in knitted frames of bending elements at height	less than 0.8 m	Ø 6 mm	“Guide to the design of concrete and reinforced concrete structures made of heavy concrete (without prestressing)”, M., Stroyizdat, 1978
	more than 0.8 m	Ø 8 mm

If you plan to build a wooden one-story building on dense soil, you can take the tabulated values for the diameters of the reinforcement. If the house is massive and the soil is heaving, the diameters of the longitudinal reinforcement are taken in the range of 12-16 mm, in exceptional cases - up to 20 mm.

In your calculations, you will need information about reinforcement from GOST-2590-2006.

Table No. 2

Rolled diameter, mm	Cross-sectional area, cm 2	Specific theoretical mass, kg/m	Specific length, m/t
6	0,283	0,222	4504,50
8	0,503	0,395	2531,65
10	0,785	0,617	1620,75
12	1,131	0,888	1126,13
14	1,540	1,210	826,45
16	2,010	1,580	632,91
18	2,540	2,000	500,00
20	3,140	2,470	404,86
22	3,800	2,980	335,57

Consumption of reinforcement for various types of foundation

Foundations of different designs differ in the area over which the load from the structure is distributed. For each type, the calculation of the amount of reinforcement is carried out according to its own requirements. For a correct comparison, we will calculate all foundations for the following house sizes:

width - 6 m;
length - 8 m;
length of load-bearing walls - 14 m.

Calculation of reinforcement for a slab foundation

This is the most material-intensive type of foundation. There are two levels of reinforcing bars in the concrete, located 50 mm below the top and above the bottom border of the slab. The laying step depends on the perceived loads. For houses made of stone/brick, the frame cell is usually 200x200 mm. At the intersection points of the reinforcement, the upper and lower levels of the frame are connected by vertically located rods.

Reinforcement frame of a slab foundation

Let's calculate the reinforcement for our reference house (see above).

1. Horizontal reinforcement, Ø 14 mm, corrugated.

8000 mm / 200 mm + 1 = 41 pcs. 6 m long.
6000 mm / 200 mm + 1 = 31 pcs. 8 m long.
Total: (41 pcs x 6 m + 31 pcs x 8 m) x 2 = 988 m - for both levels.
Weight 1 linear m rod Ø 14 mm - 1.21 kg.
Total weight - 1195.5 kg.

2. Vertical reinforcement, Ø 8 mm, smooth. For a slab thickness of 200 mm, the rod length will be 100 mm.

Number of intersections of horizontal reinforcement: 31 x 41 = 1271 pcs.
Total length: 0.1 m x 1271 pcs. = 127.1 m.
Weight: 127.1 m x 0.395 kg/m = 50.2 kg.

3. Heat-treated wire Ø 1.2-1.4 mm is usually used as a knitting wire. Since the place of one connection, as a rule, is tied twice - first when laying horizontal rods, then vertical ones, the total amount of wire doubles. One connection requires approximately 0.3 m of thin wire.

1271 pcs. x 2 x 0.3 m = 762.6 m.
The specific gravity of wire Ø 1.4 mm is 12.078 g/m.
Wire weight: (762.6 m x 12.078 g/m) / 1000 = 9.21 kg.

Since thin wire can break/get lost, you need to purchase it with a reserve.

The total amount of materials for reinforcing the slab frame is given in Table No. 3.

Table No. 3

Calculation of strip foundation reinforcement

Strip foundations are reinforced concrete beams located under all load-bearing walls. It contains straight sections, corners and tees. The calculation is performed for straight sections with a small margin for strengthening corners. We assume the width of the tape is 400 mm, the depth is 700 mm.

Schematic representation of a straight section of a strip foundation

The junction of load-bearing internal and external walls

External or internal corner of external walls

The reinforcement of strip foundations is also two-level. For longitudinal sections, a class A-III rod is used, and for vertical and transverse sections (clamps), a class A-I rod is used. The cross-section of the reinforcement is assumed to be slightly lower for strip foundations than for slab foundations, under the same construction conditions.

Let us calculate the reinforcement for the reference building chosen as an example (see above).

1. Horizontal longitudinal reinforcement, Ø 12 mm, corrugated. For a tape width of 400 mm, it is enough to lay two rods in each of two levels. For a wider tape, 3 rods should be laid.

Length of all tapes: (8 m + 6 m) x 2 + 14 m = 42 m.
Total length of reinforcement: 42 m x 4 = 168 m.
Weight of reinforcement: 168 m x 0.888 kg = 149.2 kg.
Taking into account the reinforcement of the corners, the mass of the rods will be 160 kg.

2. Vertical reinforcement Ø 8 mm, smooth. For a tape depth of 700 mm, the rod length will be 600 mm. The distance between the vertical rods along the length of the tape is taken to be 500 mm.

Total length of rods: 85 pcs. x 0.6 m = 51 m.
Weight of rods: 51 m x 0.395 kg/m = 20.1 kg.

3. Horizontal transverse (clamp) reinforcement Ø 6 mm, smooth. For a tape width of 400 mm, the rod length will be 300 mm. The distance between the transverse rods along the length of the tape is taken to be 500 mm.

Number of rods: 42 m / 0.5 + 1 = 85 pcs.
Total length of rods: 85 pcs. x 0.3 m = 25.5 m.
Weight of rods: 25.5 m x 0.222 kg/m = 5.7 kg.

4. Knitting wire. Calculation when tying each connection with one wire Ø 1.4 mm:

Number of nodes: 85 x 4 = 340 pcs.
Total length: 340 pcs. x 0.3 m = 102 m.
Total weight: (102 m x 12.078 g/m) / 1000 = 1.23 kg.
When tying knots twice, the weight of the wire will be 2.5 kg.

The total amount of materials for reinforcing the strip frame is given in Table No. 4.

Table No. 4

Consumption of metal elements for a columnar foundation

Such a foundation consists of supports, the lower part of which is below the freezing zone, and a strip foundation resting on them. For a freezing depth of 1.5 m, the height of the pillars is 1300 mm (see figure), i.e. their base is 1700 mm below the soil level.

Location of reinforcement in a columnar foundation, side view: 1 - sand cushion; 2 — fittings Ø 12 mm; 3 - pile reinforcement

The pillars are installed in the corners of the building and along the strip every 2-2.5 m.

Let's calculate the number of rods for the configuration of the house taken as an example (see above). To do this, you need to calculate the amount of reinforcement for the pillars and sum it with the calculation result for the strip foundation.

In the pillars, only vertical rods are loaded; horizontal rods are used to form the frame. A column with a diameter of 200 mm is reinforced with four vertical reinforcements. Number of pillars: 42 m / 2 m = 21 pcs.

1. Vertical reinforcement Ø 12 mm, corrugated.

Total length of fittings: 21 pcs. x 4 pcs. x 1.3 m = 109.28 m.
Weight of reinforcement: 109.29 m x 0.888 kg = 97.0 kg.

2. Horizontal reinforcement Ø 6 mm, smooth. For dressing, you need to place horizontal clamps at a distance of no more than 0.5 m. For a depth of 1.3 m, three levels of dressing are sufficient. The vertical sections are located at a distance of 100 mm from each other. The length of each horizontal segment is 130 mm.

Total length of horizontal rods: 21 pcs. x 3 pcs. x 4 pcs. x 0.13 m = 32.76 m.
Weight of rods: 32.76 m x 0.222 kg/m = 7.3 kg.

3. Knitting wire. Each column has three levels of horizontal rods that tie four vertical ones.

Length of tie wire per post: 3 pcs. x 4 pcs. x 0.3 m = 3.6 m.
Wire length for all posts: 3.6 m x 21 pcs. = 75.6 m.
Total weight: (75.6 m x 12.078 g/m) / 1000 = 0.9 kg.

The total amount of materials for reinforcing a columnar foundation, taking into account the strip frame, is given in Table No. 5.

Table No. 5

Methods and techniques for connecting reinforcement

Welding and wire knitting are used to connect intersecting rods. For foundations, welding is not the best installation method, as it weakens the structure due to the loss of structural integrity and the risk of corrosion. Therefore, as a rule, the reinforced frame is “knitted”.

This can be done manually using pliers or hooks, or with a special gun. Using pliers, unannealed wire of large diameter is knitted.

Techniques for manually knitting reinforcement using pliers: 1 - knitting with wire in bundles without pulling; 2 - knitting corner knots; 3 - double-row knot; 4 - cross knot; 5 - dead node; 6 - fastening of rods with a connecting element; 7 — rods; 8 — connecting element; 9 — front view; 10 - rear view

For thin annealed wire, it is more convenient to use hooks: simple or screw.

Video: Visual lesson on crocheting reinforcement with a homemade hook

Knitting gun

For large volumes of work, a knitting gun is used. The knitting speed is much higher than traditional methods, but there is a dependence on the power source. In addition, the gun cannot be used everywhere for foundations - some areas are difficult to access.

An owner planning to build a house must have at least some performance where to start construction.

And most importantly, necessary know where and how to start.

Capital buildings must stand on durable a foundation that can last for decades and withstand all loads.

What is reinforcement and why is it needed?

Reinforcement- This is the laying of strong steel rods along the foundation strip. Concrete stone has great performance strength in compression, but under tensile loads it is not as strong.

Various soil structures and building features can cause uneven loads, which leads to various deformations, including ruptures.

As a result of ruptures, the foundation may become covered cracked. And any of them can lead to the destruction of the house.

To strengthen the structure and compensate for this shortcoming, it is necessary reinforce strip foundation. Steel reinforcement, which is placed inside the concrete, helps eliminate its stretching, making it durable and sustainable to temperature changes and heavy weight.

What fittings should I use?

For the frame the following are usually used types of fittings:

rods made of steel A-III, the diameter of which 1,0-1,6 cm and length is about 600 cm;
clamps, whose diameter 0,5 -1 cm, they are made from auxiliary fittings Vr-I;
vertical rod-pins diameter 1 cm.

Auxiliary fittings must be used Necessarily, if the foundation is concreted with a height of more than 15 see Vertical rods are designed to connect the vertical parts of its structure and uniform distribution of loads along the entire foundation of the building.

Reinforcement calculation

When calculating the reinforcement of a strip foundation, the following parameters are taken into account:

on reinforcement frame links;

indentation rods along the perimeter;

width.

The maximum load occurs at longitudinal parts frame. Because optimal An option would be to use ribbed pins for frame reinforcement. Thanks to this, the most will be achieved quality adhesion to concrete.

The laying of the frame is carried out taking into account the difference in soil indicators. The larger it is, the thicker Reinforcement bars must be used in the frame.

Steel rods laid along the perimeter of the foundation should be located at a distance of more than 50 mm from the top edge of the base, formwork and bottom. Reinforcement placed in concrete must receive corrosion protection.

The distance between the rods is determined, for example, like this. Let the width of the foundation be 0,4 m, then distance between the rods located lengthwise there should be equals:

1-3 dm vertically depending on depth and load;
3 dm horizontally.

Smooth rods that can withstand lighter loads are used for vertical and transverse frame elements. Place them at a distance 1-3 dm from each other. Sometimes it is possible to place the rods at a distance of up to 5 dm.

Important! According to building rules, the strip foundation frame must be made in width 2 times less than the height. After all the calculations have been made, installation work can begin.

How to make a reinforcement cage?

Exist standard technological operations for reinforcing such a foundation, which involve laying four rods laid horizontally: two- at the top edge; two- at the bottom. The rods are connected to each other with clamps.

It should be noted that protruding reinforcing bars adhere better to the concrete. That is why it is best to cut slightly longer than the foundation.

Installation includes the following Steps:

under the foundation trench, and then broken bricks in layers 1-1,5 dm;
Slicing And location frame rods in longitudinal and transverse directions;
Installation reinforcement at corners;

After the formwork is installed, the supporting reinforcement rods are installed. They are located along the entire length of the trench. Right You can check whether the rods are installed using a plumb line.

The layer of broken brick at the bottom of the facade trench is intended for the so-called cushion. Sand-lime brick for this purpose unacceptable.

The transverse reinforcement can be bent so that it seems to go along the trench. A pipe is put on the rods, and with its help the rods are bent like this necessary.

Harness necessary to ensure that the foundation reinforcement is accurate and high quality. It reliably fixes the location of the fittings. In practice, plastic clamps, welding or binding wire are used for this purpose.

Most reliable is the fixation of reinforcement with tying wire.

After the reinforcement has been made, it is necessary to pour the foundation concrete. You can find out what concrete to use for these purposes from ours.

Reinforcement scheme

Its various options can be found on the Internet. Sometimes even everything necessary calculations

All builders know that reinforcement of a strip foundation is a necessary stage in the construction of buildings, thanks to which it is possible to achieve the necessary characteristics of strength, reliability, resistance to external influences, and significantly extend the service life. The tandem of concrete and metal guarantees the best properties that neither of these materials can provide separately.

Strip foundations are most popular in individual construction of residential buildings, as they are relatively inexpensive, involve low consumption of materials, and quick and simple construction. But without strengthening the foundation, a structure of this type will not have the necessary properties and will not last long. Therefore, hardening must be done; all work can be done with your own hands.

Concrete requirements

Proper reinforcement must be done using the highest quality materials. The brand and class of concrete are selected in accordance with the required indicators. The main strength properties of concrete structures are tension (Rbt,n), transverse fracture and axial compression (Rb,n). Reliability correction factors ranging from 1.0 to 1.5 can be taken into account.

Requirements for fittings

To understand what reinforcement is needed for a strip foundation, it is necessary to perform calculations and consider the main types of material. To perform the work, mechanically strengthened, hot-rolled, heat-treated construction reinforcement is used. The class is selected according to maximum loads, taking into account tensile characteristics, ductility, weldability, corrosion resistance, ability to withstand temperature changes, etc.

The main brands of rods: hot-rolled rod (A), cold-deformed wire (BP), very strong rope (K). For the foundation frames, rods of the A400 (AIII) yield strength class with a crescent-shaped herringbone pattern are selected.

Proper reinforcement involves the use of the following types of rods:

Workers - for laying around the perimeter
Transverse vertical
Transverse horizontal (clamps)
Additional - usually a binding wire is used instead

To understand which fittings are best to use, you need to remember some rules. To strengthen the base of one- and two-story buildings and light structures, rods with a diameter of 10-24 millimeters are suitable. The strength characteristics of thicker (and much more expensive) reinforcement are unlikely to be used.

The rods must be corrugated, as they provide excellent adhesion to the concrete mortar; their thickness must clearly correspond to the values specified in the documents. Smooth rods are cheaper, but they will not allow you to create a reliable and durable reinforced frame. They can only be used in transverse connections where the load is not very large.

When creating a strip foundation frame on homogeneous soil, you can choose a material with a diameter of 10-14 millimeters; on heterogeneous soil, 16-24 is better. If the side of the building is more than 3 meters, the working reinforcement of the monolithic foundation is made from rods of at least 12 millimeters, but not more than 40.

The technology requires that horizontal clamps in diameter should not be less than a quarter of the working rods - usually 6 millimeters. Vertical rods for low-damage foundations of 80 centimeters or less should be at least 6 millimeters in cross-section. Having thought everything through, you can determine what diameter of rods is needed for different types of work.

Reinforcement requirements

Before reinforcing, you need to decide what size the frame will be, make a drawing, draw a diagram of all the work and structures. The geometric dimensions of the foundation must be such that the location of the reinforcement is free. The concrete layer completely covers the frame, protecting it from external influences and corrosion.

The minimum distances between the rods must be sufficient for effective joining and compliance with all technology rules. Only high-quality fittings are used in the work, in accordance with SNiP 3.03.01. Bending of rods is performed using special devices. The bending radius corresponds to the diameter and physical parameters of the rods.

Video of manual machine for bending reinforcement

And another useful video:

Video on how to bend reinforcement using a homemade machine

Calculation of size, quantity and diameter of reinforcement

It is important to immediately know how much reinforcement is needed to make the reinforcement cage reliable and durable. Knowing the dimensions of the building, you can carefully calculate everything.

Standard frame configuration for small houses:

Bottom and top row of belt
3-4 rods for each row
The current distance between the rods is about 10 centimeters. The distance from the rods to the edges of the base should be at least 5 centimeters.
The belts are connected with clamps or sections of rods in increments of 5-30 centimeters.

So, if you need to build a building with an area of 150 square meters, the perimeter of the external walls is 50 meters. To calculate the amount of reinforcement, you need to take everything into account: 2 belts of a longitudinal row of 3 rods each equals 6 rods, multiplied by 50 meters, that gives 300 meters of main rods. If the lintels are laid in increments of 30 centimeters, the result is 167 pieces per 50 meters. The length of the transverse lintels is 30 centimeters (167x0.3=100.2 meters), vertical - 60 (167x0.6=200.4 meters).

It turns out that to the question of how much reinforcement is needed to strengthen a house with an area of 150 square meters with a wall perimeter of 50 meters, the answer is: 300 meters of thick corrugated rods and 300.6 thinner rods. Plus 10-15% for stock and docking.

Rules for reinforcing strip foundations

Working rods must comply with at least class A400.
Welding is not used to connect rods due to the likelihood of weakening the cross-section of the element.
The frame is tied at the corners, not welded.
It is better not to use smooth reinforcement even for clamps.
The layer of external protective concrete should be at least 4 centimeters, which will guarantee effective protection against rust.
In the longitudinal direction, the rods in the frame are connected with an overlap equal to at least 25 centimeters and at least 20 diameters of the rods.
The standards require that when metal rods are frequently placed, the aggregate in the concrete solution is not very large and does not get stuck between the rods.
How to properly lay reinforcement in a trench - this can be done in two ways: create a frame outside the foundation or directly in the trench. The reinforcement methods are almost equivalent, but you will have to hire someone to work in the trench, while constructing the frame separately on site can be done independently.
Knitting is carried out with a special crochet hook or knitting machine.

Many people wonder what kind of wire is used for knitting - the answer is simple: soft thin wire of not a very high level of strength. It needs to be pulled well; a strong knot is obtained in 2-3 turns of the hook.
The overlap (the distance from the edge of the rod to the knitting point) should be at least 5 centimeters.
All wire connections should be as tight as possible, with no free space between the clamps and the frame, and no element should move.

How to knit reinforcement mesh yourself

The following step-by-step instructions will give you the opportunity to learn how to properly make a frame and provide the foundation with the necessary properties. The easiest way is to knit ready-made reinforcement for a strip foundation on the ground. Straight sections of the mesh are created outside the structure, but the corners are knitted after the frame is lowered into the trench.

First you need to cut pieces of rods. It is better to start knitting with the shortest section of the foundation in order to gain a little experience. You need to cut to a minimum, trying to use the entire length of the working rods. If we take as an example a width of 40 centimeters and a height of 120 centimeters, then the indicators are as follows.
The metal is poured on all sides with a layer of concrete at least 5 centimeters thick. The net dimensions of the frame in height are a maximum of 110 centimeters, width – 30. For knitting, add 2 centimeters on both sides for an overlap. It turns out that the blanks for horizontal jumpers should be about 34 centimeters long, and vertical ones - about 144 centimeters. This is for high foundations, but usually a base with a height of about 80 centimeters is used.
2 rods are placed on a flat surface, horizontal spacers are knitted at a distance of 20 cm from the ends on both extreme sides: the wire is folded in half, pushed under the fastening point and tightened by twisting the hook.
At a distance of about 50 centimeters, all the horizontal struts are fastened in turn, the structure is put aside, another one of the same is made - these are the lower and upper frames that need to be tied together: adapt stops for both meshes between the rods and 2 struts vertically at the ends, attach the remaining pieces. The same should be done with all straight sections of the structure.
Then, pads with a height of at least 5 centimeters are laid at the bottom of the trench, side supports and a mesh are installed correctly. Now you need to knit every corner and joint, creating a single frame. The overlap of the ends of the rods must be equal to at least 50 times the diameter of the rods.
Next, the lower turn is tied, the vertical posts are attached, and the upper frame is attached to them. Then, on all surfaces of the formwork, you need to check the distances, indentations, and overlaps at the joints so that everything is done correctly and clearly.
Connecting rods along the length usually does not cause problems, but fastening the frame parts in the corners must be done in accordance with established standards. There are two ways: between two perpendicular structures or at the point where a wall adjoins another.

Corner knitting technologies:

1) Rigid with a foot - at the end of each rod, knit a foot at a right angle with a length of at least 35 diameters of the rod, connect the bent part to the perpendicular section. This is how the outer rods of the wall frame are attached to the outer rods of the other, while the inner ones are also welded to the outer ones.

2) G-clamps - instead of a clamp, take a clamp with a length of at least 50 reinforcement diameters, one side is attached to the frame of one wall, the other is attached perpendicular. The outer rods are connected to the inner ones, the pitch of the clamps is ¾ of the height of the wall.

3) U-clamps - for one corner you need to install two U-shaped clamps with a length of at least 50 reinforcement diameters, each welded to one perpendicular rod and two parallel ones.

Junctions are created using similar fastening methods.

Knitting reinforcement using a special device - a knitting machine

To create this tool, you need to take several boards 20 millimeters thick, cut 4 boards along the length of the reinforcement, connect two at a distance equal to the pitch of the vertical posts, creating 2 identical templates. Next, two vertical supports are made with a height equal to the height of the reinforcement mesh. The supports are constructed with side corner stops; it is better to choose a flat area for work.

The device is used as follows: the legs of the stops are installed on two knocked down boards, the two upper boards are placed on the top shelf of the stops and fixed. That's it, the reinforcement mesh layout is ready, now you can quickly knit it. It is enough to place the vertical reinforcement struts in the marked places, fixing them with nails, install the rods on each steel lintel, doing this on all sides of the frame. Next, take a hook and wire - that’s it, you can knit. Such a device is relevant where it is planned to create many similar mesh sections.

Video on how to knit reinforcement using a device

How to knit reinforced mesh in a trench

Working in a trench is more difficult, so you need to plan everything ahead of time. Special devices or ordinary stones are placed at the bottom of the trench at a height of at least 5 centimeters in increments of the width of the mesh. The stones are laid out with longitudinal rods, and horizontal struts are tied. Until the rods are in the desired position, a second person holds their ends.

The reinforcement is knitted with a step between spacers of 50 cm wide. We install the pegs and begin to knit the monolithic structure. This is done on all straight sections. Parts of the frame should not touch the formwork; they should be at a distance of several centimeters from the formwork.

Then the corners are knitted using one of several existing methods. It is imperative to maintain the length of the overlaps, with the installation of vertical rods. Rods are often used here with a larger diameter, increasing the strength of the material. Upon completion of the binding, the concrete solution is poured in one go, covered with polyethylene, and during the drying process, it is periodically watered with water by spraying.

Welding fittings for reinforcement

In most joints, it is better to use knitting instead of welding - the finished structure will be more durable. Welding is possible only if you have a machine and extensive experience, exclusively on straight sections.

In order for the foundation to be truly reliable, it is also necessary to take care of the correct execution of the excavation work under the tape, arranging several layers of materials (not only for the base and top of the foundation, but also for filling).

In places where there is no heavy load, you can select reinforcement in favor of bars of smaller diameter. If strength does not suffer from this, but it is possible to reduce the cost of work, this option is allowed. Deciding what diameter of reinforcement to use in your work should take into account two parameters: ensuring sufficient strength and the cost of work, choosing the optimal price-quality ratio. In some places, the use of thick reinforcement is simply not relevant, but purchasing more expensive material will significantly increase the cost of the entire construction.

The layout of the frame in the formwork must be level. Before laying the structure, it is necessary to carefully check all dimensions to exclude distortions, deformations, and non-compliance with parameters.

Video reinforcement of shallow monolithic strip foundations

And another video:

How to properly reinforce a strip foundation with your own hands

The correct selection of reinforcement and compliance with all regulatory requirements for organizing the process will make the reinforcement of a strip foundation a justified and effective stage of work. Thanks to the reinforcement frame, it will be possible to significantly improve the strength characteristics of the building, make it resistant to various impacts and loads, reliable and durable.