Correct knitting of reinforcement for a strip foundation. How to properly reinforce a strip foundation with your own hands Connect two strip foundations

Construction of a house begins with laying the foundation. The main requirement for a concrete foundation is its strength. It is achieved by laying a frame of reinforcement bars tied together inside the concrete. Such a frame is called reinforcing. This article will discuss such an important stage of construction work as tying reinforcement for the foundation.

It is necessary to first consider what methods of tying reinforcement for the foundation generally exist. They differ from each other by type:

tool;
material;
knitting patterns;

By instrument type- this can be either knitting reinforcement for the foundation manually or using a special tool. As the latter, special crochet hooks, screwdrivers, special guns, produced just to perform this operation.

As a material which is used to connect reinforcement bars to each other used:

knitting wire- This is the most common and reliable technology for tying reinforcement for the foundation, because it is performed with tying a knot.
paper clips- are wire tacks, which, unlike ligation with knitting wire, are made without tying a knot.
clamps small size made of plastic- this new material has become widespread due to its ease of installation and high knitting speed, and besides, it is not afraid of corrosion. However, such a bundle of reinforcement for the foundation causes a certain skepticism among professionals. Read more.
clips— made in the form of latches that fix adjacent rods to each other.
welded joint- this old method has not become widespread, since the welded joint, due to its fragility, is susceptible to cracking during concrete pouring and does not have the necessary reliability. To perform a high-quality welded joint, you need a highly qualified welder.

Required wire

When choosing wire, the following factors must be considered:

Manufacturing accuracy class. The accuracy class is determined by the production method. There is a wire of a higher accuracy class, its deviation of the actual size, diameter, from that declared by the manufacturer along the entire length of the wire is less than that of a wire of a lower accuracy class. However, for knitting reinforcement, the accuracy class is not particularly important.
Wire rolling method. There are two types of rolled products: cold-rolled and hot-rolled. Cold-rolled steel is rolled out from blanks by presses without heating. With the hot rolling method, rolled steel is rolled out in a heated state, which gives greater strength.
Which tensile strength group does it belong to? wire (there are the first and second groups);
Degree of corrosion resistance. On this basis, there is only one difference - whether there is a galvanized coating on the wire or not.

The criterion for choosing wire is very simple, you need wire, which is called “knitting”. It has a full set of necessary characteristics: sufficient softness with the declared strength, abrasion resistance and reliability when fastened.

Galvanized wire is considered overkill.
The optimal diameter of the knitting wire is 1.2-1.4 mm. A wire with a diameter of 1.6-2 mm takes a lot of force, as a result of which construction slows down, and the piece is too weak, it will simply burst.

Attentively you need to ensure that the connection of the reinforcement remains rigid after tying the knot: during pouring, the frame must remain motionless. This will ensure the reliability of the structure after hardening.

You need to check the rigidity of the connection of the reinforcement by touching the rods - if they are rigidly fixed, they will not move, which means everything is in order. You should not test the strength of the knot itself, otherwise there is a risk of loosening the binding.

The length of wire recommended for one knitting point is from 30 to 50 cm. The wire itself is extremely cheap - about 50 rubles. for 100 meters. To avoid running out of it at the wrong time due to loss or excessive consumption, it is recommended to buy it with a double supply. 100 rubles for 200 meters is quite inexpensive.

How to bend reinforcement correctly, all the ways

You should choose how to bend foundation reinforcement based on its diameter: with your own hands It’s quite easy to bend a small diameter, but for thicker reinforcement you’ll have to use special devices, homemade or specialized.

Among homemade devices, two methods are common. The first is when an ordinary pipe of suitable diameter is installed vertically and its base is poured with concrete so that it stands firmly.

The fittings are inserted inside all the way, and now the end protruding from the pipe can be bent by simply leaning on it. If this presents certain difficulties, then a second pipe is additionally put on the free end of the reinforcement, and now, due to the increased leverage, the thick reinforcement is easily bent.

Welding is also often used. By softening a section of the rod with heat, it becomes easy to bend. The same is done with a blowtorch and a hammer. After heating the bend point with a lamp, bend the reinforcement with a hammer.

The most radical way is to make an incision with a small grinder and then bend it completely using available tools.

It should be noted that methods using welding and notching are not the best - at the bend, in these cases, the strength of the reinforcement is reduced by up to 10%.

Crochet

The design of the hook for these purposes may be different, but this is not so important. The meaning lies in the presence of a hook as such, because it is used to thread the wire. The rules for tying reinforcement for the foundation are shown schematically in the figure.

Pay attention to the sequence of actions:

Bend the wire in half;
Follow the arrow, as in the figure, bring it into position for threading;
Insert the hook into the loop that will now be wound;
Place the hook loop inward between the free ends of the wire;
Without removing the hook, twist until tightened, but do not pinch;
Ready!

There are motorized screw hooks in which the wire is tightened by rotating a screw. It turns out very quickly and conveniently.

For strip foundation

The strip foundation reinforcement has two patterns for laying rods:

4 rod system: two at the base of the foundation, two at the top (used if the width of the foundation does not exceed 50 cm),
6 rod system: an additional longitudinal rod is placed between the two main ones (used in cases where the foundation width is more than 50 cm).

Bent reinforcement is laid at the corners, and the ends should protrude from the corner by at least 40 cm. Reinforcement connection nodes should be located apart from each other at a distance of no more than 60 rod diameters. For example, if 12 mm reinforcement is used, then the strapping should be every 72 cm or more often.

For columnar

This is a foundation that is placed on pillars that act as piles.
A tied one is placed inside the pillars before pouring. The tying of reinforcement for a columnar foundation is the same as for a strip foundation - either 4 rods, or 6 for large columnar foundations.

For vertical rods in this type of foundation, 12 mm reinforcement is used, since this is a vertical foundation. The cross rods can be thinner and smoother.

For wooden houses, it is allowed to use longitudinal and vertical reinforcement thinner than 12 mm. Sometimes, for the foundation of small wooden buildings, a welded frame is constructed from vertical rods connected with hoops like a barrel. This is incorrect, because with this bonding method you can only use welding, and this is not a completely reliable method. We have already talked about this above.

For slab

A reinforcement frame for a foundation can take the form of a two-dimensional plane, a mesh formed from reinforcement bars. The second option is volumetric, in the form of two meshes of intersecting reinforcement, located one above the other and connected by transverse rods.

Reinforcement - from 12 mm and above, up to 16 in private housing construction. The mesh cell size is 200x200 mm. The distance from the lower reinforcement belt to the pillow (or insulation) is 50 mm. The top belt is also protected from external influences by a 50 mm layer of concrete.

Cost calculation (price for work and materials)

Let's take as an example a strip foundation 10 by 10 meters. This is the perimeter of the house. In addition, there will be a foundation for internal load-bearing walls - two walls of 10 meters each. It turns out 60 m.p. foundation.

How much knitting wire will be required with the right approach?
Let's say the foundation is less than 50 cm wide - it will use a scheme with four longitudinal rods. In this case, in 1 linear meter of the foundation the following will be used:

4 longitudinal rods. That means at 60 mp. will be 240 meters.
4 vertical. With a foundation height of, say, 50 cm, their height will be no more than 45 cm.
4 x 45 cm = 1.8 m. 60 meters of foundation - 108 m.
4 transverse. With a foundation width of 45 cm, the width of the cross sections will not exceed 35 cm.
4 x 35 cm = 1.40 m. 60 meters of foundation - 84 m.

How much is it?

For longitudinal rods we use 12 mm reinforcement costing 25-30 r/m.p. 240 x 35(30) =6000 (7200)
For vertical and transverse rods, take 6-8 mm at a cost of 12-16 r/m.p. (108+84) x 12(16)=2304 (3072)

So, purchasing reinforcing rods for this foundation will cost from 8,304 to 10,072 rubles.

Now let's calculate the required quantity wire. 4 ties for a 4-bar foundation per 1 m.p. This, based on a maximum consumption of 50 cm per tie, is 2 meters of wire per meter of structure. We have 60 meters, so we need 120 meters of wire.

Attention: Wire is sold in kilograms. It is necessary to convert from meters to kg.

1 m of wire with a diameter of 1.2 mm weighs 9 grams, respectively, 120 m of wire with a diameter of 1.2 mm weighs about 1 kg, which costs about 50 rubles. The wire is cheap, so it can and should be taken with a double reserve of 240 meters for 100 rubles. All that remains is to calculate the cost of installation and knitting of the frame. As a rule, it is not calculated separately and is included in the total cost of pouring the foundation. In the regions, such work is cheaper, but the price range is approximately the same - 1000-2000 rubles per cubic meter. This price includes the construction of a trench, installation of formwork, binding of the frame, pouring concrete and removing the formwork.

The total length of the foundation we are calculating is 60 meters, width 0.4 m, height 0.5 m. Let's calculate the volume: 60 x 0.4 x 0.5 = 12 m3. With this volume, the cost of foundation work will be 12,000 - 24,000 rubles.

Useful video

How to knit reinforcement in the video below:

In contact with

The service life of a building depends on a high-quality foundation reinforced with reinforcement. The reinforcement frame preserves the spatial configuration of the foundation, the most common option of which is a strip foundation. Tying reinforcement for a strip foundation is a serious construction operation that determines the durability of the building and its resistance to external factors.

Naturally, the correct choice of concrete for pouring the foundation is important. However, the quality of installation of reinforcement in the frame plays an equally important role. Correct knitting of reinforcement for a strip foundation ensures reliable fixation of steel bars to each other and constant spacing when pouring concrete.

To ensure the strength of the reinforcement cage, it is important to understand how to properly knit the reinforcement for the foundation. The method is available for beginner builders who have mastered the manual technique of fixing steel bars. Let us dwell on this operation in detail, consider how to knit the reinforcement, and how to knit it correctly.

Performing this operation will require certain skills and perseverance.

Preparatory activities

Having decided to independently carry out the work of fixing steel bars, perform the preparatory work:

Calculate the load that the future foundation will bear. Considering the seriousness of the task, use the services of professionals.
Based on the calculation results, select the required brand and diameter of the rods, which should not be less than 12-14 millimeters. The use of rods of class A3 will allow, when making a frame, to bend them by 90⁰ without cracks, and rods of class A2 - at an angle exceeding 90⁰, while maintaining their integrity.
Calculate the need for tying wire and steel rods. The basis for determining the total volume of material is the pattern of tying reinforcement for a strip foundation.
Take care of assistants, as the knitting process is quite labor-intensive and tedious.

Methods for fixing rods

There are many ways to secure the steel bars of a mesh structure. Ensuring the immobility of the steel bars of the frame for concreting is carried out:

electric welding, which changes the structure of the metal and does not guarantee the immobility of frame elements;

Rods with a ribbed surface facilitate the knitting process

purchased metal clamps with a diameter of up to 4 mm, having a loop corresponding to the size of the rods and a clamp (hook). The use of connectors increases productivity, but requires additional costs. Their use does not require the use of tools;
elastic clamps made of plastic, allowing you to quickly connect the rods. The disadvantage is increased fragility at subzero temperatures, as well as the possibility of damaging the integrity of the fastenings when moving along the frame;
knitting wire with a diameter of 1 to 2 mm, made of annealed steel with low carbon content. It is optimal to use material with a diameter of 0.8-1.4 mm, which allows you to knit reinforcement for the frame without additional effort. A material with a diameter of 1 mm is not strong enough, and with a diameter of 2 mm the forces increase significantly.

Knitting reinforcement for a strip foundation using soft and easy-to-use wire is the optimal solution. Let's take a closer look at this option.

Knitting methods

Methods of fastening steel frame elements are carried out:

Completely manual, which requires physical effort, but provides reliable fastening at low cost.
Using semi-automatic methods that facilitate and speed up the fixation process, requiring additional acquisition costs.

If the rods are tied manually and fastening with loops is used, the elements will have to be connected separately

The manual fastening option is carried out using the following tool:

wire cutters or pliers, the working surface of which is rounded;
a self-made hook from a welding electrode or rod with a diameter of 3-4 millimeters;
a manual reversible device, the rotation of which is carried out by reciprocating movement of the handle;
special pliers, the operating principle of which is similar to a reversible tool;
a purchased crochet hook, the use of which is one of the simplest options.

Semi-automatic methods of fixing frame rods are carried out using the following devices:

An automatic knitting gun that ensures high efficiency and quality of work.
A screwdriver or electric drill equipped with a special attachment that allows you to quickly tie steel bars. You can use a regular nail bent at a right angle.

Let's consider the features of the main types of manual and semi-automatic tools, with the help of which a bunch of reinforcement for the foundation is carried out.

Crochet hook

Hand tools can be:

make it yourself from a durable rod or electrode;
purchase in specialized stores.

A practical and versatile option is a crochet hook.

Advantages of a manual device:

Ease of operation.
Cheapness of the tool.

The disadvantages include:

Low efficiency of work performance.
The need to apply certain physical efforts.

Despite a number of disadvantages, many developers prefer hand tools. With the help of a crochet hook, the reinforcement for the foundation is knitted reliably. To use a hand hook, you should first study the methods of tying reinforcement.

Hand knitting technology

Let's look at how to properly tie reinforcement to a foundation using a hand-held device.

There are several methods of knitting under the foundation. Let's consider a proven method, guided by which, perform the work according to the following algorithm:

cut a steel wire with a diameter of 1.2-1.4 mm and a length of about 20 cm for each attachment point;
bend the wire in the middle of the segment;
place diagonally at the point where the rods meet;
insert the working part of the hook into the resulting loop;
pull into the loop, using a hook, the ends of the wire located on the opposite side of the loop;
rotate the hook in the loop until the connection is strong.

When performing work manually, control the tightening force. By twisting the wire with increased tightening force, you can break it.

Wire is most often used, because it is a reliable and proven option.

Manual reversing device

A reversible tool, designed for manual twisting, is a screw working element that rotates when the handle of the device is moved back and forth. The tool handle contains a screw rod and a reversing mechanism.

How to tie foundation reinforcement using a reversible device? It's simple:

insert the hook of the device into the wire loop;
move the handle towards you in the axial direction;
move the handle to its original position;
rotate the hook again without re-fastening the tool, pulling the handle towards you.

Fast wire tightening.
Possibility of use in places with difficult access.
No fatigue when performing work.
Long service life when lubrication is carried out.
Ease of operation.

The only negative is the increased cost compared to a traditional hook.

The principle of action is similar for pliers used for knitting. The working planes fix the ends of the wire and twist them when moving the pliers. The use of reversible devices reduces the duration of the process of fixing bars and makes operations easier.

A knitting gun that independently grabs the structure and ties it

Automatic knitting gun

Using a gun ensures a strong binding of the rods for the base. The use of an automatic device has many positive aspects:

there is no need for individual cutting of wire, which is pre-wound on the tool drum;
the material is used rationally, since there is no waste representing wire cuttings;
high efficiency of the device - the loop tightening cycle takes no more than 1 second;
the ability to perform tightening work with one hand and support the bars with the other, without the help of auxiliary workers;
guaranteed quality of loops;
adjustment of tightening force and length of segments;
Possibility of operation from a rechargeable battery;
Equipped with an extension cord that allows you to tighten the hinges without bending over.

Disadvantages include:

Increased costs for purchasing a gun and special wire.
The need to train workers how to knit reinforcement for the foundation.
Difficult to use in corners and places with limited access.

Despite the set of advantages, in some cases, work on fixing rods can only be done using a hand hook.

To speed up the process, use a drill with an attachment

Having decided on the tool used for knitting, having prepared the necessary materials and performing the work, follow the following recommendations:

ensure the same distance (4-5 cm) from the horizontally located elements of the reinforcement frame to the soil, using wooden pads or non-metallic supports. The rods should not touch the ground at the bottom of the trench;
the immobility of perpendicularly located steel rods when fixed with wire can be ensured by using a simple device that clamps the ends of the rods with boards;
Do not drive vertically located rods intended for fixing horizontal rods into the soil. Use non-metallic coasters, which will prevent contact of the rods with the ground and reliably protect it with concrete from corrosion processes;
check the reliability of fixing the frame elements using wire. Errors in fixing the rods have a slight effect on the location of the reinforcement contour during manual filling. However, the use of a concrete pump that supplies the composition under pressure can affect the location of the elements, pushing them apart or displacing the structure;
Additionally, check the reliability of the fastening of the rods in the corners of the frame, which are a vulnerable area of any foundation. The ends of the rods located at right angles, which must have bends, are not allowed;
the criterion for correctly performed knitting work is the immobility of the spatial structure under the influence of human weight;

Ensuring the design of strengthening the assigned tasks is possible with the correct selection of the assortment of rods, determining the location and number of elements, according to preliminary calculations.

Remember, knitting the spatial structure rods only provides fixation of the frame elements. When pouring concrete, fix the reinforcement contour motionless, which guarantees the required performance characteristics of the monolithic foundation.

Conclusion

After reading the article and learning how to knit reinforcement to the foundation, you can independently carry out measures to fix the frame elements without resorting to the services of hired workers. This will save money and guarantee the reliability of the work, the result of which depends on the choice of the optimal knitting method and the use of high-quality materials.

How to knit reinforcement on a foundation manually: tips and tricks

How to knit reinforcement for the foundation correctly? Preparatory work. Basic methods of fixing rods and methods of tying reinforcement. Features of hand knitting technology.

The need to connect the old and new foundations arises when constructing extensions or other structures in order to increase the size of the usable area of the building.

In the immediate vicinity of the building being used, a concrete slab, strip is poured, or supports (pillars, screw piles) are installed.

Some of these types of foundations need to be “connected” to the foundation of the structure. This task can be accomplished in several ways.

Important points before docking

Before you begin work on increasing the area of your home with extensions, you need to obtain the appropriate permits. All distances from nearby buildings and neighboring plots must be taken into account and maintained.

The extension can be built as an independent building or integrated into an existing one. It is important to note that the building already in use must be older than 1 year. During this period of time, it will give the necessary shrinkage and will not carry away the new foundation built nearby.

The old and newly constructed foundations must be of the same type. If a residential building is installed on a strip foundation, the extension must be built on the same one. This will significantly reduce the risk of deformation of the combined, docked base.

Tools and materials for work

To build the foundation, a significant amount of excavation work will be required, as well as reinforcement and concreting.

Tools you will need:

Bayonet and shovel shovels;
A stretcher or garden wheelbarrow for moving soil;
Hook for tying wire;
Tape measure, marker, pegs, rope for marking the site;
A bubble or water level, but a level is the best choice.

Materials you will need:

Reinforcement bars with a cross section of 8-10 mm;
Knitting wire;
Cement grade not lower than M400;
Sand and crushed stone of the middle fraction for preparing cement-sand mortar and forming a shock-absorbing “cushion”;
Metal studs (you can use reinforcement with a cross-section of 12 mm) to connect the new foundation to the old one.

Connection steps

In order to properly combine the two foundations, you need to think through in advance all the nuances of each stage of work. It is necessary to choose a method for “ligating” the bases. Several options are possible.

Method number 1: “tape-tape”. Used to build a foundation of similar width and depth. It is carried out in several stages.

They are marking the site for the construction of an extension.

A ditch is dug around the perimeter of such a width that it can accommodate the formwork for pouring the tape of the required parameters. Level the bottom and walls of the dug trench using shovels.

A sand-crushed stone fill is made, consisting of 5-7 cm of compacted sand and 10-15 cm of crushed stone, which is also compacted.

Tamping is done with a vibrating plate and available materials. For example, a barrel half filled with stones, a piece of timber.

Formwork is assembled in a trench from any suitable lumber.

A reinforcing belt is made, consisting of two tiers of mesh with a mesh size of 15x15 or 20x20 cm, connected to each other by vertical metal rods.

A gap of 1.5-2.5 cm wide is left between the foundations, which is filled with mineral wool. The formwork is limited at the junction of the bases with a wooden or metal shield.

Using a concrete mixer, a cement-sand solution is prepared in a 1:3 ratio (1 part cement and 3 parts sand, water and filler in the form of crushed stone or gravel).

Concrete is poured into the formwork in layers. They pierce it repeatedly with a rod of reinforcement so that all the air comes out of the solution.
After the concrete has set, the formwork is dismantled.

The damper joint of the foundations is closed with a rubber band or waterproofed in another way.

This method of tying the bases allows you to be sure that the new one will shrink and carry the old one with it. After the strip foundation shrinks, it is increased in height so that it is in the same plane as the base of the residential building.

Method number 2: “plate-tape”. It is carried out similarly to the previous one, with the only difference that the damper seam is made longer: along the entire slab.

This joining method is optimal only for stable soils, when there is confidence that there will be no significant subsidence of the extension after its construction.

Rigid connection

To rigidly tie two foundations, you will need to connect them using reinforcement bars. You will need at least 20 rods per 1 m2.

To install metal rods, holes are drilled in the old foundation, reinforcement is placed in them and concreting is carried out.

Rods are also laid on the side of the new foundation and the joints are filled with concrete.

Construction of a columnar foundation

The best choice for building an extension would be to install it on poles. The soles of the supports should be located 15-20 cm below the freezing point of the soil, which will prevent them from moving during soil movements during periods of freezing and thawing.

If a columnar base is built, the house and the extension are connected at the level of the lower floors.

Possible difficulties

If the construction site has a high groundwater level (groundwater level), it is first necessary to make wall or ring drainage.

For more tips, watch the video:

When building a new foundation on moving soils (sand or sandy loam), the corners of the old one are strengthened with piles buried at least 100 cm into the soil.

The most popular foundation in private buildings is strip foundation. Most often this is a concrete strip on which the walls of the house rest.

Concrete can withstand large static loads (because it can withstand enormous compressive forces), but is vulnerable to dynamic loads.

Under tensile stress, which often occurs during movement and frost heaving of the soil, the tape may crack.

To prevent this from happening, it is reinforced with a metal rod. How to properly reinforce a strip foundation with your own hands?

Which reinforcement is best for a strip foundation?

Reinforcement of a strip foundation can be done with steel or composite materials, i.e. metal or fiberglass rods. They are sold in coils from 50 to 100 meters, sometimes in the form of cut metal from 6 to 12 meters.

The advantages of fiberglass reinforcement for foundations are corrosion resistance, chemical inertness, non-magneticity, lack of electrical conductivity and static electricity. This material is used, for example, when constructing foundations for technical structures, for which the absence of radio interference is important.

It is rarely used in private buildings: due to poor bending stretch, it does not perform its main function very effectively.

Features and diameter of reinforcement for strip foundations:

for verticals and crossbars, a smooth or corrugated rod about a centimeter thick is used;
for the longitudinal part of the frame, which takes on the main loads, choose corrugated material up to two centimeters (for a private house this is enough);
for knitting use steel wire or clamps;
sometimes welding is used to connect the rods. Metal marked “C” is suitable for it.

For foundation reinforcement it is not allowed to use:

profile corners;
metal pipes;
chain-link mesh, incl. with a large cell;
iron cables;
plastic bottles, etc.

How to calculate reinforcement for a strip foundation

For shallow foundations (no deeper than 90 centimeters), the frame is made of two longitudinal rows, two rods per row. For buried ones (below the freezing of the soil, i.e. deeper than one and a half meters), longitudinal rods are placed at three to four levels.

Distances:

between verticals the step is from 40 to 80 cm;
between horizontal lines – from 30 to 60.

note

01/52/2003 SNiP specifies the minimum amount of metal: 0.1% of the foundation cross-section. For example, if the height of the tape is 1.2 meters and the width is 0.4, then the total cross-section of the reinforcement is from 480 square millimeters.

The minimum diameter of the rods depends on the reinforcement conditions:

longitudinal rod for a side up to 3 meters long - 1 centimeter;
more than three – 1.2;
crossbars with a frame height of up to 80 cm - 0.6 cm;
more than 80 – 0.8 cm.

For clarity, we give an example of calculation.

Initial data:

Construction: 5 by 5 meters;
Tape height: 0.6 meters (a two-level frame will be required);
Width: 0.3 m;
Step between verticals: 0.5m.

Quantity of reinforcement for strip foundation: (to the obtained figures you need to add a margin of about 10%):

Length of longitudinal rods: 20 meters multiplied by 4 = 80 meters;
Vertical pins, with a five-centimeter indentation from the surface: 1.4 meters multiplied by the number of intersections (51) equals 71.4 meters;
Cross members: 40*0.3*2 = 24 meters;
At the intersection you need 30 centimeters of wire for knitting, four joints per section. With a reserve - about 70 meters.

Strip foundation reinforcement scheme

The procedure for reinforcement is as follows:

2. Fill the concrete base with a layer of 5 centimeters to protect the metal from corrosion. Instead of a sole, you can use a more economical option: place stones or broken bricks under the vertical rods. But this is a long and energy-intensive method.

4. Place the calculated number of transverse rods on the concrete in increments of 0.8 cm.

5. Lay two rows of longitudinal rods along the walls of the ditch. Link intersections. Fragments of horizontal lines are overlapped together. The overlap length is 50 rod diameters minimum.

6. Install vertical rods at the joints. They are placed perpendicular to the laid lower level; there should be no deviations from the vertical. Bind.

7. Attach the upper tier of crossbars to the verticals. The overlap of the ends of the frame should be at least 20 centimeters.

8. Lay the upper longitudinal rods and fasten them to the rest of the structure with clamps or wire.

9. Fix the frame relative to the formwork. There should be at least five centimeters between the metal and the boards. The same minimum distance is left between the rods and the upper border of the concrete.

To protect both the frame itself and the concrete from the development of corrosion, the reinforcing bars should be cleaned of rust and dirt before installation.

To work, you will need a tool: clamps, special hooks for tying wire, cloth or metal scissors.

A homemade hook can be made from a piece of reinforcement: sand the end of the rod 6 or 8 millimeters, bend it and put a wooden or plastic tube on the opposite end. The handle should be located at an obtuse angle to the working part of the hook. It is fixed on both sides with thrust washers, and the washers are secured by welding.

Actions when linking:

Place a wire bent in half under the desired joint of the rods.
Hook the fold loop.
In two or three turns, tie a loop to the other (double) end of the wire.

A problematic point during installation is corner reinforcement. Concentrated tension is formed in the corners; these are the most loaded points. To compensate for the load, L-shaped or U-shaped reinforcements with clamps are used. L-shaped ones are used for obtuse angles.

A) using an overlap and a paw, B) using an L-shaped clamp. 1. horizontal reinforcement, 2. overlap, 3. tab, 4. vertical reinforcement, 5. transverse reinforcement, 6. additional transverse reinforcement, 7. L-shaped clamp, d - reinforcement rod diameter

Clamps of the required size and cross-section are installed instead of ordinary vertical rods. In corner connections there should be twice as many clamps as in linear sections.

The need to connect the old and new foundations arises when building an extension to an existing house: this is the easiest way to increase the usable area of the house if you achieve a strong and reliable connection. Different types of foundations can be used for extensions, and in all cases it is necessary to choose the correct type of foundation connection. How to attach a new foundation to the old one, and what connection methods can be used during construction?

Difficulty connecting bases

There may be several answers to the question of how to properly build a foundation, since the choice of specific solutions directly depends on the house itself. If you are going to add an extension to a building you just built with your own hands, the foundation connection will be different than when adding an extension to an old house. Let's look at the main options for connections:

If the building was built a long time ago, it had time to go through all the stages of shrinkage and firmly took its place in the ground. In this case, it is most appropriate to connect an extension with a strip or slab base using a rigid coupling - a connection based on a common reinforcement frame.

It is created by drilling holes in concrete and inserting reinforcing bars into them. This solution is not used very often, since it is only suitable for non-heaving soils with high bearing capacity.

If the house has just been completed, and the shrinkage processes will continue for several more years, it will be necessary to build a new independent foundation with an expansion joint. It will allow you to connect the two parts of the building, but at the same time provide compensation for any impacts during shrinkage. The expansion joint also serves as a heat insulator, further protecting the lower part of the house from the penetration of cold.

The second option is most often used on heaving soils, where it is difficult to predict how shrinkage will occur and what effect it will have on the foundation of the house. Building an extension with an expansion joint means protecting it from cracks in the foundation, and it can last for a very long time.

Rigid method of connecting foundations

If you have purchased an old house, it is advisable to ask the previous owners in as much detail as possible in advance about all the features and time of construction of the house. The most difficult thing is when the building was built a very long time ago, and during its service it managed to change several owners. It will be difficult to find information about when major foundation repairs were performed and what type of foundation was used for this structure.

To check this, a trench is dug along the house, after which you need to assess the depth of the foundation and determine its condition. If it is still strong enough and will not require repairs soon, you can begin preparing for the construction of a new room. Drawings are prepared indicating the dimensions of the new room, the location of doors and windows, as well as other information.

To ensure a strong connection between the old foundation and the new one, you need to do the following:

The dried base will be completely monolithic and firmly connected to the old foundation of the house. Such an extension will receive reliable support, and any changes in its foundation will be reflected in the foundation of the house. A single basis is a reliable, although quite labor-intensive, choice.

Connecting foundations using an expansion joint

How to attach a new foundation to an existing one if the construction of the building has just been completed, and the owners realized that they would need another room. In this case, it will be necessary to construct a new foundation with an expansion joint. The buildings will also be connected to each other, but if the shrinkage is uneven, it will not affect the foundation of either the main house or the extension to it.

The construction practices are very similar, but there is one very important difference. You cannot use a connection using reinforcement; the only option for attaching a foundation to an existing foundation is to prepare an expansion joint.

It is an ordinary board, the thickness of which is 2-5 cm. It is wrapped in roofing felt, polyethylene or other material that is resistant to moisture, after which it is placed in the space between the old and new base.

The new foundation is poured with concrete onto a reinforcement frame; construction is practically no different from the first option. However, after the concrete hardens, the expansion joint is removed, and the space is filled with insulation and polyurethane foam. These are relatively elastic materials, therefore, during ground vibrations and during shrinkage, they will not allow cracks to appear in the foundations of the building and its extension.

This is a very simple solution that will solve many problems. An expansion joint reduces the risk of damage to the foundation as a result of soil movements, and the building with an extension can last much longer. Such a seam is absolutely necessary: if it is not taken care of, within a few years the building will require a major overhaul with the dismantling of the floors.

The construction of foundations is most often carried out in the autumn. At the very end of the construction season, you can pour the foundation of the house, after which it will settle within six months, and after that you can safely move on to further construction.

Construction of a columnar foundation for an extension

How to attach a foundation to an old foundation if a simple frame extension is planned? This is a fairly simple solution, since frame buildings are very inexpensive and can be erected quickly, and due to their low weight, a lightweight foundation is sufficient for them. Typically, monolithic reinforced concrete columns or metal screw piles are used for this, which are also relatively inexpensive.

It will not be difficult to install a lightweight frame structure. First of all, the dimensions of the extension and the number of pillars that will be required to support the weight of the extension are calculated. Usually they are located at a distance of 1-1.5 meters from each other, in addition, they must be placed in corners and in all places that will be subject to increased load.

Concrete pillars can be made from asbestos-cement pipes, which are dug into the ground at a level below freezing of the soil, or you can use ordinary concrete blocks. Asbestos pipes will serve, in this case, as permanent formwork.

Another option is brick columns; it will not be difficult to build a masonry, and it will be very durable. A shallow foundation is used only for the lightest structures, and if you want to build an extension from logs or other durable materials, it is better to build a strip or slab foundation for them.

Waterproofing is laid on the pillars, after which the lower framing of the frame can be placed on them and construction can continue. At the junction of the walls of the extension and the house itself, an expansion joint is also provided from waterproofed boards or other materials, and subsequently this place is firmly insulated and covered with polyurethane foam.

The advantages of a columnar base are many:

It is being built quickly. You can install several concrete columns much faster than pouring a strip base and then waiting many days for the concrete to dry completely. The columns do not need to be poured: if a small frame extension is being built, ordinary concrete blocks will be sufficient.
There is no need to involve the help of other people. You can install the posts gradually; it will not be so difficult to cope with this work alone. But there is also a minus: in order for the pillars to remain at the same level, you should not delay construction too much after installing them.
This is an inexpensive solution. Little building materials are required, in addition, sometimes the base of the extension can be built from what was left on the site after the main construction.

Strip foundation for a wooden extension

Timber and logs are the most common materials for the construction of light extensions: they are affordable, help create comfort in a living space, and in addition, they are the most environmentally friendly materials. For extensions made from these materials, a strip base made with an expansion joint or a rigid screed is most often chosen. Such a structure is a reinforced concrete strip, which is poured on a bed of sand and crushed stone.

A strip foundation is easiest to connect to an existing foundation; both a rigid connection method and an expansion joint can be used. But there is another solution: if you are building a house yourself, you can foresee in advance the location of the extension in it and include it in the project. In this case, the foundation for it can be prepared immediately, and after its shrinkage is completed, all that remains is to implement the rest of the project.

The strip base is built quickly; it is erected as follows:

The site for the extension must be prepared for construction: it must be leveled and cleared of construction debris. After marking the territory, a trench is prepared to the depth of the main foundation.
Formwork is installed along the edges of the new tape, and a reinforcement cage is laid along the bottom. Much depends on the correct reinforcement, since it will have to withstand the weight of the building.
Mortar is poured along the entire length of the new foundation. It is advisable to fill the strip base completely at one time, otherwise it will not be so strong. After this, it should dry completely.

The finished strip base of the extension is covered with multi-layer waterproofing: roofing felt and bitumen mastic can be used for this purpose. Protecting walls from moisture is necessary regardless of construction materials, since any walls will gradually collapse if they are exposed to extreme conditions.