It is a solid concrete support placed under all load-bearing walls of the house.

The construction of such bases is quite simple.

The degree of strength, resistance to emerging loads and bearing capacity form an optimal combination that allows the use of a strip foundation type in most buildings.

With some additions, this species is able to serve on different types of soil and in relatively unfavorable geological conditions.

The main structural element is the reinforcing cage, which ensures the strength of the tape and resistance to stress.

Concrete is a specific material. It is able to withstand significant pressure without visible consequences, but it is difficult to endure multidirectional, tensile loads.

A concrete block, which is a monolithic casting without additional reinforcing elements, is able to withstand only a uniform compressive load.

If the force is applied in the central part, and the edges of the block are fixed, it will break with a relatively small load. It is impossible to use it in this form as a basis for a construction object.

The problem is solved with the help of a reinforcing frame placed inside the block before casting.

Reinforcement of tape bases is necessary and prerequisite prescribed by the requirements of SNiP 52-01-2003. All working moments of creation are regulated reinforced concrete structures- composition of concrete, dimensions and material of reinforcement, type of frame construction, assembly method and other issues.

Compliance with the norms of SNiP is mandatory for all builders, since only in this way can the reliability of the construction and the safety of people be ensured.

How rebar works

Reinforcing bars are capable of carrying tensile loads about 10 times greater than concrete. Being installed inside the casting, they take on tensile loads, preventing cracks from appearing, reinforcing and strengthening the concrete tape.

The reinforcement cage is a spatial lattice consisting of load-bearing and auxiliary rods. If the tape itself in the section is a rectangle, then the frame in the section forms a similar figure, but somewhat reduced.

If a bending load acts on the tape, then those rods that are located on the side opposite to the point of application of the force begin to work. They do not allow the tape to change shape, taking on external influences.

NOTE!

For particularly critical structures, tensioned rods are used, which are tensioned before pouring concrete, and released after the mass has hardened. Such bases are able to work in difficult conditions, but are not used for private housing construction.

The main elements are horizontal rods - bearing, or working. Vertical elements serve to support the working reinforcement and in most cases are needed only until the moment of pouring. After it, the working functions are performed only by the corner elements, which experience additional stresses and operational loads.

Auxiliary reinforcement is made from thinner bars and is needed to prevent displacement of the main elements during pouring and hardening.

How to choose concrete

SNiP requirements for concrete are quite stringent.

All operating parameters of the material are regulated:

• Degree of compressive strength and axial tension.
• Frost resistance.
• Waterproof.

For residential buildings of low-rise brick or similar buildings, the best option is M300. When using light cellular or porous materials (foam concrete, expanded clay concrete), it is allowed to use less durable and dense concrete - grades M200 and even M150.

More durable grades are used for critical or multi-storey buildings. For example, M400 concrete can be used for casting foundations for residential buildings up to 20 floors high.

Types of fittings

There are two types of fittings:

• Metal.
• Composite.

The first type is the familiar hot-rolled steel bars with a notch that allows you to get a reliable grip on concrete. There are rods of different diameters, from 6 to 80 mm, designed for use in appropriate conditions.

For auxiliary reinforcement, both corrugated and smooth rods of smaller diameter can be used.

• A piece of wire is bent in half. The resulting half-loop is wound under the cross joint of the rods in a diagonal direction.
• The ends of the half-loop rise up so that the wire wraps around the knot to be connected.
• The crochet hook is wound into a loop with a tip, while leaning on the other end of the wire. With rotational movements, the ends are twisted, tightly tightening the connected rods.
• For knitting longitudinal joints, the same method is used. The only difference is in the position of the wire - it wraps around both connected rods in the transverse, and not in the diagonal direction.

A crochet hook can be purchased at the store, but it's easier to make it yourself. It is necessary to take a piece of steel wire 405 mm thick, sharpen it somewhat and bend one end by about 1.5-2 cm.

For ease of use, the hook can be slightly bent in the middle. Techniques for working with it are simple, but require some skill, which appears very quickly.

Mounting diagram

Gain strip foundation It is produced, as a rule, with the help of a metal reinforcing cage, assembled by a welded method or connected with a special soft steel wire.

The working rods are installed in a horizontal position in such a way that they form a rectangle in cross section with sides 10 cm smaller than the width and height of the concrete tape.

This ratio ensures the depth of immersion of the bars in concrete, at which the bearing capacity is high enough, but the material is reliably protected from corrosion. Vertical reinforcement is used to fix the bearing rods in the desired position during the hardening of concrete.

Both of these processes cause significant loads, so the quality of the reinforcement depends on the strength of the connection.

Drawing photo:

Corner reinforcement

The corner elements of the strip foundation, which include T-shaped junctions, are reinforced by installing curved anchors - individual rods bent at the desired angle. Often, working rods are bent if their length allows it (for example, at the corners of short walls or abutments).

The corners of the foundation are under increased stress, so the presence of additional anchoring is necessary to increase the strength of the frame connection and increase the bearing capacity of this section of the tape.

The main mistakes often encountered when reinforcing corners are:

• Using only the outer contour, with insufficient anchoring of the inner part of the corner.
• Lack of connection between outer and inner rods.
• No mechanical connection between the sole and the frame.
• Incorrect placement of bar connection points.

The use of anchors and proper connection with the main elements of the armored belt allows you to avoid mistakes and strengthen critical sections of the frame.

Sole reinforcement

The sole of the foundation is the area experiencing maximum heaving loads or lateral pressure from soil water. Exist various ways sole reinforcements, which provide a high-quality connection with the concrete preparatory part, but they are used for the construction of industrial critical structures.

To reinforce the base of the foundation of a low-rise residential building, it is customary to use reinforcing meshes that increase the strength and immobility of the lower part of the tape. The mesh is mechanically connected to the main frame, this is especially important if it has a greater width than the tape itself.

NOTE!

Ready-made or welded grids with a transverse arrangement of rods are used. For sites located on difficult soils, it is recommended to use welded structures from working rods that can withstand loads in all directions.

Useful video

In this video you will learn how to reinforce the strip foundation:

Conclusion

Reinforcement of the strip foundation is the main operation, without which all other work becomes impractical. Seasonal soil movements, changes in groundwater levels, tectonic impacts and other influence factors require the foundation to be strong and able to resist emerging loads.

These qualities can only be provided by a correctly and carefully formed armored belt, which forms the internal skeleton of a concrete belt and compensates for all axial tensile loads.

In contact with

Many believe that the cross section and the number of metal rods in the foundation does not play a special role, and they use everything that comes to hand, from knitting wire to metal pipes. But such connivance may have a bad effect in the future, both for the foundation itself and for the house standing on it.

In order for your future home to serve you for many years, it is necessary that the foundation of this house be sufficiently strong and durable, and the correct calculation of reinforcement for the foundation plays a huge role in this.

In this article, we will carry out the calculation of metal reinforcement, if you need to calculate fiberglass reinforcement, then you will need to take into account its features.

The calculation of reinforcement for the strip foundation of a private house is not as complicated as it seems at first glance, and comes down only to determining the required diameter of the reinforcement and its quantity.

Strip foundation reinforcement scheme

For the correct calculation of reinforcement in a reinforced concrete strip, it is necessary to consider typical schemes for reinforcing strip foundations.

For private low-rise buildings, two reinforcement schemes are mainly used:

• four rods
• six rods

What reinforcement scheme to choose? Everything is very simple:

According to SP 52-101-2003, the maximum distance between adjacent reinforcement bars located in the same row should be no more than 40 cm (400 mm). The distance between the extreme longitudinal reinforcement and the side wall of the foundation should be 5-7 cm (50-70 mm).
In this case, with the width of the foundation over 50cm, it is advisable to apply six-bar reinforcement scheme.

And so, depending on the width of the strip foundation, we have chosen a reinforcement scheme, now it is necessary to select the diameter of the reinforcement.

Calculation of the reinforcement diameter for the foundation

Calculation of the diameter of transverse and vertical reinforcement

The diameter of the transverse and vertical reinforcement must be selected according to the table:

In the construction of one-two-story private houses, as a rule, rods with a diameter of 8 mm are used as vertical and transverse reinforcement, and this is usually quite enough for strip foundations of low-rise private buildings.

Calculation of the diameter of the longitudinal reinforcement

According to SNiP 52-01-2003, the minimum cross-sectional area of ​​​​longitudinal reinforcement in a strip foundation should be 0,1% from the total cross section of the reinforced concrete tape. It is from this rule that it is necessary to build on when choosing the diameter of the reinforcement for the foundation.

Everything is clear with the cross-sectional area of ​​\u200b\u200bthe reinforced concrete tape, it is necessary to multiply the width of the foundation by its height, i.e. let's say you have the width of the tape 40 cm, and the height 100 cm(1 m), then the cross-sectional area will be 4000 cm2 .

The sectional area of ​​the reinforcement must be 0,1% from the cross-sectional area of ​​\u200b\u200bthe foundation, so you need the resulting area 4000 cm 2 / 1000 \u003d 4 cm 2 .

In order not to calculate the cross-sectional area of ​​\u200b\u200beach reinforcement bar, you can use a simple plate. With it, you can easily choose the required diameter of reinforcement for the foundation.

There are very minor inaccuracies in the table due to rounding of numbers, do not pay attention to them.

Important: When the tape length is less than 3m, the minimum diameter of the longitudinal reinforcement bars should be 10mm.
With a strip length of more than 3m, the minimum diameter of the longitudinal reinforcement should be 12mm.

And so, we have the minimum calculated cross-sectional area of ​​\u200b\u200bthe reinforcement in the section of the strip foundation, which is 4 cm 2 (this is taking into account the number of longitudinal rods).

With a foundation width of 40 cm, it is enough for us to use a reinforcement scheme with four rods. We return to the table and look in the column where the values ​​\u200b\u200bof 4 reinforcement bars are given, and select the most appropriate value.

Thus, we determine that for our foundation 40 cm wide, 1 m high, with a reinforcement scheme with four rods, the most suitable reinforcement with a diameter of 12 mm, since 4 rods of this diameter will have a cross-sectional area of ​​\u200b\u200b4.52 cm 2.

The calculation of the diameter of the reinforcement for a frame with six bars is carried out in a similar way, only the values ​​​​are already taken from the column with six bars.

It should be noted that the longitudinal reinforcement for the strip foundation must be of the same diameter. If for some reason you have rebars of different diameters, then the larger diameter rods must be used in the bottom row.

Calculation of the amount of reinforcement for the foundation

It often happens that the reinforcement was brought to the construction site, and when they begin to knit the frame, it turns out that it is not enough. You have to buy more, pay for delivery, and these are additional costs that are not at all desirable in the construction of a private house.

In order to prevent this from happening, it is necessary to correctly calculate the amount of reinforcement for the foundation.

Let's say we have a foundation scheme like this:

Calculation of the amount of longitudinal reinforcement

First you need to find the length of all the walls of the foundation, in our case it will be:

6 * 3 + 12 * 2 = 42 m

Since we have a 4-rod reinforcement scheme, it is necessary to multiply the resulting value by 4:

42 * 4 = 168 m

We have obtained the length of all longitudinal reinforcement bars, but do not forget that:

When calculating the amount of longitudinal reinforcement, it is necessary to take into account the launch of reinforcement during docking, because it often happens that reinforcement is delivered to a section of a long rod 4-6m, and in order to get the required 12m, we will have to butt several rods. It is necessary to join the reinforcement bars with an overlap, as shown in the diagram below, the launch of the reinforcement must be at least 30 diameters, i.e. when using rebar with a diameter of 12 mm, the minimum start should be 12*30= 360 mm (36cm).

There are two ways to account for this launch:

• Draw up a diagram of the location of the rods and calculate the number of such joints
• Add about 10-15% to the resulting figure, as a rule, this is enough.

We will use the second option and in order to calculate the amount of longitudinal reinforcement for the foundation, we need to add 10% to 168 m:

168 + 168 * 0.1 = 184.8m

We have calculated the number of only longitudinal reinforcement with a diameter of 12 mm, now let's calculate the number of transverse and vertical rods in meters.

Calculation of the amount of transverse and vertical reinforcement for a strip foundation

To calculate the amount of transverse and vertical reinforcement, we again turn to the diagram, from which it can be seen that one "rectangle" will go:

0.35 * 2 + 0.90 * 2 = 2.5 m.

I deliberately took with a margin not 0.3 and 0.8, but 0.35 and 0.90 in order for the transverse and vertical reinforcement to go a little beyond the resulting rectangle.

Important: Very often, when assembling a frame in an already dug trench, vertical reinforcement is placed at the bottom of the trench, and sometimes it is also driven a little into the ground, for better stability of the frame. So this will need to be taken into account, and then it will be necessary to take into account not the length of the vertical reinforcement 0.9 m, but increase it by about 10-20 cm.

Now let's count the number of such "rectangles" in the entire frame, given that there will be 2 such "rectangles" at the corners and at the junction of the walls of the strip foundation.

In order not to suffer with the calculation and not get confused in a bunch of numbers, you can simply draw a foundation diagram and mark on it where your “rectangles” will be located, then count them.

Let's first take the longest side (12 m) and calculate the amount of transverse and vertical reinforcement on it.

As can be seen from the diagram, on the side of 12 m we have 6 of our “rectangles” and two parts of the wall of 5.4 m each, on which 10 more jumpers will be located.

Thus, we get:

6 + 10 + 10 = 26 pcs.

26 "rectangles" on one side of 12 m. Similarly, we count the lintels on the wall 6 m and we get that there will be 10 lintels on one six-meter wall of the strip foundation.

Since we have two 12-meter walls, and 3 6-meter walls, then

26 * 2 + 10 * 3 = 82 pieces.

Remember, according to our calculation, 2.5 m of reinforcement came out for each rectangle:

2.5 * 82 = 205 m.

Final calculation of the amount of reinforcement

We have determined that we need longitudinal reinforcement with a diameter of 12 mm, and transverse and vertical reinforcement will be 8 mm in diameter.

From previous calculations, we found out that we need 184.8 m of longitudinal reinforcement, and 205 m of transverse and vertical reinforcement.

It often happens that there are a lot of pieces of rebar of small sizes that will not fit anywhere. Given this, it is necessary to buy reinforcement a little more than it turned out in the calculation.

Following the above rule, we need to buy 190 - 200 m fittings with a diameter of 12 mm and 210-220 m fittings with a diameter of 8 mm.

If the reinforcement remains - do not worry, during the construction process it will come in handy more than once.

The specifics of individual construction is determined by the influence of a huge number of factors, from the availability of roads and electricity, to a pond or hill in the neighborhood. All these factors affect the choice of foundation and the method of its installation. What formwork should be, what concrete mixtures to use, how to reinforce the foundation - these are the first questions at the start of building a reliable and durable house.

Reinforcement is required element reliable foundation Source newspasky.ru

To avoid problems

When constructing the foundation of a private house, it is difficult to foresee what loads it will undergo in the future. Perhaps the owner will need to install a massive lathe or arrange a ballroom in the house, a water pipe will break, a powerful structure will be erected in the neighborhood, which caused a rise in groundwater or a new underground current. Loads will change, the foundation, not designed for cardinal changes in loads, will burst and sag, followed by the collapse of the building.

If the developer considered the installation of a strip foundation to be the most appropriate option, then reinforcement is necessary for its guaranteed reliability. And how the reinforcement of the foundation should take place, the calculation of reinforcement, laying and knitting should be known at least approximately, even if other people will build your house.

Source ar.aviarydecor.com

Calculation with a margin

Foundation reinforcement is a device in its array of a metal frame designed to create a single indestructible structure from concrete.

It is difficult and expensive to make an accurate engineering calculation of the foundation of a small individual building, it requires geological surveys, comparisons with promising development projects for the area as a whole, soil characteristics and groundwater and solutions to a long list of questions.

Based on this, private developers are guided by two basic rules for the construction of foundations:

The base of the foundation should lie below the depth of soil freezing according to the maximum indicators of the building region.

Reinforcement of the strip foundation is mandatory and is carried out in accordance with the general recommendations of the standards with a margin of safety.

Basic rules for performing reinforcement Source sevparitet.ru

Arrangement of the foundation frame

The monolithic foundation is reinforced in the form of a single single frame to the full height. The distance between the individual reinforcing bars must ensure the free passage of the concrete mixture between them. In other words, if crushed stone of fraction 20-40 is used in concrete, then the gap between the frame bars must be at least 4 cm.

Application rubble stone much cheaper than a conventional concrete mix, but to create a single structure, it is necessary to dress the foundation around the entire perimeter. The reinforcing cage is incompatible with large stone, in such cases, the installation of an armored belt from below and above the foundation becomes a technological solution.

Even the largest fractions of concrete should freely pass through the frame. Source earny.ru

On our website you can find contacts construction companies, which offer the service of designing and repairing the foundation. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".

Stages of work on the arrangement of the reinforcing cage

The base for the foundation is made of a layer of sand of at least 10 cm, the sand is covered with a layer of crushed stone of fraction 2-5, then the sand-gravel base is rammed, and only then should the laying and knitting of the reinforcing cage be started.

Reinforcing bars, cut along the length of the foundation tape on one side, are laid out at a distance of 20-30 cm from each other along the bottom of the foundation. In the corners, they are screwed with soft knitting wire to the vertical rods, as well as to each other when overlapping.

To create the vertical corner supports of the frame, the horizontal lower bars of the frame are bent at an angle of 90 degrees. Extended by overlapping and wire fastening.

To facilitate the production of work on reinforcing the corners of the foundation, it is allowed to install anchors, the work is similar to the installation of grillages or armored belts. At all corners of the foundation, 4 metal rods are driven into the ground, covered from below with bituminous resin for waterproofing. They act as anchors for attaching the frame. In cross section, the driven anchor pins should form a square with sides parallel to the foundation strip.

Anchors driven into the ground to which the frame is attached Source sjthemes.com

Vertical reinforcing bars equal to the height of the foundation are screwed or tacked to the anchors for fixation. All vertical bars are connected or welded together along the perimeter, forming a column structure.

In order to avoid contact between the metal and the sand-gravel base, halves of a brick are placed under it along the entire length of the rod with an interval of 1 m.

Rods are cut for transverse laying of reinforcement. Their length should be less than the width of the monolithic tape by 10 cm, that is, the crossbars should be completely covered with poured concrete with a distance of 5 cm from the outer wall of the foundation.

Step of reinforcement of the foundation with transverse rods 50 cm along the entire length of the longitudinal reinforcement.

All fittings are twisted with knitting wire.

Depending on the length of the side of the foundation, the distance between the vertical rods ranges from 30 to 80 cm.

Longitudinal rows can be enough only two: top and bottom.

Each horizontal row is parallel to the bottom row and is similar to it.

It is quite possible to assemble the frame close to the foundation, and then simply lower it into a trench or formwork.

The frame does not have to be assembled inside the pit prepared for the foundation - installation can be done outside, and then lower the entire structure down Source newspasky.ru

Of course, this method is possible only if there is a flat area for assembly, otherwise it is difficult to achieve accurate work.

Binding wire

There are two common ways of connecting reinforcement in the frame structure, welding and knitting, and knitting is considered more reliable. When filling a foundation with concrete, the welded joints often cannot support the weight of the concrete.

The knitting wire cut into 40-50 cm is doubled, wound from below at the intersection of the rods, twisted with pliers.

The option with twisting with a hook is simpler and faster: the wire is wound freely with a gap around the junction of the reinforcement, its ends are twisted by hand one or two turns, a hook is inserted into the gap between the reinforcement and the wire, by turning which the wire is tightened.

Hooks are sold in hardware stores, but it is enough for this purpose to bend a cleaned welding electrode.

For large volumes of fastening reinforcement with wire, there is a special knitting gun. It is very effective in places that are easily accessible, but where access is difficult, and these are usually corner joints, a simple hook is again more useful there.

The use of a knitting gun significantly speeds up the process of tying reinforcement for the foundation Source dvamolotka.ru

Often, plastic clamps are used instead of wire. This greatly speeds up and facilitates the workflow, but at low temperatures, such fasteners lose their elasticity and strength.

How rebar works

Reinforcement in construction is called rods of various diameters and shapes to counteract compressive and tensile loads, internal and external. The division into types, classes and groups depends on the properties and characteristics given to the reinforcement.

The division into reinforcement groups depends on the characteristics:

material of manufacture;

profile shape;

method of use;

installation technique;

appointment.

In the construction of foundations, the spatial arrangement of the reinforcement is important. Longitudinally oriented reinforcing elements work to minimize the formation of cracks by redistributing the load on the surface of longitudinally directed structures.

Transverse reinforcement connects concrete in the compression zone with longitudinal reinforcement, redistributing and reducing loads.

Why reinforcement is needed: just a concrete beam on top, and reinforced on the bottom Source rmnt.mirtesen.ru

When studying the marking of reinforcing steel, the designations C and K after the numerical value of the yield strength are of practical importance for a private developer

Index C indicates the possibility of welding reinforcement, the absence of this index means that welding is undesirable due to the fragility of the joint. The designation K indicates the increased resistance of reinforcement to corrosion.

Scheme and calculation of metal

The need for metal and the estimated costs are easy to calculate if you draw a reinforcement scheme for a strip foundation with all longitudinal, transverse and vertical bars. The fittings are sold by weight, therefore, when calculating, the diameter of the fittings should be taken into account, it is possible to complete the frame with metal of different diameters and types of corrugation.

For reinforcing foundations, reinforcement of various brands and diameters is used, mainly reinforcing bars with a diameter of 10-14 mm, smooth and ribbed. For laying transverse joints, it is permissible to use round smooth reinforcement of a smaller diameter.

The most common types of reinforcement for foundations are made of steel grades M35GS and M25GS, the length of the rods is up to 12 m, the diameter is from 10 to 40 mm.

The correct selection of the reinforcement section is the key to the strength of the foundation Source armsetka16.ru

Alternative reinforcement

The difficulty of transporting steel reinforcement due to its length, many problems in working with metal, forced developers to look at alternative solutions.

One of them could well be fiberglass reinforcement.

It has many advantages, but in order to appreciate them, it is worth remembering the original purpose of reinforcing foundations. In fact, the reinforcing cage should protect the concrete foundation from stretching. The modulus of elasticity of metal rods is much lower than similar plastic rods. This means that the low elasticity threshold of plastic rods will lead to deformation much faster, and hence the destruction of the foundation, than metal. And the meaning of replacing metal with a plastic composite disappears.

The second very unpleasant drawback concerns individual developers who do not have special conditions for leveling plastic fittings rolled into bays.

The disadvantages of modern plastic reinforcement relate only to the undesirability of using it in monolithic strip foundations. There are many areas of application where this type of reinforcement will show itself better than steel, but not in foundations.

Conclusion

The reinforcement does not allow concrete to collapse when shear or torsion stresses occur in it, therefore reinforcement is an obligatory stage in the construction of a concrete foundation. Reinforcement rules are quite simple, but require strict adherence - in this case, your house will receive a reliable foundation.

On the foundation all the time there are various influences: the movement of the soil, the weight of the house, frost. Such actions lead to deformation and destruction of the base, and if it deteriorates, then the bath itself will not last long. In order for the building to serve for many years, it is important that it is done correctly. One of the stages of mounting the base is reinforcement. Let us consider in more detail what reinforcement is, why it is needed, and how to properly knit reinforcement for a strip foundation.

Reinforcement of the strip foundation: what is it and why is it needed?

Foundation reinforcement is a method of increasing the bearing capacity of a structure by mounting a frame. When building a bath, you must take into account all the requirements that the foundation must meet, specified in SNiP. Reinforcement of the strip foundation is necessary to increase the service life of the foundation and the entire structure as a whole.

The basis of the strip foundation is concrete. As you know, such a material is non-plastic, i.e., at the moment of stretching, it can easily crack. The metal frame is more stable and reliable; when reinforcing, it takes on part of the load, thereby preventing stretching and reducing the risk of destruction of the foundation; knitting reinforcement under the strip foundation is a must.

What material is better to make a reinforcing cage for a strip foundation?

Progress does not stand still, new building materials are constantly appearing. If earlier the knitting of reinforcement was strictly made of metal, today you can see plastic reinforcement, fiberglass options and composite parts. So what is the best way to knit reinforcement? Let's look at the materials in more detail.

Despite the emergence of new and more modern materials, metal fittings, time-tested, remain popular. Its service life is about 50 years. The fittings differ in the high weight, durability and reliability. Its main disadvantage is that it begins to rust under the influence of moisture.

To make reinforcement knitting for the foundation, hot-rolled building reinforcement of a periodic profile, mechanically hardened or heat-treated, is suitable.

When choosing reinforcement, the value of the yield strength must be taken into account. For the installation of longitudinal rows that carry the main load, class A400 (AIII) rods are suitable, it is permissible to use materials of a higher class. But be aware that they will cost more.

It is important that the profile is ribbed, because it adheres better to concrete and transfers the load evenly.

For lintels, class A1 smooth reinforcement is suitable, this will help reduce the cost of the foundation, while it will have sufficient strength.

Reinforcement with a diameter of 6-12 mm is suitable for a strip foundation.

If the side of the tape is less than 3 m, then it is permissible to use rods of at least 10 mm for horizontal clamps, if more than 3 m, then at least 12 mm. For vertical clamps with a foundation height of less than 80 cm, reinforcement with a diameter of 6 mm or more is suitable, more than 80 cm - from 8 mm.

Fiberglass reinforcement is 2 times stronger and 9 times lighter than metal. An important advantage of this material is that, unlike metal, it is not subject to corrosion. Fiberglass reinforcement has a service life of about 70 years. Moreover, its price is cheaper than the metal version.

Reinforcement material must be chosen carefully. If the reinforcement is of poor quality, then cracks may appear on the foundation, which will gradually expand, and as a result, the structure will serve you much less than it could.

You can make a knitting of a frame from reinforcement yourself or buy a ready-made reinforcing mesh. The second option will be more expensive, but the question of how to knit a reinforcing cage will not bother you, because specialists take care of these concerns. In addition, the advantage of the finished mesh is that the bars are firmly connected to each other in the factory. This ensures that the frame does not fall apart over time, as it can with a homemade one. In addition, in this case, it will be easier to reinforce the foundation: you just need to put the frame in two parallel layers.

How to reinforce the strip foundation with your own hands?

Sturdy and properly bonded rebar retains its shape perfectly when pouring concrete for the foundation. But in order for the design to turn out to be of high quality and reliable, you need to know how to properly knit reinforcement for the foundation, and choose the right materials.

According to the rules, any reinforcement must be protected from external factors; for this, it is poured with concrete. Moreover, it is necessary that the upper part of the frame is buried in concrete by 5 cm, and the lower part by 7 cm.

If you want to know how to properly reinforce the foundation, then do not forget to study the SNiP, where everything is described in detail. In particular, in accordance with SNiP, the total frame area must be at least 0.1% of the cross-sectional area of ​​​​the foundation.

Tension zones can appear both in the upper and lower parts of the foundation, so reinforcement should be done on both sides.

If you are making a shallow foundation, then the step between the horizontal bars during reinforcement should be 30 cm.

Strip foundation reinforcement scheme

First, preparatory work is carried out to clean up the territory. Next, you need to prepare a trench.

The scheme of knitting reinforcement for a strip foundation begins with the installation of formwork.

Do-it-yourself reinforcement of the foundation is carried out according to the following scheme:

1. Metal rods are driven in by an amount equal to the depth of the base, at a distance of 5 cm from the formwork. 40-60 cm must be left between the rods.
2. Stands are installed at the bottom, 2-3 threads of the lower row of reinforcement are placed on them. Various materials are used as coasters, for example, bricks or stones are suitable. Thanks to them, the reinforcement is located higher, and after pouring the concrete, it will be protected from all sides.
3. Rows of reinforcement are attached to perpendicularly installed pins with jumpers.
4. Joints are strengthened by welding or wire bonding.

After you have made the reinforcement cage, you need to prepare ventilation holes and pour concrete.

Foundation reinforcement schemes may be different. When choosing, you need to take into account the size of the foundation, its bearing capacity and personal preferences.

The best option is a foundation with a square or rectangular frame, because in this case a solid frame is obtained.

How to properly reinforce the strip foundation? You can knit the structure in the trench, as described above, or first prepare the reinforcement cage, and then lower it into the trench. The difference between these schemes for knitting reinforcement for the foundation is that in the second case, everything can be done independently, but if you mount the frame immediately in the trench, you will need the help of another person.

How to reinforce a strip foundation? Do a tie or weld?

Horizontal and vertical bars must form a single structure. There are two ways to connect them: by tying or by welding.

The disadvantage of welding is that such a procedure degrades the physical properties of the metal, it becomes more brittle, so this method is rarely used.

If you still decide to fasten the rods by welding, then try to reduce the number of seams.

Another option is a link. It needs a soft and thin wire with a diameter of 0.5 mm and a length of about 30 cm. It should be folded in half and put on the junction of the rods, thread the hook into the resulting loop. Then scroll it to get a knot.

Do not twist the wire too hard, it may break!

How to knit armature? Ways

Knitting reinforcement for the foundation can be done manually or with the help of tools. If you not professional builder, and build a bath for yourself, then there is no need to buy special tools - this will be a waste of time. You can also do a great job by hand.

Reinforcement knitting methods:

• Wire knitting.

This is the easiest way that does not require special skills. You need to take a wire with a diameter of 12 mm, cut into pieces 1.8-2 m long, bend in half. Next, you need to fasten the elements with wire in such a way that there are free ends 0.3-0.5 m long. After that, you need to hold the free ends with one hand, and with the other put the hook into the loop with rotational movements and twist the wire with both hands.

• Knitting with reinforcing clips.

Staples can be purchased at the store. This mounting option is suitable for hard-to-reach places. To tie the reinforcement under the strip foundation, you need to fix the paper clip in diameter on one rod, and press the adjacent reinforcement with the other end. The advantage of this fastening is that the reinforcement process is faster than other methods.

• Overlap knit.

This method is relevant in the case of knitting reinforcement at the junction of the walls of the foundation and for lengthening the reinforcing cage. The length of the overlap should be about 30 rebar diameters. Moreover, the reinforcement must be installed so as not to touch the formwork. This is necessary to protect it from moisture, high and low temperatures.

All these methods have in common that the first loop must be thrown along the spiral grooves so that the fastener holds better.

Reinforcing the corners of the strip foundation

The corner of the reinforced concrete foundation is subjected to stronger pressure compared to the walls, it is the most vulnerable point in the entire structure. If the reinforcement of the corners of the walls is done incorrectly, then this will lead to cracks, due to which the foundation will quickly collapse.

Some people think that it is enough to lay the bars at right angles, but this opinion is erroneous. This design does not allow you to make a single rigid frame, so the base will not last long.

How to reinforce the foundation in the corners? It is best to use bent rods L- or U-shaped. They reinforce the joints in the corners of the foundation. It is also necessary to reduce the step for tying the rods by 2 times. An effective option is to bend the corners and overlap them with clamps at a distance of 7 cm from the corner.

L-shaped rods are the most reliable option for connecting the corners of the foundation. They need to be laid out so that one end of the rod goes towards one wall, and the other - the other. L-shaped rods provide solidity and high strength of the foundation.

How to knit reinforcement for the foundation? Features knitting corners, see this video:

All builders know that the reinforcement of a strip foundation is a necessary stage in the construction of buildings, thanks to which it is possible to achieve the desired 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 none of these materials can provide separately.

The strip foundation is most popular in the individual construction of residential buildings, as it is relatively inexpensive, involves a small consumption of materials, 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 necessarily, all work can be done by hand.

concrete requirements

Proper reinforcement should be performed 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.

Reinforcement requirements

To understand what kind of 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 hardened, hot-rolled heat-treated building 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 are: hot-rolled rod (A), cold-formed wire (Bp), very strong rope (K). For foundation frames, rods of the yield strength class A400 (AIII) with a crescent-shaped herringbone pattern are selected.

Proper reinforcement involves the use of these types of rods:

• Working - for laying around the perimeter
• Transverse vertical
• Transverse horizontal (clamps)
• Additional - usually knitting wire is used instead

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

The rods must be grooved, as they provide excellent adhesion to the concrete mortar, their thickness must clearly correspond to the values ​​\u200b\u200bspecified in the documents. Smooth rods are cheaper, but they will not allow you to create a reliable and durable armored frame. They can only be used in transverse joints, where a not very large load is noted.

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

The technology requires that horizontal clamps in diameter not be less than a quarter of the working rods - usually they take 6 millimeters. Vertical rods for slightly ruined 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 the rods is needed for different types works.

reinforcement requirements

Before reinforcing, you need to decide what size the frame will be, make a drawing, draw a diagram of all 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 bars must be sufficient for effective joining and compliance with all technology rules. Only high-quality fittings are used in the works, in accordance with SNiP 3.03.01. Bending of rods is carried out using special devices. The bending radius corresponds to the diameter and physical parameters of the bars.

Videos manual rebar bender

And another helpful video:

Video how to bend rebar work on a homemade machine

Calculation of the size, number and diameter of reinforcement

It is important to immediately know how much reinforcement is needed to make the reinforcing cage reliable and durable. Knowing the size 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 actual distance between the bars is about 10 centimeters. The distance from the rods to the edges of the base must be at least 5 centimeters.
• The belts are connected with clamps or segments 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 outer walls is 50 meters. To calculate the amount of reinforcement, you need to take into account everything: 2 belts of a longitudinal row of 3 rods each are 6 rods, multiply by 50 meters, 300 meters of the main rods come out. If the jumpers are laid in increments of 30 centimeters, 167 pieces per 50 meters are obtained. The length of the transverse jumpers 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.

Strip foundation reinforcement rules

• Working rods must meet at least class A400.
• Welding is not used to connect the rods due to the possibility of weakening the section of the element.
• At the corners, the frame is connected, not welded.
• It is better not to take smooth fittings even for clamps.
• The layer of external protective concrete must be at least 4 centimeters, which will guarantee effective protection against rust.
• In the longitudinal direction, the bars 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 with frequent arrangement of metal bars, the aggregate in the concrete solution should not be very large and not get stuck between the bars.
• How to properly lay reinforcement in a trench - this can be done in two ways: create a frame outside the foundation or right in the trench. The methods of reinforcement are almost equivalent, but to work in a trench, you will have to involve someone, while the construction of the frame separately at the facility can be performed independently.
• Knitting is carried out with a special hook or knitting machine.

• Many people wonder what kind of wire is used for knitting - the answer is simple: soft thin wire is not of 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) must be at least 5 centimeters.
• All wire connections should be as tight as possible, without free space between the clamps and the frame, no element should move.

How to knit reinforcing mesh yourself

The following step-by-step instruction will provide an opportunity to learn how to properly make a frame and provide the foundation with the desired properties. The easiest way is to knit the finished reinforcement for the strip foundation on the ground. Outside the structure, straight sections of the grid are created, but the knitting of the corners is carried out after the frame is lowered into the trench.

1. First you need to cut pieces of rods. It is better to start knitting from the shortest section of the foundation in order to gain some 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.
2. From all sides, the metal is poured 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. We add 2 centimeters for knitting on both sides to overlap. It turns out that the blanks for horizontal jumpers should be about 34 centimeters long, vertical - about 144 centimeters. This is for high foundations, but usually use a base about 80 centimeters high.
3. 2 rods are placed on a flat area, at a distance of 20 cm from the ends, horizontal spacers are knitted on both extreme sides: the wire is folded in half, pushed under the attachment point and tightened by turning the hook.
4. At a distance of about 50 centimeters, all horizontal struts are fixed in turn, the structure is laid aside, another one is the same - these are the lower and upper frames that need to be tied together: adjust the stops for both grids between the bars and vertically along the ends, 2 struts each, attach the rest of the pieces. Similarly, you need to do with all straight sections of the structure.
5. Then, at the bottom of the trench, linings with a height of at least 5 centimeters are laid, side supports and a grid are installed correctly. Now you need to knit each corner and joint, creating a single frame. The overlap of the ends of the rods must be equal to at least 50 diameters of the bars.
6. Then they tie the lower turn, attach the vertical racks, to them - the upper frame. Then, on all surfaces of the formwork, you need to check the distances, indents, overlaps at the joints, so that everything is done correctly and clearly.
7. The connection of the rods along the length usually does not cause problems, but the fastening of 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 junction of a wall to another.

Corner knitting technologies:

1) Rigid with a foot - at the end of each rod, a foot with a length of at least 35 core diameters is knitted at a right angle, the bent part is connected to a 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) L-clamps - instead of a foot, they take a clamp with a length of at least 50 diameters of the reinforcement, with one side they are attached to the frame of one wall, the second is attached with a perpendicular one. The outer rods are connected to the inner ones, the step 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 minimum length of 50 reinforcement diameters, each welded to one perpendicular rod and two parallel ones.

Adjacencies are created using similar fastener methods.

Knitting reinforcement using a special device - a knitting machine

To create this tool, you need to take several boards with a thickness of 20 millimeters, cut 4 boards along the length of the reinforcement, connect two at a distance equal to the pitch of the vertical racks, creating 2 identical templates. Next, two vertical supports are made with a height equal to the height of the reinforcement mesh. 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 downed boards, the two upper boards are placed on the upper shelf of the stops, fixed. Everything, the layout of the reinforcing mesh is ready, now you can quickly knit. It is enough to put the vertical spacers of the reinforcement on the marked places, fixing them with nails, install the bars on each steel jumper, doing this on all sides of the frame. Next, we take a hook and wire - everything can be knitted. Such a device is relevant where it is planned to create many similar sections of the grid.

Video how to knit reinforcement with a fixture

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 laid at the bottom of the trench at a height of at least 5 centimeters with a step in the width of the grid. The stones are laid out with longitudinal rods, horizontal struts are tied. Until the bars are in the right position, the second person holds them by the ends.

Reinforcement is knitted with a step between spacers 50 cm wide. We install pegs and begin to knit a 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 in one of several existing ways. Be sure to observe the length of the overlaps, with the installation of vertical bars. Often rods are used here with a larger diameter, increasing the strength of the material. Upon completion of knitting, it is poured concrete mortar in one go, covered with polyethylene, in the process of drying, it is periodically watered with water by spraying.

Rebar welding 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 with the presence of the apparatus and extensive experience, exclusively in straight sections.

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

In places where there is no heavy load, it is possible to 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 which diameter of rebar to use in work is based on two parameters: ensuring sufficient strength and cost of work, choosing the best value for money. In some places, the use of thick rebar is simply not relevant, but buying a more expensive material will significantly increase the cost of the entire construction.

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

Video reinforcement of shallow monolithic strip foundations

And one more video:

How to properly reinforce the strip foundation with your own hands

The correct selection of reinforcement and the fulfillment of all regulatory requirements for the organization of the process will make the reinforcement of the 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 influences and loads, reliable and durable.