Reinforcement of strip foundation. Tying reinforcement for the foundation with your own hands How to properly tie reinforcement in a strip foundation

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:

1. Bend the wire in half;
2. Follow the arrow, as in the figure, bring it into position for threading;
3. Insert the hook into the loop that will now be wound;
4. Place the hook loop inward between the free ends of the wire;
5. Without removing the hook, twist until tightened, but do not pinch;
6. 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, the purchase of reinforcing rods for this foundation will cost from 8304 to 10072 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:

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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 under 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's look at 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 methods

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:

1. Completely manual, which requires physical effort, but provides reliable fastening at low cost.
2. 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.

Crochet

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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.

Advantages of the device:

• 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;

One of the advantages of private home ownership is the ability, if necessary, to increase the usable area by adding an additional one to the main structure. In this way, residential or utility rooms are obtained for whom some functionality is no longer enough. In order for the extension to improve the living conditions of the owners, and not create problems for them, it must be built using existing technologies, and not according to the principle “somehow, as long as it’s cheaper.” Therefore, we will figure out how to properly attach to a house, relying on generally accepted methods and the experience of FORUMHOUSE users.

• Foundation for extensions
• Wall materials
• Ways to connect walls
• How to make a roof
• Functionality of extensions
• Design of extensions

Foundation for extensions

There are two types of foundation construction for an extension - rigid coupling and expansion joint.

Rigid coupling
Such a connection is designed for non-heaving soil and is justified when erecting a heavy structure of two or more floors, but only if the main building has already settled and settled. The new foundation must be of the same type as the main one (strip, slab) and be the same in depth, taking into account possible shrinkage. The bundle of tapes is made using reinforcement, for which the foundation of the house is dug out to the full depth; in the working area, too much exposure is fraught with deformation.

Holes for reinforcement are drilled in a checkerboard pattern in the foundation sheet, on the basis that their length is 35 times the diameter of the rod, and the length of the reinforcement itself is twice as large as the depth of the holes. The reinforcement is driven into the holes, then the protruding part will be filled with concrete, creating a common monolith. Bonding of slabs is possible if the thickness is more than 40 cm and there is a protrusion of the main slab of 30 cm; for coupling, the reinforcement is beaten and welded to the reinforcing frame of the new slab.

To perform a rigid coupling, it is necessary to take into account that the poured one connected to the main one must settle, ideally for a year. If it is not possible to withstand such a period, it is better to use another method.

Expansion joint
The most common type of bond is when a completely independent one is poured near the old foundation. Optimal on heaving soils for lightweight structures, the thickness of the seam is from 2 to 5 cm. To aesthetically connect the foundations, and
the seam at the junction remains the same along the entire length; boards pre-wrapped in polyethylene or roofing felt are used. Since the load on the base will be less, the subsidence will also be less, and the seam will allow the extension to “play” as planned, without affecting the integrity of the house.

During the construction process, the joint between the walls is filled with insulation, and the seam itself is subsequently sealed using elastic means or covered with special strips. One of the users found an interesting solution - stainless steel linings, between which there is a layer of corrugated rubber.

zhp User FORUMHOUSE

In principle, you can buy such a “cap” for an expansion joint, immediately properly insulate the space between the walls, close it from the street with a “cap”, and if over time there is shrinkage, compression or stretching, the “cap” will compensate for this moment. And in order to return the rubber to its previous shape, you can unscrew the screws from the missing side and drill again, in new places in the bricks.

Since the foundations are not connected to each other, you can choose any type for an extension, based on the characteristics of the soil and the expected load. It can be slab (monolith or USHP), strip (MZF or freezing depth) or columnar (pile).

Users of the portal prefer joining foundations through an expansion joint, as the most justified and safe way.

mfcn FORUMHOUSE Member

No matter how good (non-heaving) the soil is, if it is not rock, then you should expect shrinkage of the foundation of the extension in relation to the main house. Accordingly, measures must be taken to ensure these shrinkages are non-destructive and ensure acceptable functional properties of the structure. Hence: an extension is actually a new house next to an old one or a light structure, the movement of which is permissible, and violations of the horizontal floor and jamming of doors are permissible.

Materials

The modern building materials market offers a large selection to suit every taste and budget. The greatest demand today is for extensions made of foam concrete, aerated concrete, cinder block and similar large-format masonry varieties and frame structures. Frames are in the lead due to the speed of construction, relative accessibility and simplicity; in terms of energy efficiency, they are not inferior to stone buildings due to the use of insulation.

However, if possible, it is recommended to choose a material similar to the main one: a wooden extension to a wooden house, etc. This is especially true for houses that are not supposed to have the same façade as the extension. If you plan to use siding or similar cladding, the choice is unlimited.

Options for connecting walls

An extension to a house can have four walls or three, then the role of the fourth is played by the outer wall of the house. Four walls are relevant in extensions made of masonry materials; a wall joint is not required, and maintaining the level of the masonry results in an even seam. The presence of a layer of insulation between the walls allows the use of thinner blocks for the adjacent wall. In frame construction, sliding ties are used: two vertical beams are placed on the wall, between which the vertical beam of the extension is inserted.

Connecting beams in an extension

When an extension is assembled from profiled or laminated timber or logs, the walls are connected to the house either with metal brackets or with special galvanized corners with a shelf of 63 mm or more.
The corners are placed on self-tapping screws, leaving a small gap for shrinkage. The seam in both cases is closed with a flashing or platband. Also, the joining of beams in the extension is carried out using a tongue-and-groove system, the grooves are selected in the load-bearing wall, the tenon is cut out on the built-in segments.

Roof installation methods

The extension is placed under a common roof, when a rigid connection is made; if an expansion joint is selected, it is easier to cover the building separately, sealing the junction. Depending on the roofing material, the seam is covered with a stainless steel apron, 30 cm wide, or with a special decorative element.

Rigid connection to a house made of timber.

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The shrinkage of the extension in relation to the main house imposes certain restrictions on the arrangement of the roof. Therefore, in practice, making an extension with a roof like a continuation of the existing one should be considered and justified.

Functional

As with the construction of a house, before constructing an extension it is necessary to determine the functionality in advance, since different purposes require appropriate construction manipulations. If you plan to make living rooms, enhanced insulation is necessary. Communications are immediately laid out for the boiler room, bathroom or kitchen. It’s easier to change your mind and plug a couple of plastic pipes into the wall than to decide that another bathroom is more necessary and dig into a newly built one.

Legalization of extension

Before constructing a major extension, permission must be obtained. Within the city limits, this is done by the department of architecture and urban planning; in rural settlements, by the administration. You can build without papers, but then when you try to sell, bequeath or donate a house with an extension, you will still have to draw up documents, but it will be more difficult, through the court. In the event of a confrontation with neighbors, they can sue for self-development and insist on demolition.

For anyone planning an extension, it is useful to study the topic on the forum. The experience of the user of our portal in the topic is also interesting. The article will help you decide on the type of foundation for the future structure. And our video will teach you how to work with aerated concrete.

More than half of the owners of country houses sooner or later face the need to expand the area of ​​their home. Naturally, this is easiest to do at the design stage of the building, but at this time, as always, the limited construction budget does not allow for a larger area. What should you do if you have received a residential building and want to build an extension to it? It is recommended to start with the most important stage - connecting a new foundation for an extension to the old one. Let's figure out what kind of foundation to pour for an extension, and how to properly combine the base of the house and the foundation of the attached module.

The need to join two foundations

Home owners often have a need to increase their living space. A convenient and practical option for expanding real estate is to add block modules, such as a veranda. Such premises are open, so time can be spent here only during the warm season.

Before constructing the module, it is necessary to take into account that an extension to the house is possible only if a list of conditions is met: obtaining the appropriate permits for the construction of new structures, maintaining all permissible distances to neighboring houses and plots, ensuring independent settlement of all elements of the house relative to each other.

Like any construction process, the construction of a veranda should begin with the development of a project. This module near the house must be positioned in such a way that you can get from it into the main room, so it is customary to build a veranda at the end of the house or near the main entrance.

Despite the simplicity of the design, the extension must be completed efficiently and competently, and one of the first problems that arises with this is the installation of a foundation for the building. The best solution when constructing a foundation for an extension next to a house is considered to be combining foundations. Otherwise, cracks may appear in the walls, subsidence of the floor and other troubles may begin.

Features of connecting the old and new foundation

To understand how to properly build a foundation for an extension, you should find out how the foundation under the house is made and what it is like. If the foundation is strip, then you need to know its width; if it is columnar, then the overall dimensions of the pillars, as well as its depth. Experts strongly advise against building a foundation for the extension, which is distinguishable from the foundation of the house. Thus, if your house is located on a monolithic reinforced concrete strip, it is better not to save money and not build a columnar base for the extension.

The bottom line is that different types of foundations interact with soils differently, and accordingly, their shrinkage is different. Therefore, in order not to want to take risks, it is better to bet on the same grounds. The depth of the foundation of the extension must match the depth of the foundation for the house - this avoids distortions. Measuring the depth is quite simple. To measure the width, take a metal rod and bend it at a right angle.

After this, hold the bent part horizontally in your hand and thread it under the foundation. Turn it so that the hook hooks on the opposite side. Next, make a mark on the rod and remove it. You can use the serif to measure the width of the base. In addition, the foundation for the block module must be connected to the existing one, because otherwise the new walls will move away from the old building after some time. And this provokes the formation of cracks and distortions.

An important point that you need to pay attention to if you are going to connect the foundations together is that in the spring there will be a decrease in the bearing capacity of the soil. As a result, its humidity increases. A building built on a new foundation will experience additional shrinkage in the spring.

Considering the fact that old and new buildings may have a significant difference in weight, it is worth understanding that subsidence of the foundations will occur unevenly. Therefore, to connect the foundations between them, you should wait one season before work and provide for a technological gap. Such a gap, as a rule, is a gap that has a size of approximately 20 - 40 centimeters, in which pieces of reinforcing bars are placed that protrude from the foundations.

To expand the foundation, ordinary concrete mortar or reinforced concrete is used. In order for the old and new parts of the foundation to be firmly connected to each other and form a monolithic structure, before pouring the new foundation with concrete, it is necessary to strengthen the foundations: weld the reinforcement of these parts of the foundation or drill reinforcing bars into the old foundation.

Methods for connecting two foundations

The connection of two foundations can be carried out based on one of two solutions: constructing the foundation of the extension separately or rigidly combining it with the foundation of a residential building. When choosing a specific solution, it is recommended to take into account the severity of the attached module and the quality indicators of the soil on the site. If it is uniform, and the built house has not undergone significant shrinkage over time, you can combine the foundation of the building and the base of the extension into a single structure. Otherwise, you should think about building a separate foundation, which will be in contact with the base of the house through an expansion joint.

Rigid connection between the base of the house and the extension

When building a house with your own hands, the most difficult thing is to make a full-fledged rigid connection to create a single residential building-extension structure. As a rule, such a solution is relevant for a situation where the site has slightly heaving or non-heaving soil (when the settlement of the new foundation can be predicted), as well as in the case where it is planned to build a two- or more-story extension with a house under one roof. After the work is completed, a single design will be obtained.

The “tape-to-tape” connection between two strip foundations with your own hands is carried out in this way:

• First you need to dig out the foundation to the depth of the foundation of a residential building; the length of the trench should be about 1.5-2 meters. You should not dig up the entire side, but only part of it, while creating a sand cushion.
• Drill holes in the base of the house that have a diameter equal to the diameter of the reinforcement. For the middle part of the strip, a hole is drilled to a depth of ¾ of the width of the strip foundation in a checkerboard pattern and for the corner parts - to 0.5 meters.
• In the holes that are drilled ¾ of the width of the tape, you need to drive reinforcement with a longitudinal slot into which a wedging insert, for example, made of wood, is inserted. Drive 14 mm reinforcement with a periodic profile into the holes made half a meter long.
• Next, they are engaged in the formation of the frame of the future foundation, using the outlets of driven reinforcement as elements of the new foundation. To join the next parts of the base, releases are made that are 30-40 centimeters long, which are subsequently welded.

A rigid connection for an open contour is formed in a similar way, only the reinforcement is driven in slightly differently and more of it is used per unit area at the points of contact of the two bases.

A rigid “slab-to-slab” connection between a slab foundation and the base for an extension can be made if the foundation is thick (from 400 millimeters), or if there are slab protrusions at the base of the residential building from the base part. As a rule, such protrusions are left when constructing a foundation for a building made of aerated concrete. In this case, the base should protrude by at least 30 centimeters, which allows the slab reinforcement to be exposed and then welded to the frame of the new slab foundation.

If there is a large difference in the weight of the new and old buildings, for example, a light veranda is attached to the house, the level of their shrinkage will differ significantly. Therefore, it is not recommended to rigidly tie the foundations of these structures. In this case, you should pay attention to the construction of a separate foundation for the extension.

Separate base and expansion joint

The simplest and therefore most common option for laying a foundation for an extension is the construction of a separate foundation, which is located in close proximity to the base of the house. In this case, it is most reliable to work in a closed circuit, when you erect a full-fledged reinforced concrete grillage near the house. Between two foundations, waterproofing is carried out by laying sheets of roofing felt.

You can also use thermal insulation material or tow. The essence of the method is simple - to create a layer that allows the new base to play during settlement, without damaging the foundation of the house. When calculating the connection of foundations using an expansion joint, it is customary to focus on the indicators of the soil mixture, as well as the potential loads from the extension on the area under its base.

The calculation of the foundation is carried out in the same way as when constructing a deep or shallow strip foundation. Before making a foundation, you need to take into account an adjustment for future shrinkage, which is implemented by laying a new foundation slightly higher than the old one. The new structure will eventually settle to the depth of the foundation of the residential building. For the construction of a frame extension, a columnar foundation is used, due to the low weight of the structure.

Another option is to place the extension on a concrete pad. They are easily molded directly on site. Pre-impregnate the finished piles with mastic, waterproofing material or other impregnations for protection, after which they are installed in a mold and filled with concrete.

The pillars are spaced from each other at a distance of approximately 1 to 1.5 meters, depending on the overall dimensions and weight of the attached module. Determine the height at which you will place the floor, cut them to a certain size. Next, the building frame is attached to them. In just two days you can begin construction, which significantly reduces the work process.

Ideal option for connecting foundations

Already at the stage of building a house, you should think about the fact that after a certain time you will want to expand your home possessions. It is much easier to lay the foundation for an extension at this stage. This is the ideal foundation technology. This approach will allow you to create a rigid structure, and you will not have to think about expansion joints and other design solutions.

In the meantime, you can cover the area that is empty in the meantime with decking - temporary structures. This approach will do nothing to a well-waterproofed foundation. In addition, during this time the base will take the strongest position and reduce the risk of settlement during the construction of the above-ground part of the extension.

Thus, a situation often arises when an extension or a new building needs to be erected next to the house. When attaching a new foundation to an old one, it is necessary to give the new part time to harden well. Ideally, at least a year should pass from the stage of designing the foundation and laying it to erecting the walls. In this case, it is necessary to take into account factors such as the topography of the site, the type of soil, the weight of the structure and other features.

One of the stages of foundation construction is the creation of a reinforcement frame. It is this design that is responsible for the strength of the foundation under the house. In combination with concrete, it forms a reliable support for the walls.

Knitting reinforcing bars under a strip base is considered the most suitable way of fastening the metal base of an entire reinforced concrete structure. This option not only preserves the linear and spatial shape of the frame, but also makes it possible to balance the structure to take the optimal position under the influence of the created loads.

Correct knitting prevents the connected elements from moving relative to each other.

Rules for reinforcing strip foundations

For greater strength and reliability of the foundation under the house, it is necessary to follow the rules for creating a reinforcing frame:

• You need to use only high-quality durable fittings.
• Smooth rods should not be used for reinforcement, since in this case the adhesion of the metal and concrete mortar, and, accordingly, the strength of the entire foundation is reduced.
• It is recommended to perform the longitudinal connection using the overlapping method.
• The knitting of reinforcement in the corners of the frame and at its intersections must have special strength.

Methods and schemes for knitting reinforcement cages

Most often, the reinforcement frame is a three-dimensional box-shaped structure made of horizontal and vertical rods. There are several ways to create a metal skeleton:

• Four lattices are created from the rods, which are connected to each other, forming the edges of a rectangular box.
• Rectangles with rounded corners are made from reinforcement. Then the rectangular rings are connected on the sides using long rods.
• The most durable and expensive method is considered to be creating a frame in the form of a rectangular crystal lattice. In principle, this option repeats the previous methods, but is distinguished by greater internal reinforcement.

Wire knitting patterns

Now let’s answer the question: how to properly knit reinforcement for a strip foundation? You can connect reinforcement bars using tying wire according to several schemes:

• A dead knot.
• Cross knot.
• Double-row knot.
• Tie knots of wire in the corners.
• Knitted in a bun without pulling.

In any case, you will need a special knitting device for the job. You can purchase a tying gun for rebar in specialized construction stores. A simpler device is a crochet hook. As a last resort, you can use ordinary pliers. The classic version of tying reinforcement using wire involves performing the following steps:

• Cut a wire about 30 cm long and fold it in half.
• The wire is taken in the left hand, and the knitting device is taken in the right hand.
• The wire is brought under the connection of the reinforcing bars and the hook is inserted into the wire loop.
• The rods are wrapped around the wire and its ends are placed on a hook.
• The knitting device is turned in a clockwise direction so that the ends of the wire are wound together.
• During the knitting process, the main thing is not to overtighten the wire to avoid breaking it. According to the advice of experienced craftsmen, it is enough to make three turns of the hook.
• The hook is pulled out of the loop - the connection is complete.

The entire knitting process is very labor-intensive and time-consuming, since reinforcement of strip foundations requires volumetric frames of sufficiently large dimensions.

Step-by-step instructions for laying and tying reinforcement

Knitting a reinforcement cage and putting it in place for one person is quite difficult and inconvenient. It is best to carry out the work as a team of two or three people.

The simplest and most convenient method is considered to be tying reinforcement on the ground and then laying the finished frame elements in a trench.

You need to create a metal skeleton in a certain sequence:

1. The reinforcement bars are being prepared. To do this, you need to cut the long rods to the desired length.
2. Two long rods are laid on a flat area and their ends are aligned.
3. Stepping back about 20 cm from the edge of the rods, one of the methods is to tie horizontal struts on both sides.
4. Maintaining a distance of 20 to 40 cm, tie similar spacers along the entire length. The result is one frame element.
5. To get the second part, you need to repeat the steps.
6. Next you need to fasten both parts together. To do this, two horizontal struts are tied along the edges of the structures.
7. Now the frame is tied along its entire length in the same way.
8. Pads with a height of about 5 cm are installed at the bottom of the trench. The bottom row of the frame will lie on these pads. Supports are installed on the sides of the trench to hold the mesh in the desired position.
9. Next, measure the unknitted corners and joints and cut off the corresponding pieces of reinforcement. These sections will be used to link the mesh collected on the ground into a single structure.
10. The reinforcement is knitted using the overlapping method. First, the lower turns are tied, then they move on to the vertical posts, and lastly, the upper turns are knitted.

Other methods of connecting reinforcement

Tying reinforcement is considered the most reliable way to connect reinforcement bars when creating a frame for a strip foundation. However, there are other options for mounting a metal skeleton:

• Using welding equipment. Having a welding machine in your arsenal and some skills in working with it, you can quickly and easily create a frame for a foundation from metal rods. But in this case, it is worth taking into account the features of such a reinforcement connection. First, welding thins the metal, making it more brittle. Secondly, the welded frame will be reliable only if the metal and electrodes are correctly selected, and all norms and rules are followed.
• Overlapping connection. This method involves not a transverse, but a longitudinal connection of the rods. In this case, individual ends of the reinforcement have an outlet of at least 15 cm for subsequent winding with wire.
• Using plastic band clamps. This method can be used when building foundations for small structures. Connecting with plastic clamps makes the knitting process somewhat easier. However, it is worth remembering that such a frame is less resistant to loads, and under the influence of low temperatures the plastic may burst.
• Using clamps or brackets made of plastic or steel.

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