Strip foundation reinforcement meter. How to properly reinforce the strip foundation with your own hands, the manufacture of a reinforcing cage
A universal strip foundation is most often used in private housing construction. He copes with all the loads. Therefore, it can be laid both under the house, and under office buildings. A key condition for structural strength is a properly made and installed reinforcing cage.
The reinforcement of the strip foundation must be approached from the position of the correct selection of the steel reinforcement itself. In terms of its diameter and the number of rods cut to a certain length. Therefore, it is very important at the design stage of the house to calculate the above indicators. Properly draw up a reinforcement diagram.
Proper reinforcement of the strip foundation is the right choice of reinforcement. So, you need to understand the assortment of this building material. The classification of reinforcement is several types and types that differ from each other in production technology and external structural data.
By type of production
- Hot rolled with marking "A";
- Cold-formed with the designation "VR";
- Rolled "K".
According to the shape of the picture
- With ring profile;
- Sickle;
- Combined.
So, when they make the frame for the strip foundation, use hot-rolled reinforcement with a sickle-shaped or combined profile. Of course, the quality of the foundation foundation for the home will largely depend on the number of bars in the reinforcing grill and the diameter of the selected reinforcement. Therefore, it is very important to correctly calculate the one and the other indicator.
Calculation of armokarkas
The rules for reinforcing the strip foundation are based on the assembly diagram of the frame structure. It is divided into three types of reinforcement laid in different planes.
Working reinforcement
These are reinforcing bars located along the trench. They are installed in several rows in height, the number of which depends on the depth of the foundation itself. The number of bars located in the horizontal plane depends on the width of the foundation trench. For example, if the depth of the foundation is 1 m, then when using reinforcement with a diameter of 8 to 14 mm, they are laid in 2 to 3 rows. As for the width, then with this indicator in half a meter two rows of reinforcing bars are installed.
Vertical
These are vertically mounted rods, which fasten together the rods of working reinforcement, due to which the main grid of the armature frame is obtained.
Transverse
These are segments of reinforcement that fasten together two or more grids installed in the formwork of the foundation tape. In fact, these are cross ties that ensure the joint work of reinforcing gratings.
There are certain norms for reinforcing monolithic strip foundations, in which the standards for dimensional indicators of reinforcement are defined.
- For transverse reinforcement, rods of at least 6 mm in diameter are used.
- Vertical rods are selected by diameter depending on the depth of the foundation structure. If the depth does not exceed 80 cm, then rods with a diameter of at least 6 mm are used. If the depth exceeds this indicator, then at least 8 mm.
- As for the bars of working reinforcement, a special calculation formula is used here:
D \u003d S x 0.001, where S is the cross-sectional area of \u200b\u200bthe foundation, and D is the total diameter of all the rods located in the longitudinal direction.
There is one condition. If the length of the working reinforcement does not exceed 3 m, then the minimum diameter for the reinforcement cage of the strip foundation will be 10 mm. If the length exceeds 3 m, then the minimum size is 12 mm.
- 4 rods of 8 mm reinforcement are 2.01 cm².
- 6 bars - this is 3.02 cm².
- 10 rods of 14 mm rods is 15.39 cm².
- The 12 - millimeter has the same quantity - 11.31 cm².
These indicators are in tables SNiPs and assortments of fittings. They are very convenient in terms of choosing exactly the quantity and diameter.
When assembling the reinforcement into the frame for the strip foundation, it is important not to forget that errors in reinforcement will necessarily lead to cracking of the foundation structure. Therefore, when assembling, you can not forget about the little things. For example, when two adjacent lattice frames are connected in the corners of trenches, it is necessary to take into account the amplification of their connection.
And these are additional clamps, wire and hooks, with the help of which not only the connection is made, with their help the armature frame construction itself is strengthened. But in the corners of the building, the foundation undergoes the greatest loads and discharges.
Video
Useful video about reinforcing a strip foundation.
Scheme
The strip foundation reinforcement scheme is the exact location in space of longitudinal, vertical and transverse rods assembled into one structure. To make it clear, consider the classic scheme as the simplest. Here it is shown in the photo below.
SNiP numbered 52 - 01 - 2003 clearly stipulates how the reinforcement is laid in the strip foundation, with which step in the transverse and longitudinal direction.
Here are a few items from this document.
- Stacking Step depends on the diameter of the reinforcement for the strip foundation, the size of the granules of crushed stone, the method of laying the concrete mortar and its compaction.
- Worker reinforcement step - this is a distance equal to two heights of the section of the reinforcing tape, but not more than 400 mm.
- Transverse reinforcement - this distance between the rods is not more than half the width of the section, but not more than 300 mm.
Pay attention to the photo again. The dimensions of the structure itself are not the dimensions of the foundation tape. The thing is that the frame should be located inside the foundation body, therefore, the same SNiP clearly states that the distance from the edges of the planes of the foundation tape to the reinforcement should not be less than 5 cm.
It is this dimensional indicator that is taken as the basiswhen the dimensions of the cross-section of the frame system are calculated. For example, if the width of the foundation is 50 cm, then the length of the transverse elements of the frame will be 40 cm. If the laying depth is 1 m, then the vertical bars are cut to a length of 90 cm. These are maximum lengths, they can be less.
According to the drawings of reinforcing the strip foundation, it is easy to designate the overall dimensions of the structure. But you need to correctly position the frame inside the trench and From the sides it will be seen how to position at what distance from the surface of the formwork. Harder with the bottom of the trench. Therefore, props are installed at the bottom with a height of 5-10 cm, on which the armature frame is laid.
Reinforcing corners of a strip foundation is a separate issue, because the corners are loaded the most. Therefore, reinforcement of the structure is carried out in various ways here. For example, additionally clamps made of reinforcement are laid in the horizontal plane, fastened with wire to the frame.
The second option is to release the rods of each structure located in separate adjacent trenches and bend them at right angles to bring them into adjacent trenches for fastening with the adjacent reinforcing cage. There are other ways.
rules
The technology of reinforcing the strip foundation is based on the accurate calculation of all structural elements, taking into account the diameter of the reinforcement and the scheme of its assembly. With the distances and the circuit sorted out, now you can go directly to the assembly process. The most difficult thing is if the task is to connect the reinforcement with clamps, which are used as the transverse fastening of reinforcing grids. Making clamps is not always easy, especially if they are of complex shape.
Thereforewho is going to do the reinforcement of the foundation with their own hands, it is recommended not to bend the reinforcing bars, but simply cut them to the required length, which corresponds to the distance between the grids. The reinforcing grids themselves are assembled on a flat platform, where they are cut to size and connected to each other with a knitting wire. As mentioned above, taking into account the installation step of steel reinforcement.
If the width of the trench allows, then the assembly can be carried out directly in place inside the formwork. For this:
- The distance from the surfaces of the formwork to the reinforced frame is set.
- At the junction of the trenches on the formwork, taking into account the distances, screws are screwed in or nails are hammered.
- Twine is drawn between them to show the location of the working reinforcement.
- Now, according to the stretched cords, vertical rods are driven into the ground (sand cushion), taking into account the installation step. In principle, there is no need to drive everything in, the main thing is that you need such an amount with which you can hold the bars of the working reinforcement. Therefore, they are driven in with a step equal to three or four design steps.
- Now at a distance of 5 - 10 cm from the bottom to the vertical rods are horizontal rods. It is very important that they are located exactly in the horizontal plane.
- Further, in exactly the same way, but only taking into account the delayed distance of 5 - 10 cm from the foundation surface, rods of working reinforcement are installed, which are fastened by wire to vertical rods.
- It remains only to lay between the gratings the transverse segments of the reinforcement and fasten them with knitting wire.
Here is such a simple guide (step-by-step instruction) of the strip foundation reinforcement scheme. With seeming simplicity, this is actually a laborious job that will take more than one day. It’s easier to assemble grids on the ground. Then install them in trenches and formwork on supports. Align vertically and secure with transverse rods.
True, if the side of the foundation is long, then the lattice will not be short. This means that it will weigh decently, so it will be difficult to raise and lower it in the opening between the formwork elements. It will take either a few helpers or lifting equipment.
Sole reinforcement
To increase the bearing capacity of the foundation tape, a sole is laid in its design by the project. In fact, this is an expanded strip foundation located under the main structure. It allows you to increase the area of \u200b\u200bthe base, which leads to lower loads on the ground. That is, the foundation is becoming more stable.
How to make reinforcement of the sole of the strip foundation is a question that worries many beginner builders. In principle, everything is the same here. The only thing is to reduce the distance between the frame element to 20 cm. In this case, the structure is mounted in the formwork under the sole, that is:
- Sole formwork is being assembled.
- A reinforcing cage is installed in it.
- The frame is mounted under the main structure, fastening it with a wire with a lower arm frame.
- The formwork is being assembled under the main tape.
Typically, this design is used for a buried foundation. To make it easy to work inside the trench, its width is made one meter larger. This is an increase in excavation, but there is no other way. After all, to install a metal structure to a great depth with the additional installation of wooden formwork requires scope. In this case, the assembly of the reinforcement cage is carried out outside the formwork. Inside, only the lower reinforcement is anchored to the upper.
Angles
It is necessary to approach the correct reinforcement of the corners of the strip foundation from the position of reinforcing the corners. It was already mentioned above that there are several methods (methods) by which the connection of two reinforcing structures in adjacent trenches is performed. Let's look at one of the easiest options, as an opportunity to do the reinforcement of the strip foundation with your own hands.
Is it necessary to reinforce the strip foundation in the corners in a special way? The answer is only positive. Look at the position “a” in the photo above, which shows the simplest diagram of a combination of two adjacent structures. It shows that the ends of the working reinforcement rods bent at 90 ° go into the adjacent formwork. There they are connected with rods of longitudinal elements.
An overlap is created in these places, which guarantees a high strength of the joint. At the same time, bent rebar rods themselves create high connecting strength of two adjacent concrete structures.
Tape reinforcement
The question of the need for reinforcing a shallow strip foundation (MLF) is often asked. To dot all the "i", we explain some points that are indicated in SNiP.
- If a one-story building is being built with a height of not more than 10 m with a reduced degree of responsibility on any soil. Reinforcing the foundation is not necessary.
- When constructing buildings above 10 m with a normal second level of responsibility. And these are residential and public buildings with several apartments. Reinforcement must be carried out. In this case, the pitch of the reinforcing rows is at least 20 cm.
In projects of constructions of light buildings, the method of reinforcing is often indicated in the form of laying one grid by the type of slab foundation. This is fundamentally wrong because in the center of the strip foundation (even slightly shallow) the loads are negligible. They are located at the edges of the tape.
That is why working reinforcement is the main in terms of bearing capacity. That is why the rods are located from the edges of the concrete structure at a distance of 5 - 10 cm, and not 30 or 40. They have the largest diameter in comparison with vertical and transverse elements.
Conclusion on the topic
So, understanding the topic of how to properly reinforce the strip foundation with your own hands, it becomes clear that this is not just reinforcement assembled in a lattice structure. This is a strict assembly diagram of reinforcing bars selected in diameter and length and laid with a certain pitch. That is, it is impossible to do armokarkas by eye. Everything in it should be in strict accordance with calculations and norms. In this case, it is very important to conduct a bunch, and not welding.
The question of whether it is necessary to reinforce the strip foundation, no one has asked for a long time. It is necessary to reinforce, taking into account the above calculations, nuances and assembly technologies. Do not forget to choose the right steel reinforcement itself.
In contact with
The strip foundation is the most popular in private construction. It is ideal for the construction of small houses, garages, baths and other outbuildings. All construction work can be done with your own hands, and the relatively small consumption of materials and the minimum amount of earthwork can reduce the price and production time. Of course, for everything to go as it should, you need to know how to properly reinforce the foundation.
Before telling how to properly reinforce the strip foundation, it is worth saying a few words about the choice of reinforcement.
- If you need to reinforce the base for a one-story or two-story house, as well as lighter buildings, you should take reinforcement with a diameter of 10-24 mm. Thicker material will cost too much, and its high strength will not be involved. Smaller reinforcement may not support the load.
- It is advisable to use special corrugated fittings. It provides the best connection with concrete, guaranteeing its high strength and reliability. A smooth analogue is slightly cheaper, but due to low adhesion it is not suitable for use. The only exception is lateral joints. The load on them is much less.
- If the soil is homogeneous over the entire area of \u200b\u200bthe foundation, then a material with a cross section of 10-14 millimeters can be used. With heterogeneous soil, the load on the base increases, so it is advisable to spend money on rods with a diameter of 16-24 mm.
Of course, buying thick corrugated reinforcement is a rather expensive pleasure. But if you decide to do the reinforcement of the strip foundation with your own hands, then the amount of work is not too large. So, you will have to overpay a maximum of several hundred rubles - this fully compensates for the high durability and reliability of the finished structure.
With the independent calculation and selection of reinforcement for the reinforcing cage of the strip foundation, the probability of error is high. In the future, it can cause the destruction of the house, so the best solution would be to order a project for reinforcing the foundation from the designer, and carry out the knitting of the frame on your own according to the drawing.
How many fittings do you need?
Before you go to the store to buy material, you need to find out how much it will be needed to reinforce the strip foundation. To do this, you should think in advance which scheme of reinforcing the strip foundation will be the best choice and carry out calculations for a specific object.
Base reinforcement example
In the construction of small houses, garages and baths, the following frame configuration is usually used:
- 2 belts: upper and lower;
- each belt consists of 3-4 reinforcement rods;
- the optimal distance between the rods is 10 centimeters. Please note that the distance from the reinforcement to the edges of the future foundation should be at least 5 centimeters;
- the connection of the belts is carried out using clamps or segments of reinforcement at a step of 5-30 centimeters, depending on the section of reinforcement.
Such a scheme is optimal. Now, knowing the dimensions of the future building, it is not at all difficult to carry out the corresponding calculations.
Suppose you want to build a spacious frame or wooden cottage with an area of \u200b\u200b150 square meters with external walls with a perimeter of 50 meters. We will carry out calculations based on this. When reinforcing the strip foundation of SNiP, we use the corresponding and described above characteristics.
We have two belts of three rods in each. Total - 6 times 50 \u003d 300 meters of the main reinforcement. We take into account the number of jumpers, which are stacked in increments of 30 centimeters. To do this, divide 50 meters by 0.3. We get 167 pieces. Cross bars in this base will have a length of 30 centimeters, and vertical - 60 centimeters. On the vertical jumpers you will need 167x0.6x2 \u003d 200.4 meters. On the horizontal - 167x0.3x2 \u003d 100.2 meters. In total, 300 meters of thick corrugated reinforcement and 300.6 meters of thinner, smooth reinforcement will be required. Having received these numbers, you can safely go to the store for material - the strip foundation will not last long without reinforcement. Some experts recommend taking reinforcement with a margin of 10-15%. After all, a certain amount of material will be needed to strengthen the angular parts of the strip foundation and go to the dock.
How to knit a frame?
The rules for reinforcing the strip foundation force us to abandon the use of welding in favor of knitting, since when using welding, in the places of welding joints, metal rods lose strength up to 2-2.5 times. In addition, it is here that corrosion most often appears, which can damage the fittings in a few years, significantly reducing the reliability and durability of the base. Only knitting is permissible. This is a rather difficult stage, for which an insufficiently experienced user will take a lot of time to complete. However, much here depends on what tool you will use.
Reliable knitting reinforcement wire
A classic tool for knitting reinforcement in a strip foundation is a special knitting hook. Using it, experienced craftsmen can issue up to 12-15 knots per minute (of course, if the knitting wire is prepared and cut in advance). The main advantage of this option is accessibility - a hook can be bought in many stores for a hundred rubles or even cheaper. Minus - the speed of working with it is not great even among masters. Note - you will have to make many hundreds of bindings even if you are reinforcing the foundations of a small size.
Wire and crochet hook
If you want to finish work as soon as possible, you can use a special knitting gun. Working with it, even an inexperienced user will easily give out 25-30 knots per minute. That is, productivity will increase at least 2 times. Alas, the cost of such equipment is not low - from 50 thousand and more. In addition, a special wire is needed to work with it - an ordinary one may not work. This further increases the cost. But if it is possible to rent a knitting gun for several hours or a day - feel free to agree to such an offer, just remember to find out the maximum diameter of the reinforcement that he can tie. Working with a high-quality tool, you will spend a maximum day on the assembly of the frame - the proper reinforcement of the strip foundation becomes much easier and faster. When working manually, this process can take a week or more.
How to make a frame?
Before proceeding with the reinforcement of the strip foundation, drawings of suitable frames should be studied. After all, it depends on the strength of the frame whether the base will serve for many decades or whether it will become cracked in the first spring due to seasonal fluctuations in the soil level.
In order not to be mistaken in the manufacture, it is necessary to remember several rules:
- The lap (the distance from the place of knitting to the edge of the rod) should be at least 5 centimeters.
- At the corner joints, the perpendicularly running rods should be interconnected - in no case should you use two separate blocks that are not interconnected. The perfect solution would be corners made of bent reinforcement - such a foundation reinforcement scheme is most reliable. But for this you need to have special equipment, if the reinforcement has a diameter of 14 or more millimeters, smaller diameters can be bent at home.
- The connections with the wire must be tight - if you use a crochet hook, tighten the wire all the way so that there is no free space between the clamp and the main reinforcement. Also check with your hand, if the clamp moves away from touching, make an additional tie with wire.
- The overlap during reinforcement should be equal to 40-50 diameters of the reinforcement. There should be a breakdown between adjacent docking rods, and the upper and lower layer, according to the design.
- The reinforcing carcass must be level in the formwork. It is also necessary to take care of the protective concrete layer for the reinforcement, to make according to the requirements of the drawing. It should be remembered that the minimum protective layer is equal to the diameter of the reinforcement.
Bending of all elements for reinforcing the foundation is performed on the cold. In no case does not heat the reinforcement, as this will lead to a loss of its strength.
As you can see, the rules are as simple as possible. But some inexperienced builders do not suspect or forget about their existence. This leads to the fact that the technology of reinforcing the strip foundation is violated and its service life is significantly reduced.
Earthwork and preparatory work
One of the advantages of the strip foundation is the relatively small amount of earthwork. A couple of people, working day with short breaks, will be able to dig a pit of a suitable size on normal soil without any problems. When the pit is ready, you can begin to equip it.
The first step is the manufacture of a foundation pillow. Thanks to it, the negative impact of groundwater on the foundation is reduced, and the load from the foundation itself and the entire structure is distributed as evenly as possible across the soil. Here you can use different materials. Most often sand or gravel is used. They do a good job of their function - the main thing is that the thickness of the pillow is at least 15-20 centimeters.
But some experts recommend a concrete pad. Yes, it is the most expensive. Costly cement and the need to reinforce pillows greatly increase the cost and construction time. But as a result, you get the most reliable foundation for the foundation, guaranteeing that it will last for many years. Therefore, we can confidently say that this money will not be thrown to the wind.
An example of a reinforced strip foundation device
If the work is carried out on weak, heaving soil, or if it is planned to build a heavy brick house, but the use of a monolithic foundation is undesirable for some reason, then you can use a strip foundation with a sole. The broadening (glass) can significantly reduce the load on the ground. Of course, do not forget about reinforcing the foundation glass - on heaving soils it will regularly withstand significant tensile and bending loads. It is very important to provide him with sufficient strength.
When using a foundation with a sole, the volume of earthwork increases. In addition, you will have to additionally spend on reinforcing the sole of the strip foundation - if it fails, this will lead to the early destruction of the entire structure.
Above the finished pillow, formwork is installed. When choosing the width, consider that the finished foundation should be 10-15 centimeters thicker than the external load-bearing walls.
The next step is waterproofing. Some builders use roofing material, but this is quite expensive material. And the heavy weight makes the styling process difficult. Therefore, it is quite possible to use building polyethylene. Yes, it is less durable. But you only need it for a few days - so that the cement milk does not go into the sand. Therefore, cheap and lightweight polyethylene is quite suitable. It is laid on top of the formwork. In the joints, overlap a little more - at least 10-15 centimeters - and glue with a wide adhesive tape.
This is where the preparatory work ends. Now let's talk about pouring and reinforcing the foundation with your own hands.
We install the frame, pour concrete
It is best to assemble the frame from the reinforcement directly in the prepared foundation pit - this allows you to fix the elements most firmly. But if we are talking about reinforcing a recessed strip foundation, or if the foundation pit is too narrow for work to be carried out directly in it, then you can assemble the frame from the outside over the trench, and then carefully lower it into place. There are usually no problems and step-by-step instructions are not needed.
The last and one of the most critical stages is the filling of the foundation.
Pouring the strip foundation with a concrete pump
It is advisable to use for this concrete grade M200 or higher. It has high strength to withstand significant loads, and also has a sufficient indicator of frost resistance.
It should be said right away that a large amount of material will be needed to work. Carry out all the necessary calculations in advance - you need to pour concrete in one go, avoiding delamination and other divisions. Otherwise, the strength of the base will decrease significantly, and this will affect the safety of the operation of the house. For the same reason, it is advisable to rent a concrete mixer. Today, many companies offer such a service. In addition, the rental of cheap models is relatively inexpensive - less than a thousand rubles a day. With intensive work during this time, it is quite possible to cope with the work. In addition, the presence of a concrete mixer allows you to increase productivity - you just need to toss sand, cement and pour water, soon getting the finished product, which you just need to pour on the frame installed in the formwork. Working with shovels, such performance cannot be achieved.
After pouring concrete, you must wait 28 days. During this time, concrete will gain sufficient strength and it will be possible to begin construction of a house, garage or bathhouse.
We recommend watching a video where an experienced civil engineer will tell you about the important nuances of reinforcing the foundation. What you should pay attention to when performing work in the first place, so that the foundation of the house is reliable.
Now you know how to reinforce the strip foundation with your own hands. To do this, it is not at all necessary to have highly specialized skills or to buy expensive equipment. It is enough to know, even in theory, how to reinforce the foundation. Experience will come into the process, and all tools can be replaced with cheap analogues or rented, saving money and time.
The foundation is the most vulnerable part of the structure. Due to the fact that the upper part of the building is subjected to compression stress, and the lower part is under tension, the correct laying of the foundation plays a big role. To perform the proper reinforcement of the strip foundation with your own hands, it is necessary to perform the calculation according to the scheme.
Such a basis, in fact, is a reinforced concrete strip passing along the outer part of the building and under the supporting walls inside.
When squeezed, concrete structures can withstand 50 times more than tensile. Both the upper and lower parts of the structure are overloaded, so it is necessary to reinforce both parts. Nothing almost exerts stress on the middle part. Metal fittings help solve these problems.
To ensure the strength, reliability, durability of the building, any base must be reinforced. After all, the foundation is subjected to various loads. This is the weight of the whole house, and various movements of the soil. The reinforcement of the strip foundation resembles a skeleton of a structure that is assembled from steel bars. In order to choose the necessary scheme for him, you need to understand what it is.
Reinforcement of the strip foundation can be easily done with your own hands, without involving specialists. It is important, first of all, to choose the right diameter of reinforcement
Reinforcing material
The choice of material is a rather important stage. Do-it-yourself steel rods of different sections are used to reinforce the strip foundation with their own hands. or fiberglass reinforcement. But most often they use metal.
The main horizontal reinforcement has a cross section of rods from 12 to 24 mm. Rods that will be located vertically, which are auxiliary. therefore usually cross section of vertical rods from 4 to 12 mm. Such a big difference is due to the spread in loads on the base and is directly dependent on the type of soil and the weight of the structure.
Auxiliary vertical rods are installed if the height of the foundation exceeds 15 cm. In this case, reinforcement with a section of 6-8 mm of class A1 is used. The frame is assembled from rods and clamps, cleaning them from rust. If necessary, the rods straighten and cut. As the connection of the rods using a knitting wire and a hook. Welding work can be performed if the marking “C” is present on the rods.
The choice of diameter is influenced by the number of horizontal levels and the pattern of reinforcing the strip foundation.
The calculation of the reinforcement of the strip foundation
The number of reinforcing elements must be calculated based on the size of the base. For foundations, the width of which is 40 cm, 4 longitudinal rods are enough - two at the top and bottom. To install a number of frames in a tape base measuring 6x6 m, an average of 24 m of reinforcement is needed. If you stack 4 rods, you will need 96 m of longitudinal rods.
For peppered and vertical reinforcement of the foundation, the width of which is 0.3 m and the height of 1.9 m for each fastening with an indent of 5 cm from the surface according to the concrete calculator, it is necessary (30-5-5) x2 + (190-5-5) x2 \u003d 400 cm or 4 m of reinforcing elements of a smooth form.
If the step of mounting the clamps is 0.5 m, the number of connections will be: 24 / 0.5 + 1 \u003d 49 pcs. So, based on the calculations, you will need 4x49 \u003d 196 m of transverse and vertical rods.
The total cross-sectional area of \u200b\u200bthe reinforcement and its weight, based on the diameter of the rods, can be calculated from the table:
Diameter of reinforcement, mm |
Estimated cross-sectional area, mm2, with the number of rods | Theoretical weight 1m of reinforcement length, kg | ||||||||
6 | 28,3 | 57 | 85 | 113 | 141 | 170 | 198 | 226 | 254 | 0,222 |
8 | 50,3 | 101 | 151 | 201 | 251 | 302 | 352 | 402 | 453 | 0,395 |
10 | 78,5 | 157 | 236 | 314 | 393 | 471 | 550 | 628 | 707 | 0,617 |
12 | 113,1 | 226 | 339 | 452 | 565 | 679 | 792 | 905 | 1018 | 0,888 |
14 | 153,9 | 308 | 462 | 616 | 769 | 923 | 1077 | 1231 | 1385 | 1,208 |
The minimum area of \u200b\u200bfoundation reinforcement is regulated by regulatory documents, and the strength of the foundation depends on this.
Which scheme is better to choose
There are two main reinforcement schemes that are most often used to strengthen the base for low-rise buildings:
- four rods;
- six rods.
In accordance with SNiP 52-101-2003, adjacent reinforcement bars should be located at a distance of 40 cm (400 mm) in the same row. The extreme longitudinal reinforcement should be at a distance of 5-7 cm (50-70 mm) from the side walls of the base. Therefore, if the width of the base is more than 50 cm, then it is better to use a reinforcement scheme with six rods.
Depending on this, the diameter of the steel rods is chosen.
Typically, for the tape base, “in a box” of rods is used. In this case, all the rods are mounted at an angle of 90 °. For longitudinal arrangement, reinforcing materials of class A3 are used, having a circular shape.
How to reinforce corners
The corners have a big load. Therefore, when reinforcing, care must be taken to strengthen them.
At This should take into account the following rules:
- the rod must be bent so that one of its sides is buried in one wall of the foundation, and the second in the other wall;
- if the rod is not long enough to bend, then to attach the rods to the corner, you can use the L-shaped profiles.
Most often, A3 class fittings are used for this.
How to do DIY reinforcement
To do this, you should take a square or rectangle as the basis.
Before installing the frame at the bottom of the trench, lay a sand cushion 1 m deep.
The frame is installed in this way:
- bricks are laid at the bottom of the trench, the height of which is 5 cm (in order to create a gap between the lower part of the base and the frame);
- to install the rack rods in advance it is necessary to make a sample in accordance with which the rods will be cut;
- rods of longitudinal form are laid on bricks;
- horizontal bridges with a length of slightly less than the thickness of the base (about 5 cm on each side) are tied to longitudinal rods with a pitch of 50 cm with a knitting wire;
- rods are attached to the corners of the formed cells vertically 10 cm less than the height of the base;
- the upper longitudinal bars are mounted to the vertical reinforcement;
- the upper transverse rods are tied to the obtained angles.
When reinforcing the strip foundation, it is necessary to adhere to the requirements of SNiP 52-01-2003
The main provisions of SNiP 52-01-2003
The main provisions of SNiP 52-01-2003 relate to the distance between the horizontal ribs of the steel frame and the diameter of the reinforcement. So, between longitudinal rods should not be less than 25 cm and more than 40 cm.
The cross section of the rods is selected according to the number of longitudinal rods. For a strip foundation, it should be at least 0.1% of the working cross section of the base. For example, if the height of the foundation is 1 m and the width is 0.5 m, the cross-sectional area should be approximately 500 mm2.
You can see more clearly about the minimum diameter of the reinforcement in the table of examples:
Armature Terms of Use | Minimum rebar diameter | Normative document |
Longitudinal working reinforcement along side 3 meters or less | 10 mm | |
Longitudinal working reinforcement along the side of more than 3 meters | 12 mm | Reinforcement of elements of monolithic reinforced concrete buildings |
Structural reinforcement | The cross section is 0.1% of the cross-sectional area along the height of the distance between the reinforcement layers and half the width of the tape | |
Transverse reinforcement (clamps) of compressed elements | At least ¼ of the largest diameter of the longitudinal reinforcement and at least 6 mm | |
Transverse reinforcement (clamps) of knitted flexible frames | not less than 6 mm | SP 52-101-2003 Concrete and reinforced concrete structures without prestressing reinforcement. |
Transverse reinforcement (clamps) of knitted frames with a section height of 80 cm and less | 6 mm | Guide to the construction of concrete and reinforced concrete structures of heavy concrete |
Clamps of knitted frames with a section height of more than 80 cm | 8 mm | Guide to the construction of concrete and reinforced concrete structures of heavy concrete |
Reinforcement of the strip foundation is easy to do with your own hands, it is enough to follow the technology and correctly perform the calculation. If it is difficult to do it yourself, it is better to resort to the help of professionals. After all, a reliable and solid foundation is the price and guarantee of the stability of the entire building.
For more information about reinforcing a strip foundation with your own hands, see the video:
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Reinforcing a strip foundation significantly increases its strength characteristics, allows you to create stable structures while reducing weight.
Strip foundation reinforcement
The calculations of reinforcement and reinforcement schemes are carried out in accordance with the provisions of the current SNiP 52-01-2003. The document has detailed calculation requirements, provides footnotes to regulatory documents and codes of practice.
SP 63.13330.2012 Concrete and reinforced concrete structures. The main provisions. Updated edition of SNiP 52-01-2003. File to download
SNiP 52-01-2003
The strip foundation must meet the requirements put forward for durability, reliability, resistance to various climatic factors and mechanical stresses.
Concrete requirements
The main strength characteristics of concrete structures is an indicator of resistance to axial compression (Rb, n), tensile (Rbt, n) and transverse kink. Depending on the normative standard indicators of concrete, its concrete brand and class are selected. In view of design responsibility, correction factors of reliability that range from 1.0 to 1.5 can be used.
Diagram of bending moments
Armature Requirements
During the reinforcement of strip foundations, the type and controlled values \u200b\u200bof the quality of the reinforcement are established. Standards allow the use of hot rolled constructional reinforcement of a periodic profile, heat-treated reinforcement or mechanically hardened reinforcement.
Building fittings
The reinforcement class is selected taking into account the guaranteed value of the yield strength at maximum loads. In addition to tensile characteristics, ductility, corrosion resistance, weldability, resistance to freezing temperatures, relaxation resistance and allowable elongation before the start of destructive processes are normalized.
Table of rebar classes and steel grades
Smooth profile | A1 (A240) | 6-40 | St3kp, St3ps, St3sp |
Periodic Profile | A2 (A300) | 10-40, 40-80 | St5sp, St5ps, 18G2S |
Periodic Profile | A3 (A400) | 6-40, 6-22 | 35GS, 35G2S, 32G2Rps |
Periodic Profile | A4 (A600) | 10-18 (6-8), 10-32 (36-40) | 80С, 20ХГ2Ц |
Periodic Profile | A5 (A800) | 10-32 (6-8), (36-40) | 23X2G2T |
Periodic Profile | A6 (A1000) | 10-22 | 22X2G2AYU, 22X2G2R |
The calculation of the strip foundation is carried out in accordance with the recommendations of GOST 27751, the indicators of ultimate loaded states by groups are calculated.
The first group includes conditions that lead to the complete unsuitability of the foundation, the second group includes conditions that lead to a partial loss of stability, which impede the normal and safe operation of buildings. According to the maximum permissible states of the second group are made:
- calculations for the appearance of primary cracks on the surface of the strip foundation;
- calculations for the time period of an increase in the cracks formed in concrete structures;
- calculations for linear strains of strip foundations.
The main indicators of resistance to deformation and the strength of building reinforcement include maximum tensile or compression strength, determined in laboratory conditions on special test benches. The technology and test methods are prescribed in state standards. In some cases, the manufacturer may use the regulatory and technical documentation developed by the enterprise. In this case, the normative and technical documentation must be approved by the regulatory authorities.
For concrete structures, these values \u200b\u200bmay be limited by maximum rates of change in the linearity of concrete. As generalized indicators, actual diagrams of the state of reinforcement with the short-term unilateral impact of the calculated standard loads are taken. The nature of the state diagrams of building reinforcement is established taking into account its specific type and brand. During the engineering calculation of the reinforced foundation, the state diagram is determined after replacing the normative indicators with actual ones.
Reinforcement Requirements
Reinforcing cage - photo
- Requirements for the dimensions of reinforced concrete structures. The geometric dimensions of the foundation should not impede the proper spatial placement of the reinforcement.
- The protective layer should provide joint resistance to the loads of reinforcement and concrete, protect against environmental influences and ensure the stability of the structure.
- The minimum distance between the individual bars of the reinforcement should guarantee its joint work with concrete, allow for proper joining and ensure the correct technological pouring of concrete.
The scheme of the tape reinforced foundation
For reinforcing, only high-quality reinforcement can be used; knitting of nets is carried out taking into account the calculated design indicators. Deviations from the values \u200b\u200bcannot go beyond the tolerance fields regulated by SNiP 3.03.01. Special construction measures must ensure reliable fixation of the reinforcing mesh in accordance with existing rules.
Reinforcing frame for strip foundations
SNiP 3.03.01-87. Bearing and enclosing structures. Building regulations. File to download
SNiP 3.03.01
During the bending of the reinforcement, special devices must be used, the minimum bending radius depends on the diameter and specific physical characteristics of the building reinforcement.
Video - Manual machine for bending reinforcement, video instruction
Video - How to bend reinforcement. Work on a homemade machine
The fittings are inserted into the formwork, the manufacture of formwork should be carried out taking into account the requirements of GOST 25781 and GOST 23478.
STEEL FORMS FOR PRODUCTION OF REINFORCED CONCRETE PRODUCTS. Technical conditions File to download
Formwork for the construction of monolithic concrete and reinforced concrete structures. Classification and General Specifications
Calculation of the number and diameter of reinforcement
For the strip foundation of baths, building reinforcement with a periodic profile of Ø 6 ÷ 12 mm is used.
Rebar fittings Ø 10 mm
Current state regulations regulate the minimum number of bars in concrete to give it maximum strength characteristics. The minimum total cross section of the longitudinal bars of the reinforcement may not be ≤ 0.1% of the cross-sectional area of \u200b\u200bthe foundation tape. For example, if the strip foundation has a cross section of 12,000 × 500 mm (the cross-sectional area is 600,000 mm2), then the total area of \u200b\u200ball longitudinal bars should be at least 600,000 × 0.01% \u003d 600 mm2. In practice, developers rarely maintain this indicator, taking into account the weight of the bath, the nature of the soil and a particular brand of concrete. This calculated value can be considered indicative; deviations from the recommended values \u200b\u200bshould not exceed ≈20% downwards.
The amount of reinforcement is calculated mathematically
To calculate the amount of reinforcement, you need to know the cross-sectional area of \u200b\u200bthe foundation tape and the cross-sectional area of \u200b\u200bthe reinforcing bar. To facilitate the calculation, we offer you a ready-made table.
Diameter mm | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
6 | 28,3 | 57 | 85 | 113 | 141 | 170 | 198 | 226 | 254 |
8 | 50,3 | 101 | 151 | 201 | 251 | 302 | 352 | 402 | 453 |
10 | 76,5 | 157 | 236 | 314 | 393 | 471 | 550 | 628 | 707 |
12 | 113 | 226 | 339 | 452 | 565 | 679 | 792 | 905 | 1018 |
14 | 154 | 308 | 462 | 616 | 769 | 923 | 1077 | 11231 | 1385 |
16 | 201 | 402 | 603 | 804 | 1005 | 1206 | 1407 | 1608 | 1810 |
18 | 254,5 | 509 | 763 | 1018 | 1272 | 1527 | 1781 | 2036 | 2290 |
20 | 314,2 | 628 | 942 | 1256 | 1571 | 1885 | 2199 | 2513 | 2828 |
Now the calculations are much easier. For example, to reinforce a strip foundation, you use eight rows of reinforcement with a diameter of 10 mm. According to the table, the total area of \u200b\u200bthe rods is 628 mm. Such a frame can work with concrete tape with a depth of 120 cm and a width of 50 cm. A few extra square millimeters can not be taken into account, they will be additional insurance in case of violation of knitting technology or the manufacture of low-quality concrete.
In addition to these indicators, you need to determine the diameters of the rods for the foundations. These indicators depend on many components, for simplified calculations, you can use the proposed table.
Permissible reinforcement diameters
Using this table, you can easily select the recommended diameter of the reinforcement for the strip foundation.
Rules for reinforcing a strip foundation
There are several schemes for knitting reinforcement, each developer can use the most convenient for himself. The choice of scheme must be carried out taking into account the size of the foundation and its bearing characteristics.
Reinforcement knitting patterns
The reinforcement can be knitted separately, and then the finished structural elements are lowered into the foundation trench and connected together, and you can immediately knit in the trench. Both methods are almost equivalent, but there is a slight difference. On earth, all the main rectilinear elements can be done independently, while working in a trench an assistant is required. For knitting, you need to make a special hook, the connection is made with a soft wire with a diameter of ≈0.5 mm.
Crochet reinforcement
Crochet reinforcement
In some articles you can find tips when using a hand-held electric drill during knitting - do not pay attention to them. So can write those who have no idea about work.
Hook drill
Firstly, from a drill the hand will get tired much more and faster than from a light hook. Secondly, cables will always get tangled underfoot, cling to the ends of fittings, etc. Thirdly, not all construction sites have electrical energy. And fourthly, your knots of wire will always be either short or torn.
For knitting reinforcement, thin soft and wire are used, and it has low strength. Pull the wire well, strong binding should occur in two or three turns of the hook. Otherwise, labor productivity decreases and fatigue increases. There are also options for welding reinforcement, we will talk about them in the next section of the article.
How to knit reinforcing mesh yourself
We already said above that in this way you can knit reinforcement on the ground. Only rectilinear sections of the mesh are made, the corners are tied after they are lowered into the trench.
Step 1. Prepare the pieces of reinforcement. The standard length of the bars is six meters; if possible, you do not need to touch them. If you are afraid that it will be difficult to work with such a dyne, cut them in half.
Rebar Cutting
We advise you to start knitting reinforcement for the shortest section of the strip foundation, this will provide an opportunity to gain little experience and already more confidently deal with long bars. Cutting them is not recommended, this increases the consumption of metal and reduces the strength of the foundation. We consider the dimensions of the blanks using the example of a strip foundation 120 cm high and 40 cm wide.
The fittings must be poured from all sides with concrete at least 5 centimeters thick. These are the baseline conditions. Given these indicators, the net dimensions of the reinforcing cage should be no more than 110 cm in height (minus 5 cm on each side) and 30 cm in width (minus 5 cm on each side). For knitting, you need to add two centimeters on each side to overlap. This means that blanks for horizontal jumpers should have a length of 34 cm, blanks for vertical jumpers should have a length of 144 cm. But you should not make such a high frame, it is enough to have a height of 80 cm.
How to knit fittings
Step 2 Choose a flat area, put two long rods, trim their ends.
Step 3 At a distance of ≈ 20 cm from the ends, tie horizontal struts on both extreme sides. For knitting you need a wire about 20 centimeters long. Fold it in half, push it under the binding site and tighten the wire by ordinary twisting of the crochet hook. Do not overdo it with effort, the wire may not withstand. The magnitude of the twisting efforts is determined empirically.
Step 3 At a distance of approximately 50 centimeters, tie in turn all the remaining horizontal struts. Everything is ready - set the structure aside for free space and make another frame element in the same way. You got the upper and lower parts, now you need to fasten them together.
Step 4 Next, you need to adjust the stops for the two parts of the grid, they can be rested against any object. The main thing is that the connected elements occupy a stable lateral position, the distance between them should be equal to the height of the knitted reinforcement.
Armokarkas knitting
Step 5 Tie two vertical struts along the ends, you already know the sizes. When the frame has become more or less resembling a finished product - tie all the other pieces. Do not rush, check all sizes. Although your workpieces are the same length, checking the size will not hurt.
Step 6 According to the same algorithm, you need to connect all the straight sections of the frame on the ground.
Step 7 Put at the bottom of the foundation trench lining with a height of at least five centimeters, the lower bars of the grid will lie on them. Put the side supports, put the net in the correct position.
Reinforcement (the frame is installed in the formwork)
Step 8 Take the dimensions of the untied corners and joints, prepare pieces of reinforcement to connect the frame into a single structure. Keep in mind that the overlap of the ends of the reinforcement must be at least fifty bar diameters.
Step 9 Tie the bottom turn, then the uprights and the top one to them. Check the reinforcement distance to all formwork surfaces.
Knitting reinforcement in the corners
Reinforcement is ready, you can start pouring concrete into the foundation.
Knitting reinforcement with a special tool
To make the fixture, you will need several boards approximately 20 mm thick, the quality of lumber can be arbitrary. It is not difficult to make a template, and it will simplify the work considerably.
Step 1. Cut four boards along the length of the reinforcement, connect them two at a step distance of the vertical posts. You should get two identical patterns. Carefully make sure that the marking of the distance between the rails is the same, otherwise there will be no vertical position of the connecting elements.
Step 2 Make two vertical supports, the height of the supports should correspond to the height of the reinforcing mesh. The supports should have lateral angular stops that prevent them from tipping over. All work on knitting should be carried out on a flat platform. Check the stability of the assembled device, exclude the possibility of it overturning during the work.
Step 3 Put the legs of the stops on two downed boards, install the two upper boards on the upper shelf of the stops. Lock their position in any way.
The scheme of knitting reinforcement using clamps
You’ve got a layout of the reinforcing mesh, now the work can be done quickly and without outside help. Install prepared vertical spacers of reinforcement on marked places, previously temporarily fix their position with nails. On each horizontal metal jumper, place a reinforcement bar. This operation should be repeated on all sides of the frame. Check their position again. That's right - grab the wire and the hook and start knitting. Adaptation is advisable to do if you have many identical sections of mesh reinforcement.
Video - How to knit reinforcement using a fixture
How to knit reinforced mesh in a trench
Working in a trench is much more difficult due to cramped conditions. It is necessary to think carefully over the knitting pattern of the individual elements so that then you do not have to crawl between the bars of the reinforcement. In addition, you cannot connect the grid yourself; you need to work with an assistant.
Step 1. Put stones or bricks at least five centimeters high at the bottom of the trench, they will lift the metal from the ground and allow the concrete to close the reinforcement from all sides. The distance between the stones should be equal to the width of the grid.
In the photo - a clamp for an armokarkas
Step 2 On the stones you need to put longitudinal bars. Horizontal and vertical rods should already be cut to size, as we have already described how to measure them.
Step 3. Begin to form the skeleton of the frame on one side of the foundation. If you previously tie horizontal braces to the lying rods, it will be easier to work. The assistant must hold the ends of the rods until they lock into position.
Reinforcement works
Step 4 Continue to knit the fittings in turn, the distance between the spacers should be approximately fifty centimeters.
Step 5 Using the same algorithm, tie the reinforcement in all the straight sections of the foundation tape.
Step 6 Check the dimensions and spatial position of the frame, if necessary, correct the position and exclude the touch of metal parts on the formwork.
Foundation reinforcement
Step 7 Now it's time to tackle the corners of the foundation. The picture shows a rather complicated version of knitting in the corners, you can think of for yourself easier. The main thing is that the length of the overlap is respected. And one more remark. In corners, the foundation works not only in bending, but also in vertical tearing. These efforts hold the vertical bars of building reinforcement, do not forget to install them. To guarantee this, fittings with a large diameter can be used.
Welding reinforcement for reinforcement
You need to know that any welding impairs the physical characteristics of the strength of the reinforcement, this method should be used only in extreme cases.
Welding reinforcement for reinforcement
If you still have to use welding, then do everything possible to put the minimum number of seams in one place, shift the step of fixing the horizontal and vertical stops by a few centimeters. During welding, accurately maintain the optimum current strength and electrode diameter. The metal in the joints should not overheat.
Welding fittings - photo
And most importantly, only special fittings are suitable for welding, brands of such fittings are indicated by the letter "C". By the way, this armature is much more expensive than ordinary.
Strip foundation reinforcement
There are several ways by which you can speed up and facilitate the knitting process and at the same time improve the quality of the structure and reduce the consumption of materials.
For struts, bend the reinforcement in the form of the letter "P". To do this, you can make an elementary machine in a couple of hours, and it will come in handy not only for bending bars. First you need to bend one sample, check its size and only then, using the sample as a template, prepare all the connections. Such struts are much easier to knit, they immediately hold the desired size of the structure. Another plus - reduced consumption of expensive material. At first glance, the savings seem inconsequential, with a maximum of ten centimeters per connection. But if you multiply ten centimeters by the number of pieces and the price of fittings, you get a very "nice" amount.
Homemade machine for bending fittings
Bent reinforcing mesh
For spacers, smaller diameter fittings and optionally expensive periodic construction profiles can be used. Even metal rods or wire rod of the appropriate diameter will do.
If you do not have any experience in carrying out such work, then it is better not to do it yourself. Having an assistant makes the process much easier and safer.
At a price, a reinforced foundation is much more expensive than an ordinary one, use this method of strengthening architectural structures in extreme cases. There are many cheaper ways to increase the bearing characteristics of a strip foundation. True, they can not always be used, it all depends on the design of the bathhouse, the characteristics of the soil and landscape.
A few words can be said about pre-loaded reinforcement. This is a complex method that can significantly improve all the performance of the strip foundation without increasing the number of fittings. The essence of the method consists in preloading the rods with forces opposite to those that will act on the structure during the operation of the foundation. For example, if the bar works in tension, then it is pre-compressed, etc.
Video - Reinforcement of monolithic shallow strip foundations
Video - DIY foundation reinforcement
The strip foundation is most common in the construction of private, low-rise houses. It is simple to execute, it does not require the involvement of special equipment, sophisticated equipment. All work can be done independently. The most important and difficult: to correctly reinforce the strip foundation with a width of 40 cm. What this is, how it affects the life of the building, we will consider in more detail below.
The strip foundation is the foundation of the building. The durability depends on its strength, the need for repair or additional strengthening. In order not to detect distortions in the walls in a year, two or five, not to watch how cracks “grow” under the windows, reinforcement should not be neglected. How to do it right, what requirements you need to comply with, this article will tell.
What is the reinforcement
Before proceeding with construction, it is necessary to familiarize yourself with the requirements of SNiP 2.03.01-84. It contains a direct indication that the strip foundation for a residential building cannot be without reinforcement. The width and height of the base and the building do not matter.
At the base there are two components:
- concrete. Resistant to compression loads. But with an increase in bending or tensile moment, the destruction of the strip foundation occurs;
- reinforcing cage. Reduces the load on the concrete mass under the influence of bending or tensile forces. It consists of longitudinal tiers connected in a single design by jumpers: transverse and vertical.
The number of tiers or belts directly depends on the height of the strip foundation:
- for shallow ones up to 1 meter high, 2 is enough;
- if the height exceeds 120 cm, an intermediate reinforcement belt is added.
Expert Opinion
Sergey Yurievich
Ask an expert a question
The width of the base is not taken into account. You can not look at her.
For longitudinal zones and jumpers, the optimal material is corrugated reinforcement with a diameter of 12-16 mm. Smooth, with a diameter of 8-10 mm, recommended only as jumpers, if a strip foundation is installed
Expert Opinion
Sergey Yurievich
Construction of houses, outbuildings, terraces and verandas.
Ask an expert a question
A special knitting wire with a diameter of 1-2 mm is used for dressing. Welding is not recommended: the metal heats up very much, and “weak” spots appear at the joints, which must be watched especially carefully during the pouring of concrete. If damaged, the reinforcement will not perform its function. At the same time, wire dressing is a complex and lengthy process that requires special skills. Welding is much faster.
Reinforcing frame configuration
When calculating the fittings, the requirements of SNiP 2.03.01-84 "Guide for the design of foundations for buildings and structures" must be taken into account:
- elements of the longitudinal frame of the tape base are located at a distance of 10 cm or less;
- between the tiers of the frame - 50 cm or less;
- transverse vertical jumpers are located at a distance of 30 cm or less;
- from the jumpers, the contour of the frame to the formwork - at least 5 cm. Otherwise, the concrete belt may be destroyed and the reinforcement may reach the surface of the strip foundation;
- the lower belt should not lie on the ground. If sand and gravel are not pre-filled, a single brick or special plastic supports are placed under the tier, depending on the state of the soil and its uniformity.
Calculation of reinforcement for reinforcing a strip foundation 40 cm wide
It is better to calculate the required volumes before starting work, so as not to stop, not to look for where to urgently buy a few bars or a coil of wire. In the above calculation, the conditional strip foundation with the following parameters was taken: height 70 cm, width 40 cm. Building perimeter - 50 meters.
Expert Opinion
Sergey Yurievich
Construction of houses, outbuildings, terraces and verandas.
Ask an expert a question
For a base 70 cm high, two reinforcing belts are sufficient.
There are 3 rods in each tier. For the connection, reinforcement with a diameter of 12 mm is used, the pitch is 30 cm.
Quantity calculations:
- for laying 3 rods in 2 tiers, 300 meters will be required;
- 167 jumpers are planned for the whole house, placed in 30 cm increments;
- for a vertical lintel, the length is 60 cm, for a transverse - 30 cm. For each joint, 2 vertical and 2 horizontal jumpers are required.
Total: vertical jumpers will have to purchase 200.4 meters of reinforcement, horizontal - 100.2 meters. In total, the building needs at least 600.6 meters of reinforcing bars with a diameter of 12 mm. This amount is not final. When placing an order, provide a margin for defective and reinforced corners. Consider also such parameters as the length and width of the facade, the number of meters in one rod. If possible, purchase pre-cut rods to the correct size to reduce waste.
How is reinforcement
For straight sections, it is important to choose whole rods. The fewer joints and joints, the stronger the strip foundation. When forming angles, overlapping of elements located perpendicularly is not allowed. The fittings must be bent with the letter “P” or “G”.
The assembly of the frame can be done both directly on the spot, in the pit, and beyond. The first may not be very convenient due to the small space. In the second case, it is important to strictly comply with all sizes so as not to subsequently deal with alterations of the frame for the strip foundation.
It is difficult, but possible, to bend the fittings at the right angles at home. To do this, you need a segment of the channel, in which the holes are cut out by the grinder strictly on the same line. An armature rod is placed in the grooves. A steel pipe is used on the long end, used as a lever. Bending requires a lot of effort, but allows you to do without buying a bending machine. The ligation of the rods is performed by wire.
Prepared for reinforcing rods are laid in a trench in accordance with the requirements described above after the installation of formwork. Tiers - strictly horizontal to the ground. At the next stage, when all belts are installed and bandaged, you can proceed to pouring concrete. It is important to ensure that the reinforcement remains in place and does not move. For a private low-rise building, the optimal concrete grade is M200. After exposure in accordance with the norms of building regulations, the strip foundation will gain strength and will be ready for further use. Concrete for 28 days should be closed with an opaque film, protected from direct sunlight and periodically moistened with water.
Expert Opinion
Sergey Yurievich
Construction of houses, outbuildings, terraces and verandas.
Ask an expert a question
To avoid problems associated with heaving of the soil, at least 10 cm each are poured into the trench to the bottom before reinforcing into the trench. Otherwise, the strip foundation will not withstand numerous freezing / thawing cycles.
Foundation foot reinforcement video
Reinforcement is a construction process that is used to enhance the structural stability and increase the period of its operation. It represents the formation of a prefabricated skeleton that acts as a protective component that resists the effects of soil on the walls of the structure.
To achieve maximum results, you should clearly calculate how much reinforcement is needed, as well as accurately conduct the reinforcement of the building foundation.
Proper reinforcement of the strip foundation with your own hands
At the base of the foundation, the concrete component formed from cement, sifted sand and clean water is the primary component. Since this solution does not have sufficient physical characteristics that can provide a guarantee for the absence of heterogeneous deformations in the foundation of the structure, metal is additionally used.
It allows you to increase the degree of resistance to base shifts, sudden changes in temperature and other negative factors. The metal itself is plastic, but it is able to provide a decent fixation, so reinforcement is an important and necessary process in the entire construction complex.
Reinforcement should be carried out only in places where there is a high degree of vulnerability to stretching. Most often it is found on the surface, so it is imperative to reinforce the upper level of the base. In order to avoid corrosion of the material, it should be protected with a layer of concrete mortar.
The permissible indicator of the distance of the reinforcing belt from the surface should be about 5 cm.
Zones of possible deformation:
- the lower part, when there is a deflection of its middle down;
- the upper part is the bending of the frame up.
Reinforcing is not necessary for an average base level, since there is practically no stretching in this zone.
Given the possible deformation options, it is imperative to reinforce the bottom and top using reinforcement with a ribbed surface and a diameter of 10–12 mm. In this embodiment, the closest contact with the concrete solution is observed. Other elements of the skeleton may be small in diameter and have a smooth surface.
If the foundation is reinforced with a width of up to 40 cm, 4 reinforcement rods with a diameter of 10–16 mm are used, which are connected in a frame with a diameter of 8 mm.
The tape type of the base of large length has a relatively small width, because of which only longitudinal stretchings without transverse ones can be present in it. Therefore, in this situation, it is best to use smooth and thin rods for forming the frame, and not for taking large loads onto the base.
Most attention should be paid when reinforcing corners, since in many cases deformations occur precisely in this part of the structure. Reinforcement of the corners of the structure must be carried out so that one of the ends of the bent metal goes into one wall, and the other into another. Since not every reinforcement material lends itself to welding, it is better to fasten elements together using a wire.
Rules for the correct reinforcement of the foundation of the tape type:
- Work begins with the establishment of formwork, which is covered on the inside with parchment. This procedure in the future allows you to quickly disassemble the created structure.
- Then reinforcing bars should be driven into the ground trenches at a distance of 5 cm from the formwork and in increments of 40-60 cm. The length of the rods should be equal to the depth of the foundation.
- A stand measuring 8–10 cm is placed at the bottom of the trench, and on top of it 2 or 3 threads of a number of reinforcement are formed. As a stand, you can use an ordinary brick laid on an edge.
- Upper and lower reinforcement belt with transverse joints attached to vertical rods.
- In places where the intersection of elements, it is necessary to carry out fastening by wire or welding.
Be sure to observe the distance to the future surface of the foundation, for this you can use bricks.
- Installing fittings, make ventilation holes and pour concrete.
The presence of ventilation holes and holes increases cushioning and prevents the occurrence of rot.
The ideal option is to use a scheme for a strip foundation, consisting of primitive geometric shapes, such as a square or rectangle, then the frame is easier to mount correctly, and the foundation as a result is more reliable and strong.
The main mistakes reinforcing the strip foundation
The most famous and often made mistakes:
- Angles. The main problem and mistake is to lay the angle rods crosswise. Due to such laying, cracks often appear in the foundation.
- Waterproofing material. When creating formwork, it is often forgotten about the use of waterproofing, as a result of which water leaches cement and makes concrete less stable and durable. It also contributes to the occurrence of shrinkage cracks. The waterproofing layer should be very well and carefully attached to the formwork in order to eliminate the formation of unwanted folds and depressions in the foundation.
- Pouring concrete. Filling the strip foundation with concrete mixture in height very often does not reach the edges, and topping up is carried out only after a couple of days. A technology of this type is no longer a monolithic structure, it is similar to two ordinary beams with single-layer reinforcement, which combines the bonding of concrete mix layers and transverse reinforcement. The pouring of concrete when creating the foundation should be continuous, and the maximum allowable interval for a break should be no more than two hours.
- Ventilation. A huge mistake is made during the installation and during operation of the products necessary for ventilation of the cold underground. They are made of pipes with a diameter of 10 cm. The smallest area required for ventilation should be about 0.05 m2 (approximately 20x25 cm).
It is forbidden to close vents for the winter, as this leads to a lack of ventilation and decay of the structure.
Why do we need reinforcement in the strip foundation?
Over time, any house has a drawdown, since the soil under the sole of the base lends itself to pressure from above and compacts. The more pressure they exert on it, the stronger and faster it condenses. If the resulting pressure is distributed evenly over the entire area of \u200b\u200bthe strip foundation, then there is no particular problem.
As a rule, in real conditions, the pressure on the base is not symmetrical due to which the building settles unevenly. To avoid a similar problem, tapes of various widths are used in the foundation, but even this technique does not always help to eliminate the equation of pressure on the foundation.
Uneven settlement of the foundation contributes to:
- Various inclusions of soil.
- Uneven and inconsistent humidity.
- Various extensions and extensions.
- Leakage of water-carrying communications.
- Absence of blind area on either side, etc.
Under the influence of the indicated causes of precipitation, the soil surface under the foundation becomes a curve relative to the vertical direction of the building. Most affected are structural angles and places with large differences in load.
In such a situation, internal stress arises in the foundation tape, which contributes to the appearance of bending moments and cracks. To eliminate unwanted pressure on the base, reduce the number of cracks and bends into the foundation add reinforcement.
What kind of reinforcement is needed for the foundation?
There are two options used in rebar construction:
- Steel, which is divided into:
- pivotal;
- wire.
- Composite fittings. It is used relatively rarely due to its disadvantages.
To reinforce the foundation of the tape type, use rod reinforcement as the main (working) material and smooth as an additional one.
The main property for working reinforcement is the ability to quickly and well adhere to concrete. A similar type of reinforcement is produced with a periodic profile, dividing it according to the strength indicators into classes.
According to GOST, which existed during the USSR period, class A-ура reinforcement or an analog of A400 (according to modern GOST) is used for a private type of construction. For transverse reinforcement, a smooth A-класса or A240 class rod (modern GOST) is used.
There is a difference between the fittings of the old and the modern sample in the form of an altered crescent-shaped profile; in other aspects, there are no differences.
To choose the right fittings for the foundation in the store, you just need to pay attention to the notation:
- Index C indicates that the reinforcing bar is welded;
- Index K indicates that the reinforcement is resistant to corrosion cracking processes that occur due to pressure on the foundation.
If these indexes are not on the package, it is better not to buy such a similar material.
Design requirements for strip foundations and their reinforcement
Due to the inability to accurately calculate the diameter for the strip foundation, special design requirements for its reinforcement were developed:
- At working rods must have a diameter of at least 12 mm.
- The number of longitudinal rods should be at least 4, and preferably 6.
- Longitudinal rods are interconnected into the spatial frame by knitting wire or welding.
- Step for transverse reinforcement should be 20-60 cm, and the diameter of the reinforcement 6-8 mm.
- Places with the highest possible rainfall, as well as T-shaped intersections require reinforced reinforcement with the help of reinforcing legs or vut with a diameter equal to that used for longitudinal rods.
- The thickness of the tape type of the baseIt is usually about 30 cm.
How much reinforcement is needed for the strip foundation?
For the foundation, reinforcement with a small diameter is used, for example, for low-rise construction, reinforcement with a diameter of 10-12 mm is used, somewhat less often - 14 mm.
Regardless of the height of the base, for reinforcing, you will need to make two belts of ribbed reinforcement of class A3 at a distance of 5 cm from the lower and upper parts of the foundation. Transverse and vertical rods can be made of a smooth type of reinforcement class A1.
For a foundation width of about 40 cm, it is enough to apply 4 longitudinal reinforcement rods, of which two are at the bottom and two at the top. If the width of the foundation is more than 40 cm or construction is carried out on moving soils, more rods should be used, approximately 3-4 for the upper and the same for the lower belt.
To calculate the amount of necessary reinforcement, there are two methods:
Self tallying
Example. The length of the foundation for a 6 by 10 m building with two walls will be 48 meters (6 + 10 + 6 + 10 + 6 + 10 \u003d 48 m).
If the width of the base is 60 cm, and the reinforcement consists of 6 longitudinal rods, then their length will be 288 meters (6 * 48 \u003d 248 m).
The step between the transverse and vertical rods is observed at 0.5 m, the width of the foundation is 60 cm, the height is 1.9 m, the spacing of the rods from the frame is 5 cm.
In this case, the length of smooth reinforcement with a diameter of 6 mm per connection is 640 cm or 6.4 m. ((60-5-5) * 2 + (190-5-5) * 3 \u003d 640 cm), and the connections will be 97 pieces (48 / 0.5 + 1 \u003d 97 pieces), they will require 620.8 meters of reinforcement (97 * 6.4 \u003d 620.8 m).
For each connection, 6 intersections are required for knitting reinforcement and approximately 12 parts of the knitting wire. One bundle requires 30 cm of wire. Based on these data, the total wire consumption will be 349.2 m (0.3 * 12 * 97 \u003d 349.2 m).
Use of reinforcement coefficient
For buildings with a small number of storeys, there is already an indicator of the amount of reinforcement, which is 80 kg / m3, already taken out by the builders.
Example. If the foundation needs 20 m3 of concrete mortar, then reinforcement will need 20 * 80 \u003d 1600 kg. Counting concrete is easy, you just need to know the perimeter of the house, the length of the internal walls, set the tape height to 30 cm and multiply it by width.
To make the calculation more economical, it is best to make a more accurate calculation of the required amount of reinforcement by drawing a reinforcement diagram. And then, after calculating the moldings for longitudinal and transverse reinforcement, VUT, and also adding about 10% of this, which will go to trim, multiply the result by the weight of a running meter for each of the diameters of the reinforcement used.
Strip foundation reinforcement - knit or cook?
Metal rods can be joined together in a frame by knitting or welding. Each option has its positive and negative qualities.
The main disadvantage of welding is the lack of the ability to make a high-quality transverse connection using a hand electrode. In factories, frames and grids are connected using a contact rather than an arc type of welding.
In this regard, very often there are insufficiently strong joints (lack of penetration) or a weakening of the longitudinal rod (undercut). Another big disadvantage of welding is that not all materials can be welded, for example, reinforcement class A3 is made of steel grade 35GS, which is not welded.
The strip foundation is one of the most common types of foundations for the home. In the process of its construction, great importance is given to reinforcing the formwork. Reinforcement allows to increase the strength of the base and its resistance to stretching. This article will help to understand and understand what kind of reinforcement is needed for the strip foundation and what details are paid attention to, so that it will last for many years.
After choosing the type of foundation, many are concerned about the question of what concrete should be, its composition and optimal proportions in order to produce a high-quality foundation pouring. The builder should also pay attention to:
- the number of floors of the future home;
- building weight;
- soil type;
- groundwater level and soil freezing.
Great importance is given to the quality of concrete mortar. Any brand of concrete consists of four components:
- Cement. The main component of concrete, which is best purchased in trusted construction stores. Cement has a shelf life, so buying it in reserve is not recommended. For pouring the strip foundation, cement or portlet cement of the M400 brand is often chosen.
- Sand. Experts recommend the use of sand, which contains both large and small particles. It is best to choose river sand with a small admixture of quarry. The sand fraction for the foundation is 2 - 2.5 mm.
- Crushed stone. In the construction of small buildings using granite crushed stone of medium fraction from 20 to 40 mm.
- Water. Use clean drinking water. High salt and sulphate water will reduce the quality of the concrete.
If there is a need to increase the properties of concrete, plasticizers are often added. Such chemical additives can affect the hardening, strength and fluidity of the mass. The ratio of plasticizers in concrete mortar is 0.2-0.3%.
Armature Requirements
To understand the importance of installing reinforcement, you need to understand what reinforcement is.
It is designed to increase the strength and reliability of the foundation. During operation, the base is subjected to loads:
- from the building itself;
- when moving soils;
- from frost heave.
Base reinforcement
From these loads, the upper part of the base is under compression and the lower one is in tension. Just in these parts, builders always fix the reinforcement, which takes part of these loads. When choosing reinforcement for the foundation, pay attention to:
- diameter of rods;
- resistance to corrosion;
- the need for welding;
- resistance to freezing temperatures.
Specialized stores offer reinforcing bars with a diameter of 5 to 32 mm with a ribbed and regular smooth surface.
Ribbed ones create better adhesion to concrete, therefore they are used as the main elements. Smooth reinforcement acts as an additional element and is installed on zones not subject to stretching.
To reinforce the foundation, ribbed reinforcement with a diameter of 8-16 mm and smooth 6 mm are needed.
In the construction of the foundation, ribbed reinforcement of class A3 (A400) is most often used. When buying, you can see different labeling of elements. The letter “K” in the marking means that the rods are coated with a special anti-corrosion compound, and the letter “C” means that the rods can be welded.
To reinforce the foundation, ribbed reinforcement with a diameter of 8-16 mm is needed
Reinforcement Requirements
In order to carry out high-quality and reliable foundation reinforcement, it is necessary to adhere to some rules:
- Make the purchase of rods in specialized stores that can provide quality certificates for products.
- Interlocked rods should not be deformed during pouring with concrete.
- To connect reinforcing elements, it is better to use the manual knitting method instead of welding the rods.
- In addition, the construction documents and standards for reinforced concrete structures describe the permissible distances between reinforcing bars:
- no more than 40 cm for longitudinal rods;
- no more than 30 cm for transverse rods;
- not less than 25 cm for elements located vertically.
According to experts, the diameter of the reinforcement for the strip foundation should be:
- for light houses on stable soil, a diameter of 8 mm is suitable;
- for loose and heaving soils and heavy buildings from 12 mm.
Foundation reinforcement requirements
Calculation of the number and diameter of reinforcement
During the calculation of the required diameter of the reinforcement, an indicator of the width and depth of the strip foundation is used. If the width of the foundation reaches 50 cm, and its depth is 100 cm, then the cross-sectional area of \u200b\u200bthe foundation tape will be:
- 50 cm X 100 cm \u003d 5000 cm2.
According to regulatory documents, the cross-sectional area of \u200b\u200bthe reinforcement should be no less than 0.01% of the base, which means:
- 5000 cm2 X 0.01% \u003d 5 cm2.
The result obtained is found in a special table for calculating the diameter of reinforcing bars. It turns out that for the foundation of a house with such a width and depth, you can use:
- 6 rods with a diameter of 10 mm;
- 8 rods with a diameter of 9 mm;
- 3 rods with a diameter of 14 mm.
- It is worth considering that if the length of the foundation is more than 3 meters, then 12 mm is the minimum permissible diameter for use.
The calculation of the amount of reinforcement is carried out independently, depending on the reinforcement scheme.
Calculation of the number and diameter of reinforcement
Some reinforce the base with four rods, others use six. Reinforcing corners also differs. Someone makes them with L-shaped clamps, possibly also U-shaped schemes and various variations.
To find out the number of longitudinal elements, when calculating, they calculate the perimeter of the house, add to it the indicators of the walls, which are placed above the foundation tapes. The resulting number is multiplied by the planned number of longitudinal rods located on the same tape width.
Reinforcing bars differ not only in class and appearance, they also differ in their purpose:
Working longitudinal (horizontal)
Rods that are located along the base and take on the main load from the factors of compression and tension. To increase the strength of the foundation they are installed in the lower and upper part of the tape. The diameter of the lower reinforcement elements must be larger than the diameter of the upper rods.
Cross mounting
It is installed to link together the individual upper or lower working rods. It ensures the integrity of the working elements and distributes the load between them.
Scheme of typical reinforcement of a strip foundation
Vertical
It is mounted vertically and connects the upper and lower longitudinal reinforcement. Proper reinforcement of the strip foundation uses all of these types of rods. Only together will they ensure the integrity of the reinforcing structure and evenly distribute the load.
How to reinforce the foundation?
The distance between the rods and the foundation surface should be 5 cm. Horizontal rods take the main load, the transverse ones only connect the frame into a single whole. The bottom layer of rods is settled on special stands.
Great importance is given to reinforcing corners. In these places, the rods do not just connect, but use separate curved L-or U-shaped clamps for this. At the corners, the rods are installed more often and denser than at the base.
The reinforcement of the pile and strip foundation is no different from the reinforcement of a conventional strip foundation.
The main mistakes in reinforcing the foundation
- reinforcing corners not with clamps, but with the usual intersection of rods;
- the location of the rods in the middle of the foundation;
Vertical foundation reinforcement
- when only two bent rods are in the corners of the foundation;
- uneven arrangement of reinforcement throughout the base.
How to knit reinforcing mesh yourself
Before starting work, it is better to become familiar with. A knitting wire and a hook are acquired for this process. Such a wire bends well, and its average diameter reaches 1.2-1.3 mm. The hook can be purchased at a hardware store or made by yourself. For knitting, rods 5-6 meters long are used. The knitting technology for all foundations is the same, and if the diameter of the rods is more than 25 mm, then the rods are connected by welding.
Knitting reinforcement can be done in a convenient place for work, then place it in the formwork, and then install the clamps at the corners of the base. To make knitting more convenient, do not use too long pieces of wire. Bite off 20 cm of the metal thread and fold it in half. The overlap of reinforcing bars during binding reaches 2 cm.
Knitting reinforcement with a special tool
In addition to conventional hooks, the construction market offers many additional accessories and tools to not only speed up the process of knitting reinforcement, but to do it reliably and firmly:
Significantly reduces the time spent on binding rods. Additional spending on the tool will be required, but it will provide a more reliable tightening of the wire. In the gun, the wire is in a special drum that is easy to replace. However, it has a weight of 2-3 kg and not all builders are comfortable working with it.
The gun for knitting of KW-0041 fittings
Semi-automatic and automatic hook for knitting reinforcement
Specialized tools that significantly reduce assembly time. Knitting rods can be done using conventional pliers. Some builders use a screwdriver at home to insert a bent nail into.
Reinforcement knitting is an important step in pouring the strip foundation and it is better not to save on quality tools.
How to knit reinforced mesh in a trench
It’s more difficult to knit a reinforcing cage in a trench than in a free territory. It is better to think over the connection diagram of the elements in advance so as not to waste time on reworking the work in the future. Obtain fixtures for fittings in a specialized store. They will place the grid above the formwork and ensure uniform application of concrete mortar to the entire reinforcement.
One person will not be able to work in the trench; with such work, an assistant is needed. In the beginning, vertical rods are driven into the trench, horizontal working fittings are attached to them. In the end, they begin to strengthen the corners of the base.
Welding reinforcement for reinforcement
Welding reinforcement for reinforcement
Welding of reinforcing elements is faster compared to knitting rods, however, it significantly reduces the strength of the metal frame. After welding, the rods become more fragile, which affects the quality of the tape base. If a heavy building with several floors is being erected, and the area has problem soil, it is better to abandon this method of connecting reinforcing bars.
To weld fittings, it is necessary to purchase special rods of class A500 and additional marking "C". Welding reinforcement can occur in various ways:
- contact;
- bathrooms
- butt;
- contact point.
- If the reinforcement is welded by contact, it is very important to control the current strength on which the quality of the seam depends.
Stacked on the mortar between the brickwork. The work process starts from the bottom. Particular attention is paid to door and window openings, as cracks often occur in them. The individual elements of the reinforcement can be connected with knitting wire.
"How to reinforce aerated concrete blocks?"
Produce reinforcing mesh. To position the reinforcement, groove the blocks in the blocks with a cutter. Ditches are cleaned of debris and stack fittings knitted with a special hook. After laying the reinforcement, the grooves are poured with cement mortar.
Correct angular reinforcement should protect the foundation from cracks and provide resistance of the base to tensile and compression forces. The rigidity of the connection is provided both by the method of knitting and by welding. High-quality durability to the angular basis is created by P- and G-shaped collars.
Proper reinforcement of the foundation can increase the strength of your building by 245%, increase its resistance to mechanical stress by more than 150%, eliminate possible subsidence and reduce brittle edges. Do you still consider reinforcement bonding a waste of money?
Important rules for knitting reinforcement and basic SNiP
Before you begin to embroider your future foundation with reinforcement or wire, you need to roughly calculate the load on it to determine which rod you will need. You do not need to know exactly, as they always take with a margin. For example, when constructing temporary metal structures with wall weights up to 400 kg / 1 m 2, reinforcement with a diameter of 8 millimeters can be used. When building a garage from cinder block with walls up to 3 meters in height, a rod with a cross section of 12 millimeters is used. If you are building a two-story cottage, then you will have to embroider it with more serious metal - a diameter of 14-18 millimeters.
Of course, you can give this project for calculations to experienced professionals who will save money and select the minimum acceptable value, but if several thousand rubles do not play a big role, take it with a margin. Often there is a desire to complete a floor with an attic or to make a multi-level heavy roof - the foundation must be ready for such a “turn of events”. There are several SNiPs that regulate the manufacture of this design. Let's consider them in more detail.
- SNiP 7.3.4 states that the minimum distance between two vertical rods must be at leastthan the cross section of the gain itself, or better, 2-3 times larger. The maximum value is not indicated, since it is already selected individually for each project, it depends on the laying method, the presence of a sealant, cement grade, aggregate quality and other factors.
- SNiP 7.3.6. The distance between two parallel longitudinal rods should be no more than 40 centimeters. The greater the load on the base, the less this distance will be. The minimum distance for the strip foundation is 10 centimeters with a reinforcement diameter of 14 mm.
- SNiP 7.3.7 regulates the pitch of the transverse reinforcement. A value of not more than half the working height of the section should be taken, but in no case should it exceed 30 centimeters.
Adhering to these Construction Norms and Regulations, reinforcement at you will turn out according to "book norms". But there are several rules that were specially developed by builders to facilitate the process of establishing the foundation. These recommendations are time-tested and will significantly improve the physical and mechanical properties of your structure, as well as save a little on the purchase of materials.
- Do not weld together reinforcement. Heating a metal significantly impairs its properties.but strong joints are generally useless there - they are held by concrete, not metal, which you will build up for hours.
- The fittings undergo corrosion, so you need to deepen it from all sides into concrete, so that it lasts for decades. On the sides, the metal should "go" into concrete by 8 centimeters at least, from below by 10, from above by 10.
- You can’t cross-connect at the corners, the rods should not intersect perpendicularly, it is better to take and bend the metal of the required shape so that the next joint is no closer than 100 centimeters from the corner. The biggest load always falls on them, and the connection on a short section of the site will not give the desired strength.
- Angles must be further strengthened by crossbars and verticals. Very often people simply do the cross-stitching, believing that the mass will rely, for some reason, precisely on the core itself. But such a knitting of reinforcement for the base is simply unacceptable, because you will get 2 separate blocks that will not have any connection with each other. The sense of this action is exactly 0.0%. U-shaped and G-shaped amplifications are needed at the corners and at the first cross-pieces from them.
We examined the basic rules of how to make high-quality reinforcement of the foundation, the scheme to which is located below. Now you can proceed to the phased construction of this design and disassemble all the nuances in more detail.
Step-by-step instructions on how to make a reinforcing cage for the foundation with your own hands
The preparation of the pit and the lay-out is a responsible process. Reinforcement plays one of the most important roles here. In order to do everything correctly, the design was the most durable and connected, it is necessary to perform everything according to the following instructions.
\u003e Step 1:We expose the formwork.
Before knitting reinforcement for the foundation, you need to prepare a place for it. First, we dig out a hole of the required size, mainly 40 centimeters wide (for home) and a depth of 90 centimeters, depending on the weight of the future structure and soil characteristics. Next, we install wooden bars 50x50 mm at the corners, to which we nail the longitudinal boards. We raise the foundation and translate it smoothly into the base.
Important: even if you have an almost flat pit below ground level, you still need to expose the formwork from the boards, and from even planks. This is done so that the reinforcing elements are at the same distance from the outside of the concrete - this is an important point that must be taken into account. The formwork is fixed on the outside with earth or sand and water, and on the inside with wooden spacers (the length should be the same).
\u003e Step 2:We install vertical supports for metal frames.
First of all, you need to set the verticals to which horizontal reinforcing belts will be tied, and then the crossbars. Assume that the foundation will have 4 angles - the simplest construction. Then in each corner you need to retreat 6 centimeters from the inner and outer walls, after which mark the place and hammer the rod, align it with a plumb line.
\u003e Step 3:We fasten the horizontal frame.
As a rule, these are 2 parallel lines, which are wound with an ordinary knitting wire. Important: you can not weld them to the verticals and crossbars, since high temperature will significantly impair their physical and mechanical properties.
\u003e Step 4:We fasten the crossbars.
This can be done manually or with the help of special knitting guns, which will greatly simplify the work. The step of the crossbars should be at least 40 centimeters, best of all - 60-65 cm. Remember that a very thick mesh is not a guarantee of high strength. We only need to give concrete flexibility and eliminate the risks of subsidence.
\u003e Step 5:We strengthen.
First of all, we strengthen the corners with L-shaped and U-shaped elements, we make oblique struts between the lower harness and the upper parallel elements. The sides can be supplemented with oblique between the parallels, set longitudinal branches from the top corner of one edge to the bottom from the other edge.
Pour concrete onto the frame
We just figured out how to reinforce the foundation, now we will consider how to properly pour concrete so as not to violate the integrity and increase the strength of the structure. The first step is to make a good foundation. To do this, under the first strapping belt, pour 5 centimeters of broken brick or cinder block. Next, fill with a liquid solution, so that it penetrates well into all the cracks, provides the maximum strength of the sole.